/*
*  $Id: documentselection.js 164 2006-12-30 02:09:25Z wingedfox $
*  $HeadURL: https://svn.debugger.ru/repos/jslibs/BrowserExtensions/tags/BrowserExtensions.003/documentselection.js $
*
*  Class implements cross-browser work with text selection
*
*  @author Ilya Lebedev
*  @author $Author: wingedfox $
*  @modified $Date: 2006-12-30 05:09:25 +0300 (Сбт, 30 Дек 2006) $
*  @version $Rev: 164 $
*  @license LGPL
*/

/*
*  @class DocumentSelection
*/
DocumentSelection = new function () {
  var self = this;
  /*
  *  Stores hash of keys, applied to elements
  *
  *  @type Object
  *  @scope private
  */
  var keys = {
    'selectionStart' : '__DSselectionStart',
    'selectionEnd' : '__DSselectionEnd'
  }
  /*
  *  Properties to save current scrolling position in Mozilla
  *
  *
  */
  var scrollTop, scrollLeft;
  //---------------------------------------------------------------------------
  //  SETTERS
  //---------------------------------------------------------------------------
  /**
   *  getSelectionRange wrapper/emulator
   *  adapted version
   *
   *  @see http://www.bazon.net/mishoo/articles.epl?art_id=1292
   *  @param {HTMLElement}
   *  @param {Number} start position
   *  @param {Number} end position
   *  @param {Boolean} related indicates calculation of range relatively to current start point
   *  @return void
   *  @scope public
   */
  this.setRange = function(el, start, end, related) {
    /*
    *  set range on relative coordinates
    */
    if (related) {
      var st = self.getStart(el);
      end = st+end;
      start = st+start;
    }
    if ('function' == typeof el.setSelectionRange) {
      /*
      *  for Mozilla
      */
      try {el.setSelectionRange(start, end)} catch (e) {}
    } else {
      /*
      *  for IE
      */
      var range;
      /*
      *  just try to create a range....
      */
      try {
        range = el.createTextRange();
      } catch(e) {
        try {
          range = document.body.createTextRange();
          range.moveToElementText(el);
        } catch(e) {
          range = false;
        }
      }
      // if cannot create range
      if (!range) return false;
      range.collapse(true);

      range.moveStart("character", start);
      range.moveEnd("character", end - start);
      range.select();
    }
    self.setCursorPosition(el,start,end);
  }
  /**
   *  Set sursor position for supplied child
   *
   *  @param {HTMLElement} element to set cursor position on
   *  @param {Number} start selection start
   *  @param {Number} end selection end
   *  @scope public
   */
  this.setCursorPosition = function (el,start,end) {
    el[keys['selectionStart']] = parseInt(start);
    el[keys['selectionEnd']] = parseInt(end);
//    if (scrollTop) el.scrollTop  = scrollTop;
//    if (scrollLeft) el.scrollLeft = scrollLeft;
//    scrollTop = null;
//    scrollLeft= null;
  }
  //---------------------------------------------------------------------------
  //  GETTERS
  //---------------------------------------------------------------------------
  /**
   *  Return contents of the current selection
   *
   *  @param {HTMLElement} el element to look position on
   *  @return {String}
   *  @scope public
   */
  this.getSelection = function(el) {
    var s = self.getCursorPosition(el),
        e = self.getEnd(el);
    /*
    *  w/o this check content might be duplicated on delete
    */
    if (e<s) e = s;
    /*
    *  check for IE, because Opera does use \r\n sequence, but calculate positions correctly
    */
    var tmp = document.selection?el.value.replace(/\r/g,""):el.value;
    return tmp.substring(s,e);
  }
  /**
   *  getSelectionStart wrapper/emulator
   *  adapted version
   *
   *  @see http://www.bazon.net/mishoo/articles.epl?art_id=1292
  *  @param {HTMLElement} el element to calculate end position for
  *  @param {HTMLElement} force force calculation
   *  @return {Number} start position
   *  @scope public
   */
  this.getStart = function (el, force) {
    var start;
    /*
    *  for IE
    */
    try {
      start = Math.abs(document.selection.createRange().moveStart("character", -100000000)); // start
      if (start>0 || force) {
        try {
          var endReal = Math.abs(el.createTextRange().moveEnd("character", -100000000));
          /*
          *  calculate node offset
          */
          var r = document.body.createTextRange();
          r.moveToElementText(el);
          var sTest = Math.abs(r.moveStart("character", -100000000));
          var eTest = Math.abs(r.moveEnd("character", -100000000));
          /*
          *  test for the TEXTAREA's dumb behavior
          */
          if (el.tagName.toLowerCase() != 'input' && eTest - endReal == sTest) {
            start -= sTest;
          }
        } catch(err) {}
      }
    } catch (e) {
      /*
      *  for Mozilla
      */
      try { start = el.selectionStart } catch (e) { start = -1 }
    }
    return start<1?(start==0&&force?0:(parseInt(el[keys['selectionStart']])?parseInt(el[keys['selectionStart']]):0)):start;
  }
  /*
  *  getSelectionStart wrapper/emulator
  *  adapted version
  *
  *  @see http://www.bazon.net/mishoo/articles.epl?art_id=1292
  *  @param {HTMLElement} el element to calculate end position for
  *  @param {HTMLElement} force force calculation
  *  @return {Number} start position
  *  @scope public
  */
  this.getEnd = function (el,force) {
    var end;
    /*
    *  for IE
    */
    try {
      end = Math.abs(document.selection.createRange().moveEnd("character", -100000000)); // end
      if (end>0 || force) {
        try {
          var endReal = Math.abs(el.createTextRange().moveEnd("character", -100000000));
          /*
          *  calculate node offset
          */
          var r = document.body.createTextRange();
          r.moveToElementText(el);
          var sTest = Math.abs(r.moveStart("character", -100000000));
          var eTest = Math.abs(r.moveEnd("character", -100000000));
          /*
          *  test for the TEXTAREA's dumb behavior
          */
          if (el.tagName.toLowerCase() != 'input' && eTest - endReal == sTest) {
            end -= sTest;
          }
        } catch(err) {}
      }
    } catch (e) {
      /*
      *  for Mozilla
      */
      try { end = el.selectionEnd } catch (e) { end = -1 }
    }
    return end<1?(end==0&&force?0:(parseInt(el[keys['selectionEnd']])?parseInt(el[keys['selectionEnd']]):0)):end;
  }
  /*
  *  Return cursor position for supplied field
  *
  *  @param {HTMLElement} element to get cursor position from
  *  @return {Number} position
  *  @scope public
  */
  this.getCursorPosition = function (el) {
//    scrollTop  = el.scrollTop;
//    scrollLeft = el.scrollLeft;

