/* ************************************************************************

   qooxdoo - the new era of web development

   http://qooxdoo.org

   Copyright:
     2011 1&1 Internet AG, Germany, http://www.1und1.de

   License:
     LGPL: http://www.gnu.org/licenses/lgpl.html
     EPL: http://www.eclipse.org/org/documents/epl-v10.php
     See the LICENSE file in the project's top-level directory for details.

   Authors:
     * Christian Hagendorn (chris_schmidt)

************************************************************************ */

/**
 * Implements the different selection modes single, multi, additive and one
 * selection with there drag and quick selection.
 *
 * Example how to use selection:
 * <pre class="javascript">
 * var rawData = [];
 * for (var i = 0; i < 2500; i++) {
 *  rawData[i] = "Item No " + i;
 * }
 *
 * var model = qx.data.marshal.Json.createModel(rawData);
 * var list = new qx.ui.list.List(model);
 *
 * // Pre-Select "Item No 20"
 * list.getSelection().push(model.getItem(20));
 *
 * // log change selection
 * list.getSelection().addListener("change", function(e) {
 *   this.debug("Selection: " + list.getSelection().getItem(0));
 * }, this);
 * </pre>
 *
 * @internal
 */
qx.Mixin.define("qx.ui.virtual.selection.MModel",
{
  construct : function()
  {
    this._initSelectionManager();
    this.initSelection(new qx.data.Array());
  },


  properties :
  {
    /** Current selected items */
    selection :
    {
      check : "qx.data.Array",
      event : "changeSelection",
      apply : "_applySelection",
      nullable : false,
      deferredInit : true
    },


    /**
     * The selection mode to use.
     *
     * For further details please have a look at:
     * {@link qx.ui.core.selection.Abstract#mode}
     */
    selectionMode :
    {
      check : ["single", "multi", "additive", "one"],
      init : "single",
      apply : "_applySelectionMode"
    },


    /**
     * Enable drag selection (multi selection of items through
     * dragging the mouse in pressed states).
     *
     * Only possible for the selection modes <code>multi</code> and <code>additive</code>
     */
    dragSelection :
    {
      check : "Boolean",
      init : false,
      apply : "_applyDragSelection"
    },


    /**
     * Enable quick selection mode, where no click is needed to change the selection.
     *
     * Only possible for the modes <code>single</code> and <code>one</code>.
     */
    quickSelection :
    {
      check : "Boolean",
      init : false,
      apply : "_applyQuickSelection"
    }
  },


  members :
  {
    /** {qx.ui.virtual.selection.Row} selection manager */
    _manager : null,


    /** {Boolean} flag to ignore the selection change from {@link #selection} */
    __ignoreChangeSelection : false,


    /** {Boolean} flag to ignore the selection change from <code>_manager</code> */
    __ignoreManagerChangeSelection : false,


    /**
     * Initialize the selection manager with his delegate.
     */
    _initSelectionManager : function()
    {
      var self = this;
      var selectionDelegate =
      {
        isItemSelectable : function(row) {
          return self._provider.isSelectable(row);
        },

        styleSelectable : function(row, type, wasAdded)
        {
          if (type != "selected") {
            return;
          }

          if (wasAdded) {
            self._provider.styleSelectabled(row);
          } else {
            self._provider.styleUnselectabled(row);
          }
        }
      }

      this._manager = new qx.ui.virtual.selection.Row(
        this.getPane(), selectionDelegate
      );
      this._manager.attachMouseEvents(this.getPane());
      this._manager.attachKeyEvents(this);
      this._manager.addListener("changeSelection", this._onManagerChangeSelection, this);
    },


    /**
     * Method to update the selection, this method can be used when the model has
     * changes.
     */
    _updateSelection : function()
    {
      if (this._manager == null) {
        return;
      }

      this._onChangeSelection();
    },


    /*
    ---------------------------------------------------------------------------
      APPLY ROUTINES
    ---------------------------------------------------------------------------
    */


