/* Methods relate to limiting the number events for a given day on a DayGrid
----------------------------------------------------------------------------------------------------------------------*/
// NOTE: all the segs being passed around in here are foreground segs

DayGrid.mixin({

	segPopover: null, // the Popover that holds events that can't fit in a cell. null when not visible
	popoverSegs: null, // an array of segment objects that the segPopover holds. null when not visible


	destroySegPopover: function() {
		if (this.segPopover) {
			this.segPopover.hide(); // will trigger destruction of `segPopover` and `popoverSegs`
		}
	},


	// Limits the number of "levels" (vertically stacking layers of events) for each row of the grid.
	// `levelLimit` can be false (don't limit), a number, or true (should be computed).
	limitRows: function(levelLimit) {
		var rowStructs = this.rowStructs || [];
		var row; // row #
		var rowLevelLimit;

		for (row = 0; row < rowStructs.length; row++) {
			this.unlimitRow(row);

			if (!levelLimit) {
				rowLevelLimit = false;
			}
			else if (typeof levelLimit === 'number') {
				rowLevelLimit = levelLimit;
			}
			else {
				rowLevelLimit = this.computeRowLevelLimit(row);
			}

			if (rowLevelLimit !== false) {
				this.limitRow(row, rowLevelLimit);
			}
		}
	},


	// Computes the number of levels a row will accomodate without going outside its bounds.
	// Assumes the row is "rigid" (maintains a constant height regardless of what is inside).
	// `row` is the row number.
	computeRowLevelLimit: function(row) {
		var rowEl = this.rowEls.eq(row); // the containing "fake" row div
		var rowHeight = rowEl.height(); // TODO: cache somehow?
		var trEls = this.rowStructs[row].tbodyEl.children();
		var i, trEl;
		var trHeight;

		function iterInnerHeights(i, childNode) {
			trHeight = Math.max(trHeight, $(childNode).outerHeight());
		}

		// Reveal one level <tr> at a time and stop when we find one out of bounds
		for (i = 0; i < trEls.length; i++) {
			trEl = trEls.eq(i).removeClass('fc-limited'); // reset to original state (reveal)

			// with rowspans>1 and IE8, trEl.outerHeight() would return the height of the largest cell,
			// so instead, find the tallest inner content element.
			trHeight = 0;
			trEl.find('> td > :first-child').each(iterInnerHeights);

			if (trEl.position().top + trHeight > rowHeight) {
				return i;
			}
		}

		return false; // should not limit at all
	},


	// Limits the given grid row to the maximum number of levels and injects "more" links if necessary.
	// `row` is the row number.
	// `levelLimit` is a number for the maximum (inclusive) number of levels allowed.
	limitRow: function(row, levelLimit) {
		var _this = this;
		var rowStruct = this.rowStructs[row];
		var moreNodes = []; // array of "more" <a> links and <td> DOM nodes
		var col = 0; // col #, left-to-right (not chronologically)
		var cell;
		var levelSegs; // array of segment objects in the last allowable level, ordered left-to-right
		var cellMatrix; // a matrix (by level, then column) of all <td> jQuery elements in the row
		var limitedNodes; // array of temporarily hidden level <tr> and segment <td> DOM nodes
		var i, seg;
		var segsBelow; // array of segment objects below `seg` in the current `col`
		var totalSegsBelow; // total number of segments below `seg` in any of the columns `seg` occupies
		var colSegsBelow; // array of segment arrays, below seg, one for each column (offset from segs's first column)
		var td, rowspan;
		var segMoreNodes; // array of "more" <td> cells that will stand-in for the current seg's cell
		var j;
		var moreTd, moreWrap, moreLink;

		// Iterates through empty level cells and places "more" links inside if need be
		function emptyCellsUntil(endCol) { // goes from current `col` to `endCol`
			while (col < endCol) {
				cell = _this.getCell(row, col);
				segsBelow = _this.getCellSegs(cell, levelLimit);
				if (segsBelow.length) {
					td = cellMatrix[levelLimit - 1][col];
					moreLink = _this.renderMoreLink(cell, segsBelow);
					moreWrap = $('<div/>').append(moreLink);
					td.append(moreWrap);
					moreNodes.push(moreWrap[0]);
				}
				col++;
			}
		}

		if (levelLimit && levelLimit < rowStruct.segLevels.length) { // is it actually over the limit?
			levelSegs = rowStruct.segLevels[levelLimit - 1];
			cellMatrix = rowStruct.cellMatrix;

			limitedNodes = rowStruct.tbodyEl.children().slice(levelLimit) // get level <tr> elements past the limit
				.addClass('fc-limited').get(); // hide elements and get a simple DOM-nodes array

