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

import { Command, l10n, LogOutputChannel, workspace } from 'vscode';
import { Commit, Repository as GitHubRepository, Maybe } from '@octokit/graphql-schema';
import type { API, AvatarQuery, AvatarQueryCommit, Repository, SourceControlHistoryItemDetailsProvider } from './typings/git.d.ts';
import { DisposableStore, getRepositoryDefaultRemote, getRepositoryDefaultRemoteUrl, getRepositoryFromUrl, groupBy, sequentialize } from './util.js';
import { AuthenticationError, OctokitService } from './auth.js';
import { getAvatarLink } from './links.js';

const ISSUE_EXPRESSION = /(([A-Za-z0-9_.\-]+)\/([A-Za-z0-9_.\-]+))?(#|GH-)([1-9][0-9]*)($|\b)/g;

const ASSIGNABLE_USERS_QUERY = `
	query assignableUsers($owner: String!, $repo: String!) {
		repository(owner: $owner, name: $repo) {
			assignableUsers(first: 100) {
				nodes {
					id
					login
					name
					email
					avatarUrl
				}
			}
		}
	}
`;

const COMMIT_AUTHOR_QUERY = `
	query commitAuthor($owner: String!, $repo: String!, $commit: String!) {
		repository(owner: $owner, name: $repo) {
			object(expression: $commit) {
				... on Commit {
					author {
						name
						email
						avatarUrl
						user {
							id
							login
						}
					}
				}
			}
		}
	}
`;

interface GitHubRepositoryStore {
	readonly users: GitHubUser[];
	readonly commits: Set<string>;
}

interface GitHubUser {
	readonly id: string;
	readonly login: string;
	readonly name?: Maybe<string>;
	readonly email: string;
	readonly avatarUrl: string;
}

function getUserIdFromNoReplyEmail(email: string | undefined): string | undefined {
	const match = email?.match(/^([0-9]+)\+[^@]+@users\.noreply\.github\.com$/);
	return match?.[1];
}

function compareAvatarQuery(a: AvatarQueryCommit, b: AvatarQueryCommit): number {
	// Email
	const emailComparison = (a.authorEmail ?? '').localeCompare(b.authorEmail ?? '');
	if (emailComparison !== 0) {
		return emailComparison;
	}

	// Name
	return (a.authorName ?? '').localeCompare(b.authorName ?? '');
}

export class GitHubSourceControlHistoryItemDetailsProvider implements SourceControlHistoryItemDetailsProvider {
	private _isUserAuthenticated = true;
	private readonly _store = new Map<string, GitHubRepositoryStore>();
	private readonly _disposables = new DisposableStore();

	constructor(
		private readonly _gitAPI: API,
		private readonly _octokitService: OctokitService,
		private readonly _logger: LogOutputChannel
	) {
		this._disposables.add(this._gitAPI.onDidCloseRepository(repository => this._onDidCloseRepository(repository)));

		this._disposables.add(this._octokitService.onDidChangeSessions(() => {
			this._isUserAuthenticated = true;
			this._store.clear();
		}));

		this._disposables.add(workspace.onDidChangeConfiguration(e => {
			if (!e.affectsConfiguration('github.showAvatar')) {
				return;
			}

			this._store.clear();
		}));
	}

	async provideAvatar(repository: Repository, query: AvatarQuery): Promise<Map<string, string | undefined> | undefined> {
		this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][provideAvatar] Avatar resolution for ${query.commits.length} commit(s) in ${repository.rootUri.fsPath}.`);

		const config = workspace.getConfiguration('github', repository.rootUri);
		const showAvatar = config.get<boolean>('showAvatar', true) === true;

		if (!this._isUserAuthenticated || !showAvatar) {
			this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][provideAvatar] Avatar resolution is disabled. (${showAvatar === false ? 'setting' : 'auth'})`);
			return undefined;
		}

