import {
  ArrayIsArray,
  getter,
  NumberIsFinite,
  ObjectCreate,
  ObjectDefineProperty as define,
  ObjectFreeze as freeze,
  RangeError,
  TypedArrayPrototypeGetBuffer as bufferOf,
  TypedArrayPrototypeGetByteLength as length,
  TypedArrayPrototypeGetByteOffset as offsetOf,
  TypedArrayPrototypeGetTag as tag,
  TypeError,
  Uint8Array,
  Uint8ArrayPrototypeSet as setBytes,
  uncurryThis,
  WeakMap,
  WeakMapPrototypeSet as set,
} from "ext:core/primordials";
import {
  promiseResolve,
  promiseThen as then,
  safePromise,
} from "ext:core/promises";
import {
  op_net_accept,
  op_net_close,
  op_net_connect_start,
  op_net_connected,
  op_net_datagram_broadcast,
  op_net_datagram_listen,
  op_net_datagram_receive,
  op_net_datagram_send,
  op_net_listen,
  op_net_read,
  op_net_shutdown,
  op_net_write,
  op_net_writev,
} from "ext:core/ops";
import type {
  NetAddress,
  NetConnection,
  NetListener,
  NetListenerId,
  NetUdpAddress,
} from "ext:core/ops";
import { array, dictionary, state, usv } from "ext:web/idl.js";
import { addListener, removeListener, signals } from "ext:web/events.js";
import { registerUncloneable } from "ext:web/serialization.js";
import {
  byobRequest,
  enqueue,
  errorStream,
  finish,
  ReadableStream,
  ReadableStreamBYOBRequest,
  WritableStream,
} from "ext:webstreams/streams.js";
import type {
  ReadableByteStreamController,
  WritableStreamDefaultController,
} from "ext:webstreams/streams.js";
import { failure, result } from "ext:file/errors.js";

interface SocketData {
  id: number | null;
  owner: object;
  reader?: ReadableByteStreamController | null;
  writer?: WritableStreamDefaultController | null;
}
interface ConnectionData<A extends NetAddress = NetAddress> extends SocketData {
  writing: Promise<void>;
  local: A;
  remote: A;
  readable: ReadableStream<Uint8Array<ArrayBuffer>> | null;
  writable: WritableStream<Uint8Array<ArrayBufferLike>> | null;
  reader: ReadableByteStreamController | null;
  writer: WritableStreamDefaultController | null;
}
interface ListenerData<A extends NetAddress = NetAddress> extends SocketData {
  id: NetListenerId<A> | null;
  local: A;
}
interface DatagramData extends SocketData {
  writing: Promise<void>;
  local: Readonly<NetUdpAddress>;
}
type Datagram = [
  bytes: Uint8Array<ArrayBufferLike>,
  remote: Readonly<NetUdpAddress>,
];
const connections = new WeakMap<object, ConnectionData>(),
  listeners = new WeakMap<object, ListenerData>(),
  datagrams = new WeakMap<object, DatagramData>();
registerUncloneable(connections);
registerUncloneable(listeners);
registerUncloneable(datagrams);
const FinalizationRegistry = globalThis.FinalizationRegistry;
const register = uncurryThis(
  (FinalizationRegistry.prototype as FinalizationRegistry<number>).register,
);
const unregister = uncurryThis(FinalizationRegistry.prototype.unregister);
const registry = new FinalizationRegistry((id: number) => op_net_close(id));
const getView = getter(ReadableStreamBYOBRequest.prototype, "view");
const respond = uncurryThis(ReadableStreamBYOBRequest.prototype.respond);
const writableError = uncurryThis(
  WritableStreamDefaultController.prototype.error,
);
const dispose: typeof Symbol.dispose = Symbol.dispose,
  asyncIterator: typeof Symbol.asyncIterator = Symbol.asyncIterator,
  empty = new Uint8Array();
const safeInteger = Number.isSafeInteger;

function args<T extends unknown[]>(...items: T): T {
