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      1 // Copyright 2013 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 // Redefine '$' here rather than including 'cr.js', since this is
      6 // the only function needed.  This allows this file to be loaded
      7 // in a browser directly for layout and some testing purposes.
      8 var $ = function(id) { return document.getElementById(id); };
      9 
     10 var currentTreatment = 0;
     11 var treatments = [];
     12 
     13 /**
     14  * Take a string of hex like '74657374' and return the ascii version 'test'.
     15  * @param {string} str The string of hex characters to convert to ascii
     16  * @return {string} The ASCII values of those hex encoded characters
     17  */
     18 function hexToChars(str) {
     19   var decoded = '';
     20   if (str.length % 2 == 0) {
     21     for (var pos = str.length; pos > 0; pos = pos - 2) {
     22       var c = String.fromCharCode(parseInt(str.substring(pos - 2, pos), 16));
     23       decoded = c + decoded;
     24     }
     25   }
     26   return decoded;
     27 }
     28 
     29 /**
     30  * Extract the experiment information out of the encoded URL string.
     31  * The format is as follows:
     32  * chrome://salsa/#HEX_ENCODED_EXPERIMENT
     33  * Experiments are encoded as:
     34  *    treatment1+treatment2+...+treatmentn
     35  * Each treatment is of the form:
     36  *    preference1,preference2,...,preferencen
     37  * Each preference is of the form:
     38  *    name:value
     39  * This function returns an object storing all the parsed data.
     40  * @param {string} url The URL to parse the experiment from
     41  * @return {list} a list of objects, each representing a single treatment
     42  *     and consisting of a set of preference name -> value pairs
     43  */
     44 function parseURL(url) {
     45   var match = url.match('#([0-9ABCDEFabcdef]*)');
     46   var experimentString = match ? match[1] : '';
     47   experimentString = hexToChars(experimentString);
     48 
     49   var treatmentsFound = [];
     50   if (experimentString == '')
     51     return treatmentsFound;
     52 
     53   var treatmentStrings = experimentString.split('+');
     54   for (var i = 0; i < treatmentStrings.length; i++) {
     55     var prefStrings = treatmentStrings[i].split(',');
     56     treatment = [];
     57     for (var j = 0; j < prefStrings.length; j++) {
     58       var key = prefStrings[j].split(':')[0];
     59       var value = prefStrings[j].split(':')[1];
     60       treatment.push({'key': key, 'value': value});
     61     }
     62     treatmentsFound.push(treatment);
     63   }
     64 
     65   return treatmentsFound;
     66 }
     67 
     68 function setPreferenceValue(key, value) {
     69   chrome.send('salsaSetPreferenceValue', [key, parseFloat(value)]);
     70 }
     71 
     72 function backupPreferenceValue(key) {
     73   chrome.send('salsaBackupPreferenceValue', [key]);
     74 }
     75 
     76 function handleKeyPress(e) {
     77   e = e || window.event;
     78   var selectedTreatment = currentTreatment;
     79 
     80   if (e.keyCode == '37' || e.keyCode == '38') {
     81     selectedTreatment = currentTreatment - 1;
     82     if (selectedTreatment < 0)
     83       selectedTreatment = 0;
     84   } else if (e.keyCode == '39' || e.keyCode == '40') {
     85     selectedTreatment = currentTreatment + 1;
     86     if (selectedTreatment >= treatments.length)
     87       selectedTreatment = treatments.length - 1;
     88   }
     89 
     90   if (selectedTreatment != currentTreatment)
     91     applyTreatment(selectedTreatment);
     92 }
     93 
     94 function applyTreatment(treatment_number) {
     95   if (treatment_number < 0)
     96     treatment_number = 0;
     97   if (treatment_number >= treatments.length)
     98     treatment_number = treatments.length;
     99 
    100   $('treatment' + currentTreatment).className = 'treatment';
    101   currentTreatment = treatment_number;
    102   $('treatment' + currentTreatment).className = 'selected treatment';
    103 
    104   for (var i = 0; i < treatments[treatment_number].length; i++) {
    105     var key = treatments[treatment_number][i].key;
    106     var value = treatments[treatment_number][i].value;
    107     setPreferenceValue(key, value);
    108   }
    109 }
    110 
    111 function initialize() {
    112   // Parse the experiment string in the URL.
    113   treatments = parseURL(document.URL);
    114 
    115   // Update the available treatments list.
    116   for (var i = 0; i < treatments.length; i++) {
    117     var newTreatment = $('treatment-template').cloneNode(true);
    118     newTreatment.id = 'treatment' + i.toString();
    119     newTreatment.removeAttribute('hidden');
    120     newTreatment.onclick = function() {
    121       applyTreatment(parseInt(this.textContent));
    122     };
    123     newTreatment.textContent = i.toString();
    124     $('treatment-list').appendChild(newTreatment);
    125   }
    126 
    127   if (treatments.length > 0) {
    128     // Store a copy of the settings right now so you can reset them afterwards.
    129     for (var i = 0; i < treatments[0].length; i++)
    130       backupPreferenceValue(treatments[0][i].key);
    131 
    132     // Select Treatment 0 to start
    133     applyTreatment(0);
    134   } else {
    135     // Make the error message visible and hide everything else
    136     $('invalid_treatment_info').removeAttribute('hidden');
    137     var div = $('valid_treatment_info');
    138     div.parentNode.removeChild(div);
    139   }
    140 }
    141 
    142 /**
    143  * A key handler so the user can use the arrow keys to select their treatments.
    144  * This should fire any time they press a key
    145  */
    146 document.onkeydown = handleKeyPress;
    147 document.addEventListener('DOMContentLoaded', initialize);
    148