using System.IO;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Input;
using ytLive.Helpers;
using ytLive.Models;

namespace ytLive.ViewModels;

/// <summary>
/// The permanent brand logo: one image layer in every scene, directly above the background.
/// Its image comes from App Settings; each scene keeps its own visibility (the eye toggle).
/// </summary>
public partial class MainViewModel
{
    internal const double BrandLogoX = 32;
    internal const double BrandLogoY = 32;
    internal const double BrandLogoWidth = 240;
    internal const double BrandLogoHeight = 120;

    private ICommand? _browseBrandLogo;

    public ICommand BrowseBrandLogoCommand => _browseBrandLogo ??= new RelayCommand(_ => BrowseBrandLogo());

    public string BrandLogoFileDisplay => _layoutStore.GetBrandLogoFileName() ?? "None";

    private ImageSource? _brandLogoPreviewImage;
    private bool _brandLogoPreviewLoaded;

    /// <summary>The current brand-logo image, for the thumbnail beside the file field in App
    /// Settings (the creator, 2026-10-30: a myopic user cannot tell what a file *name* looks
    /// like). Null until an image is set.</summary>
    public ImageSource? BrandLogoPreviewImage
    {
        get
        {
            if (!_brandLogoPreviewLoaded) RefreshBrandLogoPreview();
            return _brandLogoPreviewImage;
        }
    }

    internal void RefreshBrandLogoPreview()
    {
        _brandLogoPreviewLoaded = true;
        _brandLogoPreviewImage = LoadBrandLogoImage(_layoutStore.GetBrandLogoAssetId());
        OnPropertyChanged(nameof(BrandLogoPreviewImage));
    }

    /// <summary>Decoded once and frozen: the thumbnail and the enlarged preview share it, and a
    /// frozen bitmap can be handed to any thread without a dispatcher round-trip.</summary>
    private ImageSource? LoadBrandLogoImage(string? assetId)
    {
        if (string.IsNullOrWhiteSpace(assetId)) return null;
        var bytes = _layoutStore.GetAssetBytes(assetId);
        if (bytes is not { Length: > 0 }) return null;
        try
        {
            var image = new BitmapImage();
            image.BeginInit();
            image.CacheOption = BitmapCacheOption.OnLoad;
            image.StreamSource = new MemoryStream(bytes);
            image.EndInit();
            image.Freeze();
            return image;
        }
        catch (Exception)
        {
            return null;   // a corrupt image must not take the dialog down with it
        }
    }

    private void BrowseBrandLogo()
    {
        var dialog = new Microsoft.Win32.OpenFileDialog
        {
            Title = "Choose brand logo",
            Filter = "Images|*.png;*.jpg;*.jpeg;*.bmp;*.gif",
        };
        if (dialog.ShowDialog() != true) return;
        _layoutStore.SetBrandLogo(File.ReadAllBytes(dialog.FileName), Path.GetFileName(dialog.FileName));
        EnsureBrandLogos();
        RefreshBrandLogoPreview();
        OnPropertyChanged(nameof(BrandLogoFileDisplay));
        ScheduleSave();
    }

    internal static Source CreateBrandLogo(string? assetId) => new()
    {
        Name = "Brand logo",
        Type = SourceType.Image,
        IsBrandLogo = true,
        IsEnabled = true,
        AssetId = assetId,
        X = BrandLogoX,
        Y = BrandLogoY,
        Width = BrandLogoWidth,
        Height = BrandLogoHeight,
    };

    /// <summary>Exactly one brand logo per scene, placed directly above the background, carrying
    /// the current App Settings image.</summary>
    internal void EnsureBrandLogos()
    {
        var assetId = _layoutStore.GetBrandLogoAssetId();
        foreach (var scene in Scenes)
        {
            var logos = scene.Elements.OfType<Source>().Where(s => s.IsBrandLogo).ToList();
            foreach (var extra in logos.Skip(1))
                scene.Elements.Remove(extra);
            var logo = logos.FirstOrDefault();
            if (logo == null)
            {
                var background = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
                var index = background == null ? 0 : scene.Elements.IndexOf(background) + 1;
                logo = CreateBrandLogo(assetId);
                scene.Elements.Insert(index, logo);
            }
            else
            {
                logo.AssetId = assetId;
            }
            _sceneGraph.InvalidateBake(scene);
        }
    }
}