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

import * as nls from 'vscode-nls';
import * as vscode from 'vscode';
import fetch, { Response } from 'node-fetch';
import { v4 as uuid } from 'uuid';
import { PromiseAdapter, promiseFromEvent } from './common/utils';
import Logger from './common/logger';
import { ExperimentationTelemetry } from './experimentationService';

const localize = nls.loadMessageBundle();

export const NETWORK_ERROR = 'network error';
<<<<<<< HEAD
const AUTH_RELAY_SERVER = 'auth.code-server.dev';
=======
const AUTH_RELAY_SERVER = 'vscode-auth.github.com';
// const AUTH_RELAY_STAGING_SERVER = 'client-auth-staging-14a768b.herokuapp.com';
>>>>>>> 58ce849223667f77dc0d6d7658870ca3f815e17f

class UriEventHandler extends vscode.EventEmitter<vscode.Uri> implements vscode.UriHandler {
	public handleUri(uri: vscode.Uri) {
		this.fire(uri);
	}
}

export const uriHandler = new UriEventHandler;

const onDidManuallyProvideToken = new vscode.EventEmitter<string | undefined>();



function parseQuery(uri: vscode.Uri) {
	return uri.query.split('&').reduce((prev: any, current) => {
		const queryString = current.split('=');
		prev[queryString[0]] = queryString[1];
		return prev;
	}, {});
}

export class GitHubServer {
	private _statusBarItem: vscode.StatusBarItem | undefined;

	private _pendingStates = new Map<string, string[]>();
	private _codeExchangePromises = new Map<string, { promise: Promise<string>, cancel: vscode.EventEmitter<void> }>();

	constructor(private readonly telemetryReporter: ExperimentationTelemetry) { }

	private isTestEnvironment(url: vscode.Uri): boolean {
		return /\.azurewebsites\.net$/.test(url.authority) || url.authority.startsWith('localhost:');
	}

	// TODO@joaomoreno TODO@RMacfarlane
	private async isNoCorsEnvironment(): Promise<boolean> {
		const uri = await vscode.env.asExternalUri(vscode.Uri.parse(`${vscode.env.uriScheme}://vscode.github-authentication/did-authenticate`));
		return uri.scheme === 'https' && /^vscode\./.test(uri.authority);
	}

	public async login(scopes: string): Promise<string> {
		Logger.info('Logging in...');
		this.updateStatusBarItem(true);

		const state = uuid();

		// TODO@joaomoreno TODO@RMacfarlane
		const nocors = await this.isNoCorsEnvironment();
		const callbackUri = await vscode.env.asExternalUri(vscode.Uri.parse(`${vscode.env.uriScheme}://vscode.github-authentication/did-authenticate${nocors ? '?nocors=true' : ''}`));

		if (this.isTestEnvironment(callbackUri)) {
			const token = await vscode.window.showInputBox({ prompt: 'GitHub Personal Access Token', ignoreFocusOut: true });
			if (!token) { throw new Error('Sign in failed: No token provided'); }

			const tokenScopes = await this.getScopes(token); // Example: ['repo', 'user']
			const scopesList = scopes.split(' '); // Example: 'read:user repo user:email'
			if (!scopesList.every(scope => {
				const included = tokenScopes.includes(scope);
				if (included || !scope.includes(':')) {
					return included;
				}

				return scope.split(':').some(splitScopes => {
					return tokenScopes.includes(splitScopes);
				});
			})) {
				throw new Error(`The provided token is does not match the requested scopes: ${scopes}`);
			}

			this.updateStatusBarItem(false);
			return token;
		} else {
			const existingStates = this._pendingStates.get(scopes) || [];
			this._pendingStates.set(scopes, [...existingStates, state]);

			const uri = vscode.Uri.parse(`https://${AUTH_RELAY_SERVER}/authorize/?callbackUri=${encodeURIComponent(callbackUri.toString())}&scope=${scopes}&state=${state}&responseType=code&authServer=https://github.com${nocors ? '&nocors=true' : ''}`);
			await vscode.env.openExternal(uri);
		}

		// Register a single listener for the URI callback, in case the user starts the login process multiple times
		// before completing it.
		let codeExchangePromise = this._codeExchangePromises.get(scopes);
		if (!codeExchangePromise) {
			codeExchangePromise = promiseFromEvent(uriHandler.event, this.exchangeCodeForToken(scopes));
			this._codeExchangePromises.set(scopes, codeExchangePromise);
		}

		return Promise.race([
			codeExchangePromise.promise,
			promiseFromEvent<string | undefined, string>(onDidManuallyProvideToken.event, (token: string | undefined, resolve, reject): void => {
				if (!token) {
					reject('Cancelled');
				} else {
					resolve(token);
				}
			}).promise
		]).finally(() => {
			this._pendingStates.delete(scopes);
			codeExchangePromise?.cancel.fire();
			this._codeExchangePromises.delete(scopes);
			this.updateStatusBarItem(false);
		});
	}