		// upstream -> origin -> first
		const descriptor = getRepositoryDefaultRemote(repository, ['upstream', 'origin']);
		if (!descriptor) {
			this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][provideAvatar] Repository does not have a GitHub remote.`);
			return undefined;
		}

		try {
			const logs = { cached: 0, email: 0, github: 0, incomplete: 0 };

			// Warm up the in-memory cache with the first page
			// (100 users) from this list of assignable users
			await this._loadAssignableUsers(descriptor);

			const repositoryStore = this._store.get(this._getRepositoryKey(descriptor));
			if (!repositoryStore) {
				return undefined;
			}

			// Group the query by author
			const authorQuery = groupBy<AvatarQueryCommit>(query.commits, compareAvatarQuery);

			const results = new Map<string, string | undefined>();
			await Promise.all(authorQuery.map(async commits => {
				if (commits.length === 0) {
					return;
				}

				// Query the in-memory cache for the user
				const avatarUrl = repositoryStore.users.find(
					user => user.email === commits[0].authorEmail || user.name === commits[0].authorName)?.avatarUrl;

				// Cache hit
				if (avatarUrl) {
					// Add avatar for each commit
					logs.cached += commits.length;
					commits.forEach(({ hash }) => results.set(hash, `${avatarUrl}&s=${query.size}`));
					return;
				}

				// Check if any of the commit are being tracked in the list
				// of known commits that have incomplte author information
				if (commits.some(({ hash }) => repositoryStore.commits.has(hash))) {
					commits.forEach(({ hash }) => results.set(hash, undefined));
					return;
				}

				// Try to extract the user identifier from GitHub no-reply emails
				const userIdFromEmail = getUserIdFromNoReplyEmail(commits[0].authorEmail);
				if (userIdFromEmail) {
					logs.email += commits.length;
					const avatarUrl = getAvatarLink(userIdFromEmail, query.size);
					commits.forEach(({ hash }) => results.set(hash, avatarUrl));
					return;
				}

				// Get the commit details
				const commitAuthor = await this._getCommitAuthor(descriptor, commits[0].hash);
				if (!commitAuthor) {
					// The commit has incomplete author information, so
					// we should not try to query the authors details again
					logs.incomplete += commits.length;
					for (const { hash } of commits) {
						repositoryStore.commits.add(hash);
						results.set(hash, undefined);
					}
					return;
				}

				// Save the user to the cache
				repositoryStore.users.push(commitAuthor);

				// Add avatar for each commit
				logs.github += commits.length;
				commits.forEach(({ hash }) => results.set(hash, `${commitAuthor.avatarUrl}&s=${query.size}`));
			}));

			this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][provideAvatar] Avatar resolution for ${query.commits.length} commit(s) in ${repository.rootUri.fsPath} complete: ${JSON.stringify(logs)}.`);

			return results;
		} catch (err) {
			// A GitHub authentication session could be missing if the user has not yet
			// signed in with their GitHub account or they have signed out. Disable the
			// avatar resolution until the user signes in with their GitHub account.
			if (err instanceof AuthenticationError) {
				this._isUserAuthenticated = false;
			}

			return undefined;
		}
	}

	async provideHoverCommands(repository: Repository): Promise<Command[] | undefined> {
		// origin -> upstream -> first
		const url = getRepositoryDefaultRemoteUrl(repository, ['origin', 'upstream']);
		if (!url) {
			return undefined;
		}

		return [{
			title: l10n.t('{0} Open on GitHub', '$(github)'),
			tooltip: l10n.t('Open on GitHub'),
			command: 'github.openOnGitHub',
			arguments: [url]
		}];
	}

	async provideMessageLinks(repository: Repository, message: string): Promise<string | undefined> {
		// upstream -> origin -> first
		const descriptor = getRepositoryDefaultRemote(repository, ['upstream', 'origin']);
		if (!descriptor) {
			return undefined;
		}

		return message.replace(
			ISSUE_EXPRESSION,
			(match, _group1, owner: string | undefined, repo: string | undefined, _group2, number: string | undefined) => {
				if (!number || Number.isNaN(parseInt(number))) {
					return match;
				}

