/* FullCalendar-specific DOM Utilities
----------------------------------------------------------------------------------------------------------------------*/


// Given the scrollbar widths of some other container, create borders/margins on rowEls in order to match the left
// and right space that was offset by the scrollbars. A 1-pixel border first, then margin beyond that.
function compensateScroll(rowEls, scrollbarWidths) {
	if (scrollbarWidths.left) {
		rowEls.css({
			'border-left-width': 1,
			'margin-left': scrollbarWidths.left - 1
		});
	}
	if (scrollbarWidths.right) {
		rowEls.css({
			'border-right-width': 1,
			'margin-right': scrollbarWidths.right - 1
		});
	}
}


// Undoes compensateScroll and restores all borders/margins
function uncompensateScroll(rowEls) {
	rowEls.css({
		'margin-left': '',
		'margin-right': '',
		'border-left-width': '',
		'border-right-width': ''
	});
}


// Given a total available height to fill, have `els` (essentially child rows) expand to accomodate.
// By default, all elements that are shorter than the recommended height are expanded uniformly, not considering
// any other els that are already too tall. if `shouldRedistribute` is on, it considers these tall rows and 
// reduces the available height.
function distributeHeight(els, availableHeight, shouldRedistribute) {

	// *FLOORING NOTE*: we floor in certain places because zoom can give inaccurate floating-point dimensions,
	// and it is better to be shorter than taller, to avoid creating unnecessary scrollbars.

	var minOffset1 = Math.floor(availableHeight / els.length); // for non-last element
	var minOffset2 = Math.floor(availableHeight - minOffset1 * (els.length - 1)); // for last element *FLOORING NOTE*
	var flexEls = []; // elements that are allowed to expand. array of DOM nodes
	var flexOffsets = []; // amount of vertical space it takes up
	var flexHeights = []; // actual css height
	var usedHeight = 0;

	undistributeHeight(els); // give all elements their natural height

	// find elements that are below the recommended height (expandable).
	// important to query for heights in a single first pass (to avoid reflow oscillation).
	els.each(function(i, el) {
		var minOffset = i === els.length - 1 ? minOffset2 : minOffset1;
		var naturalOffset = $(el).outerHeight(true);

		if (naturalOffset < minOffset) {
			flexEls.push(el);
			flexOffsets.push(naturalOffset);
			flexHeights.push($(el).height());
		}
		else {
			// this element stretches past recommended height (non-expandable). mark the space as occupied.
			usedHeight += naturalOffset;
		}
	});

	// readjust the recommended height to only consider the height available to non-maxed-out rows.
	if (shouldRedistribute) {
		availableHeight -= usedHeight;
		minOffset1 = Math.floor(availableHeight / flexEls.length);
		minOffset2 = Math.floor(availableHeight - minOffset1 * (flexEls.length - 1)); // *FLOORING NOTE*
	}

	// assign heights to all expandable elements
	$(flexEls).each(function(i, el) {
		var minOffset = i === flexEls.length - 1 ? minOffset2 : minOffset1;
		var naturalOffset = flexOffsets[i];
		var naturalHeight = flexHeights[i];
		var newHeight = minOffset - (naturalOffset - naturalHeight); // subtract the margin/padding

		if (naturalOffset < minOffset) { // we check this again because redistribution might have changed things
			$(el).height(newHeight);
		}
	});
}


// Undoes distrubuteHeight, restoring all els to their natural height
function undistributeHeight(els) {
	els.height('');
}


// Given `els`, a jQuery set of <td> cells, find the cell with the largest natural width and set the widths of all the
// cells to be that width.
// PREREQUISITE: if you want a cell to take up width, it needs to have a single inner element w/ display:inline
function matchCellWidths(els) {
	var maxInnerWidth = 0;

	els.find('> *').each(function(i, innerEl) {
		var innerWidth = $(innerEl).outerWidth();
		if (innerWidth > maxInnerWidth) {
			maxInnerWidth = innerWidth;
		}
	});

	maxInnerWidth++; // sometimes not accurate of width the text needs to stay on one line. insurance

	els.width(maxInnerWidth);

	return maxInnerWidth;
}


// Turns a container element into a scroller if its contents is taller than the allotted height.
// Returns true if the element is now a scroller, false otherwise.
// NOTE: this method is best because it takes weird zooming dimensions into account
function setPotentialScroller(containerEl, height) {
	containerEl.height(height).addClass('fc-scroller');

	// are scrollbars needed?
	if (containerEl[0].scrollHeight - 1 > containerEl[0].clientHeight) { // !!! -1 because IE is often off-by-one :(
		return true;
	}

	unsetScroller(containerEl); // undo
	return false;
}


// Takes an element that might have been a scroller, and turns it back into a normal element.
function unsetScroller(containerEl) {
	containerEl.height('').removeClass('fc-scroller');
}


/* General DOM Utilities
----------------------------------------------------------------------------------------------------------------------*/


// borrowed from https://github.com/jquery/jquery-ui/blob/1.11.0/ui/core.js#L51
function getScrollParent(el) {
	var position = el.css('position'),
		scrollParent = el.parents().filter(function() {
			var parent = $(this);
			return (/(auto|scroll)/).test(
				parent.css('overflow') + parent.css('overflow-y') + parent.css('overflow-x')
			);
		}).eq(0);

	return position === 'fixed' || !scrollParent.length ? $(el[0].ownerDocument || document) : scrollParent;
}


