import {Component, EventEmitter, Input, OnInit, Output} from '@angular/core';
import {DatePipe, NgForOf, NgIf} from '@angular/common';

@Component({
  selector: 'datepicker',
  imports: [
    NgForOf,
    DatePipe,
    NgIf
  ],
  templateUrl: './datepicker.component.html',
  styleUrl: './datepicker.component.scss'
})
export class DatepickerComponent implements OnInit {
  @Input() currentDate = new Date(); // startmaand
  secondDate = new Date();  // tweede maand

  calendars: any[][] = [[], []];
  selectedDate: Date | null = null;
  @Output() onSelectedDate: EventEmitter<Date> = new EventEmitter();

  ngOnInit() {
    this.updateSecondDate();
    this.generateCalendars();
  }

  updateSecondDate() {
    this.secondDate = new Date(this.currentDate.getFullYear(), this.currentDate.getMonth() + 1, 1);
  }

  generateCalendars() {
    this.calendars[0] = this.generateCalendar(this.currentDate);
    this.calendars[1] = this.generateCalendar(this.secondDate);
  }

  generateCalendar(date: Date) {
    const year = date.getFullYear();
    const month = date.getMonth();

    const firstDay = new Date(year, month, 1);
    const lastDay = new Date(year, month + 1, 0);

    let day = new Date(firstDay);
    day.setDate(day.getDate() - ((day.getDay() + 6) % 7)); // maandag starten

    const calendar: any[] = [];

    while (day <= lastDay || day.getDay() !== 1) {
      const week = {
        number: this.getWeekNumber(day),
        days: []
      };

      for (let i = 0; i < 7; i++) {
        week.days.push(new Date(day));
        day.setDate(day.getDate() + 1);
      }

      calendar.push(week);
    }

    return calendar;
  }

  getWeekNumber(d: Date): number {
    const date = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
    const dayNum = date.getUTCDay() || 7;
    date.setUTCDate(date.getUTCDate() + 4 - dayNum);
    const yearStart = new Date(Date.UTC(date.getUTCFullYear(), 0, 1));
    return Math.ceil((((+date - +yearStart) / 86400000) + 1) / 7);
  }

  selectDate(date: Date) {
    this.selectedDate = date;
    this.onSelectedDate.emit(date);
  }

  isToday(date: Date): boolean {
    const today = new Date();
    return date.toDateString() === today.toDateString();
  }

  isSelected(date: Date): boolean {
    return this.selectedDate?.toDateString() === date.toDateString();
  }

  goToPreviousMonth() {
    this.currentDate = new Date(this.currentDate.getFullYear(), this.currentDate.getMonth() - 1, 1);
    this.updateSecondDate();
    this.generateCalendars();
  }

  goToNextMonth() {
    this.currentDate = new Date(this.currentDate.getFullYear(), this.currentDate.getMonth() + 1, 1);
    this.updateSecondDate();
    this.generateCalendars();
  }
}