pullRequestModel.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as buffer from 'buffer';
import * as path from 'path';
import equals from 'fast-deep-equal';
import gql from 'graphql-tag';
import * as vscode from 'vscode';
import { OctokitCommon } from './common';
import { ConflictResolutionModel } from './conflictResolutionModel';
import { CredentialStore } from './credentials';
import { showEmptyCommitWebview } from './emptyCommitWebview';
import { FolderRepositoryManager } from './folderRepositoryManager';
import { GitHubRepository } from './githubRepository';
import {
	AddCommentResponse,
	AddReactionResponse,
	AddReviewRequestResponse as AddReviewsResponse,
	AddReviewThreadResponse,
	ConvertPullRequestToDraftResponse,
	DeleteReactionResponse,
	DeleteReviewResponse,
	DequeuePullRequestResponse,
	EditCommentResponse,
	EnqueuePullRequestResponse,
	FileContentResponse,
	GetReviewRequestsResponse,
	MergeMethod as GraphQLMergeMethod,
	LatestReviewCommitResponse,
	MarkPullRequestReadyForReviewResponse,
	MergePullRequestInput,
	MergePullRequestResponse,
	PendingReviewIdResponse,
	PullRequestCommentsResponse,
	PullRequestFilesResponse,
	PullRequestMergabilityResponse,
	ReactionGroup,
	ResolveReviewThreadResponse,
	ReviewThread,
	StartReviewResponse,
	SubmitReviewResponse,
	TimelineEventsResponse,
	UnresolveReviewThreadResponse,
	UpdateIssueResponse,
	UpdatePullRequestBranchResponse,
} from './graphql';
import {
	AccountType,
	ConvertToDraft,
	GithubItemStateEnum,
	IAccount,
	IGitTreeItem,
	IRawFileChange,
	IRawFileContent,
	IssueReference,
	ISuggestedReviewer,
	ITeam,
	MergeMethod,
	MergeQueueEntry,
	PullRequest,
	PullRequestChecks,
	PullRequestMergeability,
	PullRequestReviewRequirement,
	ReadyForReview,
	ReviewEventEnum,
} from './interface';
import { IssueChangeEvent, IssueModel } from './issueModel';
import { compareCommits, getErrorCode, GraphQLError, GraphQLErrorType } from './loggingOctokit';
import { openIssueOrPullRequestOnGitHub } from './openOnGitHub';
import {
	convertRESTPullRequestToRawPullRequest,
	convertRESTReviewEvent,
	getReactionGroup,
	insertNewCommitsSinceReview,
	parseAccount,
	parseCombinedTimelineEvents,
	parseGraphQLComment,
	parseGraphQLReaction,
	parseGraphQLReviewers,
	parseGraphQLReviewEvent,
	parseGraphQLReviewThread,
	parseMergeability,
	parseMergeQueueEntry,
	RestAccount,
	restPaginate,
} from './utils';
import { Change, Repository } from '../api/api';
import { Status } from '../api/api1';
import { COPILOT_ACCOUNTS, DiffSide, IComment, IReviewThread, SubjectType, ViewedState } from '../common/comment';
import { getGitChangeType, getModifiedContentFromDiffHunk, parseDiff } from '../common/diffHunk';
import { commands } from '../common/executeCommands';
import { GitChangeType, InMemFileChange, SlimFileChange } from '../common/file';
import { GitHubRef } from '../common/githubRef';
import Logger from '../common/logger';
import { Remote } from '../common/remote';
import { DEFAULT_MERGE_METHOD, PR_SETTINGS_NAMESPACE } from '../common/settingKeys';
import { ITelemetry } from '../common/telemetry';
import { ClosedEvent, EventType, ReviewEvent, ReviewResolveInfo, TimelineEvent } from '../common/timelineEvent';
import { resolvePath, Schemes, toGitHubCommitUri, toPRUri, toReviewUri } from '../common/uri';
import { formatError, isDescendant } from '../common/utils';
import { InMemFileChangeModel, RemoteFileChangeModel } from '../view/fileChangeModel';

interface IPullRequestModel {
	head: GitHubRef | null;
}

export interface IResolvedPullRequestModel extends IPullRequestModel {
	head: GitHubRef;
}

export interface ReviewThreadChangeEvent {
	added: IReviewThread[];
	changed: IReviewThread[];
	removed: IReviewThread[];
}

export interface FileViewedStateChangeEvent {
	changed: {
		fileName: string;
		viewed: ViewedState;
	}[];
}

export type FileViewedState = { [key: string]: ViewedState };

type TreeDataMode = '100644' | '100755' | '120000';

const BATCH_SIZE = 50;

export class PullRequestModel extends IssueModel<PullRequest> implements IPullRequestModel {
	static override ID = 'PullRequestModel';

	public isDraft?: boolean;
	public reviewers?: (IAccount | ITeam)[];
	public localBranchName?: string;
	public mergeBase?: string;
	public mergeQueueEntry?: MergeQueueEntry;
	public conflicts?: string[];
	public suggestedReviewers?: ISuggestedReviewer[];
	public hasChangesSinceLastReview?: boolean;
	public closingIssues: IssueReference[] = [];
	private _showChangesSinceReview: boolean;
	private _hasPendingReview: boolean = false;
	private _onDidChangePendingReviewState: vscode.EventEmitter<boolean> = this._register(new vscode.EventEmitter<boolean>());
	public onDidChangePendingReviewState = this._onDidChangePendingReviewState.event;

	private _reviewThreadsCache: IReviewThread[] | undefined;
	private _reviewThreadsCacheInitialized = false;
	private _onDidChangeReviewThreads = this._register(new vscode.EventEmitter<ReviewThreadChangeEvent>());
	public onDidChangeReviewThreads = this._onDidChangeReviewThreads.event;

	private _fileChangeViewedState: FileViewedState = {};
	private _viewedFiles: Set<string> = new Set();
	private _unviewedFiles: Set<string> = new Set();
	private _onDidChangeFileViewedState = this._register(new vscode.EventEmitter<FileViewedStateChangeEvent>());
	public onDidChangeFileViewedState = this._onDidChangeFileViewedState.event;

	private _onDidChangeChangesSinceReview = this._register(new vscode.EventEmitter<void>());
	public onDidChangeChangesSinceReview = this._onDidChangeChangesSinceReview.event;

	private _hasComments: boolean;
	private _comments: readonly IComment[] | undefined;

	// Whether the pull request is currently checked out locally
	private _isActive: boolean;
	public get isActive(): boolean {
		return this._isActive;
	}
	public set isActive(isActive: boolean) {
		this._isActive = isActive;
	}


	constructor(
		private readonly credentialStore: CredentialStore,
		telemetry: ITelemetry,
		githubRepository: GitHubRepository,
		remote: Remote,
		item: PullRequest,
		isActive?: boolean,
	) {
		super(telemetry, githubRepository, remote, item, true);

		this.isActive = !!isActive;

		this._showChangesSinceReview = false;

		this.update(item);
	}

	public clear() {
		this.comments = [];
		this._reviewThreadsCacheInitialized = false;
		this._reviewThreadsCache = undefined;
	}

	public async initializeReviewThreadCache(): Promise<IReviewThread[]> {
		const threads = await this.getReviewThreads();
		this._reviewThreadsCacheInitialized = true;
		return threads;
	}

	public get reviewThreadsCache(): IReviewThread[] {
		return this._reviewThreadsCache ?? [];
	}

	public get reviewThreadsCacheReady(): boolean {
		return this._reviewThreadsCacheInitialized;
	}

	public get hasPendingReview(): boolean {
		return this._hasPendingReview;
	}

	public set hasPendingReview(hasPendingReview: boolean) {
		if (this._hasPendingReview !== hasPendingReview) {
			this._hasPendingReview = hasPendingReview;
			this._onDidChangePendingReviewState.fire(this._hasPendingReview);
		}
	}

	public get showChangesSinceReview() {
		return this._showChangesSinceReview;
	}

	public set showChangesSinceReview(isChangesSinceReview: boolean) {
		if (this._showChangesSinceReview !== isChangesSinceReview) {
			this._showChangesSinceReview = isChangesSinceReview;
			this._fileChanges.clear();
			this._onDidChangeChangesSinceReview.fire();
		}
	}

	get comments(): readonly IComment[] {
		return this._comments ?? [];
	}

	set comments(comments: readonly IComment[]) {
		this._comments = comments;
		this._onDidChange.fire({ comments: true });
	}

	get fileChangeViewedState(): FileViewedState {
		return this._fileChangeViewedState;
	}

	public isRemoteHeadDeleted?: boolean;
	public head: GitHubRef | null;
	public isRemoteBaseDeleted?: boolean;
	public base: GitHubRef;

	protected override stateToStateEnum(state: string) {
		let newState = GithubItemStateEnum.Closed;
		if (state.toLowerCase() === 'open') {
			newState = GithubItemStateEnum.Open;
		} else if (state.toLowerCase() === 'merged' || this.item.merged) {
			newState = GithubItemStateEnum.Merged;
		}
		return newState;
	}

	protected override doUpdate(item: PullRequest): IssueChangeEvent {
		const changes = super.doUpdate(item) as IssueChangeEvent;
		if (this.isDraft !== item.isDraft) {
			changes.draft = true;
			this.isDraft = item.isDraft;
		}

		this.suggestedReviewers = item.suggestedReviewers;
		this.closingIssues = item.closingIssues ?? [];
		if (item.isRemoteHeadDeleted != null) {
			this.isRemoteHeadDeleted = item.isRemoteHeadDeleted;
		}
		if (item.head) {
			this.head = new GitHubRef(item.head.ref, item.head.label, item.head.sha, item.head.repo.cloneUrl, item.head.repo.owner, item.head.repo.name, item.head.repo.isInOrganization);
		}

		if (item.isRemoteBaseDeleted != null) {
			this.isRemoteBaseDeleted = item.isRemoteBaseDeleted;
		}
		if (item.base) {
			this.base = new GitHubRef(item.base.ref, item.base!.label, item.base!.sha, item.base!.repo.cloneUrl, item.base.repo.owner, item.base.repo.name, item.base.repo.isInOrganization);
		}
		if (item.mergeQueueEntry !== undefined) {
			this.mergeQueueEntry = item.mergeQueueEntry ?? undefined;
		}
		if (item.hasComments !== undefined) {
			this._hasComments = item.hasComments;
		}
		return changes;
	}

	/**
	 * Validate if the pull request has a valid HEAD.
	 * Use only when the method can fail silently, otherwise use `validatePullRequestModel`
	 */
	isResolved(): this is IResolvedPullRequestModel {
		return !!this.head;
	}

	/**
	 * Validate if the pull request has a valid HEAD. Show a warning message to users when the pull request is invalid.
	 * @param message Human readable action execution failure message.
	 */
	validatePullRequestModel(message?: string): this is IResolvedPullRequestModel {
		if (!!this.head) {
			return true;
		}

		const reason = vscode.l10n.t('There is no upstream branch for Pull Request #{0}. View it on GitHub for more details', this.number);

		if (message) {
			message += `: ${reason}`;
		} else {
			message = reason;
		}

		const openString = vscode.l10n.t('Open on GitHub');
		vscode.window.showWarningMessage(message, openString).then(action => {
			if (action && action === openString) {
				openIssueOrPullRequestOnGitHub(vscode.Uri.parse(this.html_url), 'pullRequest', this._telemetry);
			}
		});

		return false;
	}

	protected override updateIssueInput(id: string): Object {
		return {
			pullRequestId: id,
		};
	}

	protected override updateIssueSchema(schema: any): any {
		return schema.UpdatePullRequest;
	}

