/* Event-rendering methods for the DayGrid class
----------------------------------------------------------------------------------------------------------------------*/

DayGrid.mixin({

	rowStructs: null, // an array of objects, each holding information about a row's foreground event-rendering


	// Unrenders all events currently rendered on the grid
	destroyEvents: function() {
		this.destroySegPopover(); // removes the "more.." events popover
		Grid.prototype.destroyEvents.apply(this, arguments); // calls the super-method
	},


	// Retrieves all rendered segment objects currently rendered on the grid
	getEventSegs: function() {
		return Grid.prototype.getEventSegs.call(this) // get the segments from the super-method
			.concat(this.popoverSegs || []); // append the segments from the "more..." popover
	},


	// Renders the given background event segments onto the grid
	renderBgSegs: function(segs) {

		// don't render timed background events
		var allDaySegs = $.grep(segs, function(seg) {
			return seg.event.allDay;
		});

		return Grid.prototype.renderBgSegs.call(this, allDaySegs); // call the super-method
	},


	// Renders the given foreground event segments onto the grid
	renderFgSegs: function(segs) {
		var rowStructs;

		// render an `.el` on each seg
		// returns a subset of the segs. segs that were actually rendered
		segs = this.renderFgSegEls(segs);

		rowStructs = this.rowStructs = this.renderSegRows(segs);

		// append to each row's content skeleton
		this.rowEls.each(function(i, rowNode) {
			$(rowNode).find('.fc-content-skeleton > table').append(
				rowStructs[i].tbodyEl
			);
		});

		return segs; // return only the segs that were actually rendered
	},


	// Unrenders all currently rendered foreground event segments
	destroyFgSegs: function() {
		var rowStructs = this.rowStructs || [];
		var rowStruct;

		while ((rowStruct = rowStructs.pop())) {
			rowStruct.tbodyEl.remove();
		}

		this.rowStructs = null;
	},


	// Uses the given events array to generate <tbody> elements that should be appended to each row's content skeleton.
	// Returns an array of rowStruct objects (see the bottom of `renderSegRow`).
	// PRECONDITION: each segment shoud already have a rendered and assigned `.el`
	renderSegRows: function(segs) {
		var rowStructs = [];
		var segRows;
		var row;

		segRows = this.groupSegRows(segs); // group into nested arrays

		// iterate each row of segment groupings
		for (row = 0; row < segRows.length; row++) {
			rowStructs.push(
				this.renderSegRow(row, segRows[row])
			);
		}

		return rowStructs;
	},


	// Builds the HTML to be used for the default element for an individual segment
	fgSegHtml: function(seg, disableResizing) {
		var view = this.view;
		var event = seg.event;
		var isDraggable = view.isEventDraggable(event);
		var isResizableFromStart = !disableResizing && event.allDay &&
			seg.isStart && view.isEventResizableFromStart(event);
		var isResizableFromEnd = !disableResizing && event.allDay &&
			seg.isEnd && view.isEventResizableFromEnd(event);
		var classes = this.getSegClasses(seg, isDraggable, isResizableFromStart || isResizableFromEnd);
		var skinCss = cssToStr(this.getEventSkinCss(event));
		var timeHtml = '';
		var timeText;
		var titleHtml;

		classes.unshift('fc-day-grid-event', 'fc-h-event');

		// Only display a timed events time if it is the starting segment
		if (seg.isStart) {
			timeText = this.getEventTimeText(event);
			if (timeText) {
				timeHtml = '<span class="fc-time">' + htmlEscape(timeText) + '</span>';
			}
		}

		titleHtml =
			'<span class="fc-title">' +
				(htmlEscape(event.title || '') || '&nbsp;') + // we always want one line of height
			'</span>';
		
		return '<a class="' + classes.join(' ') + '"' +
				(event.url ?
					' href="' + htmlEscape(event.url) + '"' :
					''
					) +
				(skinCss ?
					' style="' + skinCss + '"' :
					''
					) +
			'>' +
				'<div class="fc-content">' +
					(this.isRTL ?
						titleHtml + ' ' + timeHtml : // put a natural space in between
						timeHtml + ' ' + titleHtml   //
						) +
				'</div>' +
				(isResizableFromStart ?
					'<div class="fc-resizer fc-start-resizer" />' :
					''
					) +
				(isResizableFromEnd ?
					'<div class="fc-resizer fc-end-resizer" />' :
					''
					) +
			'</a>';
	},


