/*
  fvlogger v1.0
  (c) 2005 davidfmiller
  http://www.fivevoltlogic.com/code/fvlogger/
  see readme.txt for documentation
*/

// version number
var FVLOGGER_VERSION = '1.0';

// turn logging on or off;
var FVL_LOG_ON = true; //(location.href.indexOf('?debug') > -1);

// all logging statements that whose level is greater than or equal to FVL_DEFAULT_LOG_LEVEL will be processed;
// all others will be ignored
var FVL_DEFAULT_LOG_LEVEL = FVL_DEBUG;

// the id of the node that will have the logging statements appended to it
var FVL_LOG_ID = 'fvlogger';

// the element that should be wrapped around the log messages
var FVL_LOG_ELEMENT = 'p';

/* the code that follows is */

// constants for logging levels
var FVL_DEBUG = 0;
var FVL_INFO  = 1;
var FVL_WARN  = 2;
var FVL_ERROR = 3;
var FVL_FATAL = 4;

// the css classes that will be applied to the logging elements
var FVL_LOG_CLASSES = new Array("debug", "info", "warn", "error", "fatal");

/* */

// retrieves the element whose id is equal to FVL_LOG_ID
function getLogger(id) {
  if (arguments.length == 0) { id = FVL_LOG_ID; }
  return document.getElementById(id);
}

function showDebug() { FVL_showMessages(FVL_DEBUG); }
function showInfo() { FVL_showMessages(FVL_INFO); }
function showWarn() { FVL_showMessages(FVL_WARN); }
function showError() { FVL_showMessages(FVL_ERROR); }
function showFatal() { FVL_showMessages(FVL_FATAL); }
function showAll() { FVL_showMessages(); }

// removes all logging information from the logging element
function eraseLog(ask) {
  var debug = getLogger();
  if (! debug) { return false; }

  if (ask && ! confirm("Are you sure you wish to erase the log?")) {
    return false;
  }

  var ps = debug.getElementsByTagName(FVL_LOG_ELEMENT);
  var length = ps.length;
  for (var i = 0; i < length; i++) { debug.removeChild(ps[length - i - 1]); }
  return true;
} // eraseLog

function debug(message) { FVL_log("" + message, FVL_DEBUG); }
function warn(message) { FVL_log("" + message, FVL_WARN); }
function info(message) { FVL_log("" + message, FVL_INFO); }
function error(message) { FVL_log("" + message, FVL_ERROR);}
//function fatal(message) { FVL_log("" + message, FVL_FATAL);}

function windowError(message, url, line) {
  FVL_log('Error on line ' + line + ' of document ' + url + ': ' + message, FVL_FATAL);
  return true; //
} // windowError

// only override the window's error handler if we logging is turned on
if (FVL_LOG_ON) {
  window.onerror = windowError;
}

// 
function FVL_showMessages(level, hideOthers) {
  //  alert('showing ' + level);
  var showAll = false;
  // if no level has been specified, use the default
  if (arguments.length == 0) { level = FVL_DEFAULT_LOG_LEVEL; showAll = true; }
  if (arguments.length < 2) { hideOthers = true; }

  // retrieve the element and current statements
  var debug = getLogger();
  if (! debug) { return false; }
  var ps = debug.getElementsByTagName("p");
  if (ps.length == 0) { return true; }

  // get the number of nodes in the list
  var l = ps.length; 

  // get the class name for the specified level
  var lookup = FVL_LOG_CLASSES[level]; 

  // loop through all logging statements/<p> elements...
  for (var i = l - 1; i >= 0; i--) {

    // hide all elements by default, if specified
    if (hideOthers) { hide(ps[i]); } 

    // get the class name for this <p>
    var c = getNodeClass(ps[i]);
//    alert(c);
//    alert("Node #" + i + "'s class is:" + c);
    if (c && c.indexOf(lookup) > -1 || showAll) { show(ps[i]); } 
  }
} // FVL_showMessages

// appends a statement to the logging element if the threshold level is exceeded
function FVL_log(message, level) {
  // check to make sure logging is turned on
  if (! FVL_LOG_ON) { return false; } 

  // retrieve the infrastructure
  if (arguments.length == 1) { level = FVL_INFO;}
  if (level < FVL_DEFAULT_LOG_LEVEL) { return false; }
  var div = getLogger();
  if (! div) { return false; }

  // append the statement
  var p = document.createElement(FVL_LOG_ELEMENT);

  // this is a hack work around a bug in ie
  if (p.getAttributeNode("class")) {
    for (var i = 0; i < p.attributes.length; i++) {
      if (p.attributes[i].name.toUpperCase() == 'CLASS') {
        p.attributes[i].value = FVL_LOG_CLASSES[level];
      }
    }
  } else {
    p.setAttribute("class", FVL_LOG_CLASSES[level]);
  }
  var text = document.createTextNode(message);
  p.appendChild(text);
  div.appendChild(p);
  return true;
} // FVL_log

function exampleLogs() {
  // describe the four types of logging messages
  debug('Scatter debug messages throughout your code to provide a high-level overview of what your code is doing, such as which function is currently in scope and the values of loop counters.');
  info('Information messages are the meat and potatoes of logging messages; sprinkle them around to reveal more detailed information about your script\'s execution, such as the values of variables and function/method return values.');
  warn('Warning messages are used to indicate potentially hazardous situations, such as missing function arguments...');
  error('While error messages are used to indicate that something bad is about to happen; note that these kinds of errors are considered to be run-time errors, which are a different type of beast from the parse errors mentioned below.');

// generate an error to demonstrate the fatal error in ie and mozilla browsers
  a 
}

// show a node
function show(target) {
  target.style.display = "";
  return true;
}

// hide a node
function hide(target) {
  target.style.display = "none";
  return true;
}

// returns the class attribute of a node
function getNodeClass(obj) {
  var result = false;

  if (obj.getAttributeNode("class")) {
    result = obj.attributes.getNamedItem("class").value;
  }
  return result;
}