/**
 * @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 * as cf from '../utils/common-flags';
import { getBalenaSdk, stripIndent } from '../utils/lazy';
import { parseAsInteger, validateLocalHostnameOrIp } from '../utils/validation';
import * as BalenaSdk from 'balena-sdk';

interface FlagsDef {
	port?: number;
	tty: boolean;
	verbose: boolean;
	noproxy: boolean;
	help: void;
}

interface ArgsDef {
	applicationOrDevice: string;
	service?: string;
}

export default class SshCmd extends Command {
	public static description = stripIndent`
		SSH into the host or application container of a device.

		Start a shell on a local or remote device. If a service name is not provided,
		a shell will be opened on the host OS.

		If an application is provided, an interactive menu will be presented
		for the selection of an online device. A shell will then be opened for the
		host OS or service container of the chosen device.

		For local devices, the IP address and .local domain name are supported.
		If the device is referenced by IP or \`.local\` address, the connection
		is initiated directly to balenaOS on port \`22222\` via an
		openssh-compatible client. Otherwise, any connection initiated remotely
		traverses the balenaCloud VPN.

		Commands may be piped to the standard input for remote execution (see examples).
		Note however that remote command execution on service containers (as opposed to
		the host OS) is not currently possible when a device UUID is used (instead of
		an IP address) because of a balenaCloud backend limitation.

		Note: \`balena ssh\` requires an openssh-compatible client to be correctly
		installed in your shell environment. For more information (including Windows
		support) please check:
			https://github.com/balena-io/balena-cli/blob/master/INSTALL.md#additional-dependencies,
	`;

	public static examples = [
		'$ balena ssh MyApp',
		'$ balena ssh f49cefd',
		'$ balena ssh f49cefd my-service',
		'$ balena ssh f49cefd --port <port>',
		'$ balena ssh 192.168.0.1 --verbose',
		'$ balena ssh f49cefd.local my-service',
		'$ echo "uptime; exit;" | balena ssh f49cefd',
		'$ echo "uptime; exit;" | balena ssh 192.168.0.1 myService',
	];

	public static args = [
		{
			name: 'applicationOrDevice',
			description:
				'application name/slug/id, device uuid, or address of local device',
			required: true,
		},
		{
			name: 'service',
			description: 'service name, if connecting to a container',
			required: false,
		},
	];

	public static usage = 'ssh <applicationOrDevice> [service]';

	public static flags: flags.Input<FlagsDef> = {
		port: flags.integer({
			description: stripIndent`
				SSH server port number (default 22222) if the target is an IP address or .local
				hostname. Otherwise, port number for the balenaCloud gateway (default 22).`,
			char: 'p',
			parse: (p) => parseAsInteger(p, 'port'),
		}),
		tty: flags.boolean({
			default: false,
			description:
				'force pseudo-terminal allocation (bypass TTY autodetection for stdin)',
			char: 't',
		}),
		verbose: flags.boolean({
			default: false,
			description: 'increase verbosity',
			char: 'v',
		}),
		noproxy: flags.boolean({
			default: false,
			description: 'bypass global proxy configuration for the ssh connection',
		}),
		help: cf.help,
	};

	public static primary = true;

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

		// Local connection
		if (validateLocalHostnameOrIp(params.applicationOrDevice)) {
			const { performLocalDeviceSSH } = await import('../utils/device/ssh');
			return await performLocalDeviceSSH({
				address: params.applicationOrDevice,
				port: options.port,
				forceTTY: options.tty,
				verbose: options.verbose,
				service: params.service,
			});
		}

		// Remote connection
		const { getProxyConfig, which } = await import('../utils/helpers');
		const { getOnlineTargetDeviceUuid } = await import('../utils/patterns');
		const sdk = getBalenaSdk();

		const proxyConfig = getProxyConfig();
		const useProxy = !!proxyConfig && !options.noproxy;

		// this will be a tunnelled SSH connection...
		await Command.checkLoggedIn();
		const deviceUuid = await getOnlineTargetDeviceUuid(
			sdk,
			params.applicationOrDevice,
		);

		const device = await sdk.models.device.get(deviceUuid, {
			$select: ['id', 'supervisor_version', 'is_online'],
		});

		const deviceId = device.id;
		const supervisorVersion = device.supervisor_version;

		const [whichProxytunnel, username, proxyUrl] = await Promise.all([
			useProxy ? which('proxytunnel', false) : undefined,
			sdk.auth.whoami(),
			// note that `proxyUrl` refers to the balenaCloud "resin-proxy"
			// service, currently "balena-devices.com", rather than some
			// local proxy server URL
			sdk.settings.get('proxyUrl'),
		]);

		const getSshProxyCommand = () => {
			if (!proxyConfig) {
				return;
			}
			if (!whichProxytunnel) {
				console.warn(stripIndent`
					Proxy is enabled but the \`proxytunnel\` binary cannot be found.
					Please install it if you want to route the \`balena ssh\` requests through the proxy.
					Alternatively you can pass \`--noproxy\` param to the \`balena ssh\` command to ignore the proxy config
					for the \`ssh\` requests.

