/**
 * Functions for working with the network, such as connecting to a TCP server,
 * binding a UDP socket, etc.
 * 
 * This module is designed to provide a unified interface to work with network
 * in Node.js, Deno, Bun (and Cloudflare Workers for limited support), based on
 * modern Web APIs. It does not work in the browser.
 * 
 * NOTE: This module depends on the Web Streams API, in Node.js, it requires
 * Node.js v18.0 or above.
 * @module
 * @experimental
 */
import { asyncTask } from "./async.ts";
import { isBun, isDeno, isNode, isNodeLike } from "./env.ts";
import { throwUnsupportedRuntimeError } from "./error.ts";
import { ToDict } from "./types.ts";
import {
    NetAddress,
    SocketStream,
    TcpConnectOptions,
    TcpSocketStream,
    UdpBindOptions,
    UdpConnectOptions,
    UdpSocket,
    UdpSocketStream,
    UnixConnectOptions,
    UnixSocketStream,
} from "./net/types.ts";
import { getInternetIp } from "./net/util.ts";
import type { Socket as NodeSocket } from "node:net";
import type { TLSSocket } from "node:tls";
import chan from "./chan.ts";

export { getInternetIp };
export type * from "./net/types.ts";

/**
 * Returns the IP address of the current machine.
 * 
 * NOTE: This function may return the IP address of the local network or the
 * public IP address, depending on the environment and network configuration.
 * If the public IP address is intended, use {@link getInternetIp} instead.
 */
export async function getMyIp(): Promise<string> {
    if (isNodeLike) {
        const { createSocket } = await import("node:dgram");
        const socket = createSocket("udp4");

        return new Promise<string>((resolve) => {
            socket.connect(53, "8.8.8.8", () => {
                const addr = socket.address();
                socket.close();
                resolve(addr.address);
            });
        });
    } else if (isDeno) {
        const conn = await Deno.connect({
            hostname: "8.8.8.8",
            port: 53,
        });
        const addr = conn.localAddr as Deno.NetAddr;
        conn.close();

        return addr.hostname;
    } else if (typeof fetch === "function") {
        try {
            return await getInternetIp();
        } catch {
            // ignore
        }
    }

    throwUnsupportedRuntimeError();
}

/**
 * Returns a random port number that is available for listening.
 * 
 * NOTE: This function is not available in the browser and worker runtimes such
 * as Cloudflare Workers.
 * 
 * @param prefer The preferred port number to return if it is available,
 * otherwise a random port is returned.
 * 
 * @param hostname The hostname to bind the port to. Default is "0.0.0.0", only
 * used when `prefer` is set and not `0`.
 */
export async function randomPort(
    prefer: number | undefined = undefined,
    hostname: string | undefined = undefined
): Promise<number> {
    hostname ||= "0.0.0.0";
    if (isDeno) {
        try {
            const listener = Deno.listen({
                hostname,
                port: prefer ?? 0,
            });
            const { port } = listener.addr as Deno.NetAddr;
            listener.close();
            return Promise.resolve(port);
        } catch (err) {
            if (prefer) {
                return randomPort(0);
            } else {
                throw err;
            }
        }
    } else if (isBun) {
        try {
            const listener = Bun.listen({
                hostname,
                port: prefer ?? 0,
                socket: {
                    data: () => { },
                },
            }) as { port: number; stop: (force?: boolean) => void; };
            const { port } = listener;
            listener.stop(true);
            return Promise.resolve(port);
        } catch (err) {
            if (prefer) {
                return randomPort(0);
            } else {
                throw err;
            }
        }
    } else if (isNode) {
        const { createServer, connect } = await import("node:net");