  const value = array();
  for (let i = 0; i < items.length; i++) value[i] = items[i];
  return value as T;
}
function address<A extends NetAddress | NetUdpAddress>(value: A): A {
  const copy: (NetAddress | NetUdpAddress) & { __proto__?: null } =
    value.transport === "unix"
      ? { __proto__: null, transport: "unix", path: value.path }
      : {
        __proto__: null,
        transport: value.transport,
        hostname: value.hostname,
        port: value.port,
      };
  return freeze(copy) as A;
}
function options(
  value: unknown,
  connecting = false,
): NetAddress & { __proto__?: null } {
  const options = dictionary(value);
  const transport = options.transport,
    host = options.hostname,
    inputPort = options.port,
    path = options.path;
  if (transport === "unix") {
    if (host !== undefined || inputPort !== undefined) {
      throw new TypeError("Unix sockets cannot specify hostname or port");
    }
    if (path === undefined) throw new TypeError("Unix sockets require a path");
    const label = usv(path);
    if (!label) throw new TypeError("Unix sockets require a path");
    return { __proto__: null, transport: "unix", path: label };
  }
  if (path !== undefined) {
    throw new TypeError("Socket paths require Unix transport");
  }
  const port = +(inputPort as number);
  if (transport !== undefined && transport !== "tcp") {
    throw new TypeError("Expected TCP transport");
  }
  if (
    !NumberIsFinite(port) || port < (connecting ? 1 : 0) || port > 65535 ||
    port % 1 !== 0
  ) throw new RangeError("Invalid socket port");
  return {
    __proto__: null,
    transport: "tcp" as const,
    hostname: host === undefined ? "127.0.0.1" : usv(host),
    port,
  };
}
function id<I extends number>(data: { id: I | null }): I {
  if (data.id === null) throw failure("BadResource", "Socket is closed");
  return data.id;
}
function bytes(value: unknown): Uint8Array<ArrayBufferLike> {
  if (tag(value) !== "Uint8Array") {
    throw new TypeError("Socket I/O requires a Uint8Array");
  }
  setBytes(value as Uint8Array<ArrayBufferLike>, empty);
  return value as Uint8Array<ArrayBufferLike>;
}
function segment<B extends ArrayBufferLike>(
  value: Uint8Array<B>,
  offset = 0,
): Uint8Array<B> {
  const count = length(value) - offset;
  return new Uint8Array(
    bufferOf(value),
    offsetOf(value) + offset,
    count < 65536 ? count : 65536,
  );
}
function vectors(buffers: unknown): Uint8Array<ArrayBuffer>[] {
  if (!ArrayIsArray(buffers)) {
    throw new TypeError("Socket I/O requires an array of Uint8Array");
  }
  // Snapshot before queueing, without rereading caller-controlled elements.
  const count = buffers.length, pieces: Uint8Array<ArrayBuffer>[] = args();
  if (!safeInteger(count) || count < 0 || count > 4294967295) {
    throw new RangeError("Invalid vector length");
  }
  let total = 0;
  for (let i = 0; i < count; i++) {
    const view: unknown = buffers[i];
    if (tag(view) !== "Uint8Array") {
      throw new TypeError("Socket I/O requires an array of Uint8Array");
    }
    setBytes(view as Uint8Array<ArrayBufferLike>, empty);
    const size = length(view);
    if (size === 0) continue;
    if (!safeInteger(total + size)) {
      throw new RangeError("Vector exceeds safe integer range");
    }
    total += size;
    // Fixed snapshot for the native call, which needs unshared storage.
