// 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 { Event } = window.__bootstrap.event;
  const {
    ReadableStream,
    ReadableStreamPrototype,
    getReadableStreamResourceBacking,
    readableStreamClose,
    _state,
  } = window.__bootstrap.streams;
  const {
    WebSocket,
    _rid,
    _readyState,
    _eventLoop,
    _protocol,
    _idleTimeoutDuration,
    _idleTimeoutTimeout,
    _serverHandleIdleTimeout,
  } = window.__bootstrap.webSocket;
  const { _ws } = window.__bootstrap.http;
  const {
    ObjectPrototypeIsPrototypeOf,
    PromisePrototype,
    PromisePrototypeCatch,
    PromisePrototypeThen,
    SafeArrayIterator,
    SafePromiseAll,
    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;

  // 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,
    bodyLen,
    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: ${date}\r\n`;
    for (const [name, value] of new SafeArrayIterator(headerList)) {
      // header-field   = field-name ":" OWS field-value OWS
      str += `${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 < 200) {
      str += "\r\n";
      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: ${bodyLen}\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.ops.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,
    responseLen,
    end,
    respondFast,
  ) {
    let nwritten = 0;
    // TypedArray
    if (typeof response !== "string") {
      nwritten = respondFast(requestId, response, end);
    } else {
      // string
      nwritten = core.ops.op_flash_respond(
        server,
        requestId,
        response,
        end,
      );
    }

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

  // TODO(@littledivy): Woah woah, cut down the number of arguments.
  async function handleResponse(
    req,
    resp,
    body,
    hasBody,
    method,
    serverId,
    i,
    respondFast,
    respondChunked,
    tryRespondChunked,
  ) {
    // 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 length = respBody.byteLength || core.byteLength(respBody);
      const responseStr = http1Response(
        method,
        innerResp.status ?? 200,
        innerResp.headerList,
        respBody,
        length,
      );
      writeFixedResponse(
        serverId,
        i,
        responseStr,
        length,
        !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 resourceBacking = getReadableStreamResourceBacking(respBody);
        if (resourceBacking) {
          if (respBody.locked) {
            throw new TypeError("ReadableStream is locked.");
          }
          const reader = respBody.getReader(); // Aquire JS lock.
          try {
            PromisePrototypeThen(
              core.opAsync(
                "op_flash_write_resource",
                http1Response(
                  method,
                  innerResp.status ?? 200,
                  innerResp.headerList,
                  0, // Content-Length will be set by the op.
                  null,
                  true,
                ),
                serverId,
                i,
                resourceBacking.rid,
                resourceBacking.autoClose,
              ),
              () => {
                // Release JS lock.
                readableStreamClose(respBody);
              },
            );
          } catch (error) {
            await reader.cancel(error);
            throw error;
          }
        } else {
          const reader = respBody.getReader();

          // Best case: sends headers + first chunk in a single go.
          const { value, done } = await reader.read();
          writeFixedResponse(
            serverId,
            i,
            http1Response(
              method,
              innerResp.status ?? 200,
              innerResp.headerList,
              respBody.byteLength,
              null,
            ),
            respBody.byteLength,
            false,
            respondFast,
          );

          await tryRespondChunked(
            i,
            value,
            done,
          );

          if (!done) {
            while (true) {
              const chunk = await reader.read();
              await respondChunked(
                i,
                chunk.value,
                chunk.done,
              );
              if (chunk.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]();
      }
    })();
  }

  function createServe(opFn) {
    return async function serve(arg1, arg2) {
      let options = undefined;
      let handler = undefined;
      if (typeof arg1 === "function") {
        handler = arg1;
        options = arg2;
      } else if (typeof arg2 === "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 (typeof handler !== "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,
        reuseport: options.reusePort ?? false,
      };
      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 = opFn(listenOpts);
      const serverPromise = core.opAsync("op_flash_drive_server", serverId);

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

      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 = handler(req);
                if (ObjectPrototypeIsPrototypeOf(PromisePrototype, resp)) {
                  PromisePrototypeCatch(
                    PromisePrototypeThen(
                      resp,
                      (resp) =>
                        handleResponse(
                          req,
                          resp,
                          body,
                          hasBody,
                          method,
                          serverId,
                          i,
                          respondFast,
                          respondChunked,
                          tryRespondChunked,
                        ),
                    ),
                    onError,
                  );
                  continue;
                } else if (typeof resp?.then === "function") {
                  resp.then((resp) =>
                    handleResponse(
                      req,
                      resp,
                      body,
                      hasBody,
                      method,
                      serverId,
                      i,
                      respondFast,
                      respondChunked,
                      tryRespondChunked,
                    )
                  ).catch(onError);
                  continue;
                }
              } catch (e) {
                resp = await onError(e);
              }

              handleResponse(
                req,
                resp,
                body,
                hasBody,
                method,
                serverId,
                i,
                respondFast,
                respondChunked,
                tryRespondChunked,
              );
            }

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

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

      function tryRespondChunked(token, chunk, shutdown) {
        const nwritten = core.ops.op_try_flash_respond_chuncked(
          serverId,
          token,
          chunk ?? new Uint8Array(),
          shutdown,
        );
        if (nwritten > 0) {
          return core.opAsync(
            "op_flash_respond_chuncked",
            serverId,
            token,
            chunk,
            shutdown,
            nwritten,
          );
        }
      }

      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();
        }, 1000);
      }

      await SafePromiseAll([
        PromisePrototypeCatch(server.serve(), 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 = {
    createServe,
    upgradeHttpRaw,
  };
})(this);