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

TimeGrid.mixin({

	eventSkeletonEl: null, // has cells with event-containers, which contain absolutely positioned event elements


	// Renders the given foreground event segments onto the grid
	renderFgSegs: function(segs) {
		segs = this.renderFgSegEls(segs); // returns a subset of the segs. segs that were actually rendered

		this.el.append(
			this.eventSkeletonEl = $('<div class="fc-content-skeleton"/>')
				.append(this.renderSegTable(segs))
		);

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


	// Unrenders all currently rendered foreground event segments
	destroyFgSegs: function(segs) {
		if (this.eventSkeletonEl) {
			this.eventSkeletonEl.remove();
			this.eventSkeletonEl = null;
		}
	},


	// Renders and returns the <table> portion of the event-skeleton.
	// Returns an object with properties 'tbodyEl' and 'segs'.
	renderSegTable: function(segs) {
		var tableEl = $('<table><tr/></table>');
		var trEl = tableEl.find('tr');
		var segCols;
		var i, seg;
		var col, colSegs;
		var containerEl;

		segCols = this.groupSegCols(segs); // group into sub-arrays, and assigns 'col' to each seg

		this.computeSegVerticals(segs); // compute and assign top/bottom

		for (col = 0; col < segCols.length; col++) { // iterate each column grouping
			colSegs = segCols[col];
			placeSlotSegs(colSegs); // compute horizontal coordinates, z-index's, and reorder the array

			containerEl = $('<div class="fc-event-container"/>');

			// assign positioning CSS and insert into container
			for (i = 0; i < colSegs.length; i++) {
				seg = colSegs[i];
				seg.el.css(this.generateSegPositionCss(seg));

				// if the height is short, add a className for alternate styling
				if (seg.bottom - seg.top < 30) {
					seg.el.addClass('fc-short');
				}

				containerEl.append(seg.el);
			}

			trEl.append($('<td/>').append(containerEl));
		}

		this.bookendCells(trEl, 'eventSkeleton');

		return tableEl;
	},


	// Refreshes the CSS top/bottom coordinates for each segment element. Probably after a window resize/zoom.
	// Repositions business hours segs too, so not just for events. Maybe shouldn't be here.
	updateSegVerticals: function() {
		var allSegs = (this.segs || []).concat(this.businessHourSegs || []);
		var i;

		this.computeSegVerticals(allSegs);

		for (i = 0; i < allSegs.length; i++) {
			allSegs[i].el.css(
				this.generateSegVerticalCss(allSegs[i])
			);
		}
	},


	// For each segment in an array, computes and assigns its top and bottom properties
	computeSegVerticals: function(segs) {
		var i, seg;

		for (i = 0; i < segs.length; i++) {
			seg = segs[i];
			seg.top = this.computeDateTop(seg.start, seg.start);
			seg.bottom = this.computeDateTop(seg.end, seg.start);
		}
	},


	// Renders the HTML for a single event segment's default rendering
	fgSegHtml: function(seg, disableResizing) {
		var view = this.view;
		var event = seg.event;
		var isDraggable = view.isEventDraggable(event);
		var isResizableFromStart = !disableResizing && seg.isStart && view.isEventResizableFromStart(event);
		var isResizableFromEnd = !disableResizing && seg.isEnd && view.isEventResizableFromEnd(event);
		var classes = this.getSegClasses(seg, isDraggable, isResizableFromStart || isResizableFromEnd);
		var skinCss = cssToStr(this.getEventSkinCss(event));
		var timeText;
		var fullTimeText; // more verbose time text. for the print stylesheet
		var startTimeText; // just the start time text

		classes.unshift('fc-time-grid-event', 'fc-v-event');

		if (view.isMultiDayEvent(event)) { // if the event appears to span more than one day...
			// Don't display time text on segments that run entirely through a day.
			// That would appear as midnight-midnight and would look dumb.
			// Otherwise, display the time text for the *segment's* times (like 6pm-midnight or midnight-10am)
			if (seg.isStart || seg.isEnd) {
				timeText = this.getEventTimeText(seg);
				fullTimeText = this.getEventTimeText(seg, 'LT');
				startTimeText = this.getEventTimeText(seg, null, false); // displayEnd=false
			}
		} else {
			// Display the normal time text for the *event's* times
			timeText = this.getEventTimeText(event);
			fullTimeText = this.getEventTimeText(event, 'LT');
			startTimeText = this.getEventTimeText(event, null, false); // displayEnd=false
		}

