define([
	'dojo/_base/declare',
	'dojo/_base/lang',
	'dojo/dom-class',
	'dojo/dom-construct',
	'dojo/on',
	'dojo/aspect',
	'dojo/query',
	'dojo/has',
	'./util/misc',
	'dojo/_base/sniff'
], function (declare, lang, domClass, domConstruct, on, aspect, query, has, miscUtil) {
	has.add('event-mousewheel', function (global, document, element) {
		return 'onmousewheel' in element;
	});
	has.add('event-wheel', function (global, document, element) {
		return 'onwheel' in element;
	});

	var colsetidAttr = 'data-dgrid-column-set-id';

	function adjustScrollLeft(grid, root) {
		// Adjusts the scroll position of each column set in each row under the given root.
		// (root can be a row, or e.g. a tree parent row element's connected property to adjust children)
		var scrollLefts = grid._columnSetScrollLefts;
		query('.dgrid-column-set', root).forEach(function (element) {
			element.scrollLeft = scrollLefts[element.getAttribute(colsetidAttr)];
		});
	}

	function getColumnSetSubRows(subRows, columnSetId) {
		// Builds a subRow collection that only contains columns that correspond to
		// a given column set id.
		if (!subRows || !subRows.length) {
			return;
		}
		var subset = [];
		var idPrefix = columnSetId + '-';
		for (var i = 0, numRows = subRows.length; i < numRows; i++) {
			var row = subRows[i];
			var subsetRow = [];
			subsetRow.className = row.className;
			for (var k = 0, numCols = row.length; k < numCols; k++) {
				var column = row[k];
				// The column id begins with the column set id.
				if (column.id != null && column.id.indexOf(idPrefix) === 0) {
					subsetRow.push(column);
				}
			}
			subset.push(subsetRow);
		}
		return subset;
	}

	function isRootNode(node, rootNode) {
		// If we've reached the top-level node for the grid then there is no parent column set.
		// This guard prevents an error when scroll is initated over some node in the grid that is not a descendant of
		// a column set. This can happen in a grid that has empty space below its rows (grid is taller than the rows).
		return (rootNode && node === rootNode) || domClass.contains(node, 'dgrid');
	}

	function findParentColumnSet(node, root) {
		// WebKit will invoke mousewheel handlers with an event target of a text
		// node; check target and if it's not an element node, start one node higher
		// in the tree
		if (node.nodeType !== 1) {
			node = node.parentNode;
		}

		while (node && !query.matches(node, '.dgrid-column-set[' + colsetidAttr + ']', root)) {
			if (isRootNode(node, root)) {
				return null;
			}
			node = node.parentNode;
		}

		return node;
	}

	var pointerMap = {
		start: 'down',
		end: 'up'
	};

	function getTouchEventName(type) {
		// Given 'start', 'move', or 'end', returns appropriate touch or pointer event name
		// based on browser support.  (Assumes browser supports touch or pointer.)
		var hasPointer = has('pointer');
		if (hasPointer) {
			type = pointerMap[type] || type;
			if (hasPointer.slice(0, 2) === 'MS') {
				return 'MSPointer' + type.slice(0, 1).toUpperCase() + type.slice(1);
			}
			else {
				return 'pointer' + type;
			}
		}
		return 'touch' + type;
	}

	var horizTouchMove = has('touch') && function (grid) {
		return function (target, listener) {
			var listeners = [
				on(target, getTouchEventName('start'), function (event) {
					if (!grid._currentlyTouchedColumnSet) {
						var node = findParentColumnSet(event.target, target);
						// If handling pointer events, only react to touch;
						// MSPointerDown (IE10) reports 2, 3, 4 for touch, pen, mouse
						if (node && (!event.pointerType || event.pointerType === 'touch' || event.pointerType === 2)) {
							grid._currentlyTouchedColumnSet = node;
							grid._lastColumnSetTouchX = event.clientX;
							grid._lastColumnSetTouchY = event.clientY;
						}
					}
				}),
				on(target, getTouchEventName('move'), function (event) {
					if (grid._currentlyTouchedColumnSet === null) {
						return;
					}
					var node = findParentColumnSet(event.target);
					if (!node) {
						return;
					}
					listener.call(null, grid, node, grid._lastColumnSetTouchX - event.clientX);
					grid._lastColumnSetTouchX = event.clientX;
					grid._lastColumnSetTouchY = event.clientY;
				}),
				on(target, getTouchEventName('end'), function () {
					grid._currentlyTouchedColumnSet = null;
				})
			];

			return {
				remove: function () {
					for (var i = listeners.length; i--;) {
						listeners[i].remove();
					}
				}
			};
		};
	};

	var horizMouseWheel = has('event-mousewheel') || has('event-wheel') ? function (grid) {
		return function (target, listener) {
			return on(target, has('event-wheel') ? 'wheel' : 'mousewheel', function (event) {
				var node = findParentColumnSet(event.target, target),
					deltaX;

