using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;
using UnityEngine.UI;
using System;

public class Calendar : MonoBehaviour
{
    [SerializeField] private TextMeshProUGUI monthText;
    [SerializeField] private Transform daysParent;
    [SerializeField] private GameObject dayPrefab;

    private DateTime _currentDate;

    private List<GameObject> _currentMonthButtons =
        new List<GameObject>();

    private int _lastMonth = -1;
    private int _lastYear = -1;

    public void SetDate(DateTime newDate)
    {
        _currentDate = newDate;

        if (_currentDate.Month != _lastMonth ||
            _currentDate.Year != _lastYear)
        {
            _lastMonth = _currentDate.Month;
            _lastYear = _currentDate.Year;

            GenerateCalendar();
        }
        else
        {
            UpdateVisual();
        }
    }

    private void GenerateCalendar()
    {
        for (int i = daysParent.childCount - 1; i >= 0; i--)
        {
            Destroy(daysParent.GetChild(i).gameObject);
        }

        _currentMonthButtons.Clear();

        monthText.text = _currentDate.ToString("MMMM yyyy");

        DateTime firstDay =
            new DateTime(_currentDate.Year,
                         _currentDate.Month,
                         1);

        int daysInMonth =
            DateTime.DaysInMonth(_currentDate.Year,
                                 _currentDate.Month);

        int startDayOfWeek =
            ((int)firstDay.DayOfWeek + 6) % 7;

        DateTime prevMonth =
            _currentDate.AddMonths(-1);

        int daysInPrevMonth =
            DateTime.DaysInMonth(prevMonth.Year,
                                 prevMonth.Month);

        for (int i = startDayOfWeek; i > 0; i--)
        {
            int dayNumber =
                daysInPrevMonth - i + 1;

            GameObject dayObj =
                Instantiate(dayPrefab, daysParent);

            dayObj.GetComponentInChildren<TextMeshProUGUI>()
                  .text = dayNumber.ToString();

            Image img =
                dayObj.GetComponent<Image>();

            img.color = Color.gray;
        }

        for (int day = 1; day <= daysInMonth; day++)
        {
            GameObject dayObj =
                Instantiate(dayPrefab, daysParent);

            dayObj.GetComponentInChildren<TextMeshProUGUI>()
                  .text = day.ToString();

            _currentMonthButtons.Add(dayObj);
        }

        UpdateVisual();
    }

    private void UpdateVisual()
    {
        int today = _currentDate.Day;

        for (int i = 0; i < _currentMonthButtons.Count; i++)
        {
            Image img =
                _currentMonthButtons[i]
                .GetComponent<Image>();

            Transform marker =
                _currentMonthButtons[i]
                .transform.Find("CurrentData");

            int dayNumber = i + 1;

            if (dayNumber < today)
            {
                img.color = Color.gray;
                if (marker != null)
                    marker.gameObject.SetActive(false);
            }
            else if (dayNumber == today)
            {
                img.color = Color.white;
                if (marker != null)
                    marker.gameObject.SetActive(true);
            }
            else
            {
                img.color = Color.white;
                if (marker != null)
                    marker.gameObject.SetActive(false);
            }
        }
    }
}