/**
 * Calendar Script
 * Creates a calendar widget which can be used to select the date
 * Can be paired with Picker (https://yourcmc.ru/git/vitalif-js/selectbox/)
 * to create a Calendar-based text input
 *
 * (c) Vitaliy Filippov 2011+
 * Repository: http://yourcmc.ru/git/vitalif-js/calendar
 * Version: 2021-10-17
 * License: Dual-license MPL 2.0+ or GNU LGPL 3.0+
 */

import React from 'react';

export default class Calendar extends React.PureComponent
{
	// Configuration
	static defaultProps = {
		monthNames: ["Январь","Февраль","Март","Апрель","Май","Июнь","Июль","Август","Сентябрь","Октябрь","Ноябрь","Декабрь"],
		closeLabel: 'Закрыть',
		weekdays: ["Пн","Вт","Ср","Чт","Пт","Сб","Вс"],
		weekdayIds: ['Mon','Tue','Wed','Thu','Fri','Sat','Sun'],
		sunday: 6,
		selectboxes: false, // true: use selectboxes for year and month, false: show months and years in table
		minDate: null, // minimum date
		maxDate: null, // maximum date
		minYear: -70, // range of displayed years if selectboxes==true
		maxYear: 10,
		format: 'd.m.Y', // either d.m.Y or Y-m-d, other formats are not supported
		time: false, // include time
		startMode: 'days',
	}

	constructor(props)
	{
		super(props);
		const selected = this.parseValue() || new Date();
		this.state = {
			mode: props.startMode || 'days',
			year: selected.getFullYear(),
			month: selected.getMonth(),
		};
	}

	render()
	{
		return (<div className="calendar-box">
			{this.state.mode == 'months' ? this.renderMonths() : null}
			{this.state.mode == 'years' ? this.renderYears() : null}
			{this.state.mode == 'days' ? this.renderDays() : null}
			<a className="calendar-cancel" onClick={this.props.hide}>{this.props.closeLabel}</a>
			<div className="clear" />
		</div>);
	}

	/// Called when the user clicks on a date in the calendar.
	selectDate(year, month, day)
	{
		let time = this.props.value;
		if (!time)
			time = [ 0, 0, 0 ];
		else if (time instanceof Date)
			time = [ time.getHours(), time.getMinutes(), time.getSeconds() ];
		else
		{
			time = (''+time).split(/\s+/, 2)[1];
			time = time ? time.split(/:/) : [ 0, 0, 0 ];
		}
		month = Number(month)+1;
		if (!this.props.format)
		{
			// Safari does not understand new Date('YYYY-MM-DD HH:MM:SS')
			time = new Date(year-0, month-1, day-0, time[0]-0, time[1]-0, time[2]-0);
		}
		else
		{
			if (month < 10)
				month = '0'+month;
			if (day < 10)
				day = '0'+day;
			time = time.map(t => t.length == 1 ? '0'+t : t).join(':');
			time = (this.props.format == 'Y-m-d' ? year+'-'+month+'-'+day : day+'.'+month+'.'+year) +
				(this.props.time ? ' '+time : '');
		}
		this.props.onChange(time);
		this.props.hide && this.props.hide();
	}

	parseValue(update)
	{
		if (!this.prevProps || this.props.value != this.prevProps.value)
		{
			if (this.props.value instanceof Date)
				this.selected = this.props.value;
			else
			{
				this.selected = null;
				let date_in_input = (''+this.props.value).replace(/\s+.*$/, ''); // Remove time
				if (date_in_input)
				{
					// date format is HARDCODE
					let date_parts = date_in_input.split("-");
					if (date_parts.length == 3)
					{
						// Y-m-d
						date_parts[1]--; // Month starts with 0
						this.selected = new Date(date_parts[0], date_parts[1], date_parts[2]);
					}
					else if (date_parts.length == 1)
					{
						date_parts = date_in_input.split('.');
						if (date_parts.length == 3)
						{
							// d.m.Y
							date_parts[1]--; // Month starts with 0
							this.selected = new Date(date_parts[2], date_parts[1], date_parts[0]);
						}
					}
					if (isNaN(this.selected))
						this.selected = null;
				}
			}
			if (update)
			{
				setImmediate(() => this.setState({
					year: this.selected.getFullYear(),
					month: this.selected.getMonth(),
				}));
			}
			this.prevProps = this.props;
		}
		return this.selected;
	}