				if (!node) {
					return;
				}

				// Normalize reported delta value:
				// wheelDeltaX (webkit, mousewheel) needs to be negated and divided by 3
				// deltaX (FF17+, wheel) can be used exactly as-is
				deltaX = event.deltaX || -event.wheelDeltaX / 3;
				if (deltaX) {
					// only respond to horizontal movement
					listener.call(null, grid, node, deltaX);
				}
			});
		};
	} : function (grid) {
		return function (target, listener) {
			return on(target, '.dgrid-column-set[' + colsetidAttr + ']:MozMousePixelScroll', function (event) {
				if (event.axis === 1) {
					// only respond to horizontal movement
					listener.call(null, grid, this, event.detail);
				}
			});
		};
	};

	function horizMoveHandler(grid, colsetNode, amount) {
		var id = colsetNode.getAttribute(colsetidAttr),
			scroller = grid._columnSetScrollers[id],
			scrollLeft = scroller.scrollLeft + amount;

		scroller.scrollLeft = scrollLeft < 0 ? 0 : scrollLeft;
	}

	return declare(null, {
		// summary:
		//		Provides column sets to isolate horizontal scroll of sets of
		//		columns from each other. This mainly serves the purpose of allowing for
		//		column locking.

		postCreate: function () {
			var self = this;
			this.inherited(arguments);

			this.on(horizMouseWheel(this), horizMoveHandler);
			if (has('touch')) {
				this.on(horizTouchMove(this), horizMoveHandler);
			}

			this.on('.dgrid-column-set:dgrid-cellfocusin', function (event) {
				self._onColumnSetCellFocus(event, this);
			});

			if (typeof this.expand === 'function') {
				aspect.after(this, 'expand', function (promise, args) {
					promise.then(function () {
						var row = self.row(args[0]);
						if (self._expanded[row.id]) {
							// scrollLeft changes can't take effect on collapsed child rows;
							// ensure they are properly updated once re-expanded.
							adjustScrollLeft(self, row.element.connected);
						}
					});
					return promise;
				});
			}
		},

		columnSets: [],

		createRowCells: function (tag, each, subRows, object, options) {
			var row = domConstruct.create('table', { className: 'dgrid-row-table' });
			var tbody = domConstruct.create('tbody', null, row);
			var tr = domConstruct.create('tr', null, tbody);
			for (var i = 0, l = this.columnSets.length; i < l; i++) {
				// iterate through the columnSets
				var cell = domConstruct.create(tag, {
					className: 'dgrid-column-set-cell dgrid-column-set-' + i
				}, tr);
				cell = domConstruct.create('div', {
					className: 'dgrid-column-set'
				}, cell);
				cell.setAttribute(colsetidAttr, i);
				var subset = getColumnSetSubRows(subRows || this.subRows, i) || this.columnSets[i];
				cell.appendChild(this.inherited(arguments, [tag, each, subset, object, options]));
			}
			return row;
		},

		renderArray: function () {
			var rows = this.inherited(arguments);

			for (var i = 0; i < rows.length; i++) {
				adjustScrollLeft(this, rows[i]);
			}
			return rows;
		},

		insertRow: function () {
			var row = this.inherited(arguments);
			adjustScrollLeft(this, row);
			return row;
		},

		renderHeader: function () {
			// summary:
			//		Setup the headers for the grid
			this.inherited(arguments);

			var columnSets = this.columnSets,
				scrollers = this._columnSetScrollers,
				grid = this,
				i, l;

			function reposition() {
				grid._positionScrollers();
			}

			this._columnSetScrollerContents = {};
			this._columnSetScrollLefts = {};

			if (scrollers) {
				// this isn't the first time; destroy existing scroller nodes first
				for (i in scrollers) {
					domConstruct.destroy(scrollers[i]);
				}
			} else {
				// first-time-only operations: hook up event/aspected handlers
				aspect.after(this, 'resize', reposition, true);
				aspect.after(this, 'styleColumn', reposition, true);
				this._columnSetScrollerNode = domConstruct.create('div', {
					className: 'dgrid-column-set-scroller-container'
				}, this.footerNode, 'after');
			}

			// reset to new object to be populated in loop below
			scrollers = this._columnSetScrollers = {};

			for (i = 0, l = columnSets.length; i < l; i++) {
				this._putScroller(columnSets[i], i);
			}

			this._positionScrollers();
		},

		styleColumnSet: function (colsetId, css) {
			// summary:
			//		Dynamically creates a stylesheet rule to alter a columnset's style.

			var rule = this.addCssRule('#' + miscUtil.escapeCssIdentifier(this.domNode.id) +
				' .dgrid-column-set-' + miscUtil.escapeCssIdentifier(colsetId, '-'), css);
			this._positionScrollers();
			return rule;
		},

		configStructure: function () {
			// Squash the column sets together so the grid and other dgrid extensions and mixins can
			// configure the columns and create any needed subrows.
			this.columns = {};
			this.subRows = [];
			for (var i = 0, l = this.columnSets.length; i < l; i++) {
				var columnSet = this.columnSets[i];
				for (var j = 0; j < columnSet.length; j++) {
					columnSet[j] = this._configColumns(i + '-' + j + '-', columnSet[j]);
				}
			}
			this.inherited(arguments);
		},