			// iterate though segments in the last allowable level
			for (i = 0; i < levelSegs.length; i++) {
				seg = levelSegs[i];
				emptyCellsUntil(seg.leftCol); // process empty cells before the segment

				// determine *all* segments below `seg` that occupy the same columns
				colSegsBelow = [];
				totalSegsBelow = 0;
				while (col <= seg.rightCol) {
					cell = this.getCell(row, col);
					segsBelow = this.getCellSegs(cell, levelLimit);
					colSegsBelow.push(segsBelow);
					totalSegsBelow += segsBelow.length;
					col++;
				}

				if (totalSegsBelow) { // do we need to replace this segment with one or many "more" links?
					td = cellMatrix[levelLimit - 1][seg.leftCol]; // the segment's parent cell
					rowspan = td.attr('rowspan') || 1;
					segMoreNodes = [];

					// make a replacement <td> for each column the segment occupies. will be one for each colspan
					for (j = 0; j < colSegsBelow.length; j++) {
						moreTd = $('<td class="fc-more-cell"/>').attr('rowspan', rowspan);
						segsBelow = colSegsBelow[j];
						cell = this.getCell(row, seg.leftCol + j);
						moreLink = this.renderMoreLink(cell, [ seg ].concat(segsBelow)); // count seg as hidden too
						moreWrap = $('<div/>').append(moreLink);
						moreTd.append(moreWrap);
						segMoreNodes.push(moreTd[0]);
						moreNodes.push(moreTd[0]);
					}

					td.addClass('fc-limited').after($(segMoreNodes)); // hide original <td> and inject replacements
					limitedNodes.push(td[0]);
				}
			}

			emptyCellsUntil(this.colCnt); // finish off the level
			rowStruct.moreEls = $(moreNodes); // for easy undoing later
			rowStruct.limitedEls = $(limitedNodes); // for easy undoing later
		}
	},


	// Reveals all levels and removes all "more"-related elements for a grid's row.
	// `row` is a row number.
	unlimitRow: function(row) {
		var rowStruct = this.rowStructs[row];

		if (rowStruct.moreEls) {
			rowStruct.moreEls.remove();
			rowStruct.moreEls = null;
		}

		if (rowStruct.limitedEls) {
			rowStruct.limitedEls.removeClass('fc-limited');
			rowStruct.limitedEls = null;
		}
	},


	// Renders an <a> element that represents hidden event element for a cell.
	// Responsible for attaching click handler as well.
	renderMoreLink: function(cell, hiddenSegs) {
		var _this = this;
		var view = this.view;

		return $('<a class="fc-more"/>')
			.text(
				this.getMoreLinkText(hiddenSegs.length)
			)
			.on('click', function(ev) {
				var clickOption = view.opt('eventLimitClick');
				var date = cell.start;
				var moreEl = $(this);
				var dayEl = _this.getCellDayEl(cell);
				var allSegs = _this.getCellSegs(cell);

				// rescope the segments to be within the cell's date
				var reslicedAllSegs = _this.resliceDaySegs(allSegs, date);
				var reslicedHiddenSegs = _this.resliceDaySegs(hiddenSegs, date);

				if (typeof clickOption === 'function') {
					// the returned value can be an atomic option
					clickOption = view.trigger('eventLimitClick', null, {
						date: date,
						dayEl: dayEl,
						moreEl: moreEl,
						segs: reslicedAllSegs,
						hiddenSegs: reslicedHiddenSegs
					}, ev);
				}

				if (clickOption === 'popover') {
					_this.showSegPopover(cell, moreEl, reslicedAllSegs);
				}
				else if (typeof clickOption === 'string') { // a view name
					view.calendar.zoomTo(date, clickOption);
				}
			});
	},


