using System.Collections.Concurrent;
using DatReaderWriter;
using Microsoft.Extensions.Logging.Abstractions;
using Silk.NET.OpenGL;

namespace AcDream.App.Rendering;

/// <summary>
/// The subset of the production render stack that the UI Studio needs:
/// GL + dats + UiHost + the WB mesh pipeline. Constructed from the same
/// classes and the same order as <see cref="GameWindow.OnLoad"/>, minus
/// terrain / sky / physics / streaming.
/// </summary>
public sealed record RenderStack(
    GL Gl,
    DatReaderWriter.DatCollection Dats,
    string ShaderDir,
    Wb.BindlessSupport Bindless,
    TextureCache TextureCache,
    Shader MeshShader,
    Wb.WbMeshAdapter MeshAdapter,
    Wb.EntitySpawnAdapter EntitySpawnAdapter,
    Wb.WbDrawDispatcher DrawDispatcher,
    SceneLightingUboBinding LightingUbo,
    AcDream.App.UI.UiHost UiHost,
    AcDream.App.UI.UiDatFont? VitalsDatFont,
    AcDream.App.UI.UiDatFont? LargeDatFont) : System.IDisposable
{
    /// <summary>Dispose the GL pieces this stack OWNS (everything created in
    /// <see cref="RenderBootstrap.Create"/>). <see cref="Dats"/> + <see cref="Gl"/> are caller-owned
    /// and NOT disposed here. Called once at studio teardown.</summary>
    public void Dispose()
    {
        DrawDispatcher.Dispose();
        MeshAdapter.Dispose();
        TextureCache.Dispose();
        MeshShader.Dispose();
        LightingUbo.Dispose();
        UiHost.Dispose();
    }

    /// <summary>
    /// Resolves a sprite id (0x06xxxxxx) to a (GL handle, width, height) triple.
    /// Copied verbatim from GameWindow's ResolveChrome closure — it calls
    /// TextureCache.GetOrUploadRenderSurface(id, out w, out h).
    /// </summary>
    public (uint handle, int width, int height) ResolveChrome(uint spriteId)
    {
        uint t = TextureCache.GetOrUploadRenderSurface(spriteId, out int w, out int h);
        return (t, w, h);
    }

    // ── Font cache (per-stack, keyed by FontDid) ─────────────────────────────

    /// <summary>
    /// Cache of loaded dat fonts keyed by FontDid (0x40000000-range).
    /// Populated lazily by <see cref="ResolveDatFont"/>. Thread-safe for
    /// concurrent reads from the studio render loop; writes happen only
    /// during the first load of each distinct FontDid.
    /// </summary>
    private readonly ConcurrentDictionary<uint, AcDream.App.UI.UiDatFont?> _fontCache = new();

    /// <summary>
    /// Lazily load and cache a dat font by its FontDid. Returns null (and
    /// caches null) when the Font DBObj is absent or has no foreground surface —
    /// callers fall back to the global font in that case.
    ///
    /// <para>Pre-seeds <see cref="VitalsDatFont"/> (0x40000000) and
    /// <see cref="LargeDatFont"/> (0x40000001) from the already-loaded instances
    /// to avoid a redundant upload on those two ids.</para>
    /// </summary>
    public AcDream.App.UI.UiDatFont? ResolveDatFont(uint fontDid)
    {
        return _fontCache.GetOrAdd(fontDid, id =>
            AcDream.App.UI.UiDatFont.Load(Dats, TextureCache, id));
    }

    /// <summary>
    /// Pre-seeds the font cache from the two already-loaded font instances
    /// (VitalsDatFont = 0x40000000, LargeDatFont = 0x40000001) so that
    /// <see cref="ResolveDatFont"/> returns them without a redundant GL upload.
    /// Called once by <see cref="RenderBootstrap.Create"/> after the stack is
    /// fully constructed.
    /// </summary>
    internal void SeedFontCache()
    {
        if (VitalsDatFont is not null)
            _fontCache.TryAdd(AcDream.App.UI.UiDatFont.DefaultFontId, VitalsDatFont);
        if (LargeDatFont is not null)
            _fontCache.TryAdd(0x40000001u, LargeDatFont);
    }
}

/// <summary>Options for <see cref="RenderBootstrap.Create"/>.</summary>
public sealed record RenderBootstrapOptions(
    AcDream.UI.Abstractions.Settings.QualitySettings Quality);

/// <summary>
/// Constructs the UI Studio's render stack from the production classes,
/// in the same order as <see cref="GameWindow.OnLoad"/>.
/// </summary>
public static class RenderBootstrap
{
    /// <summary>
    /// Build the studio's render stack. Throws <see cref="NotSupportedException"/>
    /// (same message as GameWindow) if GL_ARB_bindless_texture or
    /// GL_ARB_shader_draw_parameters are absent — the modern path is mandatory.
    /// </summary>
    public static RenderStack Create(
        GL gl,
        DatReaderWriter.DatCollection dats,
        RenderBootstrapOptions opts)
    {
        // --- Bindless detection (GameWindow ~1701-1723) ---
        if (!Wb.BindlessSupport.TryCreate(gl, out var bindless)
            || bindless is null
            || !bindless.HasShaderDrawParameters(gl))
        {
            throw new NotSupportedException(
                "acdream requires GL_ARB_bindless_texture + GL_ARB_shader_draw_parameters " +
                "(GL 4.3+ with bindless support). Your GPU/driver does not expose these extensions. " +
                "If this is unexpected, please file a bug report with your GPU vendor + driver version.");
        }

