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

namespace LehrerApp.Desktop.ViewModels;

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

    [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; } = [];

    // Navigation-Callback – wird von App.axaml.cs verdrahtet
    public Action<Guid>? OnNavigateToGroup { get; set; }

    public DashboardViewModel(IGroupRepository groups, ILessonRepository lessons,
        IWorkTaskRepository tasks, SchoolYearService sy)
    {
        _groups = groups; _lessons = lessons; _tasks = tasks; _sy = sy;
        Load();
    }

    private void Load()
    {
        var now   = DateTime.Now;
        var today = DateOnly.FromDateTime(now);
        CurrentDate        = now.ToString("dddd, d. MMMM yyyy", new CultureInfo("de-DE"));
        CurrentSchoolYear  = _sy.CurrentSchoolYear();
        Greeting = now.Hour < 12 ? "Guten Morgen" : now.Hour < 18 ? "Guten Tag" : "Guten Abend";

        TodaysLessons.Clear();
        var groups = _groups.GetBySchoolYear(_sy.CurrentSchoolYear()).ToDictionary(g => g.Id);
        foreach (var l in groups.Keys.SelectMany(gid => _lessons.GetByGroupAndDate(gid, today))
                                     .OrderBy(l => l.LessonNumber))
        {
            if (groups.TryGetValue(l.GroupId, out var g))
                TodaysLessons.Add(new() { GroupName = g.Name, Topic = l.Topic });
        }

        OpenTasks.Clear();
        foreach (var t in _tasks.GetByStatus(WorkTaskStatus.Open)
                                .Concat(_tasks.GetByStatus(WorkTaskStatus.InProgress))
                                .OrderBy(t => t.DueDate ?? DateOnly.MaxValue).Take(5))
            OpenTasks.Add(new() { Title = t.Title,
                DueDate   = t.DueDate?.ToString("dd.MM.") ?? "",
                IsOverdue = t.DueDate.HasValue && t.DueDate < today });

        CurrentGroups.Clear();
        foreach (var g in groups.Values.OrderBy(g => g.Name))
            CurrentGroups.Add(new() { GroupId = g.Id, Name = g.Name, Subject = g.Subject ?? "" });
    }

    [RelayCommand] private void OpenGroup(GroupChip? c) { if (c is not null) OnNavigateToGroup?.Invoke(c.GroupId); }
    [RelayCommand] private void Refresh() => Load();
}

public class LessonItem { public string GroupName { get; set; } = ""; public string Topic { get; set; } = ""; }
public class TaskItem   { public string Title { get; set; } = ""; public string DueDate { get; set; } = ""; public bool IsOverdue { get; set; } }
public class GroupChip  { public Guid GroupId { get; set; } public string Name { get; set; } = ""; public string Subject { get; set; } = ""; }