					Attempting the unproxied request for now.`);
				return;
			}

			const p = proxyConfig;
			if (p.username && p.password) {
				// proxytunnel understands these variables for proxy authentication.
				// Setting the variables instead of command-line options avoids the
				// need for shell-specific escaping of special characters like '$'.
				process.env.PROXYUSER = p.username;
				process.env.PROXYPASS = p.password;
			}

			return [
				'proxytunnel',
				`--proxy=${p.host}:${p.port}`,
				// ssh replaces these %h:%p variables in the ProxyCommand option
				// https://linux.die.net/man/5/ssh_config
				'--dest=%h:%p',
				...(options.verbose ? ['--verbose'] : []),
			];
		};

		const proxyCommand = useProxy ? getSshProxyCommand() : undefined;

		// At this point, we have a long uuid of a device
		// that we know exists and is accessible
		let containerId: string | undefined;
		if (params.service != null) {
			containerId = await this.getContainerId(
				sdk,
				deviceUuid,
				params.service,
				{
					port: options.port,
					proxyCommand,
					proxyUrl: proxyUrl || '',
					username: username!,
				},
				supervisorVersion,
				deviceId,
			);
		}

		let accessCommand: string;
		if (containerId != null) {
			accessCommand = `enter ${deviceUuid} ${containerId}`;
		} else {
			accessCommand = `host ${deviceUuid}`;
		}

		const command = this.generateVpnSshCommand({
			uuid: deviceUuid,
			command: accessCommand,
			verbose: options.verbose,
			port: options.port,
			proxyCommand,
			proxyUrl: proxyUrl || '',
			username: username!,
		});

		const { spawnSshAndThrowOnError } = await import('../utils/ssh');
		return spawnSshAndThrowOnError(command);
	}

	async getContainerId(
		sdk: BalenaSdk.BalenaSDK,
		uuid: string,
		serviceName: string,
		sshOpts: {
			port?: number;
			proxyCommand?: string[];
			proxyUrl: string;
			username: string;
		},
		version?: string,
		id?: number,
	): Promise<string> {
		const semver = await import('balena-semver');

		if (version == null || id == null) {
			const device = await sdk.models.device.get(uuid, {
				$select: ['id', 'supervisor_version'],
			});
			version = device.supervisor_version;
			id = device.id;
		}

		let containerId: string | undefined;
		if (semver.gte(version, '8.6.0')) {
			const apiUrl = await sdk.settings.get('apiUrl');
			// TODO: Move this into the SDKs device model
			const request = await sdk.request.send({
				method: 'POST',
				url: '/supervisor/v2/containerId',
				baseUrl: apiUrl,
				body: {
					method: 'GET',
					deviceId: id,
				},
			});
			if (request.status !== 200) {
				throw new Error(
					`There was an error connecting to device ${uuid}, HTTP response code: ${request.status}.`,
				);
			}
			const body = request.body;
			if (body.status !== 'success') {
				throw new Error(
					`There was an error communicating with device ${uuid}.\n\tError: ${body.message}`,
				);
			}
			containerId = body.services[serviceName];
		} else {
			console.error(stripIndent`
			Using legacy method to detect container ID. This will be slow.
			To speed up this process, please update your device to an OS
			which has a supervisor version of at least v8.6.0.
		`);
			// We need to execute a balena ps command on the device,
			// and parse the output, looking for a specific
			// container
			const childProcess = await import('child_process');
			const { escapeRegExp } = await import('lodash');
			const { which } = await import('../utils/helpers');
			const { deviceContainerEngineBinary } = await import(
				'../utils/device/ssh'
			);

			const sshBinary = await which('ssh');
			const sshArgs = this.generateVpnSshCommand({
				uuid,
				verbose: false,
				port: sshOpts.port,
				command: `host ${uuid} "${deviceContainerEngineBinary}" ps --format "{{.ID}} {{.Names}}"`,
				proxyCommand: sshOpts.proxyCommand,
				proxyUrl: sshOpts.proxyUrl,
				username: sshOpts.username,
			});

			if (process.env.DEBUG) {
				console.error(`[debug] [${sshBinary}, ${sshArgs.join(', ')}]`);
			}
			const subProcess = childProcess.spawn(sshBinary, sshArgs, {
				stdio: [null, 'pipe', null],
			});
			const containers = await new Promise<string>((resolve, reject) => {
				const output: string[] = [];
				subProcess.stdout.on('data', (chunk) => output.push(chunk.toString()));
				subProcess.on('close', (code: number) => {
					if (code !== 0) {
						reject(
							new Error(
								`Non-zero error code when looking for service container: ${code}`,
							),
						);
					} else {
						resolve(output.join(''));
					}
				});
			});

			const lines = containers.split('\n');
			const regex = new RegExp(`\\/?${escapeRegExp(serviceName)}_\\d+_\\d+`);
			for (const container of lines) {
				const [cId, name] = container.split(' ');
				if (regex.test(name)) {
					containerId = cId;
					break;
				}
			}
		}

		if (containerId == null) {
			throw new Error(
				`Could not find a service ${serviceName} on device ${uuid}.`,
			);
		}
		return containerId;
	}

	generateVpnSshCommand(opts: {
		uuid: string;
		command: string;
		verbose: boolean;
		port?: number;
		username: string;
		proxyUrl: string;
		proxyCommand?: string[];
	}) {
		return [
			...(opts.verbose ? ['-vvv'] : []),
			'-t',
			...['-o', 'LogLevel=ERROR'],
			...['-o', 'StrictHostKeyChecking=no'],
			...['-o', 'UserKnownHostsFile=/dev/null'],
			...(opts.proxyCommand && opts.proxyCommand.length
				? ['-o', `ProxyCommand=${opts.proxyCommand.join(' ')}`]
				: []),
			...(opts.port ? ['-p', opts.port.toString()] : []),
			`${opts.username}@ssh.${opts.proxyUrl}`,
			opts.command,
		];
	}
}