        if (prefer) {
            // In Node.js listening on a port used by another process may work,
            // so we don't use `listen` method to check if the port is available.
            // Instead, we use the `connect` method to check if the port can be
            // reached, if so, the port is open and we don't use it.
            const isOpen = await new Promise<boolean>((resolve, reject) => {
                const conn = connect(prefer, hostname === "0.0.0.0" ? "localhost" : hostname);
                conn.once("connect", () => {
                    conn.end();
                    resolve(true);
                }).once("error", (err) => {
                    if ((err as any)["code"] === "ECONNREFUSED") {
                        resolve(false);
                    } else {
                        reject(err);
                    }
                });
            });

            if (isOpen) {
                return randomPort(0);
            } else {
                return prefer;
            }
        } else {
            const server = createServer();
            server.listen({ port: 0, exclusive: true });
            const port = (server.address() as any).port as number;

            return new Promise<number>((resolve, reject) => {
                server.close(err => err ? reject(err) : resolve(port));
            });
        }
    } else {
        throwUnsupportedRuntimeError();
    }
}

/**
 * This function provides a unified interface to connect to a TCP server or UDP
 * peer in Node.js, Deno, Bun and Cloudflare Workers, based on modern Web APIs.
 * 
 * NOTE: This function depends on the Web Streams API, in Node.js, it requires
 * Node.js v18.0 or above.
 * 
 * @example
 * ```ts
 * // TCP
 * import bytes from "@ayonli/jsext/bytes";
 * import { readAsText } from "@ayonli/jsext/reader";
 * import { connect } from "@ayonli/jsext/net";
 * 
 * const socket = await connect({ hostname: "example.com", port: 80 });
 * const writer = socket.writable.getWriter();
 * 
 * await writer.write(bytes("GET / HTTP/1.1\r\n"));
 * await writer.write(bytes("Accept: plain/html\r\n"));
 * await writer.write(bytes("Host: example.com\r\n"));
 * await writer.write(bytes("\r\n"));
 * await writer.close();
 * 
 * const message = await readAsText(socket.readable);
 * console.log(message);
 * ```
 */
export async function connect(options: TcpConnectOptions): Promise<TcpSocketStream>;
export async function connect(options: UnixConnectOptions): Promise<UnixSocketStream>;
export async function connect(options: UdpConnectOptions): Promise<UdpSocketStream>;
export function connect(
    options: TcpConnectOptions | UnixConnectOptions | UdpConnectOptions
): Promise<TcpSocketStream | UnixSocketStream | UdpSocketStream> {
    if (options.transport === "udp") {
        return connectUdp(options);
    } else if (options.transport === "unix" || "path" in options) {
        return connectUnix(options);
    } else {
        return connectTcp(options);
    }
}

async function connectTcp(options: TcpConnectOptions): Promise<TcpSocketStream> {
    const { tls = false, ..._options } = options;

    if (isNode) {
        const { createConnection } = await import("node:net");
        const { connect } = await import("node:tls");

        const _socket = tls ? connect({
            ..._options,
            rejectUnauthorized: false,
        }) : createConnection({
            host: options.hostname,
            port: options.port,
            localPort: 0,
        });
        const props = await nodeToSocket(_socket);

        return new TcpSocketStream({
            localAddress: {
                hostname: _socket.localAddress || "localhost",
                port: _socket.localPort ?? 0,
            },
            remoteAddress: {
                hostname: _socket.remoteAddress!,
                port: _socket.remotePort!,
            },
            ...props,
            setKeepAlive: _socket.setKeepAlive.bind(_socket),
            setNoDelay: _socket.setNoDelay.bind(_socket),
        });
    } else if (isDeno) {
        const _socket = tls
            ? await Deno.connectTls(_options)
            : await Deno.connect(_options);
        const { localAddr, remoteAddr } = _socket;