	/**
	 * Approve the pull request.
	 * @param message Optional approval comment text.
	 * @param expectedRemoteHead When the caller just pushed a commit
	 * themselves (e.g. an attestation commit), pass the sha they expect
	 * GitHub's PR API to now report as the head. The head check will poll
	 * briefly for the API to reflect this specific sha before proceeding -
	 * a third-party push during the same interval will still be caught and
	 * rejected because GitHub would report *that* sha instead.
	 */
	async approve(repository: Repository, message?: string, expectedRemoteHead?: string): Promise<ReviewEvent> {
		// Check that the remote head of the PR branch matches the local head of the PR branch
		let remoteHead: string | undefined;
		let localHead: string | undefined;
		let rejectMessage: string | undefined;
		if (this.isActive) {
			localHead = repository.state.HEAD?.commit;
			remoteHead = (await this.githubRepository.getPullRequest(this.number, 'PullRequestModel.approve'))?.head?.sha;
			rejectMessage = vscode.l10n.t('The remote head of the pull request branch has changed. Please pull the latest changes from the remote branch before approving.');
		} else {
			localHead = this.head?.sha;
			remoteHead = (await this.githubRepository.getPullRequest(this.number, 'PullRequestModel.approve'))?.head?.sha;
			rejectMessage = vscode.l10n.t('The remote head of the pull request branch has changed. Please refresh the pull request before approving.');
		}

		// If the caller just pushed a commit, GitHub's PR API can briefly lag
		// behind. Poll for it to catch up to *that specific sha* - never
		// bypass the check. A concurrent third-party push would leave
		// `remoteHead` at some other sha and we'd still reject below.
		if (expectedRemoteHead && remoteHead !== expectedRemoteHead) {
			const maxAttempts = 5;
			const delayMs = 750;
			for (let attempt = 0; attempt < maxAttempts && remoteHead !== expectedRemoteHead; attempt++) {
				await new Promise(resolve => setTimeout(resolve, delayMs));
				remoteHead = (await this.githubRepository.getPullRequest(this.number, 'PullRequestModel.approve'))?.head?.sha;
			}
		}

		if (!remoteHead || remoteHead !== localHead) {
			return Promise.reject(rejectMessage);
		}

		const action: Promise<ReviewEvent> = (await this.getPendingReviewId())
			? this.submitReview(ReviewEventEnum.Approve, message)
			: this.createReview(ReviewEventEnum.Approve, message);

		return action.then(x => {
			/* __GDPR__
				"pr.approve" : {}
			*/
			this._telemetry.sendTelemetryEvent('pr.approve');
			this._onDidChange.fire({ comments: true, timeline: true });
			return x;
		});
	}

	/**
	 * Request changes on the pull request.
	 * @param message Optional comment text to leave with the review.
	 */
	async requestChanges(message?: string): Promise<ReviewEvent> {
		const action: ReviewEvent = (await this.getPendingReviewId())
			? await this.submitReview(ReviewEventEnum.RequestChanges, message)
			: await this.createReview(ReviewEventEnum.RequestChanges, message);

		/* __GDPR__
			"pr.requestChanges" : {}
		*/
		this._telemetry.sendTelemetryEvent('pr.requestChanges');
		this._onDidChange.fire({ timeline: true, comments: true });
		return action;
	}

	async merge(
		repository: Repository,
		title?: string,
		description?: string,
		method?: 'merge' | 'squash' | 'rebase',
		email?: string
	): Promise<{ merged: boolean, message: string, timeline?: TimelineEvent[] }> {
		Logger.debug(`Merging PR: ${this.number} method: ${method} for user: "${email}" - enter`, PullRequestModel.ID);
		const { mutate, schema } = await this.githubRepository.ensure();

		const workingDirectorySHA = repository.state.HEAD?.commit;
		const mergingPRSHA = this.head?.sha;
		const workingDirectoryIsDirty = repository.state.workingTreeChanges.length > 0;
		let expectedHeadOid: string | undefined = this.head?.sha;

		if (this.isActive) {
			// We're on the branch of the pr being merged.
			expectedHeadOid = workingDirectorySHA;
			if (workingDirectorySHA !== mergingPRSHA) {
				// We are looking at different commit than what will be merged
				const { ahead } = repository.state.HEAD!;
				const pluralMessage = vscode.l10n.t('You have {0} unpushed commits on this pull request branch.\n\nWould you like to proceed anyway?', ahead ?? 'unknown');
				const singularMessage = vscode.l10n.t('You have 1 unpushed commit on this pull request branch.\n\nWould you like to proceed anyway?');
				if (ahead &&
					(await vscode.window.showWarningMessage(
						ahead > 1 ? pluralMessage : singularMessage,
						{ modal: true },
						vscode.l10n.t('Yes'),
					)) === undefined) {

					return {
						merged: false,
						message: vscode.l10n.t('unpushed changes'),
					};
				}
			}

			if (workingDirectoryIsDirty) {
				// We have made changes to the PR that are not committed
				if (
					(await vscode.window.showWarningMessage(
						vscode.l10n.t('You have uncommitted changes on this pull request branch.\n\n Would you like to proceed anyway?'),
						{ modal: true },
						vscode.l10n.t('Yes'),
					)) === undefined
				) {
					return {
						merged: false,
						message: vscode.l10n.t('uncommitted changes'),
					};
				}
			}
		}
		const input: MergePullRequestInput = {
			pullRequestId: this.graphNodeId,
			commitHeadline: title,
			commitBody: description,
			expectedHeadOid,
			authorEmail: email,
			mergeMethod:
				(method?.toUpperCase() ??
					vscode.workspace.getConfiguration(PR_SETTINGS_NAMESPACE).get<'merge' | 'squash' | 'rebase'>(DEFAULT_MERGE_METHOD, 'merge')?.toUpperCase()) as GraphQLMergeMethod,
		};

		return mutate<MergePullRequestResponse>({
			mutation: schema.MergePullRequest,
			variables: {
				input
			}
		})
			.then(async (result) => {
				Logger.debug(`Merging PR: ${this.number} - done`, PullRequestModel.ID);

				/* __GDPR__
					"pr.merge.success" : {}
				*/
				this._telemetry.sendTelemetryEvent('pr.merge.success');
				this._onDidChange.fire({ state: true });
				return { merged: true, message: '', timeline: await parseCombinedTimelineEvents(result.data?.mergePullRequest.pullRequest.timelineItems.nodes ?? [], await this.getCopilotTimelineEvents(), this.githubRepository) };
			})
			.catch(e => {
				/* __GDPR__
					"pr.merge.failure" : {}
				*/
				this._telemetry.sendTelemetryErrorEvent('pr.merge.failure');
				const graphQLErrors = e.graphQLErrors as GraphQLError[] | undefined;
				if (graphQLErrors?.length && graphQLErrors.find(error => error.type === GraphQLErrorType.Unprocessable && error.message?.includes('Head branch was modified'))) {
					return { merged: false, message: vscode.l10n.t('Head branch was modified. Pull, review, then try again.') };
				} else {
					throw e;
				}
			});
	}

	/**
	 * Close the pull request.
	 */
	override async close(): Promise<{ item: PullRequest; closedEvent: ClosedEvent }> {
		const { octokit, remote } = await this.githubRepository.ensure();
		const ret = await octokit.call(octokit.api.pulls.update, {
			owner: remote.owner,
			repo: remote.repositoryName,
			pull_number: this.number,
			state: 'closed',
		});

		/* __GDPR__
			"pr.close" : {}
		*/
		this._telemetry.sendTelemetryEvent('pr.close');
		const user = await this.githubRepository.getAuthenticatedUser();
		this.state = this.stateToStateEnum(ret.data.state);

		// Fire the event with a delay as GitHub needs some time to propagate the changes, we want to make sure any listeners of the event will get the right info when they query
		setTimeout(() => this._onDidChange.fire({ state: true }), 1500);

		return {
			item: convertRESTPullRequestToRawPullRequest(ret.data, this.githubRepository),
			closedEvent: {
				createdAt: ret.data.closed_at ?? '',
				event: EventType.Closed,
				id: `${ret.data.id}`,
				actor: {
					login: user.login,
					avatarUrl: user.avatarUrl,
					url: user.url
				}
			}
		};
	}

	/**
	 * Create a new review.
	 * @param event The type of review to create, an approval, request for changes, or comment.
	 * @param message The summary comment text.
	 */
	private async createReview(event: ReviewEventEnum, message?: string): Promise<ReviewEvent> {
		const { octokit, remote } = await this.githubRepository.ensure();

		const { data } = await octokit.call(octokit.api.pulls.createReview, {
			owner: remote.owner,
			repo: remote.repositoryName,
			pull_number: this.number,
			event: event,
			body: message,
		});

		this._onDidChange.fire({ timeline: true });
		return convertRESTReviewEvent(data as OctokitCommon.PullsCreateReviewResponseData, this.githubRepository);
	}

	/**
	 * Submit an existing review.
	 * @param event The type of review to create, an approval, request for changes, or comment.
	 * @param body The summary comment text.
	 */
	async submitReview(event?: ReviewEventEnum, body?: string): Promise<ReviewEvent> {
		let pendingReviewId = await this.getPendingReviewId();
		const { mutate, schema } = await this.githubRepository.ensure();

		if (!pendingReviewId && (event === ReviewEventEnum.Comment)) {
			// Create a new review so that we can comment on it.
			pendingReviewId = await this.startReview();
		}

		if (pendingReviewId) {
			const { data } = await mutate<SubmitReviewResponse>({
				mutation: schema.SubmitReview,
				variables: {
					id: pendingReviewId,
					event: event || ReviewEventEnum.Comment,
					body,
				},
			});

			this.hasPendingReview = false;
			await this.updateDraftModeContext();
			const reviewEvent = parseGraphQLReviewEvent(data!.submitPullRequestReview.pullRequestReview, this.githubRepository);

			const threadWithComment = (this._reviewThreadsCache ?? []).find(thread =>
				thread.comments.length ? (thread.comments[0].pullRequestReviewId === reviewEvent.id) : undefined,
			);
			if (threadWithComment) {
				threadWithComment.comments = reviewEvent.comments;
				threadWithComment.viewerCanResolve = true;
				this._onDidChangeReviewThreads.fire({ added: [], changed: [threadWithComment], removed: [] });
			}
			this._onDidChange.fire({ timeline: true, comments: true });
			return reviewEvent;
		} else {
			throw new Error(`Submitting review failed, no pending review for current pull request: ${this.number}.`);
		}
	}

	/**
	 * Query to see if there is an existing review.
	 */
	async getPendingReviewId(): Promise<string | undefined> {
		const { query, schema } = await this.githubRepository.ensure();
		const currentUser = (await this.githubRepository.getAuthenticatedUser()).login;
		try {
			const { data } = await query<PendingReviewIdResponse>({
				query: schema.GetPendingReviewId,
				variables: {
					pullRequestId: this.item.graphNodeId,
					author: currentUser,
				},
			});
			return data.node.reviews.nodes.length > 0 ? data.node.reviews.nodes[0].id : undefined;
		} catch (error) {
			return;
		}
	}

	async getViewerLatestReviewCommit(): Promise<{ sha: string } | undefined> {
		Logger.debug(`Fetch viewers latest review commit`, IssueModel.ID);
		const { query, remote, schema } = await this.githubRepository.ensure();
		const currentUser = (await this.githubRepository.getAuthenticatedUser()).login;

		try {
			const { data } = await query<LatestReviewCommitResponse>({
				query: schema.LatestReviewCommit,
				variables: {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
					author: currentUser,
				},
			});

			if (data.repository === null) {
				Logger.error('Unexpected null repository while getting last review commit', PullRequestModel.ID);
			}

			const latestReview = data.repository?.pullRequest.reviews.nodes[0];
			return latestReview ? {
				sha: latestReview.commit.oid,
			} : undefined;
		}
		catch (e) {
			return undefined;
		}
	}

	/**
	 * Delete an existing in progress review.
	 */
	async deleteReview(): Promise<{ deletedReviewId: number; deletedReviewComments: IComment[] }> {
		const pendingReviewId = await this.getPendingReviewId();
		if (!pendingReviewId) {
			throw new Error(`No pending review found for pull request #${this.number}.`);
		}

		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<DeleteReviewResponse>({
			mutation: schema.DeleteReview,
			variables: {
				input: { pullRequestReviewId: pendingReviewId },
			},
		});

		const { comments, databaseId } = data!.deletePullRequestReview.pullRequestReview;
		const deletedReviewComments = comments.nodes.map(comment => parseGraphQLComment(comment, false, false, this.githubRepository));