				const label = owner && repo
					? `${owner}/${repo}#${number}`
					: `#${number}`;

				owner = owner ?? descriptor.owner;
				repo = repo ?? descriptor.repo;

				return `[${label}](https://github.com/${owner}/${repo}/issues/${number})`;
			});
	}

	private _onDidCloseRepository(repository: Repository) {
		for (const remote of repository.state.remotes) {
			if (!remote.fetchUrl) {
				continue;
			}

			const repository = getRepositoryFromUrl(remote.fetchUrl);
			if (!repository) {
				continue;
			}

			this._store.delete(this._getRepositoryKey(repository));
		}
	}

	@sequentialize
	private async _loadAssignableUsers(descriptor: { owner: string; repo: string }): Promise<void> {
		if (this._store.has(this._getRepositoryKey(descriptor))) {
			return;
		}

		this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][_loadAssignableUsers] Querying assignable user(s) for ${descriptor.owner}/${descriptor.repo}.`);

		try {
			const graphql = await this._octokitService.getOctokitGraphql();
			const { repository } = await graphql<{ repository: GitHubRepository }>(ASSIGNABLE_USERS_QUERY, descriptor);

			const users: GitHubUser[] = [];
			for (const node of repository.assignableUsers.nodes ?? []) {
				if (!node) {
					continue;
				}

				users.push({
					id: node.id,
					login: node.login,
					name: node.name,
					email: node.email,
					avatarUrl: node.avatarUrl,
				} satisfies GitHubUser);
			}

			this._store.set(this._getRepositoryKey(descriptor), { users, commits: new Set() });
			this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][_loadAssignableUsers] Successfully queried assignable user(s) for ${descriptor.owner}/${descriptor.repo}: ${users.length} user(s).`);
		} catch (err) {
			this._logger.warn(`[GitHubSourceControlHistoryItemDetailsProvider][_loadAssignableUsers] Failed to load assignable user(s) for ${descriptor.owner}/${descriptor.repo}: ${err}`);
			throw err;
		}
	}

	private async _getCommitAuthor(descriptor: { owner: string; repo: string }, commit: string): Promise<GitHubUser | undefined> {
		this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][_getCommitAuthor] Querying commit author for ${descriptor.owner}/${descriptor.repo}/${commit}.`);

		try {
			const graphql = await this._octokitService.getOctokitGraphql();
			const { repository } = await graphql<{ repository: GitHubRepository }>(COMMIT_AUTHOR_QUERY, { ...descriptor, commit });

			const commitAuthor = (repository.object as Commit).author;
			if (!commitAuthor?.user?.id || !commitAuthor.user?.login ||
				!commitAuthor?.name || !commitAuthor?.email || !commitAuthor?.avatarUrl) {
				this._logger.info(`[GitHubSourceControlHistoryItemDetailsProvider][_getCommitAuthor] Incomplete commit author for ${descriptor.owner}/${descriptor.repo}/${commit}: ${JSON.stringify(repository.object)}`);

				return undefined;
			}

			const user = {
				id: commitAuthor.user.id,
				login: commitAuthor.user.login,
				name: commitAuthor.name,
				email: commitAuthor.email,
				avatarUrl: commitAuthor.avatarUrl,
			} satisfies GitHubUser;

			this._logger.trace(`[GitHubSourceControlHistoryItemDetailsProvider][_getCommitAuthor] Successfully queried commit author for ${descriptor.owner}/${descriptor.repo}/${commit}: ${user.login}.`);
			return user;
		} catch (err) {
			this._logger.warn(`[GitHubSourceControlHistoryItemDetailsProvider][_getCommitAuthor] Failed to get commit author for ${descriptor.owner}/${descriptor.repo}/${commit}: ${err}`);
			throw err;
		}
	}

	private _getRepositoryKey(descriptor: { owner: string; repo: string }): string {
		return `${descriptor.owner}/${descriptor.repo}`;
	}

	dispose(): void {
		this._disposables.dispose();
	}
}