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'use strict';
// See https://github.com/facebook/jest/issues/2549
// eslint-disable-next-line node/prefer-global/url
const {URL, urlToHttpOptions} = require('url');
const http2 = require('http2');
const {Writable} = require('stream');
const {Agent, globalAgent} = require('./agent.js');
const IncomingMessage = require('./incoming-message.js');
const proxyEvents = require('./utils/proxy-events.js');
const {
	ERR_INVALID_ARG_TYPE,
	ERR_INVALID_PROTOCOL,
	ERR_HTTP_HEADERS_SENT
} = require('./utils/errors.js');
const validateHeaderName = require('./utils/validate-header-name.js');
const validateHeaderValue = require('./utils/validate-header-value.js');
const proxySocketHandler = require('./utils/proxy-socket-handler.js');

const {
	HTTP2_HEADER_STATUS,
	HTTP2_HEADER_METHOD,
	HTTP2_HEADER_PATH,
	HTTP2_HEADER_AUTHORITY,
	HTTP2_METHOD_CONNECT
} = http2.constants;

const kHeaders = Symbol('headers');
const kOrigin = Symbol('origin');
const kSession = Symbol('session');
const kOptions = Symbol('options');
const kFlushedHeaders = Symbol('flushedHeaders');
const kJobs = Symbol('jobs');
const kPendingAgentPromise = Symbol('pendingAgentPromise');

class ClientRequest extends Writable {
	constructor(input, options, callback) {
		super({
			autoDestroy: false,
			emitClose: false
		});

		if (typeof input === 'string') {
			input = urlToHttpOptions(new URL(input));
		} else if (input instanceof URL) {
			input = urlToHttpOptions(input);
		} else {
			input = {...input};
		}

		if (typeof options === 'function' || options === undefined) {
			// (options, callback)
			callback = options;
			options = input;
		} else {
			// (input, options, callback)
			options = Object.assign(input, options);
		}

		if (options.h2session) {
			this[kSession] = options.h2session;

			if (this[kSession].destroyed) {
				throw new Error('The session has been closed already');
			}

			this.protocol = this[kSession].socket.encrypted ? 'https:' : 'http:';
		} else if (options.agent === false) {
			this.agent = new Agent({maxEmptySessions: 0});
		} else if (typeof options.agent === 'undefined' || options.agent === null) {
			this.agent = globalAgent;
		} else if (typeof options.agent.request === 'function') {
			this.agent = options.agent;
		} else {
			throw new ERR_INVALID_ARG_TYPE('options.agent', ['http2wrapper.Agent-like Object', 'undefined', 'false'], options.agent);
		}

		if (this.agent) {
			this.protocol = this.agent.protocol;
		}

		if (options.protocol && options.protocol !== this.protocol) {
			throw new ERR_INVALID_PROTOCOL(options.protocol, this.protocol);
		}

		if (!options.port) {
			options.port = options.defaultPort || (this.agent && this.agent.defaultPort) || 443;
		}

		options.host = options.hostname || options.host || 'localhost';

		// Unused
		delete options.hostname;

		const {timeout} = options;
		options.timeout = undefined;

		this[kHeaders] = Object.create(null);
		this[kJobs] = [];

		this[kPendingAgentPromise] = undefined;

		this.socket = null;
		this.connection = null;

		this.method = options.method || 'GET';

		if (!(this.method === 'CONNECT' && (options.path === '/' || options.path === undefined))) {
			this.path = options.path;
		}

		this.res = null;
		this.aborted = false;
		this.reusedSocket = false;

		const {headers} = options;
		if (headers) {
			// eslint-disable-next-line guard-for-in
			for (const header in headers) {
				this.setHeader(header, headers[header]);
			}
		}

		if (options.auth && !('authorization' in this[kHeaders])) {
			this[kHeaders].authorization = 'Basic ' + Buffer.from(options.auth).toString('base64');
		}

		options.session = options.tlsSession;
		options.path = options.socketPath;

		this[kOptions] = options;

		// Clients that generate HTTP/2 requests directly SHOULD use the :authority pseudo-header field instead of the Host header field.
		this[kOrigin] = new URL(`${this.protocol}//${options.servername || options.host}:${options.port}`);

		// A socket is being reused
		const reuseSocket = options._reuseSocket;
		if (reuseSocket) {
			options.createConnection = (...args) => {
				if (reuseSocket.destroyed) {
					return this.agent.createConnection(...args);
				}

				return reuseSocket;
			};

