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

import * as cookie from 'cookie';
import * as fs from 'fs';
import * as http from 'http';
import * as url from 'url';
import * as path from '../../base/common/path.js';
import { generateUuid } from '../../base/common/uuid.js';
import { connectionTokenCookieName, connectionTokenQueryName } from '../../base/common/network.js';
import { ServerParsedArgs } from './serverEnvironmentService.js';
import { Promises } from '../../base/node/pfs.js';

const connectionTokenRegex = /^[0-9A-Za-z_-]+$/;

export const enum ServerConnectionTokenType {
	None,
	Optional,// TODO: Remove this soon
	Mandatory
}

export class NoneServerConnectionToken {
	public readonly type = ServerConnectionTokenType.None;

	public validate(connectionToken: unknown): boolean {
		return true;
	}
}

export class MandatoryServerConnectionToken {
	public readonly type = ServerConnectionTokenType.Mandatory;

	constructor(public readonly value: string) {
	}

	public validate(connectionToken: unknown): boolean {
		return (connectionToken === this.value);
	}
}

export type ServerConnectionToken = NoneServerConnectionToken | MandatoryServerConnectionToken;

export class ServerConnectionTokenParseError {
	constructor(
		public readonly message: string
	) { }
}

export async function parseServerConnectionToken(args: ServerParsedArgs, defaultValue: () => Promise<string>): Promise<ServerConnectionToken | ServerConnectionTokenParseError> {
	const withoutConnectionToken = args['without-connection-token'];
	const connectionToken = args['connection-token'];
	const connectionTokenFile = args['connection-token-file'];

	if (withoutConnectionToken) {
		if (typeof connectionToken !== 'undefined' || typeof connectionTokenFile !== 'undefined') {
			return new ServerConnectionTokenParseError(`Please do not use the argument '--connection-token' or '--connection-token-file' at the same time as '--without-connection-token'.`);
		}
		return new NoneServerConnectionToken();
	}

	if (typeof connectionTokenFile !== 'undefined') {
		if (typeof connectionToken !== 'undefined') {
			return new ServerConnectionTokenParseError(`Please do not use the argument '--connection-token' at the same time as '--connection-token-file'.`);
		}

		let rawConnectionToken: string;
		try {
			rawConnectionToken = fs.readFileSync(connectionTokenFile).toString().replace(/\r?\n$/, '');
		} catch (e) {
			return new ServerConnectionTokenParseError(`Unable to read the connection token file at '${connectionTokenFile}'.`);
		}

		if (!connectionTokenRegex.test(rawConnectionToken)) {
			return new ServerConnectionTokenParseError(`The connection token defined in '${connectionTokenFile} does not adhere to the characters 0-9, a-z, A-Z, _, or -.`);
		}

		return new MandatoryServerConnectionToken(rawConnectionToken);
	}

	if (typeof connectionToken !== 'undefined') {
		if (!connectionTokenRegex.test(connectionToken)) {
			return new ServerConnectionTokenParseError(`The connection token '${connectionToken} does not adhere to the characters 0-9, a-z, A-Z or -.`);
		}

		return new MandatoryServerConnectionToken(connectionToken);
	}

	return new MandatoryServerConnectionToken(await defaultValue());
}

export async function determineServerConnectionToken(args: ServerParsedArgs): Promise<ServerConnectionToken | ServerConnectionTokenParseError> {
	const readOrGenerateConnectionToken = async () => {
		if (!args['user-data-dir']) {
			// No place to store it!
			return generateUuid();
		}
		const storageLocation = path.join(args['user-data-dir'], 'token');

		// First try to find a connection token
		try {
			const fileContents = await fs.promises.readFile(storageLocation);
			const connectionToken = fileContents.toString().replace(/\r?\n$/, '');
			if (connectionTokenRegex.test(connectionToken)) {
				return connectionToken;
			}
		} catch (err) { }

		// No connection token found, generate one
		const connectionToken = generateUuid();

		try {
			// Try to store it
			await Promises.writeFile(storageLocation, connectionToken, { mode: 0o600 });
		} catch (err) { }

		return connectionToken;
	};
	return parseServerConnectionToken(args, readOrGenerateConnectionToken);
}

export function requestHasValidConnectionToken(connectionToken: ServerConnectionToken, req: http.IncomingMessage, parsedUrl: url.UrlWithParsedQuery) {
	// First check if there is a valid query parameter
	if (connectionToken.validate(parsedUrl.query[connectionTokenQueryName])) {
		return true;
	}

	// Otherwise, check if there is a valid cookie
	const cookies = cookie.parse(req.headers.cookie || '');
	return connectionToken.validate(cookies[connectionTokenCookieName]);
}
