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

$.extend(DayGrid.prototype, {

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


	// Render the given events onto the Grid and return the rendered segments
	renderEvents: function(events) {
		var rowStructs = this.rowStructs = this.renderEventRows(events);
		var segs = [];

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

		this.segs = segs;
	},


	// Retrieves all segment objects that have been rendered
	getSegs: function() {
		return (this.segs || []).concat(
			this.popoverSegs || [] // segs rendered in the "more" events popover
		);
	},


	// Removes all rendered event elements
	destroyEvents: function() {
		var rowStructs;
		var rowStruct;

		Grid.prototype.destroyEvents.call(this); // call the super-method

		rowStructs = this.rowStructs || [];
		while ((rowStruct = rowStructs.pop())) {
			rowStruct.tbodyEl.remove();
		}

		this.segs = null;
		this.destroySegPopover(); // removes the "more.." events popover
	},


	// 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 `renderEventRow`).
	renderEventRows: function(events) {
		var segs = this.eventsToSegs(events);
		var rowStructs = [];
		var segRows;
		var row;

		segs = this.renderSegs(segs); // returns a new array with only visible segments
		segRows = this.groupSegRows(segs); // group into nested arrays

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

		return rowStructs;
	},


	// Builds the HTML to be used for the default element for an individual segment
	renderSegHtml: function(seg, disableResizing) {
		var view = this.view;
		var isRTL = view.opt('isRTL');
		var event = seg.event;
		var isDraggable = view.isEventDraggable(event);
		var isResizable = !disableResizing && event.allDay && seg.isEnd && view.isEventResizable(event);
		var classes = this.getSegClasses(seg, isDraggable, isResizable);
		var skinCss = this.getEventSkinCss(event);
		var timeHtml = '';
		var titleHtml;

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

		// Only display a timed events time if it is the starting segment
		if (!event.allDay && seg.isStart) {
			timeHtml = '<span class="fc-time">' + htmlEscape(view.getEventTimeText(event)) + '</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">' +
					(isRTL ?
						titleHtml + ' ' + timeHtml : // put a natural space in between
						timeHtml + ' ' + titleHtml   //
						) +
				'</div>' +
				(isResizable ?
					'<div class="fc-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.
	renderEventRow: function(row, rowSegs) {
		var view = this.view;
		var colCnt = view.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.
	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 view = this.view;
		var segRows = [];
		var i;

		for (i = 0; i < view.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;
}