    return self.getStart(el);
  }
  //---------------------------------------------------------------------------
  //  MICS FUNCTIONS
  //---------------------------------------------------------------------------
  /*
  *  Used to save cursor position on click.
  *
  *  @param {MouseEvent} click event
  *  @scope protected
  */
  this.saveCursorPosition = function (e) {
    var el = e.srcElement||e.target;
    if (!el || el.tagName.toLowerCase() == 'select') return false;
    self.setCursorPosition(el,self.getStart(el,true),self.getEnd(el,true));
  }
  /*
  *  Insert text at cursor position
  *
  *  @param {HTMLElement} text field to insert text
  *  @param {String} text to insert
  *  @scope public
  */
  this.insertAtCursor = function (fld, val) {
    var r = self.getCursorPosition(fld);
    /*
    *  check for IE, because Opera does use \r\n sequence, but calculate positions correctly
    */
    var tmp = document.selection?fld.value.replace(/\r/g,""):fld.value;
    fld.value = tmp.substring(0, r)+val+tmp.substring(r,tmp.length);
    self.setRange(fld,r+val.length,r+val.length);
  }
  /*
  *  Deletes char at cursor position
  *
  *  @param {HTMLElement} text field to delete text
  *  @param {Boolean} delete text before (backspace) or after (del) cursor
  *  @scope public
  */
  this.deleteAtCursor = function (fld, after) {
    if (!after) after = false;
    var r = self.getCursorPosition(fld),
        e = self.getEnd(fld);
    /*
    *  w/o this check content might be duplicated on delete
    */
    if (e<r) e = r;
    if (r==e) {
      r=after?r:r-1<0?0:r-1;
      e=after?e+1:e;
    }
    /*
    *  check for IE, because Opera does use \r\n sequence, but calculate positions correctly
    */
    var tmp = document.selection?fld.value.replace(/\r/g,""):fld.value;
    fld.value = tmp.substring(0, r)+tmp.substring(e,tmp.length);
    self.setRange(fld, r, r);
  }
  /**
   *  Removes the selection, if available
   * 
   *  @param {HTMLElement} fld field to delete text from
   *  @scope public
   */
  this.deleteSelection = function (fld) {
    var r = self.getCursorPosition(fld),
        e = self.getEnd(fld);
    if (r==e) return;
    /*
    *  check for IE, because Opera does use \r\n sequence, but calculate positions correctly
    */
    var tmp = document.selection?fld.value.replace(/\r/g,""):fld.value;
    fld.value = tmp.substring(0, r)+tmp.substring(e,tmp.length);
    self.setRange(fld, r, r);
  }
}
/*
*  Add cursor position saving
*/
if (document.attachEvent) {
  document.attachEvent('onmouseup', DocumentSelection.saveCursorPosition);
  document.attachEvent('onkeyup', DocumentSelection.saveCursorPosition);
} else if (document.addEventListener) {
  document.addEventListener('mouseup', DocumentSelection.saveCursorPosition,false);
  document.addEventListener('keyup', DocumentSelection.saveCursorPosition,false);
}