using Godot;
using System.Collections.Generic;
using System.IO;

namespace Theriapolis.GodotHost.Platform;

/// <summary>
/// Loads PNGs from Content/Gfx as Godot ImageTextures and caches them by
/// relative path. Texture filter is set to Nearest (project default for
/// pixel art).
///
/// This bypasses Godot's res:// import pipeline because Content/ lives
/// outside the project — but for static pixel-art assets at native size
/// the import pipeline doesn't add anything we need.
///
/// Tactical-view tile rendering (M4) will hit this from chunk streamers,
/// so the cache is per-process and never evicted; the full atlas
/// (~50 PNGs at 32x32) is well under 1 MB.
/// </summary>
public static class ContentLoader
{
    private static readonly Dictionary<string, ImageTexture> _cache = new();

    /// <summary>
    /// Loads a PNG from <c>Content/Gfx/&lt;relativePath&gt;</c>. Returns
    /// null and logs an error if the file is missing or unreadable.
    /// </summary>
    public static ImageTexture? LoadGfx(string relativePath)
    {
        if (_cache.TryGetValue(relativePath, out var cached)) return cached;

        string absolute = Path.Combine(ContentPaths.GfxDir, relativePath);
        if (!File.Exists(absolute))
        {
            // Silent miss — callers (e.g. atlas variant probes) treat null
            // as "no more variants" and shouldn't generate error noise.
            // Genuine missing-asset diagnostics live in AssetTest's summary.
            return null;
        }

        var image = Image.LoadFromFile(absolute);
        if (image is null)
        {
            GD.PrintErr($"[ContentLoader] Image.LoadFromFile failed: {absolute}");
            return null;
        }

        var tex = ImageTexture.CreateFromImage(image);
        _cache[relativePath] = tex;
        return tex;
    }

    public static int CacheCount => _cache.Count;

    /// <summary>Drops every cached texture. Useful for hot-reload tests.</summary>
    public static void ClearCache() => _cache.Clear();
}