    pieces[pieces.length] = new Uint8Array(
      new Uint8Array(
        bufferOf(view),
        offsetOf(view),
        size,
      ),
    );
  }
  return pieces;
}
function close(
  data: SocketData,
  quiet = false,
  source: "read" | "write" | null = null,
): void {
  if (data.id === null) {
    if (!quiet) id(data);
    return;
  }
  const current = data.id;
  data.id = null;
  unregister(registry, data.owner);
  const error = failure("BadResource", "Socket is closed");
  if (data.reader && source !== "read") errorStream(data.reader, error);
  if (data.writer && source !== "write") writableError(data.writer, error);
  const reply = op_net_close(current);
  if (!quiet) result(reply);
}
function queue<T>(
  data: { writing: Promise<void> },
  operation: () => T | PromiseLike<T>,
): Promise<T> {
  const promise = then(data.writing, operation, operation);
  data.writing = then(promise, () => {}, () => {});
  return promise;
}
const socketKey = Symbol();
type TcpAddr = Extract<NetAddress, { transport: "tcp" }>;
type UnixAddr = Extract<NetAddress, { transport: "unix" }>;
type TcpOptions = {
  transport?: "tcp";
  hostname?: string;
  port: number;
  signal?: AbortSignal;
};
type UnixOptions = {
  transport: "unix";
  path: string;
  hostname?: never;
  port?: never;
  signal?: AbortSignal;
};

class Conn<A extends NetAddress = NetAddress> {
  declare static readonly [Symbol.hasInstance]: (value: unknown) => value is Conn;
  #data: ConnectionData<A>;

  constructor(...args: [typeof socketKey, NetConnection<A>]) {
    const key = args[0], row = args[1];
    if (key !== socketKey) throw new TypeError("Illegal constructor");
    this.#data = {
      id: row[0],
      owner: this,
      local: address(row[1]),
      remote: address(row[2]),
      readable: null,
      writable: null,
      reader: null,
      writer: null,
      writing: promiseResolve(undefined),
    };
    set(connections, this, this.#data);
    register(registry, this, row[0], this);
  }
  get localAddr(): A {
    state(connections, this);
    return this.#data.local;
  }
  get remoteAddr(): A {
    state(connections, this);
    return this.#data.remote;
  }
  async read(buffer: Uint8Array<ArrayBufferLike>): Promise<number | null> {
    const data = state(connections, this), current = id(data);
    bytes(buffer);
    const chunk = result(
      await safePromise(op_net_read(args(current, length(buffer)))),
    );
    setBytes(buffer, empty);
    if (chunk === null) return null;
    setBytes(buffer, chunk);
    return length(chunk);
  }
  write(buffer: Uint8Array<ArrayBufferLike>): Promise<number> {
    const data = state(connections, this);
    id(data);
    const snapshot = new Uint8Array(segment(bytes(buffer)));
    return queue(
      data,
      () => then(op_net_write(args(id(data), snapshot)), result),
    );
  }
  writev(buffers: unknown): Promise<number> {
    const data = state(connections, this);
    id(data);
    const snapshots = vectors(buffers);
    return queue(data, async () => {
      if (snapshots.length === 0) {
        return result(
          await safePromise(op_net_writev(args(id(data), snapshots))),
        );
      }
      let total = 0, elem = 0, inner = 0;
      while (elem < snapshots.length) {
        const batch: Uint8Array<ArrayBuffer>[] = args();
        let budget = 65536, scan = elem, scanInner = inner;
        while (scan < snapshots.length && batch.length < 16 && budget > 0) {
          const piece = snapshots[scan], size = length(piece) - scanInner;
          if (size === 0) {
            scan++;
            scanInner = 0;
            continue;
          }
          const take = size < budget ? size : budget;
          batch[batch.length] = new Uint8Array(
            bufferOf(piece),
            offsetOf(piece) + scanInner,
            take,
          );
          budget -= take;
          scanInner += take;
          if (scanInner >= length(piece)) {
            scan++;
            scanInner = 0;
          }
        }
        const count = result(
          await safePromise(op_net_writev(args(id(data), batch))),
        );
        if (!safeInteger(count) || count <= 0 || count > 65536 - budget) {
          throw failure("IoError", "Invalid partial socket write");
        }
        total += count;
        let skip = count;
        while (skip > 0) {
          const remaining = length(snapshots[elem]) - inner;
          if (remaining === 0) {
            elem++;
            inner = 0;
            continue;
          }
          if (skip < remaining) {
            inner += skip;
            break;
          }
          skip -= remaining;
          elem++;
          inner = 0;
        }
      }
      return total;
    });
  }
  closeWrite(): Promise<void> {
    const data = state(connections, this);
    id(data);
    return queue(data, () =>
      then(op_net_shutdown(id(data)), (reply) => {