    // apply method
    _applySelection : function(value, old)
    {
      value.addListener("change", this._onChangeSelection, this);

      if (old != null) {
        old.removeListener("change", this._onChangeSelection, this);
      }

      this._onChangeSelection();
    },


    // apply method
    _applySelectionMode : function(value, old) {
      this._manager.setMode(value);
    },


    // apply method
    _applyDragSelection : function(value, old) {
      this._manager.setDrag(value);
    },


    // apply method
    _applyQuickSelection : function(value, old) {
      this._manager.setQuick(value);
    },


    /*
    ---------------------------------------------------------------------------
      SELECTION HANDLERS
    ---------------------------------------------------------------------------
    */


    /**
     * Event handler for the internal selection change {@link #selection}.
     *
     * @param e {qx.event.type.Data} the change event.
     */
    _onChangeSelection : function(e)
    {
      if (this.__ignoreManagerChangeSelection == true) {
        return;
      }

      this.__ignoreChangeSelection = true;
      var selection = this.getSelection();

      var newSelection = [];
      for (var i = 0; i < selection.getLength(); i++)
      {
        var item = selection.getItem(i);
        var index = this._getSelectables().indexOf(item);
        var row = this._reverseLookup(index);

        if (row >= 0) {
          newSelection.push(row);
        }
      }

      if (this._beforeApplySelection != null &&
          qx.lang.Type.isFunction(this._beforeApplySelection)) {
        this._beforeApplySelection(newSelection);
      }

      try {
        this._manager.replaceSelection(newSelection);
      }
      catch(e)
      {
        this._manager.selectItem(newSelection[newSelection.length - 1]);
      }
      this.__synchronizeSelection();

      if (this._afterApplySelection != null &&
          qx.lang.Type.isFunction(this._afterApplySelection)) {
        this._afterApplySelection();
      }

      this.__ignoreChangeSelection = false;
    },


    /**
     * Event handler for the selection change from the <code>_manager</code>.
     *
     * @param e {qx.event.type.Data} the change event.
     */
    _onManagerChangeSelection : function(e)
    {
      if (this.__ignoreChangeSelection == true) {
        return;
      }

      this.__ignoreManagerChangeSelection = true;

      this.__synchronizeSelection();

      this.__ignoreManagerChangeSelection = false;
    },


    /**
     * Synchronized the selection form the manager with the local one.
     */
    __synchronizeSelection : function()
    {
      if (this.__isSelectionEquals()) {
        return
      }

      var managerSelection = this._manager.getSelection();
      var newSelection = [];

      for (var i = 0; i < managerSelection.length; i++) {
        newSelection.push(this._getDataFromRow(managerSelection[i]));
      }

      this.__replaceSelection(newSelection);
    },


    /**
     * Replace the current selection with the passed selection Array.
     *
     * @param newSelection {qx.data.Array} The new selection.
     */
    __replaceSelection : function(newSelection)
    {
      var selection = this.getSelection();
      if (newSelection.length > 0)
      {
        var args = [0, selection.getLength()];
        args = args.concat(newSelection);
        selection.splice.apply(selection, args);
      } else {
        selection.removeAll();
      }
    },


    /**
     * Checks whether the local and the manager selection is equals.
     *
     * @return {Boolean} <code>true</code> when the selection is equals,
     *   <code>false</code> otherwise.
     */
    __isSelectionEquals : function()
    {
      var selection = this.getSelection();
      var managerSelection = this._manager.getSelection();

      if (selection.getLength() !== managerSelection.length) {
        return false;
      }

      for (var i = 0; i < selection.getLength(); i++)
      {
        var item = selection.getItem(i);
        var index = this._getSelectables().indexOf(item);
        var row = this._reverseLookup(index);

        if (row !== managerSelection[i]) {
          return false;
        };
      }
      return true;
    },


    /**
     * Helper Method to select default item.
     */
    _applyDefaultSelection : function() {
      if (this._manager != null) {
        this._manager._applyDefaultSelection();
      }
    }
  },


  destruct : function()
  {
    this._manager.dispose();
    this._manager = null;
  }
});