	// Given a row # and an array of segments all in the same row, render a <tbody> element, a skeleton that contains
	// the segments. Returns object with a bunch of internal data about how the render was calculated.
	// NOTE: modifies rowSegs
	renderSegRow: function(row, rowSegs) {
		var colCnt = this.colCnt;
		var segLevels = this.buildSegLevels(rowSegs); // group into sub-arrays of levels
		var levelCnt = Math.max(1, segLevels.length); // ensure at least one level
		var tbody = $('<tbody/>');
		var segMatrix = []; // lookup for which segments are rendered into which level+col cells
		var cellMatrix = []; // lookup for all <td> elements of the level+col matrix
		var loneCellMatrix = []; // lookup for <td> elements that only take up a single column
		var i, levelSegs;
		var col;
		var tr;
		var j, seg;
		var td;

		// populates empty cells from the current column (`col`) to `endCol`
		function emptyCellsUntil(endCol) {
			while (col < endCol) {
				// try to grab a cell from the level above and extend its rowspan. otherwise, create a fresh cell
				td = (loneCellMatrix[i - 1] || [])[col];
				if (td) {
					td.attr(
						'rowspan',
						parseInt(td.attr('rowspan') || 1, 10) + 1
					);
				}
				else {
					td = $('<td/>');
					tr.append(td);
				}
				cellMatrix[i][col] = td;
				loneCellMatrix[i][col] = td;
				col++;
			}
		}

		for (i = 0; i < levelCnt; i++) { // iterate through all levels
			levelSegs = segLevels[i];
			col = 0;
			tr = $('<tr/>');

			segMatrix.push([]);
			cellMatrix.push([]);
			loneCellMatrix.push([]);

			// levelCnt might be 1 even though there are no actual levels. protect against this.
			// this single empty row is useful for styling.
			if (levelSegs) {
				for (j = 0; j < levelSegs.length; j++) { // iterate through segments in level
					seg = levelSegs[j];

					emptyCellsUntil(seg.leftCol);

					// create a container that occupies or more columns. append the event element.
					td = $('<td class="fc-event-container"/>').append(seg.el);
					if (seg.leftCol != seg.rightCol) {
						td.attr('colspan', seg.rightCol - seg.leftCol + 1);
					}
					else { // a single-column segment
						loneCellMatrix[i][col] = td;
					}

					while (col <= seg.rightCol) {
						cellMatrix[i][col] = td;
						segMatrix[i][col] = seg;
						col++;
					}

					tr.append(td);
				}
			}

			emptyCellsUntil(colCnt); // finish off the row
			this.bookendCells(tr, 'eventSkeleton');
			tbody.append(tr);
		}

		return { // a "rowStruct"
			row: row, // the row number
			tbodyEl: tbody,
			cellMatrix: cellMatrix,
			segMatrix: segMatrix,
			segLevels: segLevels,
			segs: rowSegs
		};
	},


	// Stacks a flat array of segments, which are all assumed to be in the same row, into subarrays of vertical levels.
	// NOTE: modifies segs
	buildSegLevels: function(segs) {
		var levels = [];
		var i, seg;
		var j;

		// Give preference to elements with certain criteria, so they have
		// a chance to be closer to the top.
		segs.sort(compareSegs);
		
		for (i = 0; i < segs.length; i++) {
			seg = segs[i];

			// loop through levels, starting with the topmost, until the segment doesn't collide with other segments
			for (j = 0; j < levels.length; j++) {
				if (!isDaySegCollision(seg, levels[j])) {
					break;
				}
			}
			// `j` now holds the desired subrow index
			seg.level = j;

			// create new level array if needed and append segment
			(levels[j] || (levels[j] = [])).push(seg);
		}

		// order segments left-to-right. very important if calendar is RTL
		for (j = 0; j < levels.length; j++) {
			levels[j].sort(compareDaySegCols);
		}

		return levels;
	},


	// Given a flat array of segments, return an array of sub-arrays, grouped by each segment's row
	groupSegRows: function(segs) {
		var segRows = [];
		var i;

		for (i = 0; i < this.rowCnt; i++) {
			segRows.push([]);
		}

		for (i = 0; i < segs.length; i++) {
			segRows[segs[i].row].push(segs[i]);
		}

		return segRows;
	}

});


// Computes whether two segments' columns collide. They are assumed to be in the same row.
function isDaySegCollision(seg, otherSegs) {
	var i, otherSeg;

	for (i = 0; i < otherSegs.length; i++) {
		otherSeg = otherSegs[i];

		if (
			otherSeg.leftCol <= seg.rightCol &&
			otherSeg.rightCol >= seg.leftCol
		) {
			return true;
		}
	}

	return false;
}


// A cmp function for determining the leftmost event
function compareDaySegCols(a, b) {
	return a.leftCol - b.leftCol;
}