/*
 * Group-level based edit page access. Monitors current edit sessions.
 * Version 0.2.0
 *
 */

var pl_ConflictEdit = {

  // time of sleep before looped AJAX call during the editpage (in seconds)
  // !! should be at least twice shorter than 'PL_CE_AJAX_EXPIRE_TIME' defined in PHP !!
  editSleep: 30,
  // non-existent editId, which means that the editing session was finished
  nobodyEditing: -1,

  // called from body.onload to display copied pages notification list via AJAX (if there's any)
  // @param:   args[0] - article id
  // @param:   args[1..n] - list of revid's created by current user which were copied due to edit conflict
  getNotifyText : function ( args ) {
    // PHP will build copied pages notification list
    // ajax callback will display them (if available)
    sajax_do_call( "pl_ConflictEdit::getNotifyText", args , pl_ConflictEdit.displayNotification );
  },

  // called from copied pages notification list link
  clearRevId : function ( revId ) {
    // PHP will remove the selected revid from the edit conflicts table
    // ajax callback will remove the corresponding DOM entry
    sajax_do_call( "pl_ConflictEdit::clearRevId", [ revId ], pl_ConflictEdit.hideCheckout );
  },

  // loop for watching the editing page
  // can be called in two ways:
  // initlal call is performed from body.onload
  // @param   request - numeric editId
  // further calls are performed via AJAX every editSleep seconds
  // @param   request - AJAX request object, containing the value of editId
  watchEdit : function ( request ) {
    // non-existent editId indicates an error
    // OR the session is over (editid entry in DB was deleted)
    var editId = pl_ConflictEdit.nobodyEditing;
    if ( request.responseText ) {
      if ( request.status == 200) {
        // get editId from AJAX callback
        editId = request.responseText;
      }
    } else {
      // get editId from the header script call parameter
      editId = request;
    }
    if ( editId != pl_ConflictEdit.nobodyEditing ) {
      // php will update edit_time in the current edits table so the ongoing editing session won't expire
      // ajax callback will loop until the user will leave an editpage
      // setTimeout() to reduce server load
      window.setTimeout( function () { sajax_do_call( "pl_ConflictEdit::markEditing", [ editId ], pl_ConflictEdit.watchEdit ); },
        pl_ConflictEdit.editSleep * 1000 );
    }
  },

  // AJAX callback for displaying generated copied revisions notify list in the Skin 'siteSub' element
  // ( list of the copied conflicting edits )
  // @param    request.responseText - html text of "copied resivions notify list" that will be placed into 'siteSub'
  displayNotification : function ( request ) {
    var taglist = request.responseText;
    if (request.status != 200) {
      taglist = "<div class='error'> " + request.status + " " + request.statusText + ": " + taglist + "</div>";
    }
    if ( taglist != '' ) {
      try {
        var div = document.createElement( 'DIV' );
        div.setAttribute( 'id', 'pl_conflictedit_notify' );
        div.innerHTML = taglist;
        var siteSub = document.getElementById( 'siteSub' );
        siteSub.insertBefore( div, siteSub.firstChild );
      } catch ( e ) {
        alert( 'Error: current Skin doesn\'t have \'siteSub\' element' );
      }
    }
  },

  // @return   boolean: whether the element has next 'SPAN' sibling or not
  nextSpanSibling : function ( element ) {
    var next = element;
    do {
      next = next.nextSibling;
      if ( next && next.nodeType == 1 && next.tagName == 'SPAN' ) {
        return true;
      }
    } while ( next );
    return false;
  },

  // @return   boolean: whether the element has previous 'SPAN' sibling or not
  prevSpanSibling : function ( element ) {
    var prev = element;
    do {
      prev = prev.previousSibling;
      if ( prev && prev.nodeType == 1 && prev.tagName == 'SPAN' ) {
        return true;
      }
    } while ( prev );
    return false;
  },

  // called via ajax callback
  // removes a DOM node which contains revid notification entry
  // from the displayed "copied revision notify list"
  // @param   request.responseText - single revid value
  hideCheckout : function ( request ) {
    var revid = request.responseText;
    var parent_li, hasSpanSiblings;
    // !warning! the following code is depending on the structure of generated 'DIV' id='siteSub' element!
    if (request.status == 200 && revid != '') {
      try {
        // get span with selected revid link
        var span = document.getElementById( 'pl_conflictedit_' + revid );
        // check whether selected span has prev or next span siblings
        hasSpanSiblings = pl_ConflictEdit.nextSpanSibling( span ) || pl_ConflictEdit.prevSpanSibling( span );
        // get parent 'LI' of the current 'SPAN' list
        parent_li = span.parentNode;
        if ( hasSpanSiblings ) {
          // remove only current element
          parent_li.removeChild( span );
        } else {
          // no siblings - remove the parent (the whole 'LI')
          parent_li.parentNode.removeChild( parent_li );
        }
      } catch ( e ) {
        alert( 'Error: non-existent revid was given' );
      }
    }
  },