		// Update local state: remove all draft comments (and their threads if emptied) that belonged to the deleted review
		const deletedCommentIds = new Set(deletedReviewComments.map(c => c.id));
		const changedThreads: IReviewThread[] = [];
		const removedThreads: IReviewThread[] = [];
		if (!this._reviewThreadsCache) {
			this._reviewThreadsCache = [];
		}
		for (let i = this._reviewThreadsCache.length - 1; i >= 0; i--) {
			const thread = this._reviewThreadsCache[i];
			const originalLength = thread.comments.length;
			thread.comments = thread.comments.filter(c => !deletedCommentIds.has(c.id));
			if (thread.comments.length === 0 && originalLength > 0) {
				// Entire thread was composed only of comments from the deleted review; remove it.
				this._reviewThreadsCache.splice(i, 1);
				removedThreads.push(thread);
			} else if (thread.comments.length !== originalLength) {
				changedThreads.push(thread);
			}
		}
		if (changedThreads.length > 0 || removedThreads.length > 0) {
			this._onDidChangeReviewThreads.fire({ added: [], changed: changedThreads, removed: removedThreads });
		}

		// Remove from flat comments collection
		if (this._comments) {
			this.comments = this._comments.filter(c => !deletedCommentIds.has(c.id));
		}

		this.hasPendingReview = false;
		await this.updateDraftModeContext();

		// Fire change event to update timeline & comment views
		this._onDidChange.fire({ timeline: true, comments: true });
		return {
			deletedReviewId: databaseId,
			deletedReviewComments,
		};
	}

	/**
	 * Start a new review.
	 * @param initialComment The comment text and position information to begin the review with
	 * @param commitId The optional commit id to start the review on. Defaults to using the current head commit.
	 */
	async startReview(commitId?: string): Promise<string> {
		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<StartReviewResponse>({
			mutation: schema.StartReview,
			variables: {
				input: {
					body: '',
					pullRequestId: this.item.graphNodeId,
					commitOID: commitId || this.head?.sha,
				},
			},
		});

		if (!data) {
			throw new Error('Failed to start review');
		}
		this.hasPendingReview = true;
		return data.addPullRequestReview.pullRequestReview.id;
	}

	/**
	 * Creates a new review thread, either adding it to an existing pending review, or creating
	 * a new review.
	 * @param body The body of the thread's first comment.
	 * @param commentPath The path to the file being commented on.
	 * @param startLine The start line on which to add the comment.
	 * @param endLine The end line on which to add the comment.
	 * @param side The side the comment should be deleted on, i.e. the original or modified file.
	 * @param suppressDraftModeUpdate If a draft mode change should event should be suppressed. In the
	 * case of a single comment add, the review is created and then immediately submitted, so this prevents
	 * a "Pending" label from flashing on the comment.
	 * @returns The new review thread object.
	 */
	async createReviewThread(
		body: string,
		commentPath: string,
		startLine: number | undefined,
		endLine: number | undefined,
		side: DiffSide,
		suppressDraftModeUpdate?: boolean,
	): Promise<IReviewThread | undefined> {
		if (!this.validatePullRequestModel('Creating comment failed')) {
			return;
		}
		const pendingReviewId = await this.getPendingReviewId();

		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<AddReviewThreadResponse>({
			mutation: schema.AddReviewThread,
			variables: {
				input: {
					path: commentPath,
					body,
					pullRequestId: this.graphNodeId,
					pullRequestReviewId: pendingReviewId,
					startLine: startLine === endLine ? undefined : startLine,
					line: endLine,
					side,
					subjectType: (startLine === undefined || endLine === undefined) ? SubjectType.FILE : SubjectType.LINE
				}
			}
		}, { mutation: schema.LegacyAddReviewThread, deleteProps: ['subjectType'] });

		if (!data) {
			throw new Error('Creating review thread failed.');
		}

		if (!data.addPullRequestReviewThread.thread) {
			throw new Error('File has been deleted.');
		}

		if (!suppressDraftModeUpdate) {
			this.hasPendingReview = true;
			await this.updateDraftModeContext();
		}

		const thread = data.addPullRequestReviewThread.thread;
		const newThread = parseGraphQLReviewThread(thread, this.githubRepository);
		if (!this._reviewThreadsCache) {
			this._reviewThreadsCache = [];
		}
		this._reviewThreadsCache.push(newThread);
		this._onDidChangeReviewThreads.fire({ added: [newThread], changed: [], removed: [] });
		this._onDidChange.fire({ timeline: true });
		return newThread;
	}

	/**
	 * Creates a new comment in reply to an existing comment
	 * @param body The text of the comment to be created
	 * @param inReplyTo The id of the comment this is in reply to
	 * @param isSingleComment Whether this is a single comment, i.e. one that
	 * will be immediately submitted and so should not show a pending label
	 * @param commitId The commit id the comment was made on
	 * @returns The new comment
	 */
	async createCommentReply(
		body: string,
		inReplyTo: string,
		isSingleComment: boolean,
		commitId?: string,
	): Promise<IComment | undefined> {
		if (!this.validatePullRequestModel('Creating comment failed')) {
			return;
		}

		let pendingReviewId = await this.getPendingReviewId();
		if (!pendingReviewId) {
			pendingReviewId = await this.startReview(commitId);
		}

		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<AddCommentResponse>({
			mutation: schema.AddComment,
			variables: {
				input: {
					pullRequestReviewId: pendingReviewId,
					body,
					inReplyTo,
					commitOID: commitId || this.head?.sha,
				},
			},
		});

		if (!data) {
			throw new Error('Creating comment reply failed.');
		}

		const { comment } = data.addPullRequestReviewComment;
		const newComment = parseGraphQLComment(comment, false, false, this.githubRepository);

		if (isSingleComment) {
			newComment.isDraft = false;
		}

		const threadWithComment = this._reviewThreadsCache?.find(thread =>
			thread.comments.some(comment => comment.graphNodeId === inReplyTo),
		);
		if (threadWithComment) {
			threadWithComment.comments.push(newComment);
			this._onDidChangeReviewThreads.fire({ added: [], changed: [threadWithComment], removed: [] });
		}

		this._onDidChange.fire({ timeline: true, comments: true });
		return newComment;
	}

	/**
	 * Check whether there is an existing pending review and update the context key to control what comment actions are shown.
	 */
	async validateDraftMode(): Promise<boolean> {
		const inDraftMode = !!(await this.getPendingReviewId());
		if (inDraftMode !== this.hasPendingReview) {
			this.hasPendingReview = inDraftMode;
		}

		await this.updateDraftModeContext();

		return inDraftMode;
	}

	private async updateDraftModeContext() {
		if (this.isActive) {
			await vscode.commands.executeCommand('setContext', 'reviewInDraftMode', this.hasPendingReview);
		}
	}

	/**
	 * Get the timeline events of a pull request, including comments, reviews, commits, merges, deletes, and assigns.
	 */
	async getTimelineEvents(): Promise<TimelineEvent[] | undefined> {
		const getTimelineEvents = async () => {
			Logger.debug(`Fetch timeline events of PR #${this.number} - enter`, PullRequestModel.ID);
			const { query, remote, schema } = await this.githubRepository.ensure();
			try {
				const { data } = await query<TimelineEventsResponse>({
					query: schema.TimelineEvents,
					variables: {
						owner: remote.owner,
						name: remote.repositoryName,
						number: this.number,
					},
				});

				if (data.repository === null) {
					Logger.error('Unexpected null repository when fetching timeline', PullRequestModel.ID);
				}
				return data;
			} catch (e) {
				Logger.error(`Failed to get pull request timeline events: ${e}`, PullRequestModel.ID);
				console.log(e);
				return undefined;
			}
		};

		const [data, latestReviewCommitInfo, currentUser, reviewThreads] = await Promise.all([
			getTimelineEvents(),
			this.getViewerLatestReviewCommit(),
			// eslint-disable-next-line @typescript-eslint/await-thenable
			(await this.githubRepository.getAuthenticatedUser()).login,
			this.getReviewThreads()
		]);


		const ret = data?.repository?.pullRequest.timelineItems.nodes ?? [];
		const events = await parseCombinedTimelineEvents(ret, await this.getCopilotTimelineEvents(true), this.githubRepository);

		this.addReviewTimelineEventComments(events, reviewThreads);
		insertNewCommitsSinceReview(events, latestReviewCommitInfo?.sha, currentUser, this.head);
		Logger.debug(`Fetch timeline events of PR #${this.number} - done`, PullRequestModel.ID);
		this.timelineEvents = events;
		return events;
	}

	async getActivityTimelineEvents(): Promise<TimelineEvent[]> {
		Logger.debug(`Fetch timeline events of PR #${this.number} - enter`, PullRequestModel.ID);
		const { query, remote, schema } = await this.githubRepository.ensure();
		try {
			const { data } = await query<TimelineEventsResponse>({
				query: schema.PullRequestActivityTimelineEvents,
				variables: {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
				},
			});

			if (data.repository === null) {
				Logger.error('Unexpected null repository when fetching timeline', PullRequestModel.ID);
			}

			return parseCombinedTimelineEvents(data.repository?.pullRequest.timelineItems.nodes ?? [], [], this.githubRepository);
		} catch (e) {
			Logger.error(`Failed to get pull request timeline events: ${e}`, PullRequestModel.ID);
			console.log(e);
			return [];
		}
	}

	private addReviewTimelineEventComments(events: TimelineEvent[], reviewThreads: IReviewThread[]): void {
		interface CommentNode extends IComment {
			childComments?: CommentNode[];
		}

		const reviewEvents = events.filter((e): e is ReviewEvent => e.event === EventType.Reviewed);
		const reviewComments = reviewThreads.reduce((previous, current) => (previous as IComment[]).concat(current.comments), []);

		const reviewEventsById = reviewEvents.reduce((index, evt) => {
			index[evt.id] = evt;
			evt.comments = [];
			return index;
		}, {} as { [key: number]: ReviewEvent });

		const commentsById = reviewComments.reduce((index, evt) => {
			index[evt.id] = evt;
			return index;
		}, {} as { [key: number]: CommentNode });

		const roots: CommentNode[] = [];
		let i = reviewComments.length;
		while (i-- > 0) {
			const c: CommentNode = reviewComments[i];
			if (!c.inReplyToId) {
				roots.unshift(c);
				continue;
			}
			const parent = commentsById[c.inReplyToId];
			parent.childComments = parent.childComments || [];
			parent.childComments = [c, ...(c.childComments || []), ...parent.childComments];
		}

		roots.forEach(c => {
			const review = reviewEventsById[c.pullRequestReviewId!];
			if (review) {
				review.comments = review.comments.concat(c).concat(c.childComments || []);
			}
		});

		reviewThreads.forEach(thread => {
			if (!thread.prReviewDatabaseId || !reviewEventsById[thread.prReviewDatabaseId]) {
				return;
			}
			const prReviewThreadEvent = reviewEventsById[thread.prReviewDatabaseId];
			const resolveInfo: ReviewResolveInfo = {
				threadId: thread.id,
				canResolve: thread.viewerCanResolve,
				canUnresolve: thread.viewerCanUnresolve,
				isResolved: thread.isResolved
			};
			// A single review can have comments on multiple threads. Track each
			// thread's resolve info by its id so the webview can resolve the
			// correct thread when the user clicks resolve/unresolve on any of
			// the comment groups within the review.
			if (!prReviewThreadEvent.reviewThreads) {
				prReviewThreadEvent.reviewThreads = {};
			}
			prReviewThreadEvent.reviewThreads[thread.id] = resolveInfo;
		});

		const pendingReview = reviewEvents.filter(r => r.state?.toLowerCase() === 'pending')[0];
		if (pendingReview) {
			// Ensures that pending comments made in reply to other reviews are included for the pending review
			pendingReview.comments = reviewComments.filter(c => c.isDraft);
		}
	}