	showMonths(year)
	{
		this.setState({ year, mode: 'months' });
	}

	showYears(year)
	{
		this.setState({ year, mode: 'years' });
	}

	showDays(year, month)
	{
		this.setState({ year, month, mode: 'days' });
	}

	renderMonths()
	{
		let year = this.state.year;
		let today = this.props.today || new Date();
		let cur_y = today.getFullYear();
		let cur_m = today.getMonth();
		let selected = this.parseValue(true);
		let sel_m = selected && selected.getFullYear() == year ? selected.getMonth() : -1;
		let months = [ [ 0, 1, 2 ], [ 3, 4, 5 ], [ 6, 7, 8 ], [ 9, 10, 11 ] ];
		return (<table><tbody>
			<tr><th colSpan='4' className='calendar-title'>
				<a onClick={() => this.showMonths(year-1)} title={(year-1)} className='prev'></a>
				<a onClick={() => this.showYears(year)}>{year}</a>
				<a onClick={() => this.showMonths(year+1)} title={(year+1)} className='next'></a>
			</th></tr>
			{months.map((g, idx) => (<tr key={idx}>
				{g.map(i => (
					<td key={i} className={'months '+
						(year < cur_y || year == cur_y && i < cur_m ? 'past' :
						(year > cur_y || year == cur_y && i > cur_m ? 'future' : 'today'))
						+ (i == sel_m ? ' selected' : '')}>
						<a onClick={() => this.showDays(year, i)}>
							{this.props.monthNames[i]}
						</a>
					</td>
				))}
			</tr>))}
		</tbody></table>);
	}

	renderYears()
	{
		let year = this.state.year;
		let beg = year & ~15;
		let today = this.props.today || new Date();
		let cur_y = today.getFullYear();
		let selected = this.parseValue(true);
		let sel_y = selected ? selected.getFullYear() : -1;
		return (<table><tbody>
			<tr><th colSpan='4' className='calendar-title'>
				<a onClick={() => this.showYears(year-16)} title={(beg-16)+" - "+(beg-1)} className='prev'></a>
				<b>{beg+' - '+(beg+15)}</b>
				<a onClick={() => this.showYears(year+16)} title={(beg+16)+" - "+(beg+31)} className='next'></a>
			</th></tr>
			{[0, 1, 2, 3].map(r => (
				<tr key={r}>
				{[0, 1, 2, 3].map(j => {
					let i = beg + j + r*4;
					let class_name = (i < cur_y ? 'past' : (i > cur_y ? 'future' : 'today'))
						+ (i == sel_y ? ' selected' : '');
					return (<td key={j} className={'years '+class_name}>
						<a onClick={() => this.showMonths(i)}>{i}</a>
					</td>);
				})}
				</tr>
			))}
		</tbody></table>);
	}

	_yearOptions(min, max, year)
	{
		let r = [];
		for (let i = min; i < max; i++)
			r.push(<option value={i} selected={i == year}>{i}</option>);
		return r;
	}

	/// Creates a calendar with the date given in the argument as the selected date.
	renderDays()
	{
		let { year, month } = this.state;
		let { selectboxes, sunday, monthNames } = this.props;
		let selected = this.parseValue(true);
		let today = this.props.today || new Date();