        return new TcpSocketStream({
            localAddress: {
                hostname: localAddr.hostname,
                port: localAddr.port,
            },
            remoteAddress: {
                hostname: remoteAddr.hostname,
                port: remoteAddr.port,
            },
            ...denoToSocket(_socket),
            setKeepAlive: (keepAlive) => {
                if ("setKeepAlive" in _socket) {
                    _socket.setKeepAlive(keepAlive);
                }
            },
            setNoDelay: (noDelay) => {
                if ("setNoDelay" in _socket) {
                    _socket.setNoDelay(noDelay);
                }
            },
        });
    } else if (isBun) {
        const ready = asyncTask<void>();
        const closed = asyncTask<void>();
        let readCtrl: ReadableStreamDefaultController<Uint8Array<ArrayBuffer>> | null = null;
        let writeCtrl: WritableStreamDefaultController | null = null;
        const closeStreams = () => {
            try { _socket.terminate(); } catch { }
            try { readCtrl?.close(); } catch { }
            try { writeCtrl?.error(new TypeError("The stream is closed.")); } catch { }
        };

        const readable = new ReadableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                readCtrl = controller;
            },
            cancel(reason) {
                reason ? closed.reject(reason) : closed.resolve();
                closeStreams();
            },
        });
        const writable = new WritableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                writeCtrl = controller;
            },
            write(chunk) {
                _socket.write(chunk);
            },
            close() {
                writeCtrl!.error(new TypeError("The stream is closed."));
                _socket.shutdown();
            },
        });

        const _socket = await Bun.connect({
            ..._options,
            tls,
            socket: {
                binaryType: "uint8array",
                open() {
                    ready.resolve();
                },
                data(_socket, data: Uint8Array) {
                    readCtrl!.enqueue(data as Uint8Array<ArrayBuffer>);
                },
                error(_socket, error) {
                    try { readCtrl!.error(error); } catch { }
                    try { writeCtrl!.error(error); } catch { }
                    closed.reject(error);
                },
                close() {
                    closeStreams();
                    closed.resolve();
                },
            }
        });

        await ready;

        return new TcpSocketStream({
            localAddress: {
                hostname: "localhost",
                port: _socket.localPort,
            },
            remoteAddress: {
                hostname: _socket.remoteAddress,
                port: options.port,
            },
            readable,
            writable,
            closed,
            close: closeStreams,
            ref: () => _socket.ref(),
            unref: () => _socket.unref(),
            setKeepAlive: (keepAlive) => {
                if ("setKeepAlive" in _socket) {
                    _socket.setKeepAlive(keepAlive);
                }
            },
            setNoDelay: (noDelay) => {
                if ("setNoDelay" in _socket) {
                    _socket.setNoDelay(noDelay);
                }
            },
        });
    } else {
        throwUnsupportedRuntimeError();
    }
}

async function connectUnix(options: UnixConnectOptions): Promise<UnixSocketStream> {
    const { path } = options;

    if (isNode) {
        const { createConnection } = await import("node:net");
        const _socket = createConnection({ path });
        const props = await nodeToSocket(_socket);

        return new UnixSocketStream(props);
    } else if (isDeno) {
        const _socket = await Deno.connect({ transport: "unix", path });
        return new UnixSocketStream(denoToSocket(_socket));
    } else if (isBun) {
        const ready = asyncTask<void>();
        const closed = asyncTask<void>();
        let readCtrl: ReadableStreamDefaultController<Uint8Array<ArrayBuffer>> | null = null;
        let writeCtrl: WritableStreamDefaultController | null = null;
        const closeStreams = () => {
            try { _socket.terminate(); } catch { }
            try { readCtrl?.close(); } catch { }
            try { writeCtrl?.error(new TypeError("The stream is closed.")); } catch { }
        };

        const readable = new ReadableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                readCtrl = controller;
            },
            cancel(reason) {
                reason ? closed.reject(reason) : closed.resolve();
                closeStreams();
            },
        });
        const writable = new WritableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                writeCtrl = controller;
            },
            write(chunk) {
                _socket.write(chunk);
            },
            close() {
                _socket.shutdown();
            },
        });

