/**
 * Calendar Script
 * Creates a calendar widget which can be used to select the date more easily than using just a text box
 *
 * (c) Vitaliy Filippov 2018+
 * Repository: http://yourcmc.ru/git/vitalif-js/calendar
 * Version: 2021-09-19
 * License: Dual-license MPL 2.0+ or GNU LGPL 3.0+
 *
 * Example:
 * <input type="text" name="date" id="date" />
 * <script type="text/javascript">
 *     Calendar.set("date");
 * </script>
 */

import ReactCalendar from './calendar-react.js';

import preact from 'preact';
/** @jsx preact.h */

export class Calendar extends ReactCalendar
{
	componentDidMount()
	{
		this.componentDidUpdate();
	}

	componentDidUpdate()
	{
		// Position the div in the correct location...
		var input = this.props.input;
		var div = Calendar.box;
		div.style.position = "absolute";
		var xy = getOffset(input);
		var height = input.clientHeight||input.offsetHeight;
		var ww = document.body.clientWidth||document.documentElement.clientWidth;
		var wh = document.body.clientHeight||document.documentElement.clientHeight;
		if (xy.left-1+div.offsetWidth > ww)
			div.style.left = (ww-div.offsetWidth-1)+"px";
		else
			div.style.left = (xy.left-1)+"px";
		if (div.offsetHeight + xy.top+height-1 >= wh &&
			xy.top-div.offsetHeight >= 0)
			div.style.top = (xy.top-div.offsetHeight)+'px';
		else
			div.style.top = (xy.top+height-1)+"px";
	}

	static onBlur()
	{
		if (!Calendar.stopBlur || Calendar.stopBlur < Date.now()-200)
			Calendar.hideCalendar();
	}

	/// Called when the user clicks on a date in the calendar.
	static onChange(i, date)
	{
		i.value = date;
		if ("Event" in window)
		{
			var evt = document.createEvent('Event');
			evt.initEvent('change', true, true);
			i.dispatchEvent(evt);
		}
		else
			i.fireEvent("onchange");
		Calendar.hideCalendar();
	}

	/// Display the calendar - if a date exists in the input box, that will be selected in the calendar.
	static showCalendar(input, options)
	{
		// Show the calendar with the date in the input as the selected date
		const props = {
			...options,
			input,
			value: input.value,
			hide: Calendar.hideCalendar,
			onChange: date => Calendar.onChange(input, date),
		};
		Calendar.init();
		Calendar.box.style.display = "block";
		Calendar.stopBlur = Date.now();
		preact.render(<Calendar {...props} />, Calendar.box.parentNode, Calendar.box);
	}

	/// Hides the currently shown calendar.
	static hideCalendar()
	{
		if (!Calendar.box)
			return;
		Calendar.box.style.display = "none";
	}

	/// Setup a text input box to be a calendar box.
	static set(input_or_id, options)
	{
		if (typeof input_or_id == 'string')
		{
			input_or_id = document.getElementById(input_or_id);
		}
		if (!input_or_id)
		{
			return; // If the input field is not there, exit.
		}
		input_or_id.addEventListener('blur', Calendar.onBlur);
		input_or_id.addEventListener('focus', function(ev)
		{
			Calendar.showCalendar(input_or_id, options);
		});
		// FIXME: Add change listener to enable interactive date selection in calendar while typing
	}

	// Will be called once when the first input is set.
	static init()
	{
		if (!Calendar.box || !Calendar.box.parentNode)
		{
			var div = document.createElement('div');
			if (!Calendar.box)
				Calendar.box = div;
			div.className = "calendar-box";
			div.addEventListener("mousedown", function(ev)
			{
				ev = ev || window.event;
				if (ev.stopPropagation)
					ev.stopPropagation();
				else
					ev.cancelBubble = true;
				Calendar.stopBlur = Date.now();
				return true;
			});
			document.getElementsByTagName("body")[0].insertBefore(div, document.getElementsByTagName("body")[0].firstChild);
			if (!Calendar.addedListener)
			{
				document.addEventListener("mousedown", function() { Calendar.hideCalendar(); });
				Calendar.addedListener = true;
			}
		}
	}
}

window.Calendar = Calendar;

function getOffsetRect(elem)
{
	var box = elem.getBoundingClientRect();

	var body = document.body;
	var docElem = document.documentElement;

	var scrollTop = window.pageYOffset || docElem.scrollTop || body.scrollTop;
	var scrollLeft = window.pageXOffset || docElem.scrollLeft || body.scrollLeft;
	var clientTop = docElem.clientTop || body.clientTop || 0;
	var clientLeft = docElem.clientLeft || body.clientLeft || 0;
	var top = box.top + scrollTop - clientTop;
	var left = box.left + scrollLeft - clientLeft;

	return { top: Math.round(top), left: Math.round(left) };
}

function getOffsetSum(elem)
{
	var top = 0, left = 0;
	while(elem)
	{
		top = top + parseInt(elem.offsetTop);
		left = left + parseInt(elem.offsetLeft);
		elem = elem.offsetParent;
	}
	return { top: top, left: left };
}

function getOffset(elem)
{
	if (elem.getBoundingClientRect)
		return getOffsetRect(elem);
	else
		return getOffsetSum(elem);
}