		_positionScrollers: function () {
			var domNode = this.domNode,
				scrollers = this._columnSetScrollers,
				scrollerContents = this._columnSetScrollerContents,
				columnSets = this.columnSets,
				scrollerWidth = 0,
				numScrollers = 0, // tracks number of visible scrollers (sets w/ overflow)
				i, l, columnSetElement, contentWidth;

			for (i = 0, l = columnSets.length; i < l; i++) {
				// iterate through the columnSets
				columnSetElement = query('.dgrid-column-set[' + colsetidAttr + '="' + i + '"]', domNode)[0];
				scrollerWidth = columnSetElement.offsetWidth;
				contentWidth = columnSetElement.firstChild.offsetWidth;
				scrollerContents[i].style.width = contentWidth + 'px';
				scrollers[i].style.width = scrollerWidth + 'px';

				if (has('ie') < 9) {
					// IE seems to need scroll to be set explicitly
					scrollers[i].style.overflowX = contentWidth > scrollerWidth ? 'scroll' : 'auto';
				}

				// Keep track of how many scrollbars we're showing
				if (contentWidth > scrollerWidth) {
					numScrollers++;
				}
			}

			this._columnSetScrollerNode.style.bottom = this.showFooter ? this.footerNode.offsetHeight + 'px' : '0';

			// Align bottom of body node depending on whether there are scrollbars
			this.bodyNode.style.bottom = numScrollers ?
				(has('dom-scrollbar-height') + (has('ie') ? 1 : 0) + 'px') :
				'0';
		},

		_putScroller: function (columnSet, i) {
			// function called for each columnSet
			var scroller = this._columnSetScrollers[i] = domConstruct.create('span', {
				// IE8 needs dgrid-scrollbar-height class for scrollbar to be visible,
				// but for some reason IE11's scrollbar arrows become unresponsive, so avoid applying it there
				className: 'dgrid-column-set-scroller dgrid-column-set-scroller-' + i +
					(has('ie') < 9 ? ' dgrid-scrollbar-height' : '')
			}, this._columnSetScrollerNode);
			scroller.setAttribute(colsetidAttr, i);

			this._columnSetScrollerContents[i] = domConstruct.create('div', {
				className: 'dgrid-column-set-scroller-content'
			}, scroller);
			on(scroller, 'scroll', lang.hitch(this, '_onColumnSetScroll'));
		},

		_onColumnSetScroll: function (evt) {
			var scrollLeft = evt.target.scrollLeft,
				colSetId = evt.target.getAttribute(colsetidAttr),
				newScrollLeft;

			if (this._columnSetScrollLefts[colSetId] !== scrollLeft) {
				query('.dgrid-column-set[' + colsetidAttr + '="' + colSetId +
						'"],.dgrid-column-set-scroller[' + colsetidAttr + '="' + colSetId + '"]', this.domNode
					).forEach(function (element, i) {
						element.scrollLeft = scrollLeft;
						if (!i) {
							// Compute newScrollLeft based on actual resulting
							// value of scrollLeft, which may be different than
							// what we assigned under certain circumstances
							// (e.g. Chrome under 33% / 67% / 90% zoom).
							// Only need to compute this once, as it will be the
							// same for every row.
							newScrollLeft = element.scrollLeft;
						}
					});
				this._columnSetScrollLefts[colSetId] = newScrollLeft;
			}
		},

		_setColumnSets: function (columnSets) {
			this._destroyColumns();
			this.columnSets = columnSets;
			this._updateColumns();
		},

		_scrollColumnSet: function (nodeOrId, offsetLeft) {
			var id = nodeOrId.tagName ? nodeOrId.getAttribute(colsetidAttr) : nodeOrId;
			var scroller = this._columnSetScrollers[id];
			scroller.scrollLeft = offsetLeft < 0 ? 0 : offsetLeft;
		},

		_onColumnSetCellFocus: function (event, columnSetNode) {
			var focusedNode = event.target;
			var columnSetId = columnSetNode.getAttribute(colsetidAttr);
			// columnSetNode's offsetLeft is not always correct,
			// so get the columnScroller to check offsetLeft against
			var columnScroller = this._columnSetScrollers[columnSetId];
			var elementEdge = focusedNode.offsetLeft - columnScroller.scrollLeft + focusedNode.offsetWidth;

			if (elementEdge > columnSetNode.offsetWidth ||
				columnScroller.scrollLeft > focusedNode.offsetLeft) {
				this._scrollColumnSet(columnSetNode, focusedNode.offsetLeft);
			}
		}
	});
});