        result(reply);
      }));
  }
  close() {
    close(state(connections, this));
  }
  [dispose]() {
    close(state(connections, this), true);
  }
  get readable() {
    const data = state(connections, this);
    if (data.readable) return data.readable;
    id(data);
    data.readable = new ReadableStream({
      type: "bytes",
      start(controller) {
        data.reader = controller;
      },
      async pull(controller) {
        try {
          const request = byobRequest(controller),
            view = request && getView(request);
          const chunk = result(
            await safePromise(
              op_net_read(args(id(data), view ? length(view) : 65536)),
            ),
          );
          if (data.id === null) return;
          if (chunk === null) finish(controller);
          else if (request) {
            setBytes(view!, chunk);
            respond(request, length(chunk));
          } else enqueue(controller, chunk);
        } catch (error) {
          errorStream(controller, error);
          close(data, true, "read");
        }
      },
      cancel() {
        close(data, true, "read");
      },
    }, { highWaterMark: 0 });
    return data.readable;
  }
  get writable() {
    const data = state(connections, this);
    if (data.writable) return data.writable;
    id(data);
    data.writable = new WritableStream({
      start(controller) {
        data.writer = controller;
      },
      async write(value) {
        try {
          const snapshot = new Uint8Array(bytes(value));
          await safePromise(queue(data, async () => {
            let offset = 0;
            while (offset < length(snapshot)) {
              const count = result(
                await safePromise(
                  op_net_write(
                    args(
                      id(data),
                      segment(snapshot, offset),
                    ),
                  ),
                ),
              );
              if (count <= 0 || count > length(snapshot) - offset) {
                throw failure("IoError", "Invalid partial socket write");
              }
              offset += count;
            }
          }));
        } catch (error) {
          close(data, true, "write");
          throw error;
        }
      },
      close() {
        return queue(data, () => then(op_net_shutdown(id(data)), result));
      },
      abort() {
        close(data, true, "write");
      },
    }, {
      highWaterMark: 65536,
      size(value) {
        return tag(value) === "Uint8Array" ? length(value) : 1;
      },
    });
    return data.writable;
  }
}
function connection<A extends NetAddress>(row: NetConnection<A>): Conn<A> {
  return new Conn(socketKey, row);
}
class Listener<A extends NetAddress = NetAddress> {
  declare static readonly [Symbol.hasInstance]: (value: unknown) => value is Listener;
  #data: ListenerData<A>;

  constructor(...args: [typeof socketKey, NetListener<A>]) {
    const key = args[0], row = args[1];
    if (key !== socketKey) throw new TypeError("Illegal constructor");
    this.#data = { id: row[0], owner: this, local: address(row[1]) };
    set(listeners, this, this.#data);
    register(registry, this, row[0], this);
  }
  get addr(): A {
    state(listeners, this);
    return this.#data.local;
  }
  async accept(): Promise<Conn<A>> {
    state(listeners, this);
    return connection(
      result(await safePromise(op_net_accept(id(this.#data)))),
    );
  }
  close() {
    close(state(listeners, this));
  }
  [dispose]() {
    close(state(listeners, this), true);
  }
  [asyncIterator](): AsyncIterableIterator<Conn<A>, undefined> {
    state(listeners, this);
    const data = this.#data;
    return {
      async next() {
        if (data.id === null) return { done: true, value: undefined };
        try {
          return {
            done: false,
            value: connection(
              result(await safePromise(op_net_accept(id(data)))),
            ),
          };
        } catch (error) {
          if (data.id === null) return { done: true, value: undefined };
          throw error;
        }
      },
      return() {
        close(data, true);
        return promiseResolve({ done: true, value: undefined });
      },
      [asyncIterator]() {
        return this;
      },
    };
  }
}
function listen(value: TcpOptions): Listener<TcpAddr>;
function listen(value: UnixOptions): Listener<UnixAddr>;
function listen(value: unknown): Listener {
  const row = result(op_net_listen(options(value)));
  return new Listener(socketKey, row);
}
function connect(value: TcpOptions): Promise<Conn<TcpAddr>>;
function connect(value: UnixOptions): Promise<Conn<UnixAddr>>;
async function connect(value: unknown): Promise<Conn> {
  const settings = dictionary(value);
  const target = options(settings, true), signal = settings.signal;
