define(["jquery", "./slick.core"], function($, Slick) {

  /***
   * Provides item metadata for group (Slick.Group) and totals (Slick.Totals) rows produced by the DataView.
   * This metadata overrides the default behavior and formatting of those rows so that they appear and function
   * correctly when processed by the grid.
   *
   * This class also acts as a grid plugin providing event handlers to expand & collapse groups.
   * If "grid.registerPlugin(...)" is not called, expand & collapse will not work.
   *
   * @class GroupItemMetadataProvider
   * @module Data
   * @namespace Slick.Data
   * @constructor
   * @param options
   */
  function GroupItemMetadataProvider(options) {
    var _grid;
    var _defaults = {
      groupCssClass: "bk-slick-group",
      groupTitleCssClass: "bk-slick-group-title",
      totalsCssClass: "bk-slick-group-totals",
      groupFocusable: true,
      totalsFocusable: false,
      toggleCssClass: "bk-slick-group-toggle",
      toggleExpandedCssClass: "expanded",
      toggleCollapsedCssClass: "collapsed",
      enableExpandCollapse: true,
      groupFormatter: defaultGroupCellFormatter,
      totalsFormatter: defaultTotalsCellFormatter
    };

    options = $.extend(true, {}, _defaults, options);


    function defaultGroupCellFormatter(row, cell, value, columnDef, item) {
      if (!options.enableExpandCollapse) {
        return item.title;
      }

      var indentation = item.level * 15 + "px";

      return "<span class='" + options.toggleCssClass + " " +
          (item.collapsed ? options.toggleCollapsedCssClass : options.toggleExpandedCssClass) +
          "' style='margin-left:" + indentation +"'>" +
          "</span>" +
          "<span class='" + options.groupTitleCssClass + "' level='" + item.level + "'>" +
            item.title +
          "</span>";
    }

    function defaultTotalsCellFormatter(row, cell, value, columnDef, item) {
      return (columnDef.groupTotalsFormatter && columnDef.groupTotalsFormatter(item, columnDef)) || "";
    }


    function init(grid) {
      _grid = grid;
      _grid.onClick.subscribe(handleGridClick);
      _grid.onKeyDown.subscribe(handleGridKeyDown);

    }

    function destroy() {
      if (_grid) {
        _grid.onClick.unsubscribe(handleGridClick);
        _grid.onKeyDown.unsubscribe(handleGridKeyDown);
      }
    }

    function handleGridClick(e, args) {
      var item = this.getDataItem(args.row);
      if (item && item instanceof Slick.Group && $(e.target).hasClass(options.toggleCssClass)) {
        var range = _grid.getRenderedRange();
        this.getData().setRefreshHints({
          ignoreDiffsBefore: range.top,
          ignoreDiffsAfter: range.bottom
        });

        if (item.collapsed) {
          this.getData().expandGroup(item.groupingKey);
        } else {
          this.getData().collapseGroup(item.groupingKey);
        }

        e.stopImmediatePropagation();
        e.preventDefault();
      }
    }

    // TODO:  add -/+ handling
    function handleGridKeyDown(e, args) {
      if (options.enableExpandCollapse && (e.which == $.ui.keyCode.SPACE)) {
        var activeCell = this.getActiveCell();
        if (activeCell) {
          var item = this.getDataItem(activeCell.row);
          if (item && item instanceof Slick.Group) {
            var range = _grid.getRenderedRange();
            this.getData().setRefreshHints({
              ignoreDiffsBefore: range.top,
              ignoreDiffsAfter: range.bottom
            });

            if (item.collapsed) {
              this.getData().expandGroup(item.groupingKey);
            } else {
              this.getData().collapseGroup(item.groupingKey);
            }

            e.stopImmediatePropagation();
            e.preventDefault();
          }
        }
      }
    }

    function getGroupRowMetadata(item) {
      return {
        selectable: false,
        focusable: options.groupFocusable,
        cssClasses: options.groupCssClass,
        columns: {
          0: {
            colspan: "*",
            formatter: options.groupFormatter,
            editor: null
          }
        }
      };
    }

    function getTotalsRowMetadata(item) {
      return {
        selectable: false,
        focusable: options.totalsFocusable,
        cssClasses: options.totalsCssClass,
        formatter: options.totalsFormatter,
        editor: null
      };
    }


    return {
      "init": init,
      "destroy": destroy,
      "getGroupRowMetadata": getGroupRowMetadata,
      "getTotalsRowMetadata": getTotalsRowMetadata
    };
  }

  return GroupItemMetadataProvider;
});
