using UnityEditor;
using UnityEngine;
using UnityEngine.Profiling;
using System.Collections.Generic;
using System.Linq;
using UnityEngine.Rendering;

public class GpuTimingWindow : EditorWindow
{
    private const int SampleCount = 1;
    private FrameTiming[] frameTimings = new FrameTiming[SampleCount];
    private double gpuFrameTime;
    private double cpuFrameTime;

    private const int HistorySize = 50;
    private Queue<float> cpuHistory = new Queue<float>(HistorySize);
    private Queue<float> gpuHistory = new Queue<float>(HistorySize);

    private Shader shaderToProfile;
    private CustomSampler shaderSampler;

    [MenuItem("Window/Analysis/GPU Timing Viewer")]
    public static void ShowWindow()
    {
        var window = GetWindow<GpuTimingWindow>("GPU Timing");
        window.Show();
    }

    private void OnEnable()
    {
        EditorApplication.update += UpdateTimings;
    }

    private void OnDisable()
    {
        EditorApplication.update -= UpdateTimings;
    }

    private void UpdateTimings()
    {
        // Capture frame timings from the last frame
        FrameTimingManager.CaptureFrameTimings();
        uint count = FrameTimingManager.GetLatestTimings((uint)frameTimings.Length, frameTimings);

        if (count > 0)
        {
            var timing = frameTimings[0];
            gpuFrameTime = timing.gpuFrameTime;
            cpuFrameTime = timing.cpuFrameTime;

            AddToHistory(cpuHistory, (float)cpuFrameTime);
            AddToHistory(gpuHistory, (float)gpuFrameTime);

            Repaint();
        }
    }

    private void AddToHistory(Queue<float> queue, float value)
    {
        if (queue.Count >= HistorySize)
            queue.Dequeue();
        queue.Enqueue(value);
    }

    private float GetAverage(Queue<float> queue)
    {
        if (queue.Count == 0) return 0f;
        return queue.Average();
    }

    private void OnGUI()
    {
        GUILayout.Label("GPU & CPU Frame Timing", EditorStyles.boldLabel);

        EditorGUILayout.LabelField("CPU Frame Time (ms):", cpuFrameTime.ToString("F2"));
        EditorGUILayout.LabelField("GPU Frame Time (ms):", gpuFrameTime.ToString("F2"));

        float avgCpu = GetAverage(cpuHistory);
        float avgGpu = GetAverage(gpuHistory);

        EditorGUILayout.Space();
        EditorGUILayout.LabelField("CPU Avg (200 frames, ms):", avgCpu.ToString("F2"));
        EditorGUILayout.LabelField("GPU Avg (200 frames, ms):", avgGpu.ToString("F2"));

        float targetFrameRate = 1000f / Mathf.Max(0.0001f, avgGpu);
        EditorGUILayout.LabelField("Approx. Avg GPU FPS:", targetFrameRate.ToString("F1"));

        GUILayout.Space(10);
        Rect rect = GUILayoutUtility.GetRect(100, 30);
        DrawTimingBar(rect, (float)cpuFrameTime, (float)gpuFrameTime);

        GUILayout.Space(20);
        GUILayout.Label("Frame Timing History (last 200 frames)", EditorStyles.boldLabel);
        Rect graphRect = GUILayoutUtility.GetRect(position.width - 20, 100);
        DrawGraph(graphRect, cpuHistory, gpuHistory);
    }

    private void DrawTimingBar(Rect rect, float cpuMs, float gpuMs)
    {
        float maxMs = Mathf.Max(cpuMs, gpuMs, 16.67f); // baseline at ~60 FPS
        float cpuWidth = Mathf.Clamp01(cpuMs / maