// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
"use strict";

((window) => {
  const { BlobPrototype } = window.__bootstrap.file;
  const { TcpConn } = window.__bootstrap.net;
  const { fromFlashRequest, toInnerResponse, _flash } =
    window.__bootstrap.fetch;
  const core = window.Deno.core;
  const {
    ReadableStream,
    ReadableStreamPrototype,
    getReadableStreamRid,
    readableStreamClose,
    _state,
  } = window.__bootstrap.streams;
  const {
    WebSocket,
    _rid,
    _readyState,
    _eventLoop,
    _protocol,
    _idleTimeoutDuration,
    _idleTimeoutTimeout,
    _serverHandleIdleTimeout,
  } = window.__bootstrap.webSocket;
  const { _ws } = window.__bootstrap.http;
  const {
    Function,
    ObjectPrototypeIsPrototypeOf,
    PromiseAll,
    TypedArrayPrototypeSubarray,
    TypeError,
    Uint8Array,
    Uint8ArrayPrototype,
  } = window.__bootstrap.primordials;

  const statusCodes = {
    100: "Continue",
    101: "Switching Protocols",
    102: "Processing",
    200: "OK",
    201: "Created",
    202: "Accepted",
    203: "Non Authoritative Information",
    204: "No Content",
    205: "Reset Content",
    206: "Partial Content",
    207: "Multi-Status",
    208: "Already Reported",
    226: "IM Used",
    300: "Multiple Choices",
    301: "Moved Permanently",
    302: "Found",
    303: "See Other",
    304: "Not Modified",
    305: "Use Proxy",
    307: "Temporary Redirect",
    308: "Permanent Redirect",
    400: "Bad Request",
    401: "Unauthorized",
    402: "Payment Required",
    403: "Forbidden",
    404: "Not Found",
    405: "Method Not Allowed",
    406: "Not Acceptable",
    407: "Proxy Authentication Required",
    408: "Request Timeout",
    409: "Conflict",
    410: "Gone",
    411: "Length Required",
    412: "Precondition Failed",
    413: "Payload Too Large",
    414: "URI Too Long",
    415: "Unsupported Media Type",
    416: "Range Not Satisfiable",
    418: "I'm a teapot",
    421: "Misdirected Request",
    422: "Unprocessable Entity",
    423: "Locked",
    424: "Failed Dependency",
    426: "Upgrade Required",
    428: "Precondition Required",
    429: "Too Many Requests",
    431: "Request Header Fields Too Large",
    451: "Unavailable For Legal Reasons",
    500: "Internal Server Error",
    501: "Not Implemented",
    502: "Bad Gateway",
    503: "Service Unavailable",
    504: "Gateway Timeout",
    505: "HTTP Version Not Supported",
    506: "Variant Also Negotiates",
    507: "Insufficient Storage",
    508: "Loop Detected",
    510: "Not Extended",
    511: "Network Authentication Required",
  };

  const methods = {
    0: "GET",
    1: "HEAD",
    2: "CONNECT",
    3: "PUT",
    4: "DELETE",
    5: "OPTIONS",
    6: "TRACE",
    7: "POST",
    8: "PATCH",
  };

  let dateInterval;
  let date;
  let stringResources = {};

  // Construct an HTTP response message.
  // All HTTP/1.1 messages consist of a start-line followed by a sequence
  // of octets.
  //
  //  HTTP-message = start-line
  //    *( header-field CRLF )
  //    CRLF
  //    [ message-body ]
  //
  function http1Response(method, status, headerList, body, earlyEnd = false) {
    // HTTP uses a "<major>.<minor>" numbering scheme
    //   HTTP-version  = HTTP-name "/" DIGIT "." DIGIT
    //   HTTP-name     = %x48.54.54.50 ; "HTTP", case-sensitive
    //
    // status-line = HTTP-version SP status-code SP reason-phrase CRLF
    // Date header: https://datatracker.ietf.org/doc/html/rfc7231#section-7.1.1.2
    let str = `HTTP/1.1 ${status} ${statusCodes[status]}\r\nDate: ${date}\r\n`;
    for (const [name, value] of headerList) {
      // header-field   = field-name ":" OWS field-value OWS
      str += `${name}: ${value}\r\n`;
    }

    // https://datatracker.ietf.org/doc/html/rfc7231#section-6.3.6
    if (status === 205 || status === 304) {
      // MUST NOT generate a payload in a 205 response.
      // indicate a zero-length body for the response by
      // including a Content-Length header field with a value of 0.
      str += "Content-Length: 0\r\n\r\n";
      return str;
    }

    // MUST NOT send Content-Length or Transfer-Encoding if status code is 1xx or 204.
    if (status == 204 && status <= 100) {
      return str;
    }

    if (earlyEnd === true) {
      return str;
    }

    // null body status is validated by inititalizeAResponse in ext/fetch
    if (body !== null && body !== undefined) {
      str += `Content-Length: ${body.length}\r\n\r\n`;
    } else {
      str += "Transfer-Encoding: chunked\r\n\r\n";
      return str;
    }

    // A HEAD request.
    if (method === 1) return str;

    if (typeof body === "string") {
      str += body ?? "";
    } else {
      const head = core.encode(str);
      const response = new Uint8Array(head.byteLength + body.byteLength);
      response.set(head, 0);
      response.set(body, head.byteLength);
      return response;
    }

    return str;
  }

  function prepareFastCalls() {
    return core.opSync("op_flash_make_request");
  }

  function hostnameForDisplay(hostname) {
    // If the hostname is "0.0.0.0", we display "localhost" in console
    // because browsers in Windows don't resolve "0.0.0.0".
    // See the discussion in https://github.com/denoland/deno_std/issues/1165
    return hostname === "0.0.0.0" ? "localhost" : hostname;
  }

  function writeFixedResponse(
    server,
    requestId,
    response,
    end,
    respondFast,
  ) {
    let nwritten = 0;
    // TypedArray
    if (typeof response !== "string") {
      nwritten = respondFast(requestId, response, end);
    } else {
      // string
      const maybeResponse = stringResources[response];
      if (maybeResponse === undefined) {
        stringResources[response] = core.encode(response);
        nwritten = core.ops.op_flash_respond(
          server,
          requestId,
          stringResources[response],
          end,
        );
      } else {
        nwritten = respondFast(requestId, maybeResponse, end);
      }
    }

    if (nwritten < response.length) {
      core.opAsync(
        "op_flash_respond_async",
        server,
        requestId,
        response.slice(nwritten),
        end,
      );
    }
  }

  async function serve(arg1, arg2) {
    let options = undefined;
    let handler = undefined;
    if (arg1 instanceof Function) {
      handler = arg1;
      options = arg2;
    } else if (arg2 instanceof Function) {
      handler = arg2;
      options = arg1;
    } else {
      options = arg1;
    }
    if (handler === undefined) {
      if (options === undefined) {
        throw new TypeError(
          "No handler was provided, so an options bag is mandatory.",
        );
      }
      handler = options.handler;
    }
    if (!(handler instanceof Function)) {
      throw new TypeError("A handler function must be provided.");
    }
    if (options === undefined) {
      options = {};
    }

    const signal = options.signal;

    const onError = options.onError ?? function (error) {
      console.error(error);
      return new Response("Internal Server Error", { status: 500 });
    };

    const onListen = options.onListen ?? function ({ port }) {
      console.log(
        `Listening on http://${
          hostnameForDisplay(listenOpts.hostname)
        }:${port}/`,
      );
    };

    const listenOpts = {
      hostname: options.hostname ?? "127.0.0.1",
      port: options.port ?? 9000,
    };
    if (options.cert || options.key) {
      if (!options.cert || !options.key) {
        throw new TypeError(
          "Both cert and key must be provided to enable HTTPS.",
        );
      }
      listenOpts.cert = options.cert;
      listenOpts.key = options.key;
    }

    const serverId = core.ops.op_flash_serve(listenOpts);
    const serverPromise = core.opAsync("op_flash_drive_server", serverId);

    core.opAsync("op_flash_wait_for_listening", serverId).then((port) => {
      onListen({ hostname: listenOpts.hostname, port });
    }).catch(() => {});
    const finishedPromise = serverPromise.catch(() => {});

    const server = {
      id: serverId,
      transport: listenOpts.cert && listenOpts.key ? "https" : "http",
      hostname: listenOpts.hostname,
      port: listenOpts.port,
      closed: false,
      finished: finishedPromise,
      async close() {
        if (server.closed) {
          return;
        }
        server.closed = true;
        await core.opAsync("op_flash_close_server", serverId);
        await server.finished;
      },
      async serve() {
        let offset = 0;
        while (true) {
          if (server.closed) {
            break;
          }

          let tokens = nextRequestSync();
          if (tokens === 0) {
            tokens = await core.opAsync("op_flash_next_async", serverId);
            if (server.closed) {
              break;
            }
          }

