using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using LehrerApp.Templating;
using System.Collections.ObjectModel;

namespace LehrerApp.Desktop.ViewModels.Settings;

public partial class SettingsViewModel
{
    [ObservableProperty] private string _letterTemplateStatus = "";
    public ObservableCollection<LetterTemplateListItem> LetterTemplateList { get; } = [];

    private void LoadLetterTemplates()
    {
        LetterTemplateList.Clear();
        foreach (var template in _letterTemplates.GetTemplates()) LetterTemplateList.Add(CreateItem(template));
    }

    public void ImportLetterTemplate(string path)
    {
        LetterTemplateStatus = "";
        try
        {
            var template = _letterTemplates.Import(path);
            LoadLetterTemplates();
            LetterTemplateStatus = $"„{template.Name}“ wurde geprüft und lokal importiert.";
        }
        catch (Exception ex) when (ex is IOException or InvalidDataException or UnauthorizedAccessException or TemplateValidationException)
        { LetterTemplateStatus = $"Import fehlgeschlagen: {ex.Message}"; }
    }

    [RelayCommand]
    private void ValidateLetterTemplate(LetterTemplateListItem? item)
    {
        if (item is null) return;
        try
        {
            var refreshed = CreateItem(item.Model);
            var index = LetterTemplateList.IndexOf(item);
            if (index >= 0) LetterTemplateList[index] = refreshed;
            LetterTemplateStatus = $"„{item.Name}“ ist gültig (Schema {refreshed.SchemaVersion}).";
        }
        catch (Exception ex) when (ex is IOException or InvalidDataException or TemplateValidationException)
        { LetterTemplateStatus = $"„{item.Name}“ ist ungültig: {ex.Message}"; }
    }

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

    private LetterTemplateListItem CreateItem(InstalledTemplate template)
    {
        var loaded = _letterTemplates.Load(template);
        return new(template, loaded.Manifest.SchemaVersion, loaded.Manifest.Placeholders.Count,
            loaded.Manifest.Placeholders.Count(x => x.Required));
    }
}

public sealed class LetterTemplateListItem(InstalledTemplate model, int schemaVersion, int fieldCount, int requiredCount)
{
    public InstalledTemplate Model { get; } = model;
    public string Id => Model.Id;
    public string Name => Model.Name;
    public string PackageFileName => Path.GetFileName(Model.PackagePath);
    public int SchemaVersion { get; } = schemaVersion;
    public bool HasIssues => false;
    public bool HasNoIssues => true;
    public string ValidationSummary => $"Schema {SchemaVersion} · {fieldCount} Felder ({requiredCount} Pflicht)";
    public ObservableCollection<LetterTemplateIssueItem> Issues { get; } = [];
}

public sealed class LetterTemplateIssueItem(ValidationIssue issue)
{
    public string Icon => issue.Severity == ValidationSeverity.Error ? "⛔" : "ⓘ";
    public string Message => issue.Message;
    public string Color => issue.Severity == ValidationSeverity.Error ? "#DC2626" : "#6B7280";
}