using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using System.Collections.ObjectModel;

namespace LehrerApp.Desktop.ViewModels;

public partial class DashboardViewModel : ObservableObject
{
    private readonly IGroupRepository _groups;
    private readonly ILessonRepository _lessons;
    private readonly IWorkTaskRepository _tasks;
    private readonly SchoolYearService _schoolYearService;

    [ObservableProperty] private string _greeting = "";
    [ObservableProperty] private string _currentDate = "";
    [ObservableProperty] private string _currentSchoolYear = "";

    public ObservableCollection<LessonItem> TodaysLessons { get; } = [];
    public ObservableCollection<TaskItem> OpenTasks { get; } = [];
    public ObservableCollection<GroupChip> CurrentGroups { get; } = [];

    public DashboardViewModel(
        IGroupRepository groups,
        ILessonRepository lessons,
        IWorkTaskRepository tasks,
        SchoolYearService schoolYearService)
    {
        _groups = groups;
        _lessons = lessons;
        _tasks = tasks;
        _schoolYearService = schoolYearService;

        Load();
    }

    private void Load()
    {
        var now = DateTime.Now;
        var today = DateOnly.FromDateTime(now);

        CurrentDate = now.ToString("dddd, d. MMMM yyyy",
            new System.Globalization.CultureInfo("de-DE"));
        CurrentSchoolYear = _schoolYearService.CurrentSchoolYear();
        Greeting = now.Hour < 12 ? "Guten Morgen" :
                   now.Hour < 18 ? "Guten Tag" : "Guten Abend";

        // Heutige Stunden
        TodaysLessons.Clear();
        var schoolYear = _schoolYearService.CurrentSchoolYear();
        var allGroups = _groups.GetBySchoolYear(schoolYear)
            .ToDictionary(g => g.Id);

        var todayLessons = allGroups.Keys
            .SelectMany(gid => _lessons.GetByGroupAndDate(gid, today))
            .OrderBy(l => l.LessonNumber)
            .ToList();

        foreach (var lesson in todayLessons)
        {
            if (!allGroups.TryGetValue(lesson.GroupId, out var group)) continue;
            TodaysLessons.Add(new LessonItem
            {
                GroupName = group.Name,
                Topic = lesson.Topic,
                Status = lesson.Status,
            });
        }

        // Offene Aufgaben (mit Fälligkeit)
        OpenTasks.Clear();
        var openTasks = _tasks.GetByStatus(WorkTaskStatus.Open)
            .Concat(_tasks.GetByStatus(WorkTaskStatus.InProgress))
            .OrderBy(t => t.DueDate ?? DateOnly.MaxValue)
            .Take(5);

        foreach (var task in openTasks)
        {
            var isOverdue = task.DueDate.HasValue && task.DueDate < today;
            var isDueSoon = task.DueDate.HasValue &&
                            task.DueDate >= today &&
                            task.DueDate <= today.AddDays(3);

            OpenTasks.Add(new TaskItem
            {
                Title = task.Title,
                DueDate = task.DueDate?.ToString("dd.MM.") ?? "",
                IsOverdue = isOverdue,
                IsDueSoon = isDueSoon,
                Status = task.Status,
            });
        }

        // Aktuelle Lerngruppen als Chips
        CurrentGroups.Clear();
        foreach (var group in _groups.GetBySchoolYear(schoolYear)
                     .OrderBy(g => g.Name))
        {
            CurrentGroups.Add(new GroupChip
            {
                GroupId = group.Id,
                Name = group.Name,
                Subject = group.Subject ?? "",
            });
        }
    }

    [RelayCommand]
    private void Refresh() => Load();
}

// Anzeigemodelle für Dashboard-Widgets
public class LessonItem
{
    public string GroupName { get; set; } = "";
    public string Topic { get; set; } = "";
    public LessonStatus Status { get; set; }
}

public class TaskItem
{
    public string Title { get; set; } = "";
    public string DueDate { get; set; } = "";
    public bool IsOverdue { get; set; }
    public bool IsDueSoon { get; set; }
    public WorkTaskStatus Status { get; set; }
}

public class GroupChip
{
    public Guid GroupId { get; set; }
    public string Name { get; set; } = "";
    public string Subject { get; set; } = "";
}