/**
 * @license
 * Copyright 2016-2020 Balena Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { flags } from '@oclif/command';
import Command from '../command';
import {
	NoPortsDefinedError,
	InvalidPortMappingError,
	ExpectedError,
} from '../errors';
import * as cf from '../utils/common-flags';
import { getBalenaSdk, stripIndent } from '../utils/lazy';
import { getOnlineTargetUuid } from '../utils/patterns';
import * as _ from 'lodash';
import { tunnelConnectionToDevice } from '../utils/tunnel';
import { createServer, Server, Socket } from 'net';
import { IArg } from '@oclif/parser/lib/args';

interface FlagsDef {
	port: string[];
	help: void;
}

interface ArgsDef {
	deviceOrApplication: string;
}

export default class TunnelCmd extends Command {
	public static description = stripIndent`
		Tunnel local ports to your balenaOS device.

		Use this command to open local ports which tunnel to listening ports on your balenaOS device.

		For example, you could open port 8080 on your local machine to connect to your managed balenaOS
		device running a web server listening on port 3000.

		Port mappings are specified in the format: <remotePort>[:[localIP:]localPort]
		localIP defaults to 'localhost', and localPort defaults to the specified remotePort value.

		You can tunnel multiple ports at any given time.

		Note: Port mappings must come after the deviceOrApplication parameter, as per examples.
	`;

	public static examples = [
		'# map remote port 22222 to localhost:22222',
		'$ balena tunnel myApp -p 22222',
		'',
		'# map remote port 22222 to localhost:222',
		'$ balena tunnel 2ead211 -p 22222:222',
		'',
		'# map remote port 22222 to any address on your host machine, port 22222',
		'$ balena tunnel 1546690 -p 22222:0.0.0.0',
		'',
		'# map remote port 22222 to any address on your host machine, port 222',
		'$ balena tunnel myApp -p 22222:0.0.0.0:222',
		'',
		'# multiple port tunnels can be specified at any one time',
		'$ balena tunnel myApp -p 8080:3000 -p 8081:9000',
	];

	public static args: Array<IArg<any>> = [
		{
			name: 'deviceOrApplication',
			description: 'device uuid or application name/id',
			required: true,
		},
	];

	public static usage = 'tunnel <deviceOrApplication>';

	public static flags: flags.Input<FlagsDef> = {
		port: flags.string({
			description:
				'port mapping in the format <remotePort>[:[localIP:]localPort]',
			char: 'p',
			multiple: true,
		}),
		help: cf.help,
	};

	public static primary = true;
	public static authenticated = true;

	public async run() {
		const { args: params, flags: options } = this.parse<FlagsDef, ArgsDef>(
			TunnelCmd,
		);

		const Logger = await import('../utils/logger');
		const logger = Logger.getLogger();
		const sdk = getBalenaSdk();

		const logConnection = (
			fromHost: string,
			fromPort: number,
			localAddress: string,
			localPort: number,
			deviceAddress: string,
			devicePort: number,
			err?: Error,
		) => {
			const logMessage = `${fromHost}:${fromPort} => ${localAddress}:${localPort} ===> ${deviceAddress}:${devicePort}`;

			if (err) {
				logger.logError(`${logMessage} :: ${err.message}`);
			} else {
				logger.logLogs(logMessage);
			}
		};

		if (options.port === undefined) {
			throw new NoPortsDefinedError();
		}

		const uuid = await getOnlineTargetUuid(sdk, params.deviceOrApplication);
		const device = await sdk.models.device.get(uuid);

		logger.logInfo(`Opening a tunnel to ${device.uuid}...`);

		const localListeners = _.chain(options.port)
			.map((mapping) => {
				return this.parsePortMapping(mapping);
			})
			.map(async ({ localPort, localAddress, remotePort }) => {
				try {
					const handler = await tunnelConnectionToDevice(
						device.uuid,
						remotePort,
						sdk,
					);

					const server = createServer(async (client: Socket) => {
						try {
							await handler(client);
							logConnection(
								client.remoteAddress || '',
								client.remotePort || 0,
								client.localAddress,
								client.localPort,
								device.vpn_address || '',
								remotePort,
							);
						} catch (err) {
							logConnection(
								client.remoteAddress || '',
								client.remotePort || 0,
								client.localAddress,
								client.localPort,
								device.vpn_address || '',
								remotePort,
								err,
							);
						}
					});

					await new Promise<Server>((resolve, reject) => {
						server.on('error', reject);
						server.listen(localPort, localAddress, () => {
							resolve(server);
						});
					});

					logger.logInfo(
						` - tunnelling ${localAddress}:${localPort} to ${device.uuid}:${remotePort}`,
					);

					return true;
				} catch (err) {
					logger.logWarn(
						` - not tunnelling ${localAddress}:${localPort} to ${
							device.uuid
						}:${remotePort}, failed ${JSON.stringify(err.message)}`,
					);

					return false;
				}
			})
			.value();

		const results = await Promise.all(localListeners);
		if (!results.includes(true)) {
			throw new ExpectedError('No ports are valid for tunnelling');
		}

		logger.logInfo('Waiting for connections...');
	}

	/**
	 * Parse a port mapping specification string in the format:
	 *  <remotePort>[:[localIP:]localPort]
	 * @param portMapping
	 */
	parsePortMapping(portMapping: string) {
		const mappingElements = portMapping.split(':');

		let localAddress = 'localhost';

		// First element is always remotePort
		const remotePort = parseInt(mappingElements[0], undefined);
		let localPort = remotePort;

		if (mappingElements.length === 2) {
			// [1] could be localAddress or localPort
			if (/^\d+$/.test(mappingElements[1])) {
				localPort = parseInt(mappingElements[1], undefined);
			} else {
				localAddress = mappingElements[1];
			}
		} else if (mappingElements.length === 3) {
			// [1] is localAddress, [2] is localPort
			localAddress = mappingElements[1];
			localPort = parseInt(mappingElements[2], undefined);
		} else if (mappingElements.length > 3) {
			throw new InvalidPortMappingError(portMapping);
		}

		// Validate results
		if (!this.isValidPort(remotePort) || !this.isValidPort(localPort)) {
			throw new InvalidPortMappingError(portMapping);
		}

		return { remotePort, localAddress, localPort };
	}

	isValidPort(port: number) {
		const MAX_PORT_VALUE = Math.pow(2, 16) - 1;
		return port > 0 && port <= MAX_PORT_VALUE;
	}
}