var previous_chat = '';  // Keep track of changes in chat content
var chat_refresh_counter = 0; // Keep track of chat refreshes.  Reset if user sends in chat.
var chat_refresh_limit = 720; // Limit to chat refreshes (5 minutes at every 5 seconds)
var chat_initial_load = true;

// AJAX (HttpRequest) Object.
function AJAX(){
  if (window.XMLHttpRequest){
    return new XMLHttpRequest();
  } else if (window.ActiveXObject){
    return new ActiveXObject("Msxml2.XMLHTTP");
  }
}

function autoSaveInit(){
  putHTML('autosave_info','Autosave pending...');
  setInterval(autoSave,10000); // Every 10 seconds.  Will change this later.
}

function autoSave(){
  
  var posting_content = getHTML('post_content');
  if(posting_content != ''){
    
    var ajax = AJAX();
    ajax.onreadystatechange = function(){
    
      if((ajax.readyState == 4) && (ajax.status == 200)){
        var response = ajax.responseText;
        var timestamp = parseJSON(response).timestamp;
        var datetime = new Date(timestamp * 1000);
        var formatted_datetime = leadingZeroes(datetime.getHours()) + ':' + leadingZeroes(datetime.getMinutes()) + ':' + leadingZeroes(datetime.getSeconds());
        putHTML('autosave_info','Most recent autosave at: ' + formatted_datetime);

      }
    };
    
    ajax.open('POST','ajax',true);
    ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    var parameters = 'mode=autosave' + '&content=' + encodeURIComponent(posting_content) + '&nocache=' + Math.random();
    ajax.send(parameters);
    
  }
}

function autoSaveRetrieve(){
  
  var ajax = AJAX();
  ajax.onreadystatechange = function(){
    if((ajax.readyState == 4) && (ajax.status == 200)){
      var response = ajax.responseText;
      var content = parseJSON(response).content;
      putHTML('post_content',content);    
    }    
  };
  
  ajax.open('POST','ajax',true);
  ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  var parameters = 'mode=autosave_retrieve' + '&nocache=' + Math.random();
  ajax.send(parameters);
  
}

function previewPost(){
  
  var posting_content = getHTML('post_content');
  if(posting_content != ''){
  
    var ajax = AJAX();
    ajax.onreadystatechange = function(){
      if((ajax.readyState == 4) && (ajax.status == 200)){
        var response = ajax.responseText;
        var content = parseJSON(response).content;
        putHTML('post_preview',content);    
      }    
    };
    
    ajax.open('POST','ajax',true);
    ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    var parameters = 'mode=preview_post&content=' + encodeURIComponent(posting_content) + '&nocache=' + Math.random();
    ajax.send(parameters);
    document.getElementById('post_preview').style.display = 'block';
  
  }
  
}

function updateChat(){
  
  if(chat_refresh_counter >= chat_refresh_limit){
    alert('You have remained idle for an hour.  Please refresh the page in order to view the chat.');
    clearInterval(chatInterval);
    return false;
  }
  
  var ajax = AJAX();
  ajax.onreadystatechange = function(){
    if((ajax.readyState == 4) && (ajax.status == 200)){
      var response = ajax.responseText;
      var chat_lines = parseJSON(response).content;
      try{
        var chat_lines_count = chat_lines.length;
        var output = '';
        for(var i=0; i<chat_lines_count; i++){
          output += chat_lines[i] + "<br />\n";          
        }
        putHTML('chat_lines',output);
        if(output != previous_chat){
          scrollToBottom('chat_lines');
          if(!chat_initial_load){
            playNotifySound();
          }
        }
        previous_chat = output;
        chat_refresh_counter++;
        chat_initial_load = false;
      } catch(e){
          
      }
    }    
  };
  
  ajax.open('POST','ajax',true);
  ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  var parameters = 'mode=get_chat&nocache=' + Math.random();
  ajax.send(parameters);
  
}

function sendChatLine(){
  
  var o = document.getElementById('chat_input');
  var chat_line = o.value;
  
  if(chat_line != ''){
    var ajax = AJAX();
    ajax.onreadystatechange = function(){
      if((ajax.readyState == 4) && (ajax.status == 200)){
        var response = ajax.responseText;
        var chat_lines = parseJSON(response).content;
        try{
          var chat_lines_count = chat_lines.length;
          var output = '';
          for(var i=0; i<chat_lines_count; i++){
            output += chat_lines[i] + "<br />\n";          
          }
          putHTML('chat_lines',output);
          previous_chat = output;
          scrollToBottom('chat_lines');
          // playNotifySound();
          o.value = '';
          chat_refresh_counter = 0;
        } catch(e){
          
        }
      }    
    };
    
    ajax.open('POST','ajax',true);
    ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    var parameters = 'mode=put_chat&content=' + encodeURIComponent(chat_line) + '&nocache=' + Math.random();
    ajax.send(parameters);
  }  
}