/**
 * Controller for virtual-media
 *
 * @module app/serverControl
 * @exports virtualMediaController
 * @name virtualMediaController
 */

window.angular && (function(angular) {
  'use strict';

  angular.module('app.serverControl').controller('virtualMediaController', [
    '$scope', 'APIUtils', 'toastService', 'dataService', 'nbdServerService',
    function($scope, APIUtils, toastService, dataService, nbdServerService) {
      $scope.devices = [];

      // Only one Virtual Media WebSocket device is currently available.
      // Path is /vm/0/0.
      // TODO: Support more than 1 VM device, when backend support is added.
      var vmDevice = {};
      // Hardcode to 0 since /vm/0/0. Last 0 is the device ID.
      // To support more than 1 device ID, replace with a call to get the
      // device IDs and names.
      vmDevice.id = 0;
      vmDevice.deviceName = 'Virtual media device';
      findExistingConnection(vmDevice);
      $scope.devices.push(vmDevice);

      $scope.startVM = function(index) {
        $scope.devices[index].isActive = true;
        var file = $scope.devices[index].file;
        var id = $scope.devices[index].id;
        var host = dataService.getHost().replace('https://', '');
        var server = new NBDServer('wss://' + host + '/vm/0/' + id, file, id);
        $scope.devices[index].nbdServer = server;
        nbdServerService.addConnection(id, server, file);
        server.start();
      };
      $scope.stopVM = function(index) {
        $scope.devices[index].isActive = false;
        var server = $scope.devices[index].nbdServer;
        server.stop();
      };

      $scope.resetFile = function(index) {
        document.getElementById('file-upload').value = '';
        $scope.devices[index].file = '';
      };

      function findExistingConnection(vmDevice) {
        // Checks with existing connections kept in nbdServerService for an open
        // Websocket connection.
        var existingConnectionsMap = nbdServerService.getExistingConnections();
        if (existingConnectionsMap.hasOwnProperty(vmDevice.id)) {
          // Open ws will have a ready state of 1
          if (existingConnectionsMap[vmDevice.id].server.ws.readyState === 1) {
            vmDevice.isActive = true;
            vmDevice.file = existingConnectionsMap[vmDevice.id].file;
            vmDevice.nbdServer = existingConnectionsMap[vmDevice.id].server;
          }
        }
        return vmDevice;
      }
    }
  ]);
})(angular);

/* handshake flags */
const NBD_FLAG_FIXED_NEWSTYLE = 0x1;
const NBD_FLAG_NO_ZEROES = 0x2;

/* transmission flags */
const NBD_FLAG_HAS_FLAGS = 0x1;
const NBD_FLAG_READ_ONLY = 0x2;

/* option negotiation */
const NBD_OPT_EXPORT_NAME = 0x1;
const NBD_REP_FLAG_ERROR = 0x1 << 31;
const NBD_REP_ERR_UNSUP = NBD_REP_FLAG_ERROR | 1;

/* command definitions */
const NBD_CMD_READ = 0;
const NBD_CMD_WRITE = 1;
const NBD_CMD_DISC = 2;
const NBD_CMD_TRIM = 4;

/* errno */
const EPERM = 1;
const EIO = 5;
const EINVAL = 22;
const ENOSPC = 28;

/* internal object state */
const NBD_STATE_UNKNOWN = 1;
const NBD_STATE_OPEN = 2;
const NBD_STATE_WAIT_CFLAGS = 3;
const NBD_STATE_WAIT_OPTION = 4;
const NBD_STATE_TRANSMISSION = 5;

function NBDServer(endpoint, file, id) {
  this.file = file;
  this.id = id;
  this.endpoint = endpoint;
  this.ws = null;
  this.state = NBD_STATE_UNKNOWN;
  this.msgbuf = null;

  this.start = function() {
    this.ws = new WebSocket(this.endpoint);
    this.state = NBD_STATE_OPEN;
    this.ws.binaryType = 'arraybuffer';
    this.ws.onmessage = this._on_ws_message.bind(this);
    this.ws.onopen = this._on_ws_open.bind(this);
    this.ws.onclose = this._on_ws_close.bind(this);
    this.ws.onerror = this._on_ws_error.bind(this);
  };