          for (let i = offset; i < offset + tokens; i++) {
            let body = null;
            // There might be a body, but we don't expose it for GET/HEAD requests.
            // It will be closed automatically once the request has been handled and
            // the response has been sent.
            const method = getMethodSync(i);
            let hasBody = method > 2; // Not GET/HEAD/CONNECT
            if (hasBody) {
              body = createRequestBodyStream(serverId, i);
              if (body === null) {
                hasBody = false;
              }
            }

            const req = fromFlashRequest(
              serverId,
              /* streamRid */
              i,
              body,
              /* methodCb */
              () => methods[method],
              /* urlCb */
              () => {
                const path = core.ops.op_flash_path(serverId, i);
                return `${server.transport}://${server.hostname}:${server.port}${path}`;
              },
              /* headersCb */
              () => core.ops.op_flash_headers(serverId, i),
            );

            let resp;
            try {
              resp = await handler(req);
            } catch (e) {
              resp = await onError(e);
            }
            // there might've been an HTTP upgrade.
            if (resp === undefined) {
              return;
            }
            const innerResp = toInnerResponse(resp);

            // If response body length is known, it will be sent synchronously in a
            // single op, in other case a "response body" resource will be created and
            // we'll be streaming it.
            /** @type {ReadableStream<Uint8Array> | Uint8Array | null} */
            let respBody = null;
            let isStreamingResponseBody = false;
            if (innerResp.body !== null) {
              if (typeof innerResp.body.streamOrStatic?.body === "string") {
                if (innerResp.body.streamOrStatic.consumed === true) {
                  throw new TypeError("Body is unusable.");
                }
                innerResp.body.streamOrStatic.consumed = true;
                respBody = innerResp.body.streamOrStatic.body;
                isStreamingResponseBody = false;
              } else if (
                ObjectPrototypeIsPrototypeOf(
                  ReadableStreamPrototype,
                  innerResp.body.streamOrStatic,
                )
              ) {
                if (innerResp.body.unusable()) {
                  throw new TypeError("Body is unusable.");
                }
                if (
                  innerResp.body.length === null ||
                  ObjectPrototypeIsPrototypeOf(
                    BlobPrototype,
                    innerResp.body.source,
                  )
                ) {
                  respBody = innerResp.body.stream;
                } else {
                  const reader = innerResp.body.stream.getReader();
                  const r1 = await reader.read();
                  if (r1.done) {
                    respBody = new Uint8Array(0);
                  } else {
                    respBody = r1.value;
                    const r2 = await reader.read();
                    if (!r2.done) throw new TypeError("Unreachable");
                  }
                }
                isStreamingResponseBody = !(
                  typeof respBody === "string" ||
                  ObjectPrototypeIsPrototypeOf(Uint8ArrayPrototype, respBody)
                );
              } else {
                if (innerResp.body.streamOrStatic.consumed === true) {
                  throw new TypeError("Body is unusable.");
                }
                innerResp.body.streamOrStatic.consumed = true;
                respBody = innerResp.body.streamOrStatic.body;
              }
            } else {
              respBody = new Uint8Array(0);
            }

            const ws = resp[_ws];
            if (isStreamingResponseBody === false) {
              const responseStr = http1Response(
                method,
                innerResp.status ?? 200,
                innerResp.headerList,
                respBody,
              );
              writeFixedResponse(
                serverId,
                i,
                responseStr,
                !ws, // Don't close socket if there is a deferred websocket upgrade.
                respondFast,
              );
            }

            (async () => {
              if (!ws) {
                if (hasBody && body[_state] !== "closed") {
                  // TODO(@littledivy): Optimize by draining in a single op.
                  try {
                    await req.arrayBuffer();
                  } catch { /* pass */ }
                }
              }

              if (isStreamingResponseBody === true) {
                const resourceRid = getReadableStreamRid(respBody);
                if (resourceRid) {
                  if (respBody.locked) {
                    throw new TypeError("ReadableStream is locked.");
                  }
                  const reader = respBody.getReader(); // Aquire JS lock.
                  try {
                    core.opAsync(
                      "op_flash_write_resource",
                      http1Response(
                        method,
                        innerResp.status ?? 200,
                        innerResp.headerList,
                        null,
                        true,
                      ),
                      serverId,
                      i,
                      resourceRid,
                    ).then(() => {
                      // Release JS lock.
                      readableStreamClose(respBody);
                    });
                  } catch (error) {
                    await reader.cancel(error);
                    throw error;
                  }
                } else {
                  const reader = respBody.getReader();
                  writeFixedResponse(
                    serverId,
                    i,
                    http1Response(
                      method,
                      innerResp.status ?? 200,
                      innerResp.headerList,
                      null,
                    ),
                    false,
                    respondFast,
                  );
                  while (true) {
                    const { value, done } = await reader.read();
                    await respondChunked(
                      i,
                      value,
                      done,
                    );
                    if (done) break;
                  }
                }
              }