        const _socket = await Bun.connect({
            unix: path,
            socket: {
                binaryType: "uint8array",
                open() {
                    ready.resolve();
                },
                data(_socket, data: Uint8Array) {
                    readCtrl!.enqueue(data as Uint8Array<ArrayBuffer>);
                },
                error(_socket, error) {
                    try { readCtrl!.error(error); } catch { }
                    try { writeCtrl!.error(error); } catch { }
                    closed.reject(error);
                },
                close() {
                    closeStreams();
                    closed.resolve();
                },
            }
        });

        await ready;

        return new UnixSocketStream({
            readable,
            writable,
            closed,
            close: closeStreams,
            ref: () => _socket.ref(),
            unref: () => _socket.unref(),
        });
    } else {
        throwUnsupportedRuntimeError();
    }
}

async function nodeToSocket(
    socket: NodeSocket | TLSSocket
): Promise<ToDict<SocketStream>> {
    const ready = asyncTask<void>();
    const closed = asyncTask<void>();
    let readCtrl: ReadableStreamDefaultController<Uint8Array<ArrayBuffer>> | null = null;
    let writeCtrl: WritableStreamDefaultController | null = null;
    const closeStreams = () => {
        try { socket.destroyed || socket.destroy(); } catch { }
        try { readCtrl?.close(); } catch { }
        try { writeCtrl?.error(new TypeError("The stream is closed.")); } catch { }
    };

    const readable = new ReadableStream<Uint8Array<ArrayBuffer>>({
        start(controller) {
            readCtrl = controller;
        },
        cancel(reason) {
            reason ? closed.reject(reason) : closed.resolve();
            closeStreams();
        },
    });
    const writable = new WritableStream<Uint8Array<ArrayBuffer>>({
        start(controller) {
            writeCtrl = controller;
        },
        write(chunk) {
            return new Promise<void>((resolve, reject) => {
                socket.write(chunk, err => {
                    err ? reject(err) : resolve();
                });
            });
        },
        close() {
            return new Promise<void>(resolve => {
                socket.end(resolve);
            });
        },
    });

    socket.once("connect", () => {
        ready.resolve();
    }).on("data", (data: Buffer<ArrayBuffer>) => {
        readCtrl!.enqueue(new Uint8Array(data.buffer, data.byteOffset, data.byteLength));
    }).once("error", (error) => {
        try { readCtrl!.error(error); } catch { }
        try { writeCtrl!.error(error); } catch { }
        closed.reject(error);
        ready.reject(error);
    }).once("close", (hasError) => {
        if (!hasError) {
            closeStreams();
            closed.resolve();
        }
    });

    await ready;

    return {
        readable,
        writable,
        closed,
        close: () => void socket.destroy(),
        ref: () => void socket.ref(),
        unref: () => void socket.unref(),
    };
}

function denoToSocket(
    socket: Deno.TcpConn | Deno.TlsConn | Deno.UnixConn
): ToDict<SocketStream> {
    const closed = asyncTask<void>();
    let closeCalled = false;
    let readCtrl: ReadableStreamDefaultController<Uint8Array<ArrayBuffer>> | null = null;
    let writeCtrl: WritableStreamDefaultController | null = null;
    const closeStreams = () => {
        try { socket.close(); } catch { }
        try { readCtrl?.close(); } catch { }
        try { writeCtrl?.error(new TypeError("The stream is closed.")); } catch { }
    };

    return {
        readable: new ReadableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                readCtrl = controller;
            },
            async pull(readCtrl) {
                try {
                    while (true) {
                        const value = new Uint8Array(4096);
                        const n = await socket.read(value);

                        if (n === null) {
                            closeStreams();
                            closed.resolve();
                            break;
                        }