// Given a container element, return an object with the pixel values of the left/right scrollbars.
// Left scrollbars might occur on RTL browsers (IE maybe?) but I have not tested.
// PREREQUISITE: container element must have a single child with display:block
function getScrollbarWidths(container) {
	var containerLeft = container.offset().left;
	var containerRight = containerLeft + container.width();
	var inner = container.children();
	var innerLeft = inner.offset().left;
	var innerRight = innerLeft + inner.outerWidth();

	return {
		left: innerLeft - containerLeft,
		right: containerRight - innerRight
	};
}


// Returns a boolean whether this was a left mouse click and no ctrl key (which means right click on Mac)
function isPrimaryMouseButton(ev) {
	return ev.which == 1 && !ev.ctrlKey;
}


/* FullCalendar-specific Misc Utilities
----------------------------------------------------------------------------------------------------------------------*/


// Creates a basic segment with the intersection of the two ranges. Returns undefined if no intersection.
// Expects all dates to be normalized to the same timezone beforehand.
function intersectionToSeg(subjectStart, subjectEnd, intervalStart, intervalEnd) {
	var segStart, segEnd;
	var isStart, isEnd;

	if (subjectEnd > intervalStart && subjectStart < intervalEnd) { // in bounds at all?

		if (subjectStart >= intervalStart) {
			segStart = subjectStart.clone();
			isStart = true;
		}
		else {
			segStart = intervalStart.clone();
			isStart =  false;
		}

		if (subjectEnd <= intervalEnd) {
			segEnd = subjectEnd.clone();
			isEnd = true;
		}
		else {
			segEnd = intervalEnd.clone();
			isEnd = false;
		}

		return {
			start: segStart,
			end: segEnd,
			isStart: isStart,
			isEnd: isEnd
		};
	}
}


function smartProperty(obj, name) { // get a camel-cased/namespaced property of an object
	obj = obj || {};
	if (obj[name] !== undefined) {
		return obj[name];
	}
	var parts = name.split(/(?=[A-Z])/),
		i = parts.length - 1, res;
	for (; i>=0; i--) {
		res = obj[parts[i].toLowerCase()];
		if (res !== undefined) {
			return res;
		}
	}
	return obj['default'];
}


/* Date Utilities
----------------------------------------------------------------------------------------------------------------------*/

var dayIDs = [ 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat' ];


// Diffs the two moments into a Duration where full-days are recorded first, then the remaining time.
// Moments will have their timezones normalized.
function dayishDiff(a, b) {
	return moment.duration({
		days: a.clone().stripTime().diff(b.clone().stripTime(), 'days'),
		ms: a.time() - b.time()
	});
}


function isNativeDate(input) {
	return  Object.prototype.toString.call(input) === '[object Date]' || input instanceof Date;
}


function dateCompare(a, b) { // works with Moments and native Dates
	return a - b;
}


/* General Utilities
----------------------------------------------------------------------------------------------------------------------*/

fc.applyAll = applyAll; // export


// Create an object that has the given prototype. Just like Object.create
function createObject(proto) {
	var f = function() {};
	f.prototype = proto;
	return new f();
}


// Copies specifically-owned (non-protoype) properties of `b` onto `a`.
// FYI, $.extend would copy *all* properties of `b` onto `a`.
function extend(a, b) {
	for (var i in b) {
		if (b.hasOwnProperty(i)) {
			a[i] = b[i];
		}
	}
}


function applyAll(functions, thisObj, args) {
	if ($.isFunction(functions)) {
		functions = [ functions ];
	}
	if (functions) {
		var i;
		var ret;
		for (i=0; i<functions.length; i++) {
			ret = functions[i].apply(thisObj, args) || ret;
		}
		return ret;
	}
}


function firstDefined() {
	for (var i=0; i<arguments.length; i++) {
		if (arguments[i] !== undefined) {
			return arguments[i];
		}
	}
}


function htmlEscape(s) {
	return (s + '').replace(/&/g, '&amp;')
		.replace(/</g, '&lt;')
		.replace(/>/g, '&gt;')
		.replace(/'/g, '&#039;')
		.replace(/"/g, '&quot;')
		.replace(/\n/g, '<br />');
}


function stripHtmlEntities(text) {
	return text.replace(/&.*?;/g, '');
}


function capitaliseFirstLetter(str) {
	return str.charAt(0).toUpperCase() + str.slice(1);
}


// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds.
// https://github.com/jashkenas/underscore/blob/1.6.0/underscore.js#L714
function debounce(func, wait) {
	var timeoutId;
	var args;
	var context;
	var timestamp; // of most recent call
	var later = function() {
		var last = +new Date() - timestamp;
		if (last < wait && last > 0) {
			timeoutId = setTimeout(later, wait - last);
		}
		else {
			timeoutId = null;
			func.apply(context, args);
			if (!timeoutId) {
				context = args = null;
			}
		}
	};

	return function() {
		context = this;
		args = arguments;
		timestamp = +new Date();
		if (!timeoutId) {
			timeoutId = setTimeout(later, wait);
		}
	};
}