              if (ws) {
                const wsRid = await core.opAsync(
                  "op_flash_upgrade_websocket",
                  serverId,
                  i,
                );
                ws[_rid] = wsRid;
                ws[_protocol] = resp.headers.get("sec-websocket-protocol");

                ws[_readyState] = WebSocket.OPEN;
                const event = new Event("open");
                ws.dispatchEvent(event);

                ws[_eventLoop]();
                if (ws[_idleTimeoutDuration]) {
                  ws.addEventListener(
                    "close",
                    () => clearTimeout(ws[_idleTimeoutTimeout]),
                  );
                }
                ws[_serverHandleIdleTimeout]();
              }
            })().catch(onError);
          }

          offset += tokens;
        }
        await server.finished;
      },
    };

    signal?.addEventListener("abort", () => {
      clearInterval(dateInterval);
      server.close().then(() => {}, () => {});
    }, {
      once: true,
    });

    function respondChunked(token, chunk, shutdown) {
      return core.opAsync(
        "op_flash_respond_chuncked",
        serverId,
        token,
        chunk,
        shutdown,
      );
    }

    const fastOp = prepareFastCalls();
    let nextRequestSync = () => fastOp.nextRequest();
    let getMethodSync = (token) => fastOp.getMethod(token);
    let respondFast = (token, response, shutdown) =>
      fastOp.respond(token, response, shutdown);
    if (serverId > 0) {
      nextRequestSync = () => core.ops.op_flash_next_server(serverId);
      getMethodSync = (token) => core.ops.op_flash_method(serverId, token);
      respondFast = (token, response, shutdown) =>
        core.ops.op_flash_respond(serverId, token, response, null, shutdown);
    }

    if (!dateInterval) {
      date = new Date().toUTCString();
      dateInterval = setInterval(() => {
        date = new Date().toUTCString();
        stringResources = {};
      }, 1000);
    }

    await PromiseAll([
      server.serve().catch(console.error),
      serverPromise,
    ]);
  }

  function createRequestBodyStream(serverId, token) {
    // The first packet is left over bytes after parsing the request
    const firstRead = core.ops.op_flash_first_packet(
      serverId,
      token,
    );
    if (!firstRead) return null;
    let firstEnqueued = firstRead.byteLength == 0;

    return new ReadableStream({
      type: "bytes",
      async pull(controller) {
        try {
          if (firstEnqueued === false) {
            controller.enqueue(firstRead);
            firstEnqueued = true;
            return;
          }
          // This is the largest possible size for a single packet on a TLS
          // stream.
          const chunk = new Uint8Array(16 * 1024 + 256);
          const read = await core.opAsync(
            "op_flash_read_body",
            serverId,
            token,
            chunk,
          );
          if (read > 0) {
            // We read some data. Enqueue it onto the stream.
            controller.enqueue(TypedArrayPrototypeSubarray(chunk, 0, read));
          } else {
            // We have reached the end of the body, so we close the stream.
            controller.close();
          }
        } catch (err) {
          // There was an error while reading a chunk of the body, so we
          // error.
          controller.error(err);
          controller.close();
        }
      },
    });
  }

  function upgradeHttpRaw(req) {
    if (!req[_flash]) {
      throw new TypeError(
        "Non-flash requests can not be upgraded with `upgradeHttpRaw`. Use `upgradeHttp` instead.",
      );
    }

    // NOTE(bartlomieju):
    // Access these fields so they are cached on `req` object, otherwise
    // they wouldn't be available after the connection gets upgraded.
    req.url;
    req.method;
    req.headers;

    const { serverId, streamRid } = req[_flash];
    const connRid = core.ops.op_flash_upgrade_http(streamRid, serverId);
    // TODO(@littledivy): return already read first packet too.
    return [new TcpConn(connRid), new Uint8Array()];
  }

  window.__bootstrap.flash = {
    serve,
    upgradeHttpRaw,
  };
})(this);