                        readCtrl.enqueue(value.subarray(0, n));
                    }
                } catch (err) {
                    try { socket.close(); } catch { }
                    try { readCtrl.error(err); } catch { }
                    try { writeCtrl?.error(err); } catch { }
                    closeCalled ? closed.resolve() : closed.reject(err);
                }
            },
            cancel(reason) {
                reason ? closed.reject(reason) : closed.resolve();
                closeStreams();
            },
        }),
        writable: new WritableStream<Uint8Array<ArrayBuffer>>({
            start(controller) {
                writeCtrl = controller;
            },
            async write(chunk) {
                await socket.write(chunk);
            },
            close() {
                return socket.closeWrite();
            },
        }),
        closed,
        close: () => {
            closeCalled = true;
            closeStreams();
        },
        ref: socket.ref.bind(socket),
        unref: socket.unref.bind(socket),
    };
}

async function connectUdp(remoteAddress: NetAddress): Promise<UdpSocketStream> {
    const socket = await udpSocket();
    return socket.connect(remoteAddress);
}

/**
 * This function provides a unified interface to bind a UDP socket in Node.js,
 * Deno and Bun, based on modern Web APIs.
 * 
 * NOTE: This function depends on the Web Streams API, in Node.js, it requires
 * Node.js v18.0 or above.
 * 
 * @example
 * ```ts
 * import { udpSocket } from "@ayonli/jsext/net";
 * 
 * const socket = await udpSocket({ port: 8080 });
 * 
 * for await (const [data, addr] of socket) {
 *     console.log(`Received ${data.byteLength} bytes from ${addr.hostname}:${addr.port}`);
 * }
 * ```
 */
export async function udpSocket(localAddress: UdpBindOptions = {}): Promise<UdpSocket> {
    // if (isDeno) {
    //     const _socket = Deno.listenDatagram({
    //         hostname: localAddress.hostname ?? "0.0.0.0",
    //         port: localAddress.port ?? 0,
    //         transport: "udp",
    //     });
    //     const addr = _socket.addr as Deno.NetAddr;
    //     const closed = asyncTask<void>();

    //     return new UdpSocket({
    //         localAddress: constructNetAddress({
    //             hostname: addr.hostname,
    //             port: addr.port,
    //         }),
    //         closed,
    //         close: _socket.close.bind(_socket),
    //         ref: () => void 0,
    //         unref: () => void 0,
    //         receive: async () => {
    //             try {
    //                 const [data, addr] = await _socket.receive();
    //                 return [data, {
    //                     hostname: (addr as Deno.NetAddr).hostname,
    //                     port: (addr as Deno.NetAddr).port,
    //                 }];
    //             } catch (err) {
    //                 closed.reject(err);
    //                 try { _socket.close(); } catch { }
    //                 throw err;
    //             }
    //         },
    //         send: (data, remoteAddress) => {
    //             return _socket.send(data, { transport: "udp", ...remoteAddress });
    //         },
    //         connect: (remoteAddress) => {
    //             void remoteAddress;
    //             throw new Error("Deno does not support UDP connection at the moment");
    //         },
    //     });
    // } else if (isNodeLike) {
    if (isDeno || isNodeLike) {
        const { createSocket } = await import("node:dgram");
        const _socket = createSocket(localAddress.hostname?.includes(":") ? "udp6" : "udp4");
        let isConnected = false;
        let isClosed = false;
        const closed = asyncTask<void>();
        const channel = chan<[Uint8Array<ArrayBuffer>, NetAddress]>(Infinity);

        await new Promise<void>(resolve => {
            _socket.bind(localAddress.port, localAddress.hostname, resolve);
        });

