define([
	'dojo/_base/lang',
	'dojo/_base/declare',
	'dojo/sniff',
	'dojo/query',
	'../util/misc'
], function (lang, declare, has, query, miscUtil) {
	return declare(null, {
		// summary:
		//		Extension allowing for specification of columns with additional
		//		header rows spanning multiple columns for strictly display purposes.
		//		Only works on `columns` arrays, not `columns` objects or `subRows`
		//		(nor ColumnSets).
		// description:
		//		CompoundColumns allows nested header cell configurations, wherein the
		//		higher-level headers may span multiple columns and are for
		//		display purposes only.
		//		These nested header cells are configured using a special recursive
		//		`children` property in the column definition, where only the deepest
		//		children are ultimately rendered in the grid as actual columns.
		//		In addition, the deepest child columns may be rendered without
		//		individual headers by specifying `showChildHeaders: false` on the parent.

		configStructure: function () {
			// create a set of sub rows for the header row so we can do compound columns
			// the first row is a special spacer row
			var columns = (this.subRows && this.subRows[0]) || this.columns,
				headerRows = [[]],
				topHeaderRow = headerRows[0],
				contentColumns = [];
			// This first row is spacer row that will be made invisible (zero height)
			// with CSS, but it must be rendered as the first row since that is what
			// the table layout is driven by.
			headerRows[0].className = 'dgrid-spacer-row';

			function processColumns(columns, level, hasLabel, parent) {
				var numColumns = 0,
					noop = function () {},
					children,
					hasChildLabels;

				function processColumn(column, i) {
					// Handle the column config when it is an object rather
					// than an array.
					if (typeof column === 'string') {
						column = {label: column};
					}
					if (!(columns instanceof Array) && !column.field) {
						column.field = i;
					}
					children = column.children;
					hasChildLabels = children && (column.showChildHeaders !== false);
					// Set a reference to the parent column so later the children's ids can
					// be updated to indicate the parent-child relationship.
					column.parentColumn = parent;
					if (children) {
						// it has children
						// make sure the column has an id
						if (column.id == null) {
							column.id = ((parent && parent.id) || level - 1) + '-' + topHeaderRow.length;
						}
						else if (parent && parent.id) {
							// Make sure nested compound columns have ids that are prefixed with
							// their parent's ids.
							column.id = parent.id + '-' + column.id;
						}
					}
					else {
						// it has no children, it is a normal header, add it to the content columns
						contentColumns.push(column);
						// add each one to the first spacer header row for proper layout of the header cells
						topHeaderRow.push(lang.delegate(column, {renderHeaderCell: noop}));
						numColumns++;
					}
					if (!hasChildLabels) {
						// create a header version of the column where we can define a specific rowSpan
						// we define the rowSpan as a negative, the number of levels less than the
						// total number of rows, which we don't know yet
						column = lang.delegate(column, {rowSpan: -level});
					}

					if (children) {
						// Recursively process the children; this is specifically
						// performed *after* any potential lang.delegate calls
						// so the parent reference will receive additional info
						numColumns += (column.colSpan =
							processColumns(children, level + 1, hasChildLabels, column));
					}

					// add the column to the header rows at the appropriate level
					if (hasLabel) {
						(headerRows[level] || (headerRows[level] = [])).push(column);
					}
				}

				miscUtil.each(columns, processColumn, this);
				return numColumns;
			}

			processColumns(columns, 1, true);

			var numHeaderRows = headerRows.length,
				i, j, headerRow, headerColumn;
			// Now go back through and increase the rowSpans of the headers to be
			// total rows minus the number of levels they are at.
			for (i = 0; i < numHeaderRows; i++) {
				headerRow = headerRows[i];
				for (j = 0; j < headerRow.length; j++) {
					headerColumn = headerRow[j];
					if (headerColumn.rowSpan < 1) {
						headerColumn.rowSpan += numHeaderRows;
					}
				}
			}
			// we need to set this to be used for subRows, so we make it a single row
			contentColumns = [contentColumns];
			// set our header rows so that the grid will use the alternate header row
			// configuration for rendering the headers
			contentColumns.headerRows = headerRows;
			this.subRows = contentColumns;
			this.inherited(arguments);
		},

		renderHeader: function () {
			var i,
				columns = this.subRows[0],
				headerColumns = this.subRows.headerRows[0];

			this.inherited(arguments);

