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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Custom binding for the Bluetooth API.
      6 
      7 var binding = require('binding').Binding.create('bluetooth');
      8 
      9 var chrome = requireNative('chrome').GetChrome();
     10 var Event = require('event_bindings').Event;
     11 var lastError = require('lastError');
     12 var sendRequest = require('sendRequest').sendRequest;
     13 
     14 // Use custom binding to create an undocumented event listener that will
     15 // receive events about device discovery and call the event listener that was
     16 // provided with the request to begin discovery.
     17 binding.registerCustomHook(function(api) {
     18   var apiFunctions = api.apiFunctions;
     19 
     20   var bluetooth = {};
     21 
     22   function callCallbackIfPresent(name, args, error) {
     23     var callback = args[args.length - 1];
     24     if (typeof(callback) == 'function')
     25       lastError.run(name, error, callback);
     26   }
     27 
     28   bluetooth.deviceDiscoveredHandler = null;
     29   bluetooth.onDeviceDiscovered = new Event('bluetooth.onDeviceDiscovered');
     30   function clearDeviceDiscoveredHandler() {
     31     bluetooth.onDeviceDiscovered.removeListener(
     32         bluetooth.deviceDiscoveredHandler);
     33     bluetooth.deviceDiscoveredHandler = null;
     34   }
     35   apiFunctions.setHandleRequest('startDiscovery',
     36       function() {
     37         var args = arguments;
     38         if (args.length > 0 && args[0] && args[0].deviceCallback) {
     39           if (bluetooth.deviceDiscoveredHandler != null) {
     40             callCallbackIfPresent('bluetooth.startDiscovery',
     41                                   args,
     42                                   'Concurrent discovery is not allowed.');
     43             return;
     44           }
     45 
     46           bluetooth.deviceDiscoveredHandler = args[0].deviceCallback;
     47           bluetooth.onDeviceDiscovered.addListener(
     48               bluetooth.deviceDiscoveredHandler);
     49           sendRequest(this.name,
     50                       args,
     51                       this.definition.parameters,
     52                       {customCallback:this.customCallback});
     53         } else {
     54           callCallbackIfPresent(
     55             'bluetooth.startDiscovery',
     56             args,
     57             'deviceCallback is required in the options object');
     58           return;
     59         }
     60       });
     61   apiFunctions.setCustomCallback('startDiscovery',
     62       function(name, request, response) {
     63         if (chrome.runtime.lastError) {
     64           clearDeviceDiscoveredHandler();
     65           return;
     66         }
     67       });
     68   apiFunctions.setHandleRequest('stopDiscovery',
     69       function() {
     70         clearDeviceDiscoveredHandler();
     71         sendRequest(this.name, arguments, this.definition.parameters);
     72       });
     73 
     74   // An object to hold state during one call to getDevices.
     75   bluetooth.getDevicesState = null;
     76 
     77   // Hidden events used to deliver getDevices data to the client callbacks
     78   bluetooth.onDeviceSearchResult = new Event('bluetooth.onDeviceSearchResult');
     79   bluetooth.onDeviceSearchFinished =
     80       new Event('bluetooth.onDeviceSearchFinished');
     81 
     82   function deviceSearchResultHandler(device) {
     83     bluetooth.getDevicesState.actualEvents++;
     84     bluetooth.getDevicesState.deviceCallback(device);
     85     maybeFinishDeviceSearch();
     86   }
     87 
     88   function deviceSearchFinishedHandler(info) {
     89     bluetooth.getDevicesState.expectedEventCount = info.expectedEventCount;
     90     maybeFinishDeviceSearch();
     91   }
     92 
     93   function addDeviceSearchListeners() {
     94     bluetooth.onDeviceSearchResult.addListener(deviceSearchResultHandler);
     95     bluetooth.onDeviceSearchFinished.addListener(deviceSearchFinishedHandler);
     96   }
     97 
     98   function removeDeviceSearchListeners() {
     99     bluetooth.onDeviceSearchResult.removeListener(deviceSearchResultHandler);
    100     bluetooth.onDeviceSearchFinished.removeListener(
    101         deviceSearchFinishedHandler);
    102   }
    103 
    104   function maybeFinishDeviceSearch() {
    105     var state = bluetooth.getDevicesState;
    106     if (typeof(state.expectedEventCount) != 'undefined' &&
    107         state.actualEvents >= state.expectedEventCount) {
    108       finishDeviceSearch();
    109     }
    110   }
    111 
    112   function finishDeviceSearch() {
    113     var finalCallback = bluetooth.getDevicesState.finalCallback;
    114     removeDeviceSearchListeners();
    115     bluetooth.getDevicesState = null;
    116 
    117     if (finalCallback) {
    118       finalCallback();
    119     }
    120   }
    121 
    122   apiFunctions.setUpdateArgumentsPostValidate('getDevices',
    123       function() {
    124         var args = $Array.slice(arguments);
    125 
    126         if (bluetooth.getDevicesState != null) {
    127           throw new Error('Concurrent calls to getDevices are not allowed.');
    128         }
    129 
    130         var state = { actualEvents: 0 };
    131 
    132         if (typeof(args[args.length - 1]) == 'function') {
    133           state.finalCallback = args.pop();
    134           $Array.push(args,
    135               function() {
    136                 if (chrome.runtime.lastError) {
    137                   finishDeviceSearch();
    138                 }
    139               });
    140         } else {
    141           throw new Error('getDevices must have a final callback parameter.');
    142         }
    143 
    144         if (typeof(args[0].deviceCallback) == 'function') {
    145           state.deviceCallback = args[0].deviceCallback;
    146         } else {
    147           throw new Error('getDevices must be passed options with a ' +
    148               'deviceCallback.');
    149         }
    150 
    151         bluetooth.getDevicesState = state;
    152         addDeviceSearchListeners();
    153 
    154         return args;
    155       });
    156 });
    157 
    158 exports.binding = binding.generate();
    159