	/**
	 * Edit an existing review comment.
	 * @param comment The comment to edit
	 * @param text The new comment text
	 */
	async editReviewComment(comment: IComment, text: string): Promise<IComment> {
		const { mutate, schema } = await this.githubRepository.ensure();
		let threadWithComment = this._reviewThreadsCache?.find(thread =>
			thread.comments.some(c => c.graphNodeId === comment.graphNodeId),
		);

		if (!threadWithComment) {
			return this.editIssueComment(comment, text);
		}

		const { data } = await mutate<EditCommentResponse>({
			mutation: schema.EditComment,
			variables: {
				input: {
					pullRequestReviewCommentId: comment.graphNodeId,
					body: text,
				},
			},
		});

		if (!data) {
			throw new Error('Editing review comment failed.');
		}

		const newComment = parseGraphQLComment(
			data.updatePullRequestReviewComment.pullRequestReviewComment,
			!!comment.isResolved,
			!!comment.isOutdated,
			this.githubRepository
		);
		if (threadWithComment) {
			const index = threadWithComment.comments.findIndex(c => c.graphNodeId === comment.graphNodeId);
			threadWithComment.comments.splice(index, 1, newComment);
			this._onDidChangeReviewThreads.fire({ added: [], changed: [threadWithComment], removed: [] });
			this._onDidChange.fire({ timeline: true });
		}

		return newComment;
	}

	/**
	 * Deletes a review comment.
	 * @param commentId The comment id to delete
	 */
	async deleteReviewComment(commentId: string): Promise<void> {
		try {
			const { octokit, remote } = await this.githubRepository.ensure();
			const id = Number(commentId);
			const threadIndex = this._reviewThreadsCache?.findIndex(thread => thread.comments.some(c => c.id === id)) ?? -1;

			if (threadIndex === -1) {
				this.deleteIssueComment(commentId);
			} else {
				await octokit.call(octokit.api.pulls.deleteReviewComment, {
					owner: remote.owner,
					repo: remote.repositoryName,
					comment_id: id,
				});

				if (threadIndex > -1) {
					const threadWithComment = this._reviewThreadsCache![threadIndex];
					const index = threadWithComment.comments.findIndex(c => c.id === id);
					threadWithComment.comments.splice(index, 1);
					if (threadWithComment.comments.length === 0) {
						this._reviewThreadsCache?.splice(threadIndex, 1);
						this._onDidChangeReviewThreads.fire({ added: [], changed: [], removed: [threadWithComment] });
					} else {
						this._onDidChangeReviewThreads.fire({ added: [], changed: [threadWithComment], removed: [] });
					}
					this._onDidChange.fire({ timeline: true });
				}
			}
		} catch (e) {
			throw new Error(formatError(e));
		}
	}

	private async getFileContent(owner: string, sha: string, file: string): Promise<string | undefined> {
		Logger.debug(`Fetch file content - enter`, GitHubRepository.ID);
		const { query, remote, schema } = await this.githubRepository.ensure();
		const { data } = await query<FileContentResponse>({
			query: schema.GetFileContent,
			variables: {
				owner,
				name: remote.repositoryName,
				expression: `${sha}:${file}`
			}
		});

		if (!data.repository?.object.text) {
			return undefined;
		}

		Logger.debug(`Fetch file content - end`, GitHubRepository.ID);

		return data.repository.object.text;
	}

	public async compareBaseBranchForMerge(headOwner: string, headRef: string, baseOwner: string, baseRef: string): Promise<IRawFileChange[]> {
		const { octokit, remote } = await this.githubRepository.ensure();

		// Get the files that would change as part of the merge
		const compareData = await octokit.call(octokit.api.repos.compareCommits, {
			repo: remote.repositoryName,
			owner: headOwner,
			base: `${headOwner}:${headRef}`, // flip base and head because we are comparing for a merge to update the PR
			head: `${baseOwner}:${baseRef}`,
		});

		return compareData?.data?.files?.filter<IRawFileChange>((change): change is IRawFileChange => change !== undefined) ?? [];
	}

	private async getUpdateBranchFiles(baseCommitSha: string, headTreeSha: string, model: ConflictResolutionModel): Promise<IGitTreeItem[]> {
		if (this.item.mergeable === PullRequestMergeability.Conflict && (!model.resolvedConflicts || model.resolvedConflicts.size === 0)) {
			throw new Error('Pull Request has conflicts but no resolutions were provided.');
		}
		const { octokit } = await this.githubRepository.ensure();

		// Get the files that would change as part of the merge
		const compareData = await this.compareBaseBranchForMerge(model.prHeadOwner, model.prHeadBranchName, model.prBaseOwner, baseCommitSha);
		const baseTreeSha = (await octokit.call(octokit.api.repos.getCommit, { owner: model.prBaseOwner, repo: model.repositoryName, ref: baseCommitSha })).data.commit.tree.sha;
		const baseTree = await octokit.call(octokit.api.git.getTree, { owner: model.prBaseOwner, repo: model.repositoryName, tree_sha: baseTreeSha, recursive: 'true' });

		const files: IGitTreeItem[] = (await Promise.all(compareData.map(async (file) => {
			if (!file) {
				return;
			}

			const baseTreeData = baseTree.data.tree.find(f => f.path === file.filename);
			const baseMode: TreeDataMode = (baseTreeData?.mode as TreeDataMode | undefined) ?? '100644';

			const headTree = await octokit.call(octokit.api.git.getTree, { owner: model.prHeadOwner, repo: model.repositoryName, tree_sha: headTreeSha, recursive: 'true' });
			const headTreeData = headTree.data.tree.find(f => f.path === file.filename);
			const headMode: TreeDataMode = (headTreeData?.mode as TreeDataMode | undefined) ?? '100644';

			if (file.status === 'removed') {
				// The file was removed so we use a null sha to indicate that (per GitHub's API).
				// If we've made it this far, we already know that there are no conflicts in the file and it's safe to delete.
				return { path: file.filename, sha: null, mode: headTreeData?.mode ?? '100644' };
			}

			const treeItem: IGitTreeItem = {
				path: file.filename,
				mode: baseMode
			};

			const resolvedConflict = model.resolvedConflicts.get(file.filename);
			if (resolvedConflict?.resolvedContents !== undefined) {
				if (file.status !== 'modified') {
					throw new Error(`Only modified file are supported for conflict resolution ${file.filename}: ${file.status}`);
				}

				if (baseMode !== headMode) {
					throw new Error(`Conflict resolution not supported for file with different modes ${file.filename}: ${baseMode} -> ${headMode}`);
				}

				if (file.previous_filename) {
					throw new Error('Conflict resolution not supported for renamed files');
				}
				treeItem.content = resolvedConflict.resolvedContents;
				return treeItem;
			}

			if ((!file.previous_filename || !this._fileChanges.has(file.previous_filename)) && !this._fileChanges.has(file.filename)) {
				// File is not part of the PR, so we don't need to bother getting any content and can just use the sha
				treeItem.sha = file.sha;
				return treeItem;
			}

			// File is part of the PR. We have to apply the patch of the base to the head content.
			const { data: headData }: { data: IRawFileContent } = await octokit.call(octokit.api.repos.getContent, {
				owner: model.prHeadOwner,
				repo: model.repositoryName,
				path: file?.previous_filename ?? file.filename,
				ref: model.prHeadBranchName
			}) as { data: IRawFileContent };

			if (file.status === 'modified' && file.patch && headData.content) {
				const buff = buffer.Buffer.from(headData.content, 'base64');
				const asString = new TextDecoder().decode(buff);
				treeItem.content = getModifiedContentFromDiffHunk(asString, file.patch);
			} else {
				// binary file or file that otherwise doesn't have a patch
				// This cannot be resolved by us and must manually be resolved by the user
				Logger.error(`File ${file.filename} has status ${file.status} and can't be merged.`, GitHubRepository.ID);
				// We don't want to commit something that's going to break, so throw
				throw new Error(`File ${file.filename} has status ${file.status} and can't be merged,`);
			}
			return treeItem;

		}))).filter<IGitTreeItem>((file): file is IGitTreeItem => file !== undefined);
		return files;
	}

	async getLatestBaseCommitSha(): Promise<string> {
		const base = this.base;
		if (!base) {
			throw new Error('Base branch not yet set.');
		}
		const { octokit, remote } = await this.githubRepository.ensure();
		return (await octokit.call(octokit.api.repos.getBranch, { owner: remote.owner, repo: remote.repositoryName, branch: this.base.ref })).data.commit.sha;
	}

	async updateBranch(model: ConflictResolutionModel): Promise<boolean> {
		if (!model.resolvedConflicts || model.resolvedConflicts.size === 0) {
			throw new Error('Pull Request has conflicts but no resolutions were provided.');
		}
		Logger.debug(`Updating branch ${model.prHeadBranchName} to ${model.prBaseBranchName} - enter`, GitHubRepository.ID);
		// For Conflict state, use the REST API approach with conflict resolution.
		// For Unknown or NotMergeable states, the REST API approach will also be used as a fallback,
		// though these states may fail for other reasons (e.g., blocked by branch protection).
		return this.updateBranchWithConflictResolution(model);
	}

	/**
	 * Update the branch using the GitHub GraphQL API's UpdatePullRequestBranch mutation.
	 * This is used when there are no conflicts between the head and base branches.
	 */
	public async updateBranchWithGraphQL(): Promise<boolean> {
		Logger.debug(`Updating branch using GraphQL UpdatePullRequestBranch mutation - enter`, GitHubRepository.ID);

		if (!this.head?.sha) {
			Logger.error(`Cannot update branch: head SHA is not available`, GitHubRepository.ID);
			return false;
		}

		try {
			const { mutate, schema } = await this.githubRepository.ensure();

			await mutate<UpdatePullRequestBranchResponse>({
				mutation: schema.UpdatePullRequestBranch,
				variables: {
					input: {
						pullRequestId: this.graphNodeId,
						expectedHeadOid: this.head.sha
					}
				}
			});

			Logger.debug(`Updating branch using GraphQL UpdatePullRequestBranch mutation - done`, GitHubRepository.ID);
			return true;
		} catch (e) {
			Logger.error(`Updating branch using GraphQL UpdatePullRequestBranch mutation failed: ${e}`, GitHubRepository.ID);
			return false;
		}
	}

	/**
	 * Update the branch with conflict resolution using the REST API.
	 * This is used when there are conflicts between the head and base branches.
	 */
	private async updateBranchWithConflictResolution(model: ConflictResolutionModel): Promise<boolean> {
		Logger.debug(`Updating branch ${model.prHeadBranchName} with conflict resolution - enter`, GitHubRepository.ID);
		try {
			const { octokit } = await this.githubRepository.ensure();

			const lastCommitSha = (await octokit.call(octokit.api.repos.getBranch, { owner: model.prHeadOwner, repo: model.repositoryName, branch: model.prHeadBranchName })).data.commit.sha;
			const lastTreeSha = (await octokit.call(octokit.api.repos.getCommit, { owner: model.prHeadOwner, repo: model.repositoryName, ref: lastCommitSha })).data.commit.tree.sha;

			const treeItems: IGitTreeItem[] = await this.getUpdateBranchFiles(model.latestPrBaseSha, lastTreeSha, model);

			const newTreeSha = (await octokit.call(octokit.api.git.createTree, { owner: model.prHeadOwner, repo: model.repositoryName, base_tree: lastTreeSha, tree: treeItems })).data.sha;
			let message: string;
			if (model.prBaseOwner === model.prHeadOwner) {
				message = `Merge branch \`${model.prBaseBranchName}\` into ${model.prHeadBranchName}`;
			} else {
				message = `Merge branch \`${model.prBaseOwner}:${model.prBaseBranchName}\` into ${model.prHeadBranchName}`;
			}
			const newCommitSha = (await octokit.call(octokit.api.git.createCommit, { owner: model.prHeadOwner, repo: model.repositoryName, message, tree: newTreeSha, parents: [lastCommitSha, model.latestPrBaseSha] })).data.sha;
			await octokit.call(octokit.api.git.updateRef, { owner: model.prHeadOwner, repo: model.repositoryName, ref: `heads/${model.prHeadBranchName}`, sha: newCommitSha });

		} catch (e) {
			Logger.error(`Updating branch ${model.prHeadBranchName} with conflict resolution failed: ${e}`, GitHubRepository.ID);
			return false;
		}
		Logger.debug(`Updating branch ${model.prHeadBranchName} with conflict resolution - done`, GitHubRepository.ID);
		return true;
	}

