/**
 * @provide pskl.drawingtools.BaseSelect
 *
 * @require pskl.utils
 */
(function() {
  var ns = $.namespace("pskl.drawingtools");

  ns.BaseSelect = function() {
    this.secondaryToolId = "tool-move";
    this.BodyRoot = $('body');

    // Select's first point coordinates (set in applyToolAt)
    this.startCol = null;
    this.startRow = null;
  };

  pskl.utils.inherit(ns.BaseSelect, ns.BaseTool);

  /**
   * @override
   */
  ns.BaseSelect.prototype.applyToolAt = function(col, row, color, frame, overlay, event) {
    this.startCol = col;
    this.startRow = row;

    this.lastCol = col;
    this.lastRow = row;

    // The select tool can be in two different state.
    // If the inital click of the tool is not on a selection, we go in "select"
    // mode to create a selection.
    // If the initial click is on a previous selection, we go in "moveSelection"
    // mode to allow to move the selection by drag'n dropping it.
    if(overlay.getPixel(col, row) != Constants.SELECTION_TRANSPARENT_COLOR) {

      this.mode = "select";
      this.onSelectStart_(col, row, color, frame, overlay);
    }
    else {

      this.mode = "moveSelection";
      this.onSelectionDragStart_(col, row, color, frame, overlay);
    }
  };

  /**
   * @override
   */
  ns.BaseSelect.prototype.moveToolAt = function(col, row, color, frame, overlay, event) {
    if(this.mode == "select") {

      this.onSelect_(col, row, color, frame, overlay);
    }
    else if(this.mode == "moveSelection") {

      this.onSelectionDrag_(col, row, color, frame, overlay);
    }
  };

  /**
   * @override
   */
  ns.BaseSelect.prototype.releaseToolAt = function(col, row, color, frame, overlay, event) {
    if(this.mode == "select") {
      this.onSelectEnd_(col, row, color, frame, overlay);
    } else if(this.mode == "moveSelection") {

      this.onSelectionDragEnd_(col, row, color, frame, overlay);
    }
  };


  /**
   * If we mouseover the selection draw inside the overlay frame, show the 'move' cursor
   * instead of the 'select' one. It indicates that we can move the selection by dragndroping it.
   * @override
   */
  ns.BaseSelect.prototype.moveUnactiveToolAt = function(col, row, color, frame, overlay, event) {

    if(overlay.getPixel(col, row) != Constants.SELECTION_TRANSPARENT_COLOR) {
      // We're hovering the selection, show the move tool:
      this.BodyRoot.addClass(this.toolId);
      this.BodyRoot.removeClass(this.secondaryToolId);
    } else {
      // We're not hovering the selection, show create selection tool:
      this.BodyRoot.addClass(this.secondaryToolId);
      this.BodyRoot.removeClass(this.toolId);
    }
  };

  /**
   * For each pixel in the selection draw it in white transparent on the tool overlay
   * @protected
   */
  ns.BaseSelect.prototype.drawSelectionOnOverlay_ = function (selection, overlay) {
    var pixels = selection.pixels;
    for(var i=0, l=pixels.length; i<l; i++) {
      overlay.setPixel(pixels[i].col, pixels[i].row, Constants.SELECTION_TRANSPARENT_COLOR);
    }
  };

  /**
   * Move the overlay frame filled with semi-transparent pixels that represent the selection.
   * @private
   */
  ns.BaseSelect.prototype.shiftOverlayFrame_ = function (colDiff, rowDiff, overlayFrame, reference) {
    var color;
    for (var col = 0 ; col < overlayFrame.getWidth() ; col++) {
      for (var row = 0 ; row < overlayFrame.getHeight() ; row++) {
        if (reference.containsPixel(col - colDiff, row - rowDiff)) {
          color = reference.getPixel(col - colDiff, row - rowDiff);
        } else {
          color = Constants.TRANSPARENT_COLOR;
        }
        overlayFrame.setPixel(col, row, color);
      }
    }
  };


  // The list of callbacks to implement by specialized tools to implement the selection creation behavior.
  /** @protected */
  ns.BaseSelect.prototype.onSelectStart_ = function (col, row, color, frame, overlay) {};
  /** @protected */
  ns.BaseSelect.prototype.onSelect_ = function (col, row, color, frame, overlay) {};
  /** @protected */
  ns.BaseSelect.prototype.onSelectEnd_ = function (col, row, color, frame, overlay) {};


  // The list of callbacks that define the drag'n drop behavior of the selection.
  /** @private */
  ns.BaseSelect.prototype.onSelectionDragStart_ = function (col, row, color, frame, overlay) {
    // Since we will move the overlayFrame in which  the current selection is rendered,
    // we clone it to have a reference for the later shifting process.
    this.overlayFrameReference = overlay.clone();
  };

  /** @private */
  ns.BaseSelect.prototype.onSelectionDrag_ = function (col, row, color, frame, overlay) {
    var deltaCol = col - this.lastCol;
    var deltaRow = row - this.lastRow;

    var colDiff = col - this.startCol, rowDiff = row - this.startRow;

    // Shifting selection on overlay frame:
    this.shiftOverlayFrame_(colDiff, rowDiff, overlay, this.overlayFrameReference);

    // Update selection model:
    $.publish(Events.SELECTION_MOVE_REQUEST, [deltaCol, deltaRow]);

    this.lastCol = col;
    this.lastRow = row;
  };

  /** @private */
  ns.BaseSelect.prototype.onSelectionDragEnd_ = function (col, row, color, frame, overlay) {
    this.onSelectionDrag_(col, row, color, frame, overlay);
  };
})();