		// Display the table
		let next_month = month+1;
		let next_month_year = year;
		if (next_month >= 12)
		{
			next_month = 0;
			next_month_year++;
		}

		let previous_month = month-1;
		let previous_month_year = year;
		if (previous_month < 0)
		{
			previous_month = 11;
			previous_month_year--;
		}

		let current_year = today.getFullYear();

		// Get the first day of this month
		let first_day = new Date(year, month, 1);
		let start_day = (first_day.getDay()+sunday)%7;

		let d = 1;
		let flag = 0;

		// Leap year support
		let days_in_this_month = (month == 2
			? (!(year % 4) && ((year % 100) || !(year % 400)) ? 29 : 28)
			: ((month < 7) == !(month & 1) ? 31 : 30));

		const all_diff = (year - today.getFullYear()) || (month - today.getMonth());
		const minDate = this.props.minDate === 'today' ? today : this.props.minDate;
		const maxDate = this.props.maxDate === 'today' ? today : this.props.maxDate;
		const month_disabled = minDate && (year < minDate.getFullYear() ||
			year == minDate.getFullYear() && month < minDate.getMonth()) ||
			maxDate && (year > maxDate.getFullYear() ||
			year == maxDate.getFullYear() && month > maxDate.getMonth());
		const min_md = minDate && year == minDate.getFullYear() &&
			month == minDate.getMonth() ? minDate.getDate() : null;
		const max_md = maxDate && year == maxDate.getFullYear() &&
			month == maxDate.getMonth() ? maxDate.getDate() : null;
		const sel_day = selected && year == selected.getFullYear() && month == selected.getMonth() ? selected.getDate() : -1;

		return (<table><tbody>
			<tr><th colSpan='7' className='calendar-title'>
				<a onClick={() => this.showDays(previous_month_year, previous_month)}
					title={monthNames[previous_month]+" "+previous_month_year} className='prev'></a>
				{!selectboxes ?
					[
						<a key="1" onClick={() => this.showMonths(year, month)}>{monthNames[month]}</a>,
						<a key="2" onClick={() => this.showYears(year)}>{year}</a>
					] : [
						<select name='calendar-month' className='calendar-month' onChange={(e) => this.showDays(year, e.target.value)}>
							{monthNames.map((name, i) => (
								<option value={i} selected={(i == month)}>{name}</option>
							))}
						</select>,
						<select name='calendar-year' className='calendar-year' onChange={(e) => this.showDays(e.target.value, month)}>
							{this._yearOptions(current_year+this.props.minYear, current_year+this.props.maxYear, year)}
						</select>
					]
				}
				<a onClick={() => this.showDays(next_month_year,next_month)}
					title={this.props.monthNames[next_month]+" "+next_month_year} className='next'></a>
			</th></tr>
			<tr className='header'>
				{this.props.weekdays.map((name, idx) => (<td key={idx}>{name}</td>))}
			</tr>
			{[0, 1, 2, 3, 4].map(i => (
				(i*7 < days_in_this_month+start_day ? <tr key={i}>
					{[0, 1, 2, 3, 4, 5, 6].map(j =>
					{
						let d = i*7+j+1-start_day;
						let visible = (i > 0 || j >= start_day) && (d <= days_in_this_month);
						if (visible)
						{
							let class_name = 'days';
							let diff = all_diff || (d - today.getDate());
							let disabled = month_disabled ||
								min_md !== null && d < min_md ||
								max_md !== null && d > max_md;
							if (diff < 0)
								class_name += ' past';
							else if (!diff)
								class_name += ' today';
							else
								class_name += ' future';
							if (d == sel_day)
								class_name += ' selected';
							if (disabled)
								class_name += ' disabled';
							class_name += ' '+this.props.weekdayIds[j].toLowerCase();
							return (<td key={j} className={class_name}>
								<a onClick={disabled ? null : () => this.selectDate(year, month, d)}>{d}</a>
							</td>);
						}
						else
							return (<td key={j} className='days'>&nbsp;</td>);
					})}
				</tr> : null)
			))}
		</tbody></table>);
	}
}