			// The object delegation performed in configStructure unfortunately
			// "protects" the original column definition objects (referenced by
			// columns and subRows) from obtaining headerNode information, so
			// copy them back in.
			for (i = columns.length; i--;) {
				columns[i].headerNode = headerColumns[i].headerNode;
			}
		},

		_findSortArrowParent: function () {
			var parent = this.inherited(arguments),
				spacerRow = query('.dgrid-spacer-row', this.headerNode)[0],
				columnId,
				nodes;

			if (parent && spacerRow.contains(parent)) {
				columnId = parent.columnId;
				nodes = query('.dgrid-column-' + columnId, this.headerNode);
				return nodes[nodes.length - 1];
			}
		},

		_configColumn: function (column, rowColumns, prefix) {
			// Updates the id on a column definition that is a child to include
			// the parent's id.
			var parent = column.parentColumn;
			var columnId = column.id;
			if (parent) {
				// Adjust the id to incorporate the parent's id.
				// Remove the prefix if it was used to create the id
				var id = columnId.indexOf(prefix) === 0 ? columnId.substring(prefix.length) : columnId;
				prefix = parent.id + '-';
				columnId = column.id = prefix + id;
			}
			this.inherited(arguments, [column, rowColumns, prefix]);
		},

		cell: function (target, columnId) {
			// summary:
			//		Get the cell object by node, event, or id, plus a columnId.
			//		This extension prefixes children's column ids with the parents' column ids,
			//		so cell takes that into account when looking for a column id.

			if (typeof columnId !== 'object') {
				// Find the columnId that corresponds with the provided id.
				// The provided id may be a suffix of the actual id.
				var column = this.column(columnId);
				if (column) {
					columnId = column.id;
				}
			}
			return this.inherited(arguments, [target, columnId]);
		},

		column: function (target) {
			// summary:
			//		Get the column object by node, event, or column id.  Take into account parent column id
			//		prefixes that may be added by this extension.
			var results = this.inherited(arguments);
			if (results == null && typeof target !== 'object') {
				// Find a column id that ends with the provided column id.  This will locate a child column
				// by an id that was provided in the original column configuration.  For example, if a compound column
				// was given the id "compound" and a child column was given the id "child", this will find the column
				// using only "child".  If "compound-child" was being searched for, the inherited call
				// above would have found the cell.
				var suffix = '-' + target,
					suffixLength = suffix.length;
				for (var completeId in this.columns) {
					if (completeId.indexOf(suffix, completeId.length - suffixLength) !== -1) {
						return this.columns[completeId];
					}
				}
			}
			return results;
		},

		_updateCompoundHiddenStates: function (id, hidden) {
			// summary:
			//		Called from _hideColumn and _showColumn (for ColumnHider)
			//		to adjust parent header cells

			var column = this.columns[id],
				colSpan;

			if (column && column.hidden === hidden) {
				// Avoid redundant processing (since it would cause colSpan skew)
				return;
			}

			// column will be undefined when this is called for parents
			while (column && column.parentColumn) {
				// Update colSpans / hidden state of parents
				column = column.parentColumn;
				colSpan = column.colSpan = column.colSpan + (hidden ? -1 : 1);

				if (colSpan) {
					column.headerNode.colSpan = colSpan;
				}
				if (colSpan === 1 && !hidden) {
					this._showColumn(column.id);
				}
				else if (!colSpan && hidden) {
					this._hideColumn(column.id);
				}
			}
		},

		_hideColumn: function (id) {
			var self = this;

			this._updateCompoundHiddenStates(id, true);
			this.inherited(arguments);

			if (has('ff')) {
				// Firefox causes display quirks in certain situations;
				// avoid them by forcing reflow of the header
				this.headerNode.style.display = 'none';
				setTimeout(function () {
					self.headerNode.style.display = '';
					self.resize();
				}, 0);
			}
		},

		_showColumn: function (id) {
			this._updateCompoundHiddenStates(id, false);
			this.inherited(arguments);
		},

		_getResizedColumnWidths: function () {
			// Overrides ColumnResizer method to report the total width and
			// last column correctly for CompoundColumns structures

			var total = 0,
				columns = this.columns,
				id;

			for (id in columns) {
				total += columns[id].headerNode.offsetWidth;
			}

			return {
				totalWidth: total,
				lastColId: this.subRows[0][this.subRows[0].length - 1].id
			};
		}
	});
});