using System.Text.Json;

namespace Meezi.Infrastructure.Data;

public static class MenuImageManifest
{
    private static IReadOnlyDictionary<string, string>? _urls;
    private static string? _defaultDrinkUrl;
    private static string? _defaultFoodUrl;

    private const string FallbackDrinkUrl =
        "https://images.unsplash.com/photo-1509042239860-f550ce710b93?w=600&auto=format&fit=crop";

    private const string FallbackFoodUrl =
        "https://images.unsplash.com/photo-1546793665-c74683f339c1?w=600";

    public static string? GetImageUrl(string itemId)
    {
        EnsureLoaded();
        return _urls!.TryGetValue(itemId, out var url) ? url : null;
    }

    public static string GetDefaultDrinkImageUrl()
    {
        EnsureLoaded();
        return _defaultDrinkUrl ?? FallbackDrinkUrl;
    }

    public static string GetDefaultFoodImageUrl()
    {
        EnsureLoaded();
        return _defaultFoodUrl ?? FallbackFoodUrl;
    }

    public static string ResolveImageUrl(string itemId, string fallback)
        => GetLocalImageOverride(itemId) ?? fallback;

    /// <summary>Only imported Kaggle/upload paths override Food-101 fallbacks (not stale CDN URLs in manifest).</summary>
    public static string? GetLocalImageOverride(string itemId)
    {
        var url = GetImageUrl(itemId);
        if (string.IsNullOrWhiteSpace(url)) return null;
        if (url.StartsWith("/uploads/", StringComparison.OrdinalIgnoreCase)
            || url.StartsWith("uploads/", StringComparison.OrdinalIgnoreCase))
            return url.StartsWith('/') ? url : $"/{url}";
        return null;
    }

    private static void EnsureLoaded()
    {
        if (_urls is not null) return;
        LoadFromDisk();
    }

    private static void LoadFromDisk()
    {
        var paths = new[]
        {
            Path.Combine(AppContext.BaseDirectory, "data", "menu-image-manifest.json"),
            Path.Combine(Directory.GetCurrentDirectory(), "data", "menu-image-manifest.json"),
            Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "data", "menu-image-manifest.json")),
            Path.GetFullPath(Path.Combine(Directory.GetCurrentDirectory(), "..", "..", "data", "menu-image-manifest.json")),
        };

        foreach (var path in paths)
        {
            if (!File.Exists(path)) continue;
            try
            {
                var json = File.ReadAllText(path);
                var doc = JsonDocument.Parse(json);
                if (doc.RootElement.TryGetProperty("defaults", out var defaults))
                {
                    if (defaults.TryGetProperty("drink", out var drink))
                        _defaultDrinkUrl = drink.GetString();
                    if (defaults.TryGetProperty("food", out var food))
                        _defaultFoodUrl = food.GetString();
                }

                var map = new Dictionary<string, string>(StringComparer.Ordinal);
                if (doc.RootElement.TryGetProperty("items", out var items))
                {
                    foreach (var prop in items.EnumerateObject())
                    {
                        if (prop.Value.TryGetProperty("imageUrl", out var url))
                            map[prop.Name] = url.GetString() ?? "";
                    }
                }

                _urls = map;
                return;
            }
            catch
            {
                // try next path
            }
        }

        _urls = new Dictionary<string, string>(StringComparer.Ordinal);
    }
}