        // --- Shared infra (GameWindow ~1198, ~1211) ---
        string shaderDir = Path.Combine(AppContext.BaseDirectory, "Rendering", "Shaders");
        var lightingUbo  = new SceneLightingUboBinding(gl);

        // --- Mesh shader (GameWindow ~1769-1771) ---
        var meshShader = new Shader(gl,
            Path.Combine(shaderDir, "mesh_modern.vert"),
            Path.Combine(shaderDir, "mesh_modern.frag"));

        // --- TextureCache (GameWindow ~1774) ---
        var textureCache = new TextureCache(gl, dats, bindless);

        // --- AnimLoader (GameWindow ~1240) ---
        var animLoader = new AcDream.Core.Physics.DatCollectionLoader(dats);

        // --- WbMeshAdapter (GameWindow ~2286-2287) ---
        var wbLogger     = NullLogger<Wb.WbMeshAdapter>.Instance;
        var meshAdapter  = new Wb.WbMeshAdapter(gl, dats, wbLogger);

        // --- SequencerFactory (GameWindow ~2306-2334) ---
        var capturedDats      = dats;
        var capturedAnimLoader = animLoader;
        AcDream.Core.Physics.AnimationSequencer SequencerFactory(AcDream.Core.World.WorldEntity e)
        {
            if (capturedDats is not null && capturedAnimLoader is not null)
            {
                var setup = capturedDats.Get<DatReaderWriter.DBObjs.Setup>(e.SourceGfxObjOrSetupId);
                if (setup is not null)
                {
                    uint mtableId = (uint)setup.DefaultMotionTable;
                    if (mtableId != 0)
                    {
                        var mtable = capturedDats.Get<DatReaderWriter.DBObjs.MotionTable>(mtableId);
                        if (mtable is not null)
                            return new AcDream.Core.Physics.AnimationSequencer(
                                setup, mtable, capturedAnimLoader);
                    }
                    // Setup exists but no motion table — no-op sequencer.
                    return new AcDream.Core.Physics.AnimationSequencer(
                        setup,
                        new DatReaderWriter.DBObjs.MotionTable(),
                        capturedAnimLoader);
                }
            }
            // Complete fallback: empty setup + empty motion table + null loader.
            return new AcDream.Core.Physics.AnimationSequencer(
                new DatReaderWriter.DBObjs.Setup(),
                new DatReaderWriter.DBObjs.MotionTable(),
                new NullAnimLoader());
        }

        // --- EntitySpawnAdapter (GameWindow ~2335-2336) ---
        var entitySpawnAdapter = new Wb.EntitySpawnAdapter(
            textureCache, SequencerFactory, meshAdapter);

        // --- EntityClassificationCache (GameWindow ~217 — field initializer, new()) ---
        var classificationCache = new Wb.EntityClassificationCache();

        // --- WbDrawDispatcher (GameWindow ~2377-2381) ---
        var drawDispatcher = new Wb.WbDrawDispatcher(
            gl, meshShader, textureCache, meshAdapter, entitySpawnAdapter,
            bindless, classificationCache);
        drawDispatcher.AlphaToCoverage = opts.Quality.AlphaToCoverage;

        // --- Vitals dat font (GameWindow ~1820-1822) ---
        var vitalsDatFont = AcDream.App.UI.UiDatFont.Load(dats, textureCache);

        // --- Larger retail font (0x40000001, MaxCharHeight=18) for attribute row text.
        // The default font (0x40000000, 16px) renders the row names too small; the 18px
        // variant (confirmed in client_portal.dat 2026-06-26) matches the retail character
        // window list more closely (≈ icon height ≈ 24px target, 18px is best available).
        var largeDatFont = AcDream.App.UI.UiDatFont.Load(dats, textureCache, 0x40000001u);

        // --- UiHost (GameWindow ~1790); pass null for debugFont (only used as
        //     a fallback BitmapFont for the world-space HUD — not needed for the
        //     UI Studio, and BitmapFont requires a system font byte array) ---
        var uiHost = new AcDream.App.UI.UiHost(gl, shaderDir, defaultFont: null);

        var stack = new RenderStack(
            Gl:                  gl,
            Dats:                dats,
            ShaderDir:           shaderDir,
            Bindless:            bindless,
            TextureCache:        textureCache,
            MeshShader:          meshShader,
            MeshAdapter:         meshAdapter,
            EntitySpawnAdapter:  entitySpawnAdapter,
            DrawDispatcher:      drawDispatcher,
            LightingUbo:         lightingUbo,
            UiHost:              uiHost,
            VitalsDatFont:       vitalsDatFont,
            LargeDatFont:        largeDatFont);

        // Pre-seed the font cache with the two already-uploaded atlas instances
        // so ResolveDatFont(0x40000000) and ResolveDatFont(0x40000001) hit the cache
        // rather than re-uploading the same GL texture a second time.
        stack.SeedFontCache();

        return stack;
    }

    // NullAnimLoader mirrors GameWindow's private NullAnimLoader (GameWindow ~13327-13330).
    private sealed class NullAnimLoader : AcDream.Core.Physics.IAnimationLoader
    {
        public DatReaderWriter.DBObjs.Animation? LoadAnimation(uint id) => null;
    }
}