/**
 * Convert a single file-input element into a 'multiple' input list
 *
 * Usage:
 *
 *   1. Create a file input element (no name)
 *      eg. <input type="file" id="first_file_element">
 *
 *   2. Create a DIV for the output to be written to
 *      eg. <div id="files_list"></div>
 *
 *   3. Instantiate a MultiSelector object, passing in the DIV and an (optional) maximum number of files
 *      eg. var multi_selector = new MultiSelector( document.getElementById( 'files_list' ), 3 );
 *
 *   4. Add the first element
 *      eg. multi_selector.addElement( document.getElementById( 'first_file_element' ) );
 *
 *   5. That's it.
 *
 *   You might (will) want to play around with the addListRow() method to make the output prettier.
 *
 *   You might also want to change the line
 *       element.name = 'file_' + this.count;
 *   ...to a naming convention that makes more sense to you.
 *
 * Licence:
 *   Use this however/wherever you like, just don't blame me if it breaks anything.
 *
 * Credit:
 *   If you're nice, you'll leave this bit:
 *
 *   Class by Stickman -- http://www.the-stickman.com
 *      with thanks to:
 *      [for Safari fixes]
 *         Luis Torrefranca -- http://www.law.pitt.edu
 *         and
 *         Shawn Parker & John Pennypacker -- http://www.fuzzycoconut.com
 *      [for duplicate name bug]
 *         'neal'
 */
function MultiSelector( list_target, max ){

  // Where to write the list
  this.list_target = list_target;
  // How many elements?
  this.count = 0;
  // How many elements?
  this.id = 0;
  // Is there a maximum?
  if( max ){
    this.max = max;
  } else {
    this.max = -1;
  };
  
  /**
   * Add a new file input element
   */
  this.addElement = function( element ){

    // Make sure it's a file input element
    if ( element.tagName == 'INPUT' && element.type == 'file' ){

      // Element name -- what number am I?
      element.name = 'file_' + this.id++;

      // Add reference to this object
      element.multi_selector = this;

      // What to do when a file is selected
      element.onchange = function(){

        // New file input
        var new_element = document.createElement( 'input' );
        new_element.type = 'file';
        new_element.className = 'caja';
        
        // Add new element
        this.parentNode.insertBefore( new_element, this );
  
        // Apply 'update' to element
        this.multi_selector.addElement( new_element );
  
        // Update list
        this.multi_selector.addListRow( this );
  
        // Hide this: we can't use display:none because Safari doesn't like it
        this.style.position = 'absolute';
        this.style.left = '-1000px';

      };
      // If we've reached maximum number, disable input element
      if( this.max != -1 && this.count >= this.max ){
        element.disabled = true;
      };

      // File element counter
      this.count++;
      // Most recent element
      this.current_element = element;
      
    } else {
      // This can only be applied to file input elements!
      alert( 'Error: not a file input element' );
    };

  };

  /**
   * Add a new row to the list of files
   */
  this.addListRow = function( element ){

    // Row div
    var new_row = document.createElement( 'div' );
    new_row.className = 'contenido';

    // Delete button
    var new_row_button = document.createElement( 'input' );
    new_row_button.type = 'button';
    new_row_button.value = 'Borrar';
    new_row_button.className = 'caja';
    
    // References
    new_row.element = element;

    // Delete function
    new_row_button.onclick= function(){

      // Remove element from form
      this.parentNode.element.parentNode.removeChild( this.parentNode.element );

      // Remove this row from the list
      this.parentNode.parentNode.removeChild( this.parentNode );

      // Decrement counter
      this.parentNode.element.multi_selector.count--;

      // Re-enable input element (if it's disabled)
      this.parentNode.element.multi_selector.current_element.disabled = false;

      // Appease Safari
      //    without it Safari wants to reload the browser window
      //    which nixes your already queued uploads
      return false;
    };

    // Set row value
    new_row.innerHTML = element.value + "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";

    // Add button
    new_row.appendChild( new_row_button );

    // Add it to the list
    this.list_target.appendChild( new_row );
    
  };

};