  // browser-independent addevent function
	addEvent : function ( obj, type, fn ) {
  	if ( document.getElementById && document.createTextNode ) {
      if (obj.addEventListener) {
        obj.addEventListener( type, fn, false );
      }
      else if (obj.attachEvent) {
        obj["e"+type+fn] = fn;
        obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
        obj.attachEvent( "on"+type, obj[type+fn] );
      }
      else {
        obj["on"+type] = obj["e"+type+fn];
      }
    }
	},

  // get absolute on-page coordinates of the selected DOM obj
  // @param    obj - DOM obj
  // @return   object { left:x,top:y } - the values of coordinates
  GetElementPosition : function ( obj ) {
    var coords = { left: 0, top: 0 };
    while ( obj ) {
      coords.left += obj.offsetLeft;
      coords.top += obj.offsetTop;
      obj = obj.offsetParent;
    }
    return coords;
  },

  // edit action anchor
  editAnchor : null,
  // original (saved) value of edit action anchor href
  editHref : null,
  // popup div element
  popup : null,

  // attach ajax php call to anchor onclick event
  // @param    articleId - article_id of the current title
  // @param    a - anchor
  // @param    disallowEdit - whether the user of higher weight already edits the article
  attachToEditAnchor : function ( articleId, a, disallowEdit ) {
    pl_ConflictEdit.editAnchor = a;
    // save original anchor href
    pl_ConflictEdit.editHref = a.getAttribute( 'href' );
    pl_ConflictEdit.editTooltip = a.getAttribute( 'title' );
    // disable anchor href because event "return false" may fail sometimes
    // ( we will use window.location.href instead )
    a.href = '#';
    if ( disallowEdit ) {
      // clear invitation tooltip
      a.setAttribute( 'title', '' );
    }
    pl_ConflictEdit.addEvent( a, "click",
      function () {
        // php will check, whether another user with higher edit weight alreay edits the page
        // ajax callback will go to edit page or will display a warning that editing is not allowed,
        // ( based on the result from php call )
        sajax_do_call( "pl_ConflictEdit::checkEditButton", [ articleId ] , pl_ConflictEdit.clickEventResult );
        return true;
      }
    );
  },

  // create popup div message
  // this.popup property will store div popup object
  createPopup : function ( text ) {
    var div = document.createElement( 'DIV' );
    div.setAttribute( 'id', 'pl_conflictedit_popup' );
    div.innerHTML = text;
    document.body.appendChild( div );
    pl_ConflictEdit.popup = div;
  },

  // display the popup div message just below the obj in the selected number of seconds
  displayPopup : function ( obj, seconds ) {
    var coords = pl_ConflictEdit.GetElementPosition( obj );
    var displayShift = { x: 30, y: 26 };
    if ( coords.left + displayShift.x > document.body.scrollWidth ) {
      displayShift.x = -displayShift.x;
    }
    if ( coords.top + displayShift.y > document.body.scrollHeight ) {
      displayShift.y = -displayShift.y;
    }
    pl_ConflictEdit.popup.style.left = (coords.left + displayShift.x) + "px";
    pl_ConflictEdit.popup.style.top = (coords.top + displayShift.y) + "px";
    pl_ConflictEdit.popup.style.visibility = 'visible';
    window.setTimeout(
      function () {
        pl_ConflictEdit.popup.style.visibility = 'hidden';
      },
      seconds * 1000
    );
  },

  // called from body.onload to find edit anchor and to attach an event to it
  // @param    articleId - article_id of current title
  // @param    disallowEdit - whether the user of higher weight already edits the article
  findEditKey : function ( articleId, disallowEdit ) {
    var as = document.body.getElementsByTagName('a');
    for ( var i=0; i<as.length; i++ ) {
      // find an edit access key
      if ( as[i].getAttribute( 'accesskey' ) == 'e' ) {
        pl_ConflictEdit.createPopup( 'Пользователь с более высоким статусом<br />уже редактирует данную страницу.<br/>Пожалуйста подождите окончания редактирования.' );
        pl_ConflictEdit.attachToEditAnchor( articleId, as[i], disallowEdit );
        return;
      }
    }
  },

  // ajax callback
  // @param    request.responseText - 'y' allows to go to edit page; 'n' - blocks edit link and outputs a popup warning
  clickEventResult : function ( request ) {
    var result = request.responseText;
    var clickEventResult = true;
    if (request.status == 200 ) {
      if (request.responseText == 'y') {
        // editing is allowed, going to edit location
        window.location.href = pl_ConflictEdit.editHref;
      } else {
        // editing is disabled - show a popup warning for 5 seconds
        pl_ConflictEdit.editAnchor.blur();
        pl_ConflictEdit.editAnchor.setAttribute('title','');
        pl_ConflictEdit.displayPopup( pl_ConflictEdit.editAnchor, 5 );
      }
    }
  }
}