	/**
	 * Update the base branch of the pull request.
	 * @param newBaseBranch The new base branch name
	 */
	async updateBaseBranch(newBaseBranch: string): Promise<void> {
		Logger.debug(`Updating base branch to ${newBaseBranch} - enter`, PullRequestModel.ID);
		try {
			const { mutate, schema } = await this.githubRepository.ensure();

			const { data } = await mutate<UpdateIssueResponse>({
				mutation: schema.UpdatePullRequest,
				variables: {
					input: {
						pullRequestId: this.graphNodeId,
						baseRefName: newBaseBranch,
					},
				},
			});

			if (data?.updateIssue?.issue) {
				// Update the local base branch reference by creating a new GitHubRef instance
				const cloneUrl = this.base.repositoryCloneUrl.toString() || '';
				this.base = new GitHubRef(
					newBaseBranch,
					`${this.base.owner}:${newBaseBranch}`,
					this.base.sha,
					cloneUrl,
					this.base.owner,
					this.base.name,
					this.base.isInOrganization
				);
				this._onDidChange.fire({ base: true });
			}
			Logger.debug(`Updating base branch to ${newBaseBranch} - done`, PullRequestModel.ID);
		} catch (e) {
			Logger.error(`Updating base branch to ${newBaseBranch} failed: ${e}`, PullRequestModel.ID);
			throw e;
		}
	}

	/**
	 * Get existing requests to review.
	 */
	async getReviewRequests(): Promise<(IAccount | ITeam)[]> {
		Logger.debug('Get Review Requests - enter', PullRequestModel.ID);

		const githubRepository = this.githubRepository;
		const { remote, query, schema } = await githubRepository.ensure();

		const { data } = await query<GetReviewRequestsResponse>({
			query: this.credentialStore.isAuthenticatedWithAdditionalScopes(githubRepository.remote.authProviderId) ? schema.GetReviewRequestsAdditionalScopes : schema.GetReviewRequests,
			variables: {
				number: this.number,
				owner: remote.owner,
				name: remote.repositoryName
			},
		});

		if (data.repository === null) {
			Logger.error('Unexpected null repository while getting review requests', PullRequestModel.ID);
			return [];
		}

		const reviewers: (IAccount | ITeam)[] = parseGraphQLReviewers(data, githubRepository);
		if (this.reviewers?.length !== reviewers.length || (this.reviewers.some(r => !reviewers.some(rr => rr.id === r.id)))) {
			this.reviewers = reviewers;
			this._onDidChange.fire({ reviewers: true });
		}
		Logger.debug('Get Review Requests - done', PullRequestModel.ID);
		return reviewers;
	}

	/**
	 * Add reviewers to a pull request
	 * @param reviewers A list of GitHub logins
	 */
	async requestReview(reviewers: IAccount[], teamReviewers: ITeam[], union: boolean = false): Promise<void> {
		const { mutate, schema } = await this.githubRepository.ensure();
		const input: { pullRequestId: string, teamIds: string[], userIds: string[], botIds?: string[], union: boolean } = {
			pullRequestId: this.graphNodeId,
			teamIds: teamReviewers.map(t => t.id),
			userIds: reviewers.filter(r => r.accountType !== AccountType.Bot).map(r => r.id),
			union
		};
		if (!this.githubRepository.areQueriesLimited) {
			input.botIds = reviewers.filter(r => r.accountType === AccountType.Bot).map(r => r.id);
		}

		const { data } = await mutate<AddReviewsResponse>({
			mutation: schema.AddReviewers,
			variables: {
				input
			},
		});

		if (!data?.requestReviews) {
			Logger.error('Unexpected null repository while getting review requests', PullRequestModel.ID);
			return;
		}

		const newReviewers: (IAccount | ITeam)[] = [...reviewers, ...teamReviewers].filter(r => !this.reviewers?.some(rr => rr.id === r.id));
		if (this.reviewers?.length !== newReviewers.length) {
			if (!this.reviewers) {
				this.reviewers = newReviewers;
			} else {
				this.reviewers.push(...newReviewers);
			}
			this.reviewers = [...this.reviewers, ...newReviewers];
			this._onDidChange.fire({ reviewers: true });
		}
	}

	/**
	 * Remove a review request that has not yet been completed
	 * @param reviewer A GitHub Login
	 */
	async deleteReviewRequest(reviewers: IAccount[], teamReviewers: ITeam[]): Promise<void> {
		if (reviewers.length === 0 && teamReviewers.length === 0) {
			return;
		}
		const { octokit, remote } = await this.githubRepository.ensure();
		await octokit.call(octokit.api.pulls.removeRequestedReviewers, {
			owner: remote.owner,
			repo: remote.repositoryName,
			pull_number: this.number,
			reviewers: reviewers.map(r => r.id),
			team_reviewers: teamReviewers.map(t => t.id),
		});

		this.reviewers = this.reviewers?.filter(r => !reviewers.some(rr => rr.id === r.id) && !teamReviewers.some(t => t.id === r.id)) || [];
		this._onDidChange.fire({ reviewers: true });
	}

	private diffThreads(oldReviewThreads: IReviewThread[], newReviewThreads: IReviewThread[]): void {
		const added: IReviewThread[] = [];
		const changed: IReviewThread[] = [];
		const removed: IReviewThread[] = [];

		newReviewThreads.forEach(thread => {
			const existingThread = oldReviewThreads.find(t => t.id === thread.id);
			if (existingThread) {
				if (!equals(thread, existingThread)) {
					changed.push(thread);
				}
			} else {
				added.push(thread);
			}
		});

		oldReviewThreads.forEach(thread => {
			if (!newReviewThreads.find(t => t.id === thread.id)) {
				removed.push(thread);
			}
		});

		if (added.length > 0 || changed.length > 0 || removed.length > 0) {
			this._onDidChangeReviewThreads.fire({
				added,
				changed,
				removed,
			});
		}
	}

	async initializeReviewThreadCacheAndReviewComments(): Promise<void> {
		const threads = await this.initializeReviewThreadCache();

		this.comments = threads.map(node => node.comments)
			.reduce((prev, curr) => prev.concat(curr), [])
			.sort((a: IComment, b: IComment) => {
				return a.createdAt > b.createdAt ? 1 : -1;
			});
	}

	private setReviewThreadCacheFromRaw(raw: ReviewThread[]): IReviewThread[] {
		const reviewThreads: IReviewThread[] = raw.map(thread => parseGraphQLReviewThread(thread, this.githubRepository));
		const oldReviewThreads = this._reviewThreadsCache ?? [];
		this._reviewThreadsCache = reviewThreads;
		this.diffThreads(oldReviewThreads, reviewThreads);
		return reviewThreads;
	}

	private async getRawReviewComments(): Promise<ReviewThread[]> {
		Logger.debug(`Fetching review comments for PR #${this.number} - enter`, PullRequestModel.ID);

		const { remote, query, schema } = await this.githubRepository.ensure();
		let after: string | null = null;
		let pageSize = 20;
		const reviewThreads: ReviewThread[] = [];
		try {
			while (reviewThreads.length < 1000) {
				const variables = {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
					first: pageSize,
					after,
				};
				let data: PullRequestCommentsResponse | null;
				try {
					({ data } = await query<PullRequestCommentsResponse>({
						query: schema.PullRequestComments,
						variables,
					}, false, { query: schema.LegacyPullRequestComments, variables }));
				} catch (e) {
					if (getErrorCode(e) !== '502' || pageSize === 1) {
						throw e;
					}
					// Large review-thread queries can fail with HTTP 502.
					// Retry the same cursor with 5, then 1 thread, and keep that size.
					pageSize = Math.max(1, Math.floor(pageSize / 4));
					Logger.warn(`Retrying review comments for PR #${this.number} with ${pageSize} threads per page after HTTP 502.`, PullRequestModel.ID);
					continue;
				}

				if (!data?.repository) {
					throw new Error('Review comments response did not include a repository.');
				}
				const page = data.repository.pullRequest.reviewThreads;
				reviewThreads.push(...page.nodes);

				if (!page.pageInfo.hasNextPage) {
					break;
				}
				after = page.pageInfo.endCursor;
			}
			Logger.debug(`Fetching review comments for PR #${this.number} - exit`, PullRequestModel.ID);

			return reviewThreads;
		} catch (e) {
			Logger.error(`Failed to get pull request review comments: ${e}`, PullRequestModel.ID);
			return [];
		}
	}

	async getReviewThreads(): Promise<IReviewThread[]> {
		const raw = await this.getRawReviewComments();
		return this.setReviewThreadCacheFromRaw(raw);
	}

	/**
	 * Get a list of the commits within a pull request.
	 */
	async getCommits(): Promise<OctokitCommon.PullsListCommitsResponseData> {
		try {
			Logger.debug(`Fetch commits of PR #${this.number} - enter`, PullRequestModel.ID);
			const { remote, octokit } = await this.githubRepository.ensure();
			const commitData = await restPaginate<typeof octokit.api.pulls.listCommits, OctokitCommon.PullsListCommitsResponseData[0]>(octokit.api.pulls.listCommits, {
				pull_number: this.number,
				owner: remote.owner,
				repo: remote.repositoryName,
			});
			Logger.debug(`Fetch commits of PR #${this.number} - done`, PullRequestModel.ID);

			return commitData;
		} catch (e) {
			vscode.window.showErrorMessage(`Fetching commits failed: ${formatError(e)}`);
			return [];
		}
	}

	/**
	 * Get all changed files within a commit
	 * @param commit The commit
	 */
	async getCommitChangedFiles(
		commit: OctokitCommon.PullsListCommitsResponseData[0],
	): Promise<OctokitCommon.ReposGetCommitResponseFiles> {
		try {
			Logger.debug(`Fetch file changes of commit ${commit.sha} in PR #${this.number} - enter`, PullRequestModel.ID,);
			const { octokit, remote } = await this.githubRepository.ensure();
			const fullCommit = await octokit.call(octokit.api.repos.getCommit, {
				owner: remote.owner,
				repo: remote.repositoryName,
				ref: commit.sha,
			});
			Logger.debug(`Fetch file changes of commit ${commit.sha} in PR #${this.number} - done`, PullRequestModel.ID,);

			return fullCommit.data.files ?? [];
		} catch (e) {
			vscode.window.showErrorMessage(`Fetching commit file changes failed: ${formatError(e)}`);
			return [];
		}
	}

	async getCoAuthors(): Promise<IAccount[]> {
		// To save time, we only do for Copilot now as that's where we need it
		if (!COPILOT_ACCOUNTS[this.item.user.login]) {
			return [];
		}
		const { octokit, remote } = await this.githubRepository.ensure();
		const timeline = await octokit.call(octokit.api.issues.listEventsForTimeline, {
			issue_number: this.number,
			owner: remote.owner,
			repo: remote.repositoryName,
			per_page: 100
		});
		const workStartedInitiator = (timeline.data.find(event => event.event === 'copilot_work_started') as { actor: RestAccount } | undefined)?.actor;
		return workStartedInitiator ? [parseAccount(workStartedInitiator, this.githubRepository)] : [];
	}

	protected override getUpdatesQuery(schema: any): any {
		return schema.LatestUpdates;
	}

	/**
	 * Get the status checks of the pull request, those for the last commit.
	 */
	async getStatusChecks(): Promise<[PullRequestChecks | null, PullRequestReviewRequirement | null]> {
		return this.githubRepository.getStatusChecks(this.number);
	}

	static async openChanges(folderManager: FolderRepositoryManager, pullRequestModel: PullRequestModel, openToTheSide?: boolean): Promise<void> {
		const changeModels = await PullRequestModel.getChangeModels(folderManager, pullRequestModel);
		const args: [vscode.Uri, vscode.Uri | undefined, vscode.Uri | undefined][] = [];
		for (const changeModel of changeModels) {
			args.push([changeModel.filePath, changeModel.parentFilePath, changeModel.filePath]);
		}