			// eslint-disable-next-line promise/prefer-await-to-then
			this.agent.getSession(this[kOrigin], this[kOptions]).catch(() => {});
		}

		if (timeout) {
			this.setTimeout(timeout);
		}

		if (callback) {
			this.once('response', callback);
		}

		this[kFlushedHeaders] = false;
	}

	get method() {
		return this[kHeaders][HTTP2_HEADER_METHOD];
	}

	set method(value) {
		if (value) {
			this[kHeaders][HTTP2_HEADER_METHOD] = value.toUpperCase();
		}
	}

	get path() {
		const header = this.method === 'CONNECT' ? HTTP2_HEADER_AUTHORITY : HTTP2_HEADER_PATH;

		return this[kHeaders][header];
	}

	set path(value) {
		if (value) {
			const header = this.method === 'CONNECT' ? HTTP2_HEADER_AUTHORITY : HTTP2_HEADER_PATH;

			this[kHeaders][header] = value;
		}
	}

	get host() {
		return this[kOrigin].hostname;
	}

	set host(_value) {
		// Do nothing as this is read only.
	}

	get _mustNotHaveABody() {
		return this.method === 'GET' || this.method === 'HEAD' || this.method === 'DELETE';
	}

	_write(chunk, encoding, callback) {
		// https://github.com/nodejs/node/blob/654df09ae0c5e17d1b52a900a545f0664d8c7627/lib/internal/http2/util.js#L148-L156
		if (this._mustNotHaveABody) {
			callback(new Error('The GET, HEAD and DELETE methods must NOT have a body'));
			/* istanbul ignore next: Node.js 12 throws directly */
			return;
		}

		this.flushHeaders();

		const callWrite = () => this._request.write(chunk, encoding, callback);
		if (this._request) {
			callWrite();
		} else {
			this[kJobs].push(callWrite);
		}
	}

	_final(callback) {
		this.flushHeaders();

		const callEnd = () => {
			// For GET, HEAD and DELETE and CONNECT
			if (this._mustNotHaveABody || this.method === 'CONNECT') {
				callback();
				return;
			}

			this._request.end(callback);
		};

		if (this._request) {
			callEnd();
		} else {
			this[kJobs].push(callEnd);
		}
	}

	abort() {
		if (this.res && this.res.complete) {
			return;
		}

		if (!this.aborted) {
			process.nextTick(() => this.emit('abort'));
		}

		this.aborted = true;

		this.destroy();
	}

	async _destroy(error, callback) {
		if (this.res) {
			this.res._dump();
		}

		if (this._request) {
			this._request.destroy();
		} else {
			process.nextTick(() => {
				this.emit('close');
			});
		}

		try {
			await this[kPendingAgentPromise];
		} catch (internalError) {
			if (this.aborted) {
				error = internalError;
			}
		}

		callback(error);
	}

	async flushHeaders() {
		if (this[kFlushedHeaders] || this.destroyed) {
			return;
		}

		this[kFlushedHeaders] = true;

		const isConnectMethod = this.method === HTTP2_METHOD_CONNECT;

		// The real magic is here
		const onStream = stream => {
			this._request = stream;

			if (this.destroyed) {
				stream.destroy();
				return;
			}

			// Forwards `timeout`, `continue`, `close` and `error` events to this instance.
			if (!isConnectMethod) {
				// TODO: Should we proxy `close` here?
				proxyEvents(stream, this, ['timeout', 'continue']);
			}

			stream.once('error', error => {
				this.destroy(error);
			});

			stream.once('aborted', () => {
				const {res} = this;
				if (res) {
					res.aborted = true;
					res.emit('aborted');
					res.destroy();
				} else {
					this.destroy(new Error('The server aborted the HTTP/2 stream'));
				}
			});

			const onResponse = (headers, flags, rawHeaders) => {
				// If we were to emit raw request stream, it would be as fast as the native approach.
				// Note that wrapping the raw stream in a Proxy instance won't improve the performance (already tested it).
				const response = new IncomingMessage(this.socket, stream.readableHighWaterMark);
				this.res = response;

				// Undocumented, but it is used by `cacheable-request`
				response.url = `${this[kOrigin].origin}${this.path}`;

				response.req = this;
				response.statusCode = headers[HTTP2_HEADER_STATUS];
				response.headers = headers;
				response.rawHeaders = rawHeaders;

				response.once('end', () => {
					response.complete = true;

					// Has no effect, just be consistent with the Node.js behavior
					response.socket = null;
					response.connection = null;
				});

				if (isConnectMethod) {
					response.upgrade = true;

					// The HTTP1 API says the socket is detached here,
					// but we can't do that so we pass the original HTTP2 request.
					if (this.emit('connect', response, stream, Buffer.alloc(0))) {
						this.emit('close');
					} else {
						// No listeners attached, destroy the original request.
						stream.destroy();
					}
				} else {
					// Forwards data
					stream.on('data', chunk => {
						if (!response._dumped && !response.push(chunk)) {
							stream.pause();
						}
					});

					stream.once('end', () => {
						if (!this.aborted) {
							response.push(null);
						}
					});

					if (!this.emit('response', response)) {
						// No listeners attached, dump the response.
						response._dump();
					}
				}
			};