		return '<a class="' + classes.join(' ') + '"' +
			(event.url ?
				' href="' + htmlEscape(event.url) + '"' :
				''
				) +
			(skinCss ?
				' style="' + skinCss + '"' :
				''
				) +
			'>' +
				'<div class="fc-content">' +
					(timeText ?
						'<div class="fc-time"' +
						' data-start="' + htmlEscape(startTimeText) + '"' +
						' data-full="' + htmlEscape(fullTimeText) + '"' +
						'>' +
							'<span>' + htmlEscape(timeText) + '</span>' +
						'</div>' :
						''
						) +
					(event.title ?
						'<div class="fc-title">' +
							htmlEscape(event.title) +
						'</div>' :
						''
						) +
				'</div>' +
				'<div class="fc-bg"/>' +
				/* TODO: write CSS for this
				(isResizableFromStart ?
					'<div class="fc-resizer fc-start-resizer" />' :
					''
					) +
				*/
				(isResizableFromEnd ?
					'<div class="fc-resizer fc-end-resizer" />' :
					''
					) +
			'</a>';
	},


	// Generates an object with CSS properties/values that should be applied to an event segment element.
	// Contains important positioning-related properties that should be applied to any event element, customized or not.
	generateSegPositionCss: function(seg) {
		var shouldOverlap = this.view.opt('slotEventOverlap');
		var backwardCoord = seg.backwardCoord; // the left side if LTR. the right side if RTL. floating-point
		var forwardCoord = seg.forwardCoord; // the right side if LTR. the left side if RTL. floating-point
		var props = this.generateSegVerticalCss(seg); // get top/bottom first
		var left; // amount of space from left edge, a fraction of the total width
		var right; // amount of space from right edge, a fraction of the total width

		if (shouldOverlap) {
			// double the width, but don't go beyond the maximum forward coordinate (1.0)
			forwardCoord = Math.min(1, backwardCoord + (forwardCoord - backwardCoord) * 2);
		}

		if (this.isRTL) {
			left = 1 - forwardCoord;
			right = backwardCoord;
		}
		else {
			left = backwardCoord;
			right = 1 - forwardCoord;
		}

		props.zIndex = seg.level + 1; // convert from 0-base to 1-based
		props.left = left * 100 + '%';
		props.right = right * 100 + '%';

		if (shouldOverlap && seg.forwardPressure) {
			// add padding to the edge so that forward stacked events don't cover the resizer's icon
			props[this.isRTL ? 'marginLeft' : 'marginRight'] = 10 * 2; // 10 is a guesstimate of the icon's width
		}

		return props;
	},


	// Generates an object with CSS properties for the top/bottom coordinates of a segment element
	generateSegVerticalCss: function(seg) {
		return {
			top: seg.top,
			bottom: -seg.bottom // flipped because needs to be space beyond bottom edge of event container
		};
	},


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

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

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

		return segCols;
	}

});


// Given an array of segments that are all in the same column, sets the backwardCoord and forwardCoord on each.
// NOTE: Also reorders the given array by date!
function placeSlotSegs(segs) {
	var levels;
	var level0;
	var i;

	segs.sort(compareSegs); // order by date
	levels = buildSlotSegLevels(segs);
	computeForwardSlotSegs(levels);

	if ((level0 = levels[0])) {

		for (i = 0; i < level0.length; i++) {
			computeSlotSegPressures(level0[i]);
		}

		for (i = 0; i < level0.length; i++) {
			computeSlotSegCoords(level0[i], 0, 0);
		}
	}
}


// Builds an array of segments "levels". The first level will be the leftmost tier of segments if the calendar is
// left-to-right, or the rightmost if the calendar is right-to-left. Assumes the segments are already ordered by date.
function buildSlotSegLevels(segs) {
	var levels = [];
	var i, seg;
	var j;

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

		// go through all the levels and stop on the first level where there are no collisions
		for (j=0; j<levels.length; j++) {
			if (!computeSlotSegCollisions(seg, levels[j]).length) {
				break;
			}
		}

		seg.level = j;