		/* __GDPR__
			"pr.openChanges" : {}
		*/
		folderManager.telemetry.sendTelemetryEvent('pr.openChanges');

		if (openToTheSide) {
			if (vscode.window.tabGroups.all.length < 2) {
				await vscode.commands.executeCommand('workbench.action.splitEditor');
			}

			await vscode.commands.executeCommand('workbench.action.focusSecondEditorGroup');
		}

		return vscode.commands.executeCommand('vscode.changes', vscode.l10n.t('Changes in Pull Request #{0}', pullRequestModel.number), args);
	}

	static async openReadonlyChanges(folderManager: FolderRepositoryManager, pullRequestModel: PullRequestModel): Promise<void> {
		const headCommit = pullRequestModel.head?.sha;
		if (!headCommit) {
			throw new Error(`Pull request #${pullRequestModel.number} has no head commit.`);
		}

		let startCommit = pullRequestModel.item.merged
			? pullRequestModel.base.sha
			: await this.getLocalMergeBase(folderManager.repository, pullRequestModel.base.sha, headCommit);
		let localChanges: Change[] | undefined;
		if (startCommit && await this.commitsExistLocally(folderManager.repository, startCommit, headCommit)) {
			localChanges = await folderManager.repository.diffBetween(startCommit, headCommit);
		}

		let remoteChanges: (InMemFileChange | SlimFileChange)[] | undefined;
		if (!localChanges) {
			const allChanges = await pullRequestModel.getAllFileChangesInfo();
			remoteChanges = allChanges.changes;
			startCommit = allChanges.mergeBase;
			if (await this.commitsExistLocally(folderManager.repository, startCommit, headCommit)) {
				localChanges = await folderManager.repository.diffBetween(startCommit, headCommit);
			}
		}

		if (!startCommit) {
			throw new Error(`Pull request #${pullRequestModel.number} has no base commit.`);
		}

		let args: [vscode.Uri, vscode.Uri | undefined, vscode.Uri | undefined][];
		if (localChanges) {
			args = localChanges.map(change => this.localChangeToMultiDiffEntry(change, startCommit, headCommit));
		} else {
			if (!remoteChanges) {
				throw new Error(`Pull request #${pullRequestModel.number} has no file changes.`);
			}
			const remote = pullRequestModel.githubRepository.remote;
			args = remoteChanges.map((change): [vscode.Uri, vscode.Uri | undefined, vscode.Uri | undefined] => {
				const rightUri = toGitHubCommitUri(change.fileName, { commit: headCommit, owner: remote.owner, repo: remote.repositoryName });
				const parentFileName = change.status === GitChangeType.RENAME ? change.previousFileName ?? change.fileName : change.fileName;
				const leftUri = toGitHubCommitUri(parentFileName, { commit: startCommit, owner: remote.owner, repo: remote.repositoryName });
				if (change.status === GitChangeType.ADD) {
					return [rightUri, undefined, rightUri];
				} else if (change.status === GitChangeType.DELETE) {
					return [rightUri, leftUri, undefined];
				}
				return [rightUri, leftUri, rightUri];
			});
		}

		/* __GDPR__
			"pr.viewChanges" : {
				"source" : { "classification": "SystemMetaData", "purpose": "FeatureInsight" }
			}
		*/
		folderManager.telemetry.sendTelemetryEvent('pr.viewChanges', { source: localChanges ? 'git' : 'github' });
		return vscode.commands.executeCommand('vscode.changes', vscode.l10n.t('Changes in Pull Request #{0}', pullRequestModel.number), args);
	}

	private static async getLocalMergeBase(repository: Repository, baseCommit: string, headCommit: string): Promise<string | undefined> {
		if (!await this.commitsExistLocally(repository, baseCommit, headCommit)) {
			return;
		}
		try {
			return await repository.getMergeBase(baseCommit, headCommit);
		} catch (error) {
			Logger.debug(`Using GitHub to determine the pull request merge base: ${formatError(error)}`, PullRequestModel.ID);
			return;
		}
	}

	private static async commitsExistLocally(repository: Repository, startCommit: string, endCommit: string): Promise<boolean> {
		try {
			await Promise.all([repository.getCommit(startCommit), repository.getCommit(endCommit)]);
			return true;
		} catch (error) {
			Logger.debug(`Using GitHub content because the pull request commit range is not available locally: ${formatError(error)}`, PullRequestModel.ID);
			return false;
		}
	}

	private static localChangeToMultiDiffEntry(change: Change, startCommit: string, endCommit: string): [vscode.Uri, vscode.Uri | undefined, vscode.Uri | undefined] {
		const rightFileUri = change.renameUri ?? change.uri;
		const leftFileUri = change.originalUri;
		const rightUri = this.toGitCommitUri(rightFileUri, endCommit);
		const leftUri = this.toGitCommitUri(leftFileUri, startCommit);

		switch (change.status) {
			case Status.INDEX_ADDED:
			case Status.ADDED_BY_US:
			case Status.ADDED_BY_THEM:
			case Status.UNTRACKED:
			case Status.INTENT_TO_ADD:
				return [rightUri, undefined, rightUri];
			case Status.INDEX_DELETED:
			case Status.DELETED:
			case Status.DELETED_BY_US:
			case Status.DELETED_BY_THEM:
				return [rightUri, leftUri, undefined];
			default:
				return [rightUri, leftUri, rightUri];
		}
	}

	private static toGitCommitUri(fileUri: vscode.Uri, commit: string): vscode.Uri {
		return fileUri.with({
			scheme: Schemes.Git,
			query: JSON.stringify({ path: fileUri.fsPath, ref: commit }),
		});
	}

	static async openCommitChanges(extensionUri: vscode.Uri, githubRepository: GitHubRepository, commitSha: string) {
		try {
			const parentCommit = await githubRepository.getCommitParent(commitSha);
			if (!parentCommit) {
				vscode.window.showErrorMessage(vscode.l10n.t('Commit {0} has no parent', commitSha.substring(0, 7)));
				return;
			}

			const changes = await githubRepository.compareCommits(parentCommit, commitSha);
			if (!changes?.files || changes.files.length === 0) {
				// Show a webview with the empty commit message instead of a notification
				showEmptyCommitWebview(extensionUri, commitSha);
				return;
			}

			// Create URI pairs for the multi diff editor using review scheme
			const args: [vscode.Uri, vscode.Uri | undefined, vscode.Uri | undefined][] = [];
			for (const change of changes.files) {
				const rightUri = toGitHubCommitUri(change.filename, { commit: commitSha, owner: githubRepository.remote.owner, repo: githubRepository.remote.repositoryName });
				const leftUri = toGitHubCommitUri(change.previous_filename ?? change.filename, { commit: parentCommit, owner: githubRepository.remote.owner, repo: githubRepository.remote.repositoryName });
				const changeType = getGitChangeType(change.status);
				if (changeType === GitChangeType.ADD) {
					// For added files, show against empty
					args.push([rightUri, undefined, rightUri]);
				} else if (changeType === GitChangeType.DELETE) {
					// For deleted files, show old version against empty
					args.push([rightUri, leftUri, undefined]);
				} else {
					args.push([rightUri, leftUri, rightUri]);
				}
			}

			/* __GDPR__
				"pr.openCommitChanges" : {}
			*/
			githubRepository.telemetry.sendTelemetryEvent('pr.openCommitChanges');

			return commands.executeCommand('vscode.changes', vscode.l10n.t('Changes in Commit {0}', commitSha.substring(0, 7)), args);
		} catch (error) {
			const errorMessage = error instanceof Error ? error.message : String(error);
			vscode.window.showErrorMessage(vscode.l10n.t('Failed to open commit changes: {0}', errorMessage));
		}
	}

	static async openDiffFromComment(
		folderManager: FolderRepositoryManager,
		pullRequestModel: PullRequestModel,
		comment: IComment,
	): Promise<void> {
		const contentChanges = await pullRequestModel.getFileChangesInfo();
		const change = contentChanges.find(
			fileChange => fileChange.fileName === comment.path || fileChange.previousFileName === comment.path,
		);
		if (!change) {
			throw new Error(`Can't find matching file`);
		}

		const pathSegments = comment.path!.split('/');
		const line = (comment.diffHunks && comment.diffHunks.length > 0) ? comment.diffHunks[0].newLineNumber : undefined;
		this.openDiff(folderManager, pullRequestModel, change, pathSegments[pathSegments.length - 1], line);
	}

	static async openFirstDiff(
		folderManager: FolderRepositoryManager,
		pullRequestModel: PullRequestModel,
	) {
		const contentChanges = await pullRequestModel.getFileChangesInfo();
		if (!contentChanges.length) {
			return;
		}

		const firstChange = contentChanges[0];
		this.openDiff(folderManager, pullRequestModel, firstChange, firstChange.fileName);
	}

	static async openDiff(
		folderManager: FolderRepositoryManager,
		pullRequestModel: PullRequestModel,
		change: SlimFileChange | InMemFileChange,
		diffTitle: string,
		line?: number
	): Promise<void> {
		let headUri, baseUri: vscode.Uri;
		if (!pullRequestModel.equals(folderManager.activePullRequest)) {
			const headCommit = pullRequestModel.head!.sha;
			const parentFileName = change.status === GitChangeType.RENAME ? change.previousFileName! : change.fileName;
			headUri = toPRUri(
				vscode.Uri.file(resolvePath(folderManager.repository.rootUri, change.fileName)),
				pullRequestModel,
				change.baseCommit,
				headCommit,
				change.fileName,
				false,
				change.status,
				change.previousFileName
			);
			baseUri = toPRUri(
				vscode.Uri.file(resolvePath(folderManager.repository.rootUri, parentFileName)),
				pullRequestModel,
				change.baseCommit,
				headCommit,
				change.fileName,
				true,
				change.status,
				change.previousFileName
			);
		} else {
			const uri = vscode.Uri.file(path.resolve(folderManager.repository.rootUri.fsPath, change.fileName));

			headUri =
				change.status === GitChangeType.DELETE
					? toReviewUri(
						uri,
						undefined,
						undefined,
						'',
						false,
						{ base: false },
						folderManager.repository.rootUri,
					)
					: uri;

			const mergeBase = pullRequestModel.mergeBase || pullRequestModel.base.sha;
			baseUri = toReviewUri(
				uri,
				change.status === GitChangeType.RENAME ? change.previousFileName : change.fileName,
				undefined,
				change.status === GitChangeType.ADD ? '' : mergeBase,
				false,
				{ base: true },
				folderManager.repository.rootUri,
			);
		}

		vscode.commands.executeCommand(
			'vscode.diff',
			baseUri,
			headUri,
			`${diffTitle} (Pull Request)`,
			line ? { selection: { start: { line, character: 0 }, end: { line, character: 0 } } } : {},
		);
	}

	private _fileChanges: Map<string, SlimFileChange | InMemFileChange> = new Map();
	get fileChanges(): Map<string, SlimFileChange | InMemFileChange> {
		return this._fileChanges;
	}

	private _rawFileChangesCache: IRawFileChange[] | undefined;
	get rawFileChanges(): IRawFileChange[] | undefined {
		return this._rawFileChangesCache;
	}

	async getFileChangesInfo() {
		this._fileChanges.clear();
		const data = await this.getRawFileChangesInfo();
		const mergebase = this.mergeBase || this.base.sha;
		const parsed = await parseDiff(data, mergebase);
		parsed.forEach(fileChange => {
			this._fileChanges.set(fileChange.fileName, fileChange);
		});
		return parsed;
	}

	async getAllFileChangesInfo(): Promise<{ changes: (InMemFileChange | SlimFileChange)[], mergeBase: string }> {
		const githubRepository = this.githubRepository;
		const { octokit, remote } = await githubRepository.ensure();
		if (this.item.merged) {
			const files = await restPaginate<typeof octokit.api.pulls.listFiles, IRawFileChange>(octokit.api.pulls.listFiles, {
				repo: remote.repositoryName,
				owner: remote.owner,
				pull_number: this.number,
			});
			return { changes: await parseDiff(files, this.base.sha), mergeBase: this.base.sha };
		}

		if (!this.head) {
			throw new Error(`Pull request #${this.number} has no head commit.`);
		}
		const { files, mergeBaseSha } = await compareCommits(remote, octokit, this.base, this.head, this.base.sha, this.number, PullRequestModel.ID);
		return { changes: await parseDiff(files, mergeBaseSha), mergeBase: mergeBaseSha };
	}

	async getPatch(): Promise<string> {
		const githubRepository = this.githubRepository;
		const { octokit, remote } = await githubRepository.ensure();

		const { data } = await octokit.call(octokit.api.pulls.get, {
			owner: remote.owner,
			repo: remote.repositoryName,
			pull_number: this.number,
			mediaType: {
				format: 'diff'
			}
		});

		if (typeof data === 'string') {
			return data;
		} else {
			throw new Error('Expected diff data to be a string');
		}
	}

	public static async getChangeModels(folderManager: FolderRepositoryManager, pullRequestModel: PullRequestModel): Promise<(RemoteFileChangeModel | InMemFileChangeModel)[]> {
		const isCurrentPR = folderManager.activePullRequest?.number === pullRequestModel.number;
		const changes = pullRequestModel.fileChanges.size > 0 ? pullRequestModel.fileChanges.values() : await pullRequestModel.getFileChangesInfo();
		const changeModels: (RemoteFileChangeModel | InMemFileChangeModel)[] = [];
		for (const change of changes) {
			let changeModel;
			if (change instanceof SlimFileChange) {
				changeModel = new RemoteFileChangeModel(folderManager, change, pullRequestModel);
			} else {
				changeModel = new InMemFileChangeModel(folderManager, pullRequestModel as (PullRequestModel & IResolvedPullRequestModel), change, isCurrentPR, pullRequestModel.mergeBase!);
			}
			changeModels.push(changeModel);
		}
		return changeModels;
	}

