using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Core.Interfaces;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using LehrerApp.Data;
using LehrerApp.Desktop.Services;
using LehrerApp.Desktop.ViewModels.Planning;
using LehrerApp.Sync;
using LehrerApp.Sync.Crypto;
using System.Collections.ObjectModel;
using System.Globalization;
using System.Security.Cryptography;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace LehrerApp.Desktop.ViewModels.Settings;

public partial class SettingsViewModel
{
    // ── Notenschlüssel-Vorlagen (1.3.2) ──────────────────────────────────────

    [ObservableProperty] private string _newTemplateName = "";
    [ObservableProperty] private string _newTemplateGradingSystemName = "Noten 1–6";
    [ObservableProperty] private string _newTemplateNameError = "";

    public List<string> GradingSystemOptions { get; } = ["Noten 1–6", "Punkte 0–15"];
    public ObservableCollection<GradingKeyTemplateEditItem> GradingKeyTemplateList { get; } = [];

    // ── Notenschlüssel-Vorlagen: Laden / Hinzufügen / Löschen ────────────────

    private void LoadGradingKeyTemplates()
    {
        GradingKeyTemplateList.Clear();
        foreach (var t in _gradingKeyTemplates.GetAll())
            GradingKeyTemplateList.Add(new GradingKeyTemplateEditItem(t, _gradingKeyTemplates, _grading));
    }

    [RelayCommand]
    private void AddGradingKeyTemplate()
    {
        if (string.IsNullOrWhiteSpace(NewTemplateName)) { NewTemplateNameError = "Vorlagenname erforderlich."; return; }

        var system = NewTemplateGradingSystemName == "Punkte 0–15"
            ? GradingSystem.Points0To15 : GradingSystem.Grades1To6;
        var defaults = system == GradingSystem.Grades1To6
            ? GradingService.DefaultKey1To6() : GradingService.DefaultKey0To15();

        var template = new GradingKeyTemplate
        {
            Name = NewTemplateName.Trim(),
            GradingSystem = system,
            Entries = defaults.Select(e => new GradingKeyEntry { Grade = e.Grade, MinPercent = e.MinPercent }).ToList(),
        };
        _gradingKeyTemplates.Save(template);
        GradingKeyTemplateList.Add(new GradingKeyTemplateEditItem(template, _gradingKeyTemplates, _grading));
        NewTemplateName = "";
        NewTemplateNameError = "";
    }

    [RelayCommand]
    private void DeleteGradingKeyTemplate(GradingKeyTemplateEditItem? item)
    {
        if (item is null) return;
        _gradingKeyTemplates.Delete(item.Id);
        GradingKeyTemplateList.Remove(item);
    }
}

public partial class GradingKeyTemplateEditItem : ObservableObject
{
    private readonly GradingKeyTemplate _template;
    private readonly IGradingKeyTemplateRepository _repo;
    private readonly GradingService _grading;

    public Guid   Id                 { get; }
    public string Name               { get; }
    public string GradingSystemLabel { get; }

    [ObservableProperty] private string _newGrade = "";
    [ObservableProperty] private double _newMinPercent;
    [ObservableProperty] private string _newGradeError = "";
    [ObservableProperty] private string _newMinPercentError = "";
    [ObservableProperty] private string _completenessWarning = "";

    public ObservableCollection<GradingKeyEntryVm> Entries { get; } = [];

    public GradingKeyTemplateEditItem(GradingKeyTemplate template, IGradingKeyTemplateRepository repo,
        GradingService grading)
    {
        _template = template; _repo = repo; _grading = grading;
        Id   = template.Id;
        Name = template.Name;
        GradingSystemLabel = template.GradingSystem == GradingSystem.Grades1To6
            ? "Noten 1–6" : "Punkte 0–15";

        foreach (var e in template.Entries.OrderByDescending(e => e.MinPercent))
            Entries.Add(new GradingKeyEntryVm(e, DeleteEntry));
        RecomputeCompleteness();
    }

    [RelayCommand]
    private void AddEntry()
    {
        NewGradeError = ""; NewMinPercentError = "";
        var valid = true;

        if (string.IsNullOrWhiteSpace(NewGrade)) { NewGradeError = "Bezeichnung erforderlich."; valid = false; }
        if (NewMinPercent is < 0 or > 100) { NewMinPercentError = "Muss zwischen 0 und 100 liegen."; valid = false; }
        else if (_template.Entries.Any(e => Math.Abs(e.MinPercent - NewMinPercent) < 0.0001))
        { NewMinPercentError = "Diese Prozentgrenze existiert bereits."; valid = false; }

        if (!valid) return;

        var entry = new GradingKeyEntry { Grade = NewGrade.Trim(), MinPercent = NewMinPercent };
        _template.Entries.Add(entry);
        _template.Entries = _template.Entries.OrderByDescending(e => e.MinPercent).ToList();
        _repo.Save(_template);

        Entries.Clear();
        foreach (var e in _template.Entries) Entries.Add(new GradingKeyEntryVm(e, DeleteEntry));
        NewGrade = ""; NewMinPercent = 0;
        RecomputeCompleteness();
    }

    private void DeleteEntry(GradingKeyEntryVm vm)
    {
        _template.Entries.RemoveAll(e => e.Grade == vm.Grade && Math.Abs(e.MinPercent - vm.MinPercent) < 0.0001);
        _repo.Save(_template);
        Entries.Remove(vm);
        RecomputeCompleteness();
    }

    private void RecomputeCompleteness() =>
        CompletenessWarning = _grading.ValidateGradingKey(_template.Entries) ?? "";
}

// ── GradingKeyEntryVm ─────────────────────────────────────────────────────────

public class GradingKeyEntryVm
{
    public string Grade      { get; }
    public double MinPercent { get; }
    public string Display    { get; }
    public IRelayCommand DeleteCommand { get; }

    public GradingKeyEntryVm(GradingKeyEntry e, Action<GradingKeyEntryVm> onDelete)
    {
        Grade      = e.Grade;
        MinPercent = e.MinPercent;
        Display    = $"{Grade} — ab {MinPercent.ToString("0.##")} %";
        DeleteCommand = new RelayCommand(() => onDelete(this));
    }
}