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
{
    // ── Word-Briefvorlagen (7.1.4 / 11.5) ───────────────────────────────────

    [ObservableProperty] private string _letterTemplateStatus = "";
    public ObservableCollection<LetterTemplateListItem> LetterTemplateList { get; } = [];
    public IReadOnlyList<LetterPlaceholder> SupportedLetterPlaceholders =>
        LetterTemplateService.SupportedPlaceholders;

    // ── Word-Briefvorlagen: Import und Validierung ──────────────────────────

    private void LoadLetterTemplates()
    {
        LetterTemplateList.Clear();
        foreach (var template in _letterTemplates.GetTemplates())
            LetterTemplateList.Add(new LetterTemplateListItem(template, _letterTemplates.Validate(template)));
    }

    public void ImportLetterTemplate(string path)
    {
        LetterTemplateStatus = "";
        try
        {
            var template = _letterTemplates.Import(path);
            var validation = _letterTemplates.Validate(template);
            LoadLetterTemplates();
            LetterTemplateStatus = validation.Issues.Count == 0
                ? "Vorlage importiert und ohne Auffälligkeiten geprüft."
                : $"Vorlage importiert. Die Prüfung meldet {validation.Issues.Count} Hinweis(e).";
        }
        catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException)
        {
            LetterTemplateStatus = $"Import fehlgeschlagen: {ex.Message}";
        }
    }

    [RelayCommand]
    private void ValidateLetterTemplate(LetterTemplateListItem? item)
    {
        if (item is null) return;
        var index = LetterTemplateList.IndexOf(item);
        var refreshed = new LetterTemplateListItem(item.Model, _letterTemplates.Validate(item.Model));
        if (index >= 0) LetterTemplateList[index] = refreshed;
        LetterTemplateStatus = refreshed.Validation.Issues.Count == 0
            ? $"„{item.Name}“ ist ohne Auffälligkeiten."
            : $"„{item.Name}“: {refreshed.Validation.Issues.Count} Hinweis(e).";
    }

    [RelayCommand]
    private void DeleteLetterTemplate(LetterTemplateListItem? item)
    {
        if (item is null) return;
        _letterTemplates.Delete(item.Id);
        LetterTemplateList.Remove(item);
        LetterTemplateStatus = "Vorlage gelöscht.";
    }
}

public sealed class LetterTemplateListItem
{
    public LetterTemplateInfo Model { get; }
    public TemplateValidationResult Validation { get; }
    public Guid Id => Model.Id;
    public string Name => Model.Name;
    public string OriginalFileName => Model.OriginalFileName;
    public bool HasIssues => Validation.Issues.Count > 0;
    public bool HasNoIssues => !HasIssues;
    public string ValidationSummary => HasNoIssues
        ? $"{Validation.Tags.Count} Feld(er) · keine Auffälligkeiten"
        : $"{Validation.Tags.Count} Feld(er) · {Validation.Issues.Count} Hinweis(e)";
    public ObservableCollection<LetterTemplateIssueItem> Issues { get; }

    public LetterTemplateListItem(LetterTemplateInfo model, TemplateValidationResult validation)
    {
        Model = model;
        Validation = validation;
        Issues = new(validation.Issues.Select(i => new LetterTemplateIssueItem(i)));
    }
}

public sealed class LetterTemplateIssueItem(TemplateValidationIssue issue)
{
    public string Icon => issue.Severity switch
    {
        TemplateIssueSeverity.Error => "⛔",
        TemplateIssueSeverity.StrongWarning => "⚠",
        _ => "ⓘ",
    };
    public string Message => issue.Message;
    public string Color => issue.Severity switch
    {
        TemplateIssueSeverity.Error => "#DC2626",
        TemplateIssueSeverity.StrongWarning => "#D97706",
        _ => "#6B7280",
    };
}