	/**
	 * List the changed files in a pull request.
	 */
	public async getRawFileChangesInfo(): Promise<IRawFileChange[]> {
		Logger.debug(`Fetch file changes, base, head and merge base of PR #${this.number} - enter`, PullRequestModel.ID);

		const githubRepository = this.githubRepository;
		const { octokit, remote } = await githubRepository.ensure();

		if (!this.base) {
			Logger.appendLine('No base branch found for PR, fetching it now', PullRequestModel.ID);
			Logger.trace(`Fetching from ${remote.owner}/${remote.repositoryName}. PR #${this.number}`, PullRequestModel.ID);
			const info = await octokit.call(octokit.api.pulls.get, {
				owner: remote.owner,
				repo: remote.repositoryName,
				pull_number: this.number,
			});
			this.update(convertRESTPullRequestToRawPullRequest(info.data, githubRepository));
		}

		let compareWithBaseRef = this.base.sha;
		const latestReview = await this.getViewerLatestReviewCommit();
		const oldHasChangesSinceReview = this.hasChangesSinceLastReview;
		this.hasChangesSinceLastReview = latestReview !== undefined && this.head?.sha !== latestReview.sha;

		if (this._showChangesSinceReview && this.hasChangesSinceLastReview && latestReview != undefined) {
			compareWithBaseRef = latestReview.sha;
		}

		if (this.item.merged) {
			Logger.appendLine('PR is merged, fetching all file changes', PullRequestModel.ID);
			const response = await restPaginate<typeof octokit.api.pulls.listFiles, IRawFileChange>(octokit.api.pulls.listFiles, {
				repo: remote.repositoryName,
				owner: remote.owner,
				pull_number: this.number,
			});

			// Use the original base to compare against for merged PRs
			this.mergeBase = this.base.sha;
			this._rawFileChangesCache = response;
			return response;
		}

		Logger.debug(`Comparing commits for ${remote.owner}/${remote.repositoryName} with base ${this.base.repositoryCloneUrl.owner}:${compareWithBaseRef} and head ${this.head!.repositoryCloneUrl.owner}:${this.head!.sha}`, PullRequestModel.ID);
		const { files, mergeBaseSha } = await compareCommits(remote, octokit, this.base, this.head!, compareWithBaseRef, this.number, PullRequestModel.ID);
		this.mergeBase = mergeBaseSha;

		if (oldHasChangesSinceReview !== undefined && oldHasChangesSinceReview !== this.hasChangesSinceLastReview && this.hasChangesSinceLastReview && this._showChangesSinceReview) {
			this._onDidChangeChangesSinceReview.fire();
		}

		Logger.debug(`Fetch file changes and merge base of PR #${this.number} - done, total files ${files.length} `, PullRequestModel.ID,);
		this._rawFileChangesCache = files;
		return files;
	}

	get autoMerge(): boolean {
		return !!this.item.autoMerge;
	}

	get autoMergeMethod(): MergeMethod | undefined {
		return this.item.autoMergeMethod;
	}

	get allowAutoMerge(): boolean {
		return !!this.item.allowAutoMerge;
	}

	get mergeCommitMeta(): { title: string; description: string } | undefined {
		return this.item.mergeCommitMeta;
	}

	get squashCommitMeta(): { title: string; description: string } | undefined {
		return this.item.squashCommitMeta;
	}

	get hasComments(): boolean {
		return this._hasComments;
	}

	/**
	 * Get the current mergeability of the pull request.
	 */
	async getMergeability(): Promise<{ mergeability: PullRequestMergeability, conflicts?: string[] }> {
		try {
			Logger.debug(`Fetch pull request mergeability ${this.number} - enter`, PullRequestModel.ID);
			const { query, remote, schema } = await this.githubRepository.ensure();

			// hard code the users for selfhost purposes
			const { data } = /*(schema.PullRequestMergeabilityMergeRequirements && ((await this.credentialStore.getCurrentUser(this.remote.authProviderId))?.login === 'alexr00')) ? await query<PullRequestMergabilityResponse>({
				query: schema.PullRequestMergeabilityMergeRequirements,
				variables: {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
				},
				context: {
					headers: {
						'GraphQL-Features': 'pull_request_merge_requirements_api' // This flag allows specific users to test a private field.
					}
				}
			}) : */await query<PullRequestMergabilityResponse>({
				query: schema.PullRequestMergeability,
				variables: {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
				}
			});
			if (data.repository === null) {
				Logger.error('Unexpected null repository while getting mergeability', PullRequestModel.ID);
			}

			Logger.debug(`Fetch pull request mergeability ${this.number} - done`, PullRequestModel.ID);
			const mergeability = parseMergeability(data.repository?.pullRequest.mergeable, data.repository?.pullRequest.mergeStateStatus);
			this.item.mergeable = mergeability;
			this.conflicts = data.repository?.pullRequest.mergeRequirements?.conditions.find(condition => condition.__typename === 'PullRequestMergeConflictStateCondition')?.conflicts;
			this.update(this.item);
			return { mergeability, conflicts: this.conflicts };
		} catch (e) {
			Logger.error(`Unable to fetch PR Mergeability: ${e}`, PullRequestModel.ID);
			return { mergeability: PullRequestMergeability.Unknown };
		}
	}

	/**
	 * Set a draft pull request as ready to be reviewed.
	 */
	async setReadyForReview(): Promise<ReadyForReview> {
		try {
			const { mutate, schema } = await this.githubRepository.ensure();

			const { data } = await mutate<MarkPullRequestReadyForReviewResponse>({
				mutation: schema.ReadyForReview,
				variables: {
					input: {
						pullRequestId: this.graphNodeId,
					},
				},
			});

			/* __GDPR__
				"pr.readyForReview.success" : {}
			*/
			this._telemetry.sendTelemetryEvent('pr.readyForReview.success');

			const result: ReadyForReview = {
				isDraft: data!.markPullRequestReadyForReview.pullRequest.isDraft,
				mergeable: parseMergeability(data!.markPullRequestReadyForReview.pullRequest.mergeable, data!.markPullRequestReadyForReview.pullRequest.mergeStateStatus),
				allowAutoMerge: data!.markPullRequestReadyForReview.pullRequest.viewerCanEnableAutoMerge || data!.markPullRequestReadyForReview.pullRequest.viewerCanDisableAutoMerge
			};
			this.item.isDraft = result.isDraft;
			this.item.mergeable = result.mergeable;
			this.item.allowAutoMerge = result.allowAutoMerge;
			this._onDidChange.fire({ draft: true });
			return result;
		} catch (e) {
			/* __GDPR__
				"pr.readyForReview.failure" : {}
			*/
			this._telemetry.sendTelemetryErrorEvent('pr.readyForReview.failure');
			throw e;
		}
	}

	/**
	 * Convert a pull request to draft.
	 */
	async convertToDraft(): Promise<ConvertToDraft> {
		try {
			const { mutate, schema } = await this.githubRepository.ensure();

			const { data } = await mutate<ConvertPullRequestToDraftResponse>({
				mutation: schema.ConvertToDraft,
				variables: {
					input: {
						pullRequestId: this.graphNodeId,
					},
				},
			});

			/* __GDPR__
				"pr.convertToDraft.success" : {}
			*/
			this._telemetry.sendTelemetryEvent('pr.convertToDraft.success');

			const result: ConvertToDraft = {
				isDraft: data!.convertPullRequestToDraft.pullRequest.isDraft,
				mergeable: parseMergeability(data!.convertPullRequestToDraft.pullRequest.mergeable, data!.convertPullRequestToDraft.pullRequest.mergeStateStatus),
			};
			this.item.isDraft = result.isDraft;
			this.item.mergeable = result.mergeable;
			this._onDidChange.fire({ draft: true });
			return result;
		} catch (e) {
			/* __GDPR__
				"pr.convertToDraft.failure" : {}
			*/
			this._telemetry.sendTelemetryErrorEvent('pr.convertToDraft.failure');
			throw e;
		}
	}

	private updateCommentReactions(graphNodeId: string, reactionGroups: ReactionGroup[]) {
		const reviewThread = this._reviewThreadsCache?.find(thread =>
			thread.comments.some(c => c.graphNodeId === graphNodeId),
		);
		if (reviewThread) {
			const updatedComment = reviewThread.comments.find(c => c.graphNodeId === graphNodeId);
			if (updatedComment) {
				updatedComment.reactions = parseGraphQLReaction(reactionGroups);
				this._onDidChangeReviewThreads.fire({ added: [], changed: [reviewThread], removed: [] });
			}
		}
	}

	async addCommentReaction(graphNodeId: string, reaction: vscode.CommentReaction): Promise<AddReactionResponse | undefined> {
		const reactionEmojiToContent = getReactionGroup().reduce((prev, curr) => {
			prev[curr.label] = curr.title;
			return prev;
		}, {} as { [key: string]: string });
		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<AddReactionResponse>({
			mutation: schema.AddReaction,
			variables: {
				input: {
					subjectId: graphNodeId,
					content: reactionEmojiToContent[reaction.label!],
				},
			},
		});

		if (!data) {
			throw new Error('Add comment reaction failed.');
		}

		const reactionGroups = data.addReaction.subject.reactionGroups;
		this.updateCommentReactions(graphNodeId, reactionGroups);

		return data;
	}

	async deleteCommentReaction(
		graphNodeId: string,
		reaction: vscode.CommentReaction,
	): Promise<DeleteReactionResponse | undefined> {
		const reactionEmojiToContent = getReactionGroup().reduce((prev, curr) => {
			prev[curr.label] = curr.title;
			return prev;
		}, {} as { [key: string]: string });
		const { mutate, schema } = await this.githubRepository.ensure();
		const { data } = await mutate<DeleteReactionResponse>({
			mutation: schema.DeleteReaction,
			variables: {
				input: {
					subjectId: graphNodeId,
					content: reactionEmojiToContent[reaction.label!],
				},
			},
		});

		if (!data) {
			throw new Error('Delete comment reaction failed.');
		}

		const reactionGroups = data.removeReaction.subject.reactionGroups;
		this.updateCommentReactions(graphNodeId, reactionGroups);

		return data;
	}

	private undoOptimisticResolveState(oldThread: IReviewThread | undefined) {
		if (oldThread) {
			oldThread.isResolved = !oldThread.isResolved;
			oldThread.viewerCanResolve = !oldThread.viewerCanResolve;
			oldThread.viewerCanUnresolve = !oldThread.viewerCanUnresolve;
			this._onDidChangeReviewThreads.fire({ added: [], changed: [oldThread], removed: [] });
		}
	}

	async resolveReviewThread(threadId: string): Promise<void> {
		const oldThread = this._reviewThreadsCache?.find(thread => thread.id === threadId);

		try {
			Logger.debug(`Resolve review thread - enter`, PullRequestModel.ID);

			const { mutate, schema } = await this.githubRepository.ensure();