  if (signal !== undefined && state(signals, signal).aborted) {
    throw state(signals, signal).reason;
  }
  const current = result(op_net_connect_start(target));
  const cancel = () => op_net_close(current);
  if (signal !== undefined) {
    addListener(signal, "abort", cancel, { once: true });
  }
  try {
    const row = result(await safePromise(op_net_connected(current)));
    if (signal !== undefined && state(signals, signal).aborted) {
      cancel();
      throw state(signals, signal).reason;
    }
    return connection(row);
  } catch (error) {
    cancel();
    if (signal !== undefined && state(signals, signal).aborted) {
      throw state(signals, signal).reason;
    }
    throw error;
  } finally {
    if (signal !== undefined) removeListener(signal, "abort", cancel);
  }
}
function datagramOptions(
  value: unknown,
  sending = false,
): NetUdpAddress & { __proto__?: null } {
  const options = dictionary(value);
  const transport = options.transport,
    inputHost = options.hostname,
    inputPort = options.port,
    path = options.path;
  if (transport !== undefined && transport !== "udp") {
    throw new TypeError("Expected UDP transport");
  }
  if (path !== undefined) {
    throw new TypeError("UDP sockets cannot specify a path");
  }
  const port = +(inputPort as number);
  if (
    !NumberIsFinite(port) || port < (sending ? 1 : 0) || port > 65535 ||
    port % 1 !== 0
  ) throw new RangeError("Invalid UDP port");
  return {
    __proto__: null,
    transport: "udp" as const,
    hostname: inputHost === undefined ? "127.0.0.1" : usv(inputHost),
    port,
  };
}
async function receiveDatagram(
  data: DatagramData,
  buffer: Uint8Array<ArrayBufferLike> | undefined,
): Promise<Datagram> {
  const current = id(data);
  if (buffer !== undefined) bytes(buffer);
  const row = result(
    await safePromise(
      op_net_datagram_receive(
        args(current, buffer === undefined ? 65535 : length(buffer)),
      ),
    ),
  );
  let message: Uint8Array<ArrayBufferLike> = row[0];
  if (buffer !== undefined) {
    setBytes(buffer, empty);
    setBytes(buffer, message);
    message = new Uint8Array(
      bufferOf(buffer),
      offsetOf(buffer),
      length(message),
    );
  }
  return [message, address(row[1])];
}
class DatagramConn {
  declare static readonly [Symbol.hasInstance]: (value: unknown) => value is DatagramConn;
  private constructor() {
    throw new TypeError("Illegal constructor");
  }
  get addr() {
    return state(datagrams, this).local;
  }
  receive(
    buffer: Uint8Array<ArrayBufferLike> | undefined = undefined,
  ): Promise<Datagram> {
    return receiveDatagram(state(datagrams, this), buffer);
  }
  send(buffer: Uint8Array<ArrayBufferLike>, target: unknown): Promise<number> {
    const data = state(datagrams, this);
    id(data);
    bytes(buffer);
    if (length(buffer) > 65507) {
      throw new RangeError("Datagram exceeds 65507 bytes");
    }
    const snapshot: Uint8Array<ArrayBuffer> = new Uint8Array(buffer),
      destination = datagramOptions(target, true);
    return queue(
      data,
      () =>
        then(
          op_net_datagram_send(args(id(data), snapshot, destination)),
          result,
        ),
    );
  }
  setBroadcast(enabled = true): void {
    result(
      op_net_datagram_broadcast(args(id(state(datagrams, this)), !!enabled)),
    );
  }
  close() {
    close(state(datagrams, this));
  }
  [dispose]() {
    close(state(datagrams, this), true);
  }
  [asyncIterator](): AsyncIterableIterator<Datagram, undefined> {
    const data = state(datagrams, this);
    return {
      async next() {
        if (data.id === null) return { done: true, value: undefined };
        try {
          return {
            done: false,
            value: await safePromise(receiveDatagram(data, undefined)),
          };
        } catch (error) {
          if (data.id === null) return { done: true, value: undefined };
          throw error;
        }
      },
      return() {
        close(data, true);
        return promiseResolve({ done: true, value: undefined });
      },
      [asyncIterator]() {
        return this;
      },
    };
  }
}
function listenDatagram(value: unknown): DatagramConn {
  const row = result(op_net_datagram_listen(datagramOptions(value)));
  const socket = ObjectCreate(DatagramConn.prototype) as DatagramConn;
  set(datagrams, socket, {
    id: row[0],
    owner: socket,
    local: address(row[1]),
    writing: promiseResolve(undefined),
  });
  register(registry, socket, row[0], socket);
  return socket;
}
for (
  const pair of [[Conn, "Conn"], [Listener, "Listener"], [
    DatagramConn,
    "DatagramConn",
  ]] as const
) {
  define(pair[0].prototype, Symbol.toStringTag, {
    value: pair[1],
    configurable: true,
  });
}
export { Conn, connect, DatagramConn, listen, listenDatagram, Listener };