using System;
using System.Diagnostics.CodeAnalysis;
using ADOFAIRenderer.Core;
using HarmonyLib;
using UnityEngine;

namespace ADOFAIRenderer.Patch.Game;

// === [MARKER: FIX_SET_FRAMERATE_BUG START] ===
/// <summary>
/// Fixes the in-game and render bug where objects (floors, decorations, planets) disappear on the first frame of
/// a SetFramerate event (due to camera Z=0 near clip culling) and where parallax/tiles lag behind on subsequent frames.
/// <para>
/// Defers the manual camera rendering (<c>scrCamera.UpdateCustomFrameRateScreen</c>) to the very end of the frame
/// (execution order <c>int.MaxValue - 1</c>), after all components (<c>scrCamera</c>, <c>scrFloor</c>,
/// <c>scrDecorationManager</c>, <c>scrPlanet</c>, <c>scrParallax</c>, and <c>scrController</c>) have finished their
/// <c>LateUpdate</c>.
/// </para>
/// </summary>
[HarmonyPatch]
[SuppressMessage("ReSharper", "InconsistentNaming")]
public static class CustomFrameRateDeferPatch
{
    private static bool _isExecutingDeferred;
    private static scrCamera? _pendingCamera;

    private static readonly Action<scrCamera>? UpdateCustomFrameRateScreenInvoker =
        AccessTools.MethodDelegate<Action<scrCamera>>(AccessTools.Method(typeof(scrCamera), "UpdateCustomFrameRateScreen"));

    /// <summary>
    /// Checks whether the SetFramerate render timing fix is enabled.
    /// Active if rendering session has the option enabled, or enabled by default during normal in-game play.
    /// </summary>
    public static bool IsEnabled
    {
        get
        {
            if (RenderManager.IsActive && RenderManager.Instance?.Configuration?.AdvancedConfig != null)
            {
                return RenderManager.Instance.Configuration.AdvancedConfig.FixCustomFrameRate;
            }

            return true;
        }
    }

    /// <summary>
    /// Intercepts manual camera render calls from SetCustomFrameRate (Update phase) or CheckUpdateFrameRateScreen
    /// (LateUpdate phase). If not currently executing the deferred render pass, records the camera instance and
    /// suppresses the premature render.
    /// </summary>
    [HarmonyPrefix]
    [HarmonyPatch(typeof(scrCamera), "UpdateCustomFrameRateScreen")]
    private static bool DeferManualRender(scrCamera __instance)
    {
        if (!IsEnabled) return true;
        if (_isExecutingDeferred) return true;

        _pendingCamera = __instance;
        return false;
    }

    /// <summary>
    /// Ensures that the runner component is attached to the camera when it starts.
    /// </summary>
    [HarmonyPostfix]
    [HarmonyPatch(typeof(scrCamera), "Start")]
    private static void AttachRunner(scrCamera __instance)
    {
        if (!__instance) return;
        if (!__instance.gameObject.GetComponent<CustomFrameRateDeferredRunner>())
        {
            __instance.gameObject.AddComponent<CustomFrameRateDeferredRunner>();
        }
    }

    /// <summary>
    /// Invoked at the very end of LateUpdate (Order int.MaxValue - 1). If a manual render was requested during the frame,
    /// executes the camera's original UpdateCustomFrameRateScreen once with all objects fully prepared.
    /// </summary>
    internal static void ExecuteDeferredRender()
    {
        if (_pendingCamera == null) return;

        var cam = _pendingCamera;
        _pendingCamera = null;

        if (!cam) return;

        _isExecutingDeferred = true;
        try
        {
            UpdateCustomFrameRateScreenInvoker?.Invoke(cam);
        }
        finally
        {
            _isExecutingDeferred = false;
        }
    }
}

/// <summary>
/// Runner component attached to scrCamera that executes deferred custom frame rate renders at the end of LateUpdate.
/// Execution order <c>int.MaxValue - 1</c> guarantees it runs after all normal game components (including
/// scrController at 400), but right before PostRenderHook at <c>int.MaxValue</c>.
/// </summary>
[DefaultExecutionOrder(int.MaxValue - 1)]
internal class CustomFrameRateDeferredRunner : MonoBehaviour
{
    private void LateUpdate()
    {
        CustomFrameRateDeferPatch.ExecuteDeferredRender();
    }
}
// === [MARKER: FIX_SET_FRAMERATE_BUG END] ===