using System.Collections.ObjectModel;
using System.Windows;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using MySqlConnector;
using UtopiaCanteenSystem.Models;
using UtopiaCanteenSystem.Services;

namespace UtopiaCanteenSystem.ViewModels;

/// <summary>
/// Admin CRUD for meal schedules in production (hrms.meal_schedule). No SQLite. Load all on open; optional Site filter (local).
/// </summary>
public partial class MealSchedulesViewModel : ObservableObject
{
    private readonly IMealScheduleService _mealScheduleService;
    private readonly INavigationService _navigation;

    [ObservableProperty]
    private ObservableCollection<MealSchedule> _schedules = new();

    /// <summary>Full list from production; Schedules is filtered by SelectedSiteFilter.</summary>
    private List<MealSchedule> _allSchedules = new();

    [ObservableProperty]
    private ObservableCollection<string> _siteFilterChoices = new() { "All" };

    [ObservableProperty]
    private string _selectedSiteFilter = "All";

    [ObservableProperty]
    private MealSchedule? _selectedSchedule;

    [ObservableProperty]
    private string _locationSiteId = string.Empty;

    [ObservableProperty]
    private int _mealSessionIndex; // 0=Breakfast, 1=Lunch, 2=Tea, 3=Dinner

    [ObservableProperty]
    private string _startTime = "06:00:00";

    [ObservableProperty]
    private string _endTime = "09:00:00";

    [ObservableProperty]
    private string _message = string.Empty;

    [ObservableProperty]
    private bool _isError;

    [ObservableProperty]
    private bool _isLoading;

    public static readonly string[] MealSessionNames = { "Breakfast", "Lunch", "Tea", "Dinner" };

    public MealSchedulesViewModel(IMealScheduleService mealScheduleService, INavigationService navigation)
    {
        _mealScheduleService = mealScheduleService;
        _navigation = navigation;
        _ = LoadSchedulesAsync();
    }

    partial void OnSelectedSiteFilterChanged(string value)
    {
        ApplyFilter();
    }

    partial void OnSelectedScheduleChanged(MealSchedule? value)
    {
        if (value == null) return;
        LocationSiteId = value.LocationSiteId ?? string.Empty;
        MealSessionIndex = value.MealSession;
        StartTime = value.StartTime ?? "00:00:00";
        EndTime = value.EndTime ?? "23:59:59";
    }

    private void ApplyFilter()
    {
        if (string.IsNullOrEmpty(SelectedSiteFilter) || SelectedSiteFilter == "All")
        {
            Schedules = new ObservableCollection<MealSchedule>(_allSchedules);
            return;
        }
        var filtered = _allSchedules.Where(s => string.Equals(s.LocationSiteId?.Trim(), SelectedSiteFilter.Trim(), StringComparison.OrdinalIgnoreCase)).ToList();
        Schedules = new ObservableCollection<MealSchedule>(filtered);
    }

    private async Task LoadSchedulesAsync()
    {
        IsLoading = true;
        Message = string.Empty;
        IsError = false;
        try
        {
            var list = await _mealScheduleService.GetAllSchedulesAsync().ConfigureAwait(true);
            _allSchedules = list.ToList();
            var siteIds = _allSchedules.Select(s => s.LocationSiteId?.Trim() ?? "").Where(s => !string.IsNullOrEmpty(s)).Distinct().OrderBy(s => s, StringComparer.Ordinal).ToList();
            SiteFilterChoices = new ObservableCollection<string>(new[] { "All" }.Concat(siteIds));
            SelectedSiteFilter = "All";
            ApplyFilter();
            if (_allSchedules.Count == 0)
                Message = "No schedules in production. Add one below (HRMS MySQL must be configured).";
        }
        catch (Exception ex)
        {
            IsError = true;
            var msg = ex is MySqlException mysql
                ? $"{mysql.Message}{Environment.NewLine}{Environment.NewLine}{mysql.StackTrace}"
                : $"{ex.Message}{Environment.NewLine}{Environment.NewLine}{ex.StackTrace}";
            Message = "Could not load schedules from production.";
            MessageBox.Show(msg, "Meal Schedules – Load Error", MessageBoxButton.OK, MessageBoxImage.Error);
        }
        finally
        {
            IsLoading = false;
        }
    }

    [RelayCommand]
    private void AddNew()
    {
        SelectedSchedule = null;
        LocationSiteId = "02";
        MealSessionIndex = 0;
        StartTime = "06:00:00";
        EndTime = "09:00:00";
        Message = string.Empty;
    }

    [RelayCommand]
    private async Task Save()
    {
        Message = string.Empty;
        IsError = false;

        if (!TimeSpan.TryParse(StartTime?.Trim(), out var start) || !TimeSpan.TryParse(EndTime?.Trim(), out var end))
        {
            Message = "Start time and end time must be in HH:mm:ss format.";
            IsError = true;
            return;
        }
        if (start >= end)
        {
            Message = "Start time must be before end time.";
            IsError = true;
            return;
        }

        var siteId = (LocationSiteId ?? string.Empty).Trim();
        if (string.IsNullOrEmpty(siteId))
        {
            Message = "Location site ID is required.";
            IsError = true;
            return;
        }

        try
        {
            if (SelectedSchedule != null)
            {
                var dto = new MealSchedule
                {
                    Id = SelectedSchedule.Id,
                    LocationSiteId = siteId,
                    MealSession = MealSessionIndex,
                    StartTime = StartTime.Trim(),
                    EndTime = EndTime.Trim()
                };
                await _mealScheduleService.UpdateAsync(dto).ConfigureAwait(true);
                Message = "Schedule updated in production.";
            }
            else
            {
                var dto = new MealSchedule
                {
                    LocationSiteId = siteId,
                    MealSession = MealSessionIndex,
                    StartTime = StartTime.Trim(),
                    EndTime = EndTime.Trim()
                };
                await _mealScheduleService.CreateAsync(dto).ConfigureAwait(true);
                Message = "Schedule added to production.";
            }
            await LoadSchedulesAsync().ConfigureAwait(true);
        }
        catch (Exception ex)
        {
            IsError = true;
            var msg = ex is MySqlException mysql
                ? $"{mysql.Message}{Environment.NewLine}{Environment.NewLine}{mysql.StackTrace}"
                : $"{ex.Message}{Environment.NewLine}{Environment.NewLine}{ex.StackTrace}";
            Message = "Failed to save to production.";
            MessageBox.Show(msg, "Meal Schedules – Save Error", MessageBoxButton.OK, MessageBoxImage.Error);
        }
    }

    [RelayCommand]
    private async Task Delete()
    {
        if (SelectedSchedule == null)
        {
            Message = "Select a schedule to delete.";
            IsError = true;
            return;
        }
        Message = string.Empty;
        IsError = false;
        try
        {
            await _mealScheduleService.DeleteAsync(SelectedSchedule.Id).ConfigureAwait(true);
            Message = "Schedule deleted from production.";
            SelectedSchedule = null;
            await LoadSchedulesAsync().ConfigureAwait(true);
        }
        catch (Exception ex)
        {
            IsError = true;
            var msg = ex is MySqlException mysql
                ? $"{mysql.Message}{Environment.NewLine}{Environment.NewLine}{mysql.StackTrace}"
                : $"{ex.Message}{Environment.NewLine}{Environment.NewLine}{ex.StackTrace}";
            Message = "Failed to delete.";
            MessageBox.Show(msg, "Meal Schedules – Delete Error", MessageBoxButton.OK, MessageBoxImage.Error);
        }
    }

    [RelayCommand]
    private void Back()
    {
        _navigation.NavigateToSettings();
    }
}