	// Reveals the popover that displays all events within a cell
	showSegPopover: function(cell, moreLink, segs) {
		var _this = this;
		var view = this.view;
		var moreWrap = moreLink.parent(); // the <div> wrapper around the <a>
		var topEl; // the element we want to match the top coordinate of
		var options;

		if (this.rowCnt == 1) {
			topEl = view.el; // will cause the popover to cover any sort of header
		}
		else {
			topEl = this.rowEls.eq(cell.row); // will align with top of row
		}

		options = {
			className: 'fc-more-popover',
			content: this.renderSegPopoverContent(cell, segs),
			parentEl: this.el,
			top: topEl.offset().top,
			autoHide: true, // when the user clicks elsewhere, hide the popover
			viewportConstrain: view.opt('popoverViewportConstrain'),
			hide: function() {
				// destroy everything when the popover is hidden
				_this.segPopover.destroy();
				_this.segPopover = null;
				_this.popoverSegs = null;
			}
		};

		// Determine horizontal coordinate.
		// We use the moreWrap instead of the <td> to avoid border confusion.
		if (this.isRTL) {
			options.right = moreWrap.offset().left + moreWrap.outerWidth() + 1; // +1 to be over cell border
		}
		else {
			options.left = moreWrap.offset().left - 1; // -1 to be over cell border
		}

		this.segPopover = new Popover(options);
		this.segPopover.show();
	},


	// Builds the inner DOM contents of the segment popover
	renderSegPopoverContent: function(cell, segs) {
		var view = this.view;
		var isTheme = view.opt('theme');
		var title = cell.start.format(view.opt('dayPopoverFormat'));
		var content = $(
			'<div class="fc-header ' + view.widgetHeaderClass + '">' +
				'<span class="fc-close ' +
					(isTheme ? 'ui-icon ui-icon-closethick' : 'fc-icon fc-icon-x') +
				'"></span>' +
				'<span class="fc-title">' +
					htmlEscape(title) +
				'</span>' +
				'<div class="fc-clear"/>' +
			'</div>' +
			'<div class="fc-body ' + view.widgetContentClass + '">' +
				'<div class="fc-event-container"></div>' +
			'</div>'
		);
		var segContainer = content.find('.fc-event-container');
		var i;

		// render each seg's `el` and only return the visible segs
		segs = this.renderFgSegEls(segs, true); // disableResizing=true
		this.popoverSegs = segs;

		for (i = 0; i < segs.length; i++) {

			// because segments in the popover are not part of a grid coordinate system, provide a hint to any
			// grids that want to do drag-n-drop about which cell it came from
			segs[i].cell = cell;

			segContainer.append(segs[i].el);
		}

		return content;
	},


	// Given the events within an array of segment objects, reslice them to be in a single day
	resliceDaySegs: function(segs, dayDate) {

		// build an array of the original events
		var events = $.map(segs, function(seg) {
			return seg.event;
		});

		var dayStart = dayDate.clone().stripTime();
		var dayEnd = dayStart.clone().add(1, 'days');
		var dayRange = { start: dayStart, end: dayEnd };

		// slice the events with a custom slicing function
		segs = this.eventsToSegs(
			events,
			function(range) {
				var seg = intersectionToSeg(range, dayRange); // undefind if no intersection
				return seg ? [ seg ] : []; // must return an array of segments
			}
		);

		// force an order because eventsToSegs doesn't guarantee one
		segs.sort(compareSegs);

		return segs;
	},


	// Generates the text that should be inside a "more" link, given the number of events it represents
	getMoreLinkText: function(num) {
		var opt = this.view.opt('eventLimitText');

		if (typeof opt === 'function') {
			return opt(num);
		}
		else {
			return '+' + num + ' ' + opt;
		}
	},


	// Returns segments within a given cell.
	// If `startLevel` is specified, returns only events including and below that level. Otherwise returns all segs.
	getCellSegs: function(cell, startLevel) {
		var segMatrix = this.rowStructs[cell.row].segMatrix;
		var level = startLevel || 0;
		var segs = [];
		var seg;

		while (level < segMatrix.length) {
			seg = segMatrix[level][cell.col];
			if (seg) {
				segs.push(seg);
			}
			level++;
		}

		return segs;
	}

});