  this.stop = function() {
    this.ws.close();
    this.state = NBD_STATE_UNKNOWN;
  };

  this._on_ws_error = function(ev) {
    console.log('vm/0/' + id + 'error: ' + ev);
  };

  this._on_ws_close = function(ev) {
    console.log(
        'vm/0/' + id + ' closed with code: ' + ev.code +
        ' reason: ' + ev.reason);
  };

  /* websocket event handlers */
  this._on_ws_open = function(ev) {
    console.log('vm/0/' + id + ' opened');
    this.client = {
      flags: 0,
    };
    this._negotiate();
  };

  this._on_ws_message = function(ev) {
    var data = ev.data;

    if (this.msgbuf == null) {
      this.msgbuf = data;
    } else {
      var tmp = new Uint8Array(this.msgbuf.byteLength + data.byteLength);
      tmp.set(new Uint8Array(this.msgbuf), 0);
      tmp.set(new Uint8Array(data), this.msgbuf.byteLength);
      this.msgbuf = tmp.buffer;
    }

    for (;;) {
      var handler = this.recv_handlers[this.state];
      if (!handler) {
        console.log('no handler for state ' + this.state);
        this.stop();
        break;
      }

      var consumed = handler(this.msgbuf);
      if (consumed < 0) {
        console.log(
            'handler[state=' + this.state + '] returned error ' + consumed);
        this.stop();
        break;
      }

      if (consumed == 0) {
        break;
      }

      if (consumed > 0) {
        if (consumed == this.msgbuf.byteLength) {
          this.msgbuf = null;
          break;
        }
        this.msgbuf = this.msgbuf.slice(consumed);
      }
    }
  };

  this._negotiate = function() {
    var buf = new ArrayBuffer(18);
    var data = new DataView(buf, 0, 18);

    /* NBD magic: NBDMAGIC */
    data.setUint32(0, 0x4e42444d);
    data.setUint32(4, 0x41474943);

    /* newstyle negotiation: IHAVEOPT */
    data.setUint32(8, 0x49484156);
    data.setUint32(12, 0x454F5054);

    /* flags: fixed newstyle negotiation, no padding */
    data.setUint16(16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);

    this.state = NBD_STATE_WAIT_CFLAGS;
    this.ws.send(buf);
  };

  /* handlers */
  this._handle_cflags = function(buf) {
    if (buf.byteLength < 4) {
      return 0;
    }

    var data = new DataView(buf, 0, 4);
    this.client.flags = data.getUint32(0);

    this.state = NBD_STATE_WAIT_OPTION;
    return 4;
  };

  this._handle_option = function(buf) {
    if (buf.byteLength < 16) return 0;

    var data = new DataView(buf, 0, 16);
    if (data.getUint32(0) != 0x49484156 || data.getUint32(4) != 0x454F5054) {
      console.log('invalid option magic');
      return -1;
    }

    var opt = data.getUint32(8);
    var len = data.getUint32(12);


    if (buf.byteLength < 16 + len) {
      return 0;
    }

    switch (opt) {
      case NBD_OPT_EXPORT_NAME:
        var n = 10;
        if (!(this.client.flags & NBD_FLAG_NO_ZEROES)) n += 124;
        var resp = new ArrayBuffer(n);
        var view = new DataView(resp, 0, 10);
        /* export size. */
        var size = this.file.size;
        view.setUint32(0, Math.floor(size / (2 ** 32)));
        view.setUint32(4, size & 0xffffffff);
        /* transmission flags: read-only */
        view.setUint16(8, NBD_FLAG_HAS_FLAGS | NBD_FLAG_READ_ONLY);
        this.ws.send(resp);

        this.state = NBD_STATE_TRANSMISSION;
        break;