		(levels[j] || (levels[j] = [])).push(seg);
	}

	return levels;
}


// For every segment, figure out the other segments that are in subsequent
// levels that also occupy the same vertical space. Accumulate in seg.forwardSegs
function computeForwardSlotSegs(levels) {
	var i, level;
	var j, seg;
	var k;

	for (i=0; i<levels.length; i++) {
		level = levels[i];

		for (j=0; j<level.length; j++) {
			seg = level[j];

			seg.forwardSegs = [];
			for (k=i+1; k<levels.length; k++) {
				computeSlotSegCollisions(seg, levels[k], seg.forwardSegs);
			}
		}
	}
}


// Figure out which path forward (via seg.forwardSegs) results in the longest path until
// the furthest edge is reached. The number of segments in this path will be seg.forwardPressure
function computeSlotSegPressures(seg) {
	var forwardSegs = seg.forwardSegs;
	var forwardPressure = 0;
	var i, forwardSeg;

	if (seg.forwardPressure === undefined) { // not already computed

		for (i=0; i<forwardSegs.length; i++) {
			forwardSeg = forwardSegs[i];

			// figure out the child's maximum forward path
			computeSlotSegPressures(forwardSeg);

			// either use the existing maximum, or use the child's forward pressure
			// plus one (for the forwardSeg itself)
			forwardPressure = Math.max(
				forwardPressure,
				1 + forwardSeg.forwardPressure
			);
		}

		seg.forwardPressure = forwardPressure;
	}
}


// Calculate seg.forwardCoord and seg.backwardCoord for the segment, where both values range
// from 0 to 1. If the calendar is left-to-right, the seg.backwardCoord maps to "left" and
// seg.forwardCoord maps to "right" (via percentage). Vice-versa if the calendar is right-to-left.
//
// The segment might be part of a "series", which means consecutive segments with the same pressure
// who's width is unknown until an edge has been hit. `seriesBackwardPressure` is the number of
// segments behind this one in the current series, and `seriesBackwardCoord` is the starting
// coordinate of the first segment in the series.
function computeSlotSegCoords(seg, seriesBackwardPressure, seriesBackwardCoord) {
	var forwardSegs = seg.forwardSegs;
	var i;

	if (seg.forwardCoord === undefined) { // not already computed

		if (!forwardSegs.length) {

			// if there are no forward segments, this segment should butt up against the edge
			seg.forwardCoord = 1;
		}
		else {

			// sort highest pressure first
			forwardSegs.sort(compareForwardSlotSegs);

			// this segment's forwardCoord will be calculated from the backwardCoord of the
			// highest-pressure forward segment.
			computeSlotSegCoords(forwardSegs[0], seriesBackwardPressure + 1, seriesBackwardCoord);
			seg.forwardCoord = forwardSegs[0].backwardCoord;
		}

		// calculate the backwardCoord from the forwardCoord. consider the series
		seg.backwardCoord = seg.forwardCoord -
			(seg.forwardCoord - seriesBackwardCoord) / // available width for series
			(seriesBackwardPressure + 1); // # of segments in the series

		// use this segment's coordinates to computed the coordinates of the less-pressurized
		// forward segments
		for (i=0; i<forwardSegs.length; i++) {
			computeSlotSegCoords(forwardSegs[i], 0, seg.forwardCoord);
		}
	}
}


// Find all the segments in `otherSegs` that vertically collide with `seg`.
// Append into an optionally-supplied `results` array and return.
function computeSlotSegCollisions(seg, otherSegs, results) {
	results = results || [];

	for (var i=0; i<otherSegs.length; i++) {
		if (isSlotSegCollision(seg, otherSegs[i])) {
			results.push(otherSegs[i]);
		}
	}

	return results;
}


// Do these segments occupy the same vertical space?
function isSlotSegCollision(seg1, seg2) {
	return seg1.bottom > seg2.top && seg1.top < seg2.bottom;
}


// A cmp function for determining which forward segment to rely on more when computing coordinates.
function compareForwardSlotSegs(seg1, seg2) {
	// put higher-pressure first
	return seg2.forwardPressure - seg1.forwardPressure ||
		// put segments that are closer to initial edge first (and favor ones with no coords yet)
		(seg1.backwardCoord || 0) - (seg2.backwardCoord || 0) ||
		// do normal sorting...
		compareSegs(seg1, seg2);
}