using AcDream.App.Rendering.Wb;
using AcDream.App.UI;
using AcDream.Core.Lighting;
using AcDream.Core.World;

namespace AcDream.App.Rendering;

/// <summary>
/// CC6b-MOUNT: narrow seam mirroring <c>IPaperdollDollRenderer</c> so
/// <see cref="ChargenPreviewController"/>'s rebuild/render logic can be
/// exercised with a fake in tests without a live GPU device.
/// </summary>
internal interface IChargenPreviewRenderer
{
    void SetPreview(WorldEntity? entity);

    /// <summary>
    /// Sets or clears the environment backdrop entity drawn BEHIND the
    /// preview (Campaign CC gate round 1 Batch D, GF-7/GF-14) — retail's
    /// <c>gmCG3DView::m_pbgObject</c>. See
    /// <see cref="ChargenPreviewEntityBuilder.TryBuildBackdrop"/> for the
    /// decomp-cited placement.
    /// </summary>
    void SetBackdrop(WorldEntity? entity);

    uint Render(int width, int height);
}

/// <summary>
/// Chargen-specific facade over the shared private creature viewport
/// (<see cref="PrivateEntityViewportRenderer"/>) — CC6a's foundation half of
/// the campaign plan's "chargen preview renderer" deliverable. Mirrors
/// <see cref="PaperdollViewportRenderer"/>'s shape exactly, with a
/// heading-capable <see cref="ChargenPreviewViewportCamera"/> in place of the
/// paperdoll's fixed one.
///
/// <para>
/// <b>NOT wired here (CC6b page-mount half, after CC4 merges per the
/// campaign's parallelism contract):</b> mounting into the authored
/// Appearance/Summary viewport ids (<c>0x100003bb</c> / <c>0x10000406</c>)
/// and binding the spin/color-wheel/rotate/zoom widgets to
/// <see cref="ChargenPreviewAnimator"/>/<see cref="ChargenPreviewRotationController"/>/
/// <see cref="ChargenPreviewZoomController"/>. This class is a standalone,
/// composition-root-agnostic renderer — nothing in
/// <c>AcDream.App/UI/Layout/</c> or <c>RetailUiRuntime.cs</c> references it
/// yet.
/// </para>
///
/// <para>
/// <b>CC6b (pre-mount half):</b> the preview now HAS a real live idle loop
/// (<see cref="ChargenPreviewAnimator"/>, retail's <c>m_didAnimation</c> DID
/// at 30fps via <c>set_sequence_animation</c>) instead of the CC6a-only held
/// rest pose — TS-83 is retired. <see cref="SetPreview"/> still accepts a
/// static <c>WorldEntity</c> for callers that only want
/// <c>ChargenPreviewEntityBuilder.TryBuild</c>'s unchanged rest-pose
/// snapshot; a caller that wants the animated preview constructs a
/// <see cref="ChargenPreviewAnimator"/> from
/// <c>ChargenPreviewEntityBuilder.TryBuildAnimated</c> and passes its
/// <c>Entity</c> here once — the animator mutates that SAME entity's
/// <c>MeshRefs</c> in place every <c>Tick</c>, and <c>Render</c> reads it
/// fresh (no re-<c>SetPreview</c> needed per frame; see
/// <c>WorldEntity.MeshRefs</c>'s own "mutable so the animation tick can
/// replace it each frame" doc comment).
/// </para>
/// </summary>
internal sealed class ChargenPreviewRenderer :
    IUiViewportRenderer,
    IChargenPreviewRenderer,
    IDisposable
{
    private readonly PrivateEntityViewportRenderer _renderer;
    private readonly ChargenPreviewViewportCamera _camera;

    internal ChargenPreviewRenderer(
        IWorldPassScope scope,
        AcDream.App.Rendering.Gpu.IGpuDevice device,
        ICurrentGpuFrameSource frames,
        WbDrawDispatcher dispatcher,
        SceneLightingUboBinding lightUbo,
        IEntityTextureLifetime textureLifetime,
        IWbMeshAdapter meshAdapter,
        uint heritageId = 0u,
        ChargenPreviewCamera? camera = null,
        // F16 (Campaign CC gate round 1 closeout): the Appearance and
        // Summary pages each construct their OWN ChargenPreviewRenderer but
        // share ONE process-wide TextureCache — see
        // ChargenPreviewEntityBuilder.SummaryPreviewRenderId's own doc for
        // the full collision trace. Defaulting to the Appearance page's
        // pair keeps every pre-existing call site byte-identical; the
        // composition root passes the Summary pair explicitly for its own
        // instance.
        uint renderId = ChargenPreviewEntityBuilder.PreviewRenderId,
        uint backdropRenderId = ChargenPreviewEntityBuilder.PreviewBackdropRenderId)
    {
        // CC6b-MOUNT: when a caller supplies its own camera instance (the
        // page-mount composition, which needs a SETTABLE camera for
        // ChargenPreviewZoomController to tween — see
        // ChargenPreviewController's own doc comment), wrap that exact
        // instance instead of building a private, unreachable one.
        _camera = camera is not null
            ? new ChargenPreviewViewportCamera(camera)
            : new ChargenPreviewViewportCamera(heritageId);
        _renderer = new PrivateEntityViewportRenderer(
            scope,
            device,
            frames,
            dispatcher,
            lightUbo,
            textureLifetime,
            meshAdapter,
            renderId,
            _camera,
            "chargen preview",
            // Batch D (GF-7/GF-14): reserves the second draw-entity slot for
            // the heritage's environment Setup — see PrivateEntityViewportRenderer's
            // own doc comment on backdropRenderId.
            backdropRenderId);
    }

    public bool TextureIsBottomUp => _renderer.TextureIsBottomUp;

    /// <summary>
    /// Re-derives the fixed per-heritage camera eye
    /// (<see cref="ChargenPreviewCamera.ResolveDefaultEye"/>) — call whenever
    /// the selected heritage changes, BEFORE the next <see cref="Render"/>.
    /// </summary>
    public void SetHeritage(uint heritageId) => _camera.SetHeritage(heritageId);

    public void SetPreview(WorldEntity? entity) => _renderer.SetEntity(entity);

    public void SetBackdrop(WorldEntity? entity) => _renderer.SetBackdrop(entity);

    public uint Render(int width, int height) => _renderer.Render(width, height);

    public void Dispose() => _renderer.Dispose();
}