			// This event tells we are ready to listen for the data.
			stream.once('response', onResponse);

			// Emits `information` event
			stream.once('headers', headers => this.emit('information', {statusCode: headers[HTTP2_HEADER_STATUS]}));

			stream.once('trailers', (trailers, flags, rawTrailers) => {
				const {res} = this;

				// https://github.com/nodejs/node/issues/41251
				if (res === null) {
					onResponse(trailers, flags, rawTrailers);
					return;
				}

				// Assigns trailers to the response object.
				res.trailers = trailers;
				res.rawTrailers = rawTrailers;
			});

			stream.once('close', () => {
				const {aborted, res} = this;
				if (res) {
					if (aborted) {
						res.aborted = true;
						res.emit('aborted');
						res.destroy();
					}

					const finish = () => {
						res.emit('close');

						this.destroy();
						this.emit('close');
					};

					if (res.readable) {
						res.once('end', finish);
					} else {
						finish();
					}

					return;
				}

				if (!this.destroyed) {
					this.destroy(new Error('The HTTP/2 stream has been early terminated'));
					this.emit('close');
					return;
				}

				this.destroy();
				this.emit('close');
			});

			this.socket = new Proxy(stream, proxySocketHandler);

			for (const job of this[kJobs]) {
				job();
			}

			this.emit('socket', this.socket);
		};

		if (!(HTTP2_HEADER_AUTHORITY in this[kHeaders]) && !isConnectMethod) {
			this[kHeaders][HTTP2_HEADER_AUTHORITY] = this[kOrigin].host;
		}

		// Makes a HTTP2 request
		if (this[kSession]) {
			try {
				onStream(this[kSession].request(this[kHeaders]));
			} catch (error) {
				this.destroy(error);
			}
		} else {
			this.reusedSocket = true;

			try {
				const promise = this.agent.request(this[kOrigin], this[kOptions], this[kHeaders]);
				this[kPendingAgentPromise] = promise;

				onStream(await promise);

				this[kPendingAgentPromise] = false;
			} catch (error) {
				this[kPendingAgentPromise] = false;

				this.destroy(error);
			}
		}
	}

	get connection() {
		return this.socket;
	}

	set connection(value) {
		this.socket = value;
	}

	getHeaderNames() {
		return Object.keys(this[kHeaders]);
	}

	hasHeader(name) {
		if (typeof name !== 'string') {
			throw new ERR_INVALID_ARG_TYPE('name', 'string', name);
		}

		return Boolean(this[kHeaders][name.toLowerCase()]);
	}

	getHeader(name) {
		if (typeof name !== 'string') {
			throw new ERR_INVALID_ARG_TYPE('name', 'string', name);
		}

		return this[kHeaders][name.toLowerCase()];
	}

	get headersSent() {
		return this[kFlushedHeaders];
	}

	removeHeader(name) {
		if (typeof name !== 'string') {
			throw new ERR_INVALID_ARG_TYPE('name', 'string', name);
		}

		if (this.headersSent) {
			throw new ERR_HTTP_HEADERS_SENT('remove');
		}

		delete this[kHeaders][name.toLowerCase()];
	}

	setHeader(name, value) {
		if (this.headersSent) {
			throw new ERR_HTTP_HEADERS_SENT('set');
		}

		validateHeaderName(name);
		validateHeaderValue(name, value);

		const lowercased = name.toLowerCase();

		if (lowercased === 'connection') {
			if (value.toLowerCase() === 'keep-alive') {
				return;
			}

			throw new Error(`Invalid 'connection' header: ${value}`);
		}

		if (lowercased === 'host' && this.method === 'CONNECT') {
			this[kHeaders][HTTP2_HEADER_AUTHORITY] = value;
		} else {
			this[kHeaders][lowercased] = value;
		}
	}

	setNoDelay() {
		// HTTP2 sockets cannot be malformed, do nothing.
	}

	setSocketKeepAlive() {
		// HTTP2 sockets cannot be malformed, do nothing.
	}

	setTimeout(ms, callback) {
		const applyTimeout = () => this._request.setTimeout(ms, callback);

		if (this._request) {
			applyTimeout();
		} else {
			this[kJobs].push(applyTimeout);
		}

		return this;
	}

	get maxHeadersCount() {
		if (!this.destroyed && this._request) {
			return this._request.session.localSettings.maxHeaderListSize;
		}

		return undefined;
	}

	set maxHeadersCount(_value) {
		// Updating HTTP2 settings would affect all requests, do nothing.
	}
}

module.exports = ClientRequest;