        _socket.on("message", (data, rinfo) => {
            channel.send([
                new Uint8Array(data.buffer as ArrayBuffer, data.byteOffset, data.byteLength),
                {
                    hostname: rinfo.address,
                    port: rinfo.port,
                }
            ]).catch(() => { });
        }).once("error", err => {
            channel.close(err);
            closed.reject(err);
        }).once("close", () => {
            isClosed = true;
            channel.close();
            closed.resolve();
        });

        const localAddr = _socket.address();
        const props: Pick<UdpSocket, "localAddress" | "closed" | "close" | "ref" | "unref"> = {
            localAddress: {
                hostname: localAddr.address,
                port: localAddr.port,
            },
            closed,
            close: () => void _socket.close(),
            ref: _socket.ref.bind(_socket),
            unref: _socket.unref.bind(_socket),
        };
        const checkState = () => {
            if (isConnected) {
                throw new TypeError("The socket is connected.");
            } else if (isClosed) {
                throw new TypeError("The socket is closed.");
            }
        };

        return new UdpSocket({
            ...props,
            joinMulticast: _socket.addMembership.bind(_socket),
            leaveMulticast: _socket.dropMembership.bind(_socket),
            setBroadcast: _socket.setBroadcast.bind(_socket),
            setMulticastLoopback: _socket.setMulticastLoopback.bind(_socket),
            setMulticastTTL: _socket.setMulticastTTL.bind(_socket),
            setTTL: _socket.setTTL.bind(_socket),
            receive: async () => {
                checkState();
                const msg = await channel.recv();
                if (msg) {
                    return msg;
                } else {
                    throw new TypeError("The socket is closed.");
                }
            },
            send: async (data, remoteAddress) => {
                checkState();
                return new Promise<number>((resolve, reject) => {
                    _socket.send(data, remoteAddress.port, remoteAddress.hostname, (err, n) => {
                        err ? reject(err) : resolve(n);
                    });
                });
            },
            connect: (remoteAddress) => {
                return new Promise<UdpSocketStream>(resolve => {
                    isConnected = true;
                    _socket.connect(remoteAddress.port, remoteAddress.hostname, () => {
                        const localAddr = _socket.address();
                        const remoteAddr = _socket.remoteAddress();
                        let readCtrl: ReadableStreamDefaultController<Uint8Array<ArrayBuffer>> | null = null;
                        let writeCtrl: WritableStreamDefaultController | null = null;
                        const closeStreams = () => {
                            channel.close();
                            try { _socket.close(); } catch { }
                            try { readCtrl?.close(); } catch { }
                            try { writeCtrl?.error(new TypeError("The stream is closed.")); } catch { }
                        };

                        resolve(new UdpSocketStream({
                            ...props,
                            localAddress: {
                                hostname: localAddr.address,
                                port: localAddr.port,
                            },
                            remoteAddress: {
                                hostname: remoteAddr.address,
                                port: remoteAddr.port,
                            },
                            readable: new ReadableStream<Uint8Array<ArrayBuffer>>({
                                start(controller) {
                                    readCtrl = controller;
                                },
                                async pull(readCtrl) {
                                    try {
                                        while (true) {
                                            const msg = await channel.recv();

                                            if (msg === undefined) {
                                                closeStreams();
                                                closed.resolve();
                                                break;
                                            }

                                            readCtrl.enqueue(msg[0]);
                                        }
                                    } catch (err) {
                                        channel.close(err as Error);
                                        try { _socket.close(); } catch { }
                                        try { readCtrl.error(err); } catch { }
                                        try { writeCtrl?.error(err); } catch { }
                                        isClosed ? closed.resolve() : closed.reject(err);
                                    }
                                },
                                cancel(reason) {
                                    reason ? closed.reject(reason) : closed.resolve();
                                    closeStreams();
                                },
                            }),
                            writable: new WritableStream<Uint8Array<ArrayBuffer>>({
                                start(controller) {
                                    writeCtrl = controller;
                                },
                                write(chunk) {
                                    return new Promise((resolve, reject) => {
                                        _socket.send(chunk, err => {
                                            err ? reject(err) : resolve();
                                        });
                                    });
                                },
                            }),
                        }));
                    });
                });
            },
        });
    } else {
        throwUnsupportedRuntimeError();
    }
}