      default:
        console.log('handle_option: Unsupported option: ' + opt);
        /* reject other options */
        var resp = new ArrayBuffer(20);
        var view = new DataView(resp, 0, 20);
        view.setUint32(0, 0x0003e889);
        view.setUint32(4, 0x045565a9);
        view.setUint32(8, opt);
        view.setUint32(12, NBD_REP_ERR_UNSUP);
        view.setUint32(16, 0);
        this.ws.send(resp);
    }

    return 16 + len;
  };

  this._create_cmd_response = function(req, rc, data = null) {
    var len = 16;
    if (data) len += data.byteLength;
    var resp = new ArrayBuffer(len);
    var view = new DataView(resp, 0, 16);
    view.setUint32(0, 0x67446698);
    view.setUint32(4, rc);
    view.setUint32(8, req.handle_msB);
    view.setUint32(12, req.handle_lsB);
    if (data) new Uint8Array(resp, 16).set(new Uint8Array(data));
    return resp;
  };

  this._handle_cmd = function(buf) {
    if (buf.byteLength < 28) {
      return 0;
    }

    var view = new DataView(buf, 0, 28);

    if (view.getUint32(0) != 0x25609513) {
      console.log('invalid request magic');
      return -1;
    }

    var req = {
      flags: view.getUint16(4),
      type: view.getUint16(6),
      handle_msB: view.getUint32(8),
      handle_lsB: view.getUint32(12),
      offset_msB: view.getUint32(16),
      offset_lsB: view.getUint32(20),
      length: view.getUint32(24),
    };

    /* we don't support writes, so nothing needs the data at present */
    /* req.data = buf.slice(28); */

    var err = 0;
    var consumed = 28;

    /* the command handlers return 0 on success, and send their
     * own response. Otherwise, a non-zero error code will be
     * used as a simple error response
     */
    switch (req.type) {
      case NBD_CMD_READ:
        err = this._handle_cmd_read(req);
        break;

      case NBD_CMD_DISC:
        err = this._handle_cmd_disconnect(req);
        break;

      case NBD_CMD_WRITE:
        /* we also need length bytes of data to consume a write
         * request */
        if (buf.byteLength < 28 + req.length) {
          return 0;
        }
        consumed += req.length;
        err = EPERM;
        break;

      case NBD_CMD_TRIM:
        err = EPERM;
        break;

      default:
        console.log('invalid command 0x' + req.type.toString(16));
        err = EINVAL;
    }

    if (err) {
      console.log('error handle_cmd: ' + err);
      var resp = this._create_cmd_response(req, err);
      this.ws.send(resp);
    }

    return consumed;
  };

  this._handle_cmd_read = function(req) {
    var offset;

    offset = (req.offset_msB * 2 ** 32) + req.offset_lsB;

    if (offset > Number.MAX_SAFE_INTEGER) return ENOSPC;

    if (offset + req.length > Number.MAX_SAFE_INTEGER) return ENOSPC;

    if (offset + req.length > file.size) return ENOSPC;

    var blob = this.file.slice(offset, offset + req.length);
    var reader = new FileReader();

    reader.onload = (function(ev) {
                      var reader = ev.target;
                      if (reader.readyState != FileReader.DONE) return;
                      var resp =
                          this._create_cmd_response(req, 0, reader.result);
                      this.ws.send(resp);
                    }).bind(this);

    reader.onerror = (function(ev) {
                       var reader = ev.target;
                       console.log('error reading file: ' + reader.error);
                       var resp = this._create_cmd_response(req, EIO);
                       this.ws.send(resp);
                     }).bind(this);
    reader.readAsArrayBuffer(blob);

    return 0;
  };

  this._handle_cmd_disconnect = function(req) {
    this.stop();
    return 0;
  };

  this.recv_handlers = Object.freeze({
    [NBD_STATE_WAIT_CFLAGS]: this._handle_cflags.bind(this),
    [NBD_STATE_WAIT_OPTION]: this._handle_option.bind(this),
    [NBD_STATE_TRANSMISSION]: this._handle_cmd.bind(this),
  });
}