			// optimistically update
			if (oldThread && oldThread.viewerCanResolve) {
				oldThread.isResolved = true;
				oldThread.viewerCanResolve = false;
				oldThread.viewerCanUnresolve = true;
				this._onDidChangeReviewThreads.fire({ added: [], changed: [oldThread], removed: [] });
			}

			const { data } = await mutate<ResolveReviewThreadResponse>({
				mutation: schema.ResolveReviewThread,
				variables: {
					input: {
						threadId,
					},
				},
			}, { mutation: schema.LegacyResolveReviewThread, deleteProps: [] });

			if (!data) {
				this.undoOptimisticResolveState(oldThread);
				throw new Error('Resolve review thread failed.');
			}

			const index = this._reviewThreadsCache?.findIndex(thread => thread.id === threadId) ?? -1;
			if (index > -1) {
				const thread = parseGraphQLReviewThread(data.resolveReviewThread.thread, this.githubRepository);
				this._reviewThreadsCache?.splice(index, 1, thread);
				this._onDidChangeReviewThreads.fire({ added: [], changed: [thread], removed: [] });
			}
			Logger.debug(`Resolve review thread - done`, PullRequestModel.ID);
		} catch (e) {
			Logger.error(`Resolve review thread failed: ${e}`, PullRequestModel.ID);
			this.undoOptimisticResolveState(oldThread);
		}
	}

	async unresolveReviewThread(threadId: string): Promise<void> {
		const oldThread = this._reviewThreadsCache?.find(thread => thread.id === threadId);

		try {
			Logger.debug(`Unresolve review thread - enter`, PullRequestModel.ID);

			const { mutate, schema } = await this.githubRepository.ensure();

			// optimistically update
			if (oldThread && oldThread.viewerCanUnresolve) {
				oldThread.isResolved = false;
				oldThread.viewerCanUnresolve = false;
				oldThread.viewerCanResolve = true;
				this._onDidChangeReviewThreads.fire({ added: [], changed: [oldThread], removed: [] });
			}

			const { data } = await mutate<UnresolveReviewThreadResponse>({
				mutation: schema.UnresolveReviewThread,
				variables: {
					input: {
						threadId,
					},
				},
			}, { mutation: schema.LegacyUnresolveReviewThread, deleteProps: [] });

			if (!data) {
				this.undoOptimisticResolveState(oldThread);
				throw new Error('Unresolve review thread failed.');
			}

			const index = this._reviewThreadsCache?.findIndex(thread => thread.id === threadId) ?? -1;
			if (index > -1) {
				const thread = parseGraphQLReviewThread(data.unresolveReviewThread.thread, this.githubRepository);
				this._reviewThreadsCache?.splice(index, 1, thread);
				this._onDidChangeReviewThreads.fire({ added: [], changed: [thread], removed: [] });
			}
			Logger.debug(`Unresolve review thread - done`, PullRequestModel.ID);
		} catch (e) {
			Logger.error(`Unresolve review thread failed: ${e}`, PullRequestModel.ID);
			this.undoOptimisticResolveState(oldThread);
		}
	}

	async enableAutoMerge(mergeMethod: MergeMethod): Promise<void> {
		try {
			const { mutate, schema } = await this.githubRepository.ensure();
			const { data } = await mutate({
				mutation: schema.EnablePullRequestAutoMerge,
				variables: {
					input: {
						mergeMethod: mergeMethod.toUpperCase(),
						pullRequestId: this.graphNodeId
					}
				}
			});

			if (!data) {
				throw new Error('Enable auto-merge failed.');
			}
			this.item.autoMerge = true;
			this.item.autoMergeMethod = mergeMethod;
		} catch (e) {
			if (e.message === 'GraphQL error: ["Pull request Pull request is in clean status"]') {
				vscode.window.showWarningMessage(vscode.l10n.t('Unable to enable auto-merge. Pull request status checks are already green.'));
			} else {
				throw e;
			}
		}
	}

	async disableAutoMerge(): Promise<void> {
		try {
			const { mutate, schema } = await this.githubRepository.ensure();
			const { data } = await mutate({
				mutation: schema.DisablePullRequestAutoMerge,
				variables: {
					input: {
						pullRequestId: this.graphNodeId
					}
				}
			});

			if (!data) {
				throw new Error('Disable auto-merge failed.');
			}
			this.item.autoMerge = false;
		} catch (e) {
			if (e.message === 'GraphQL error: ["Pull request Pull request is in clean status"]') {
				vscode.window.showWarningMessage(vscode.l10n.t('Unable to enable auto-merge. Pull request status checks are already green.'));
			} else {
				throw e;
			}
		}
	}

	async dequeuePullRequest(): Promise<boolean> {
		Logger.debug(`Dequeue pull request ${this.number} - enter`, GitHubRepository.ID);
		const { mutate, schema } = await this.githubRepository.ensure();
		if (!schema.DequeuePullRequest) {
			return false;
		}
		try {
			await mutate<DequeuePullRequestResponse>({
				mutation: schema.DequeuePullRequest,
				variables: {
					input: {
						id: this.graphNodeId
					}
				}
			});

			Logger.debug(`Dequeue pull request ${this.number} - done`, GitHubRepository.ID);
			this.mergeQueueEntry = undefined;
			return true;
		} catch (e) {
			Logger.error(`Dequeueing pull request failed: ${e}`, GitHubRepository.ID);
			return false;
		}
	}

	async enqueuePullRequest(): Promise<MergeQueueEntry | undefined> {
		Logger.debug(`Enqueue pull request ${this.number} - enter`, GitHubRepository.ID);
		const { mutate, schema } = await this.githubRepository.ensure();
		if (!schema.EnqueuePullRequest) {
			return;
		}
		try {
			const { data } = await mutate<EnqueuePullRequestResponse>({
				mutation: schema.EnqueuePullRequest,
				variables: {
					input: {
						pullRequestId: this.graphNodeId
					}
				}
			});

			Logger.debug(`Enqueue pull request ${this.number} - done`, GitHubRepository.ID);
			const temp = parseMergeQueueEntry(data?.enqueuePullRequest.mergeQueueEntry) ?? undefined;
			return temp;
		} catch (e) {
			Logger.error(`Enqueuing pull request failed: ${e}`, GitHubRepository.ID);
		}
	}

	async initializePullRequestFileViewState(): Promise<void> {
		const { query, schema, remote } = await this.githubRepository.ensure();

		const changed: { fileName: string, viewed: ViewedState }[] = [];
		let after: string | null = null;
		let hasNextPage = false;

		do {
			const { data } = await query<PullRequestFilesResponse>({
				query: schema.PullRequestFiles,
				variables: {
					owner: remote.owner,
					name: remote.repositoryName,
					number: this.number,
					after: after,
				},
			});

			data.repository.pullRequest.files.nodes.forEach(n => {
				if (this._fileChangeViewedState[n.path] !== n.viewerViewedState) {
					changed.push({ fileName: n.path, viewed: n.viewerViewedState });
				}
				// No event for setting the file viewed state here.
				// Instead, wait until all the changes have been made and set the context at the end.
				this.setFileViewedState(n.path, n.viewerViewedState, false);
			});

			hasNextPage = data.repository.pullRequest.files.pageInfo.hasNextPage;
			after = data.repository.pullRequest.files.pageInfo.endCursor;
		} while (hasNextPage);

		if (changed.length) {
			this._onDidChangeFileViewedState.fire({ changed });
		}
	}

	private markFilesInProgressRefCount: Map<string, number> = new Map();
	private updateMarkFilesInProgressRefCount(filePathOrSubpaths: string[], direction: 'increment' | 'decrement'): string[] {
		const completed: string[] = [];
		for (const f of filePathOrSubpaths) {
			let count = this.markFilesInProgressRefCount.get(f) || 0;
			if (direction === 'increment') {
				count++;
			} else {
				count--;
			}
			if (count === 0) {
				this.markFilesInProgressRefCount.delete(f);
				completed.push(f);
			} else {
				this.markFilesInProgressRefCount.set(f, count);
			}
		}
		return completed;
	}

	async markFiles(filePathOrSubpaths: string[], event: boolean, state: 'viewed' | 'unviewed'): Promise<void> {
		const allFilenames = filePathOrSubpaths
			.map((f) =>
				isDescendant(this.githubRepository.rootUri.path, f, false, '/')
					? f.substring(this.githubRepository.rootUri.path.length + 1)
					: f
			);

		this.updateMarkFilesInProgressRefCount(allFilenames, 'increment');

		const { mutate } = await this.githubRepository.ensure();
		const pullRequestId = this.graphNodeId;

		const mutationName = state === 'viewed'
			? 'markFileAsViewed'
			: 'unmarkFileAsViewed';

		// We only ever send 100 mutations at once. Any more than this and
		// we risk a timeout from GitHub.
		for (let i = 0; i < allFilenames.length; i += BATCH_SIZE) {
			try {
				const batch = allFilenames.slice(i, i + BATCH_SIZE);
				// See below for an example of what a mutation produced by this
				// will look like
				const mutation = gql`mutation Batch${mutationName}{
					${batch.map((filename, i) =>
					`alias${i}: ${mutationName}(
							input: {path: "${filename}", pullRequestId: "${pullRequestId}"}
						) { clientMutationId }
						`
				)}
				}`;
				await mutate<void>({ mutation });
			} catch (e) {
				Logger.error(`Error marking files as ${state}: ${e}`, PullRequestModel.ID);
			}
		}

		// mutation BatchUnmarkFileAsViewedInline {
		// 	alias0: unmarkFileAsViewed(
		// 	  input: { path: "some_folder/subfolder/A.txt", pullRequestId: "PR_someid" }
		// 	) {
		// 	  clientMutationId
		// 	}
		// 	alias1: unmarkFileAsViewed(
		// 	  input: { path: "some_folder/subfolder/B.txt", pullRequestId: "PR_someid" }
		// 	) {
		// 	  clientMutationId
		// 	}
		// }

		// We keep a ref count of the files who's states are in the process of being modified so that we don't have UI flickering
		const completed = this.updateMarkFilesInProgressRefCount(allFilenames, 'decrement');
		completed.forEach(path => this.setFileViewedState(path, state === 'viewed' ? ViewedState.VIEWED : ViewedState.UNVIEWED, event));
	}

	async unmarkAllFilesAsViewed(): Promise<void> {
		return this.markFiles(Array.from(this.fileChanges.keys()), true, 'unviewed');
	}

	private setFileViewedState(fileSubpath: string, viewedState: ViewedState, event: boolean) {
		const uri = vscode.Uri.joinPath(this.githubRepository.rootUri, fileSubpath);
		const filePath = (this.githubRepository.rootUri.scheme === Schemes.VscodeVfs) ? uri.path : uri.fsPath;
		switch (viewedState) {
			case ViewedState.DISMISSED: {
				this._viewedFiles.delete(filePath);
				this._unviewedFiles.delete(filePath);
				break;
			}
			case ViewedState.UNVIEWED: {
				this._viewedFiles.delete(filePath);
				this._unviewedFiles.add(filePath);
				break;
			}
			case ViewedState.VIEWED: {
				this._viewedFiles.add(filePath);
				this._unviewedFiles.delete(filePath);
			}
		}
		this._fileChangeViewedState[fileSubpath] = viewedState;
		if (event) {
			this._onDidChangeFileViewedState.fire({ changed: [{ fileName: fileSubpath, viewed: viewedState }] });
		}
	}

	public getViewedFileStates() {
		return {
			viewed: this._viewedFiles,
			unviewed: this._unviewedFiles
		};
	}
}

export async function isCopilotOnMyBehalf(pullRequestModel: PullRequestModel, currentUser: IAccount, coAuthors?: IAccount[]): Promise<boolean> {
	if (!COPILOT_ACCOUNTS[pullRequestModel.author.login]) {
		return false;
	}

	if (!coAuthors) {
		coAuthors = await pullRequestModel.getCoAuthors();
	}
	if (!coAuthors || coAuthors.length === 0) {
		return false;
	}

	return coAuthors.some(c => c.login === currentUser.login);
}