	private exchangeCodeForToken: (scopes: string) => PromiseAdapter<vscode.Uri, string> =
		(scopes) => async (uri, resolve, reject) => {
			Logger.info('Exchanging code for token...');
			const query = parseQuery(uri);
			const code = query.code;

			const acceptedStates = this._pendingStates.get(scopes) || [];
			if (!acceptedStates.includes(query.state)) {
				reject('Received mismatched state');
				return;
			}

			const url = `https://${AUTH_RELAY_SERVER}/token?code=${code}&state=${query.state}`;

			// TODO@joao: remove
			if (query.nocors) {
				try {
					const json: any = await vscode.commands.executeCommand('_workbench.fetchJSON', url, 'POST');
					Logger.info('Token exchange success!');
					resolve(json.access_token);
				} catch (err) {
					reject(err);
				}
			} else {
				try {
					const result = await fetch(url, {
						method: 'POST',
						headers: {
							Accept: 'application/json'
						}
					});

					if (result.ok) {
						const json = await result.json();
						Logger.info('Token exchange success!');
						resolve(json.access_token);
					} else {
						reject(result.statusText);
					}
				} catch (ex) {
					reject(ex);
				}
			}
		};

	private updateStatusBarItem(isStart?: boolean) {
		if (isStart && !this._statusBarItem) {
			this._statusBarItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Left);
			this._statusBarItem.text = localize('signingIn', "$(mark-github) Signing in to github.com...");
			this._statusBarItem.command = 'github.provide-token';
			this._statusBarItem.show();
		}

		if (!isStart && this._statusBarItem) {
			this._statusBarItem.dispose();
			this._statusBarItem = undefined;
		}
	}

	public async manuallyProvideToken() {
		const uriOrToken = await vscode.window.showInputBox({ prompt: 'Token', ignoreFocusOut: true });
		if (!uriOrToken) {
			onDidManuallyProvideToken.fire(undefined);
			return;
		}

		try {
			const uri = vscode.Uri.parse(uriOrToken.trim());
			if (!uri.scheme || uri.scheme === 'file') { throw new Error; }
			uriHandler.handleUri(uri);
		} catch (e) {
			// If it doesn't look like a URI, treat it as a token.
			Logger.info('Treating input as token');
			onDidManuallyProvideToken.fire(uriOrToken);
		}
	}

	private async getScopes(token: string): Promise<string[]> {
		try {
			Logger.info('Getting token scopes...');
			const result = await fetch('https://api.github.com', {
				headers: {
					Authorization: `token ${token}`,
					'User-Agent': 'Visual-Studio-Code'
				}
			});

			if (result.ok) {
				const scopes = result.headers.get('X-OAuth-Scopes');
				return scopes ? scopes.split(',').map(scope => scope.trim()) : [];
			} else {
				Logger.error(`Getting scopes failed: ${result.statusText}`);
				throw new Error(result.statusText);
			}
		} catch (ex) {
			Logger.error(ex.message);
			throw new Error(NETWORK_ERROR);
		}
	}

	public async getUserInfo(token: string): Promise<{ id: string, accountName: string }> {
		let result: Response;
		try {
			Logger.info('Getting user info...');
			result = await fetch('https://api.github.com/user', {
				headers: {
					Authorization: `token ${token}`,
					'User-Agent': 'Visual-Studio-Code'
				}
			});
		} catch (ex) {
			Logger.error(ex.message);
			throw new Error(NETWORK_ERROR);
		}

		if (result.ok) {
			const json = await result.json();
			Logger.info('Got account info!');
			return { id: json.id, accountName: json.login };
		} else {
			Logger.error(`Getting account info failed: ${result.statusText}`);
			throw new Error(result.statusText);
		}
	}

	public async checkIsEdu(token: string): Promise<void> {
		const nocors = await this.isNoCorsEnvironment();

		if (nocors) {
			return;
		}

		try {
			const result = await fetch('https://education.github.com/api/user', {
				headers: {
					Authorization: `token ${token}`,
					'faculty-check-preview': 'true',
					'User-Agent': 'Visual-Studio-Code'
				}
			});

			if (result.ok) {
				const json: { student: boolean, faculty: boolean } = await result.json();

				/* __GDPR__
					"session" : {
						"isEdu": { "classification": "NonIdentifiableDemographicInfo", "purpose": "FeatureInsight" }
					}
				*/
				this.telemetryReporter.sendTelemetryEvent('session', {
					isEdu: json.student
						? 'student'
						: json.faculty
							? 'faculty'
							: 'none'
				});
			}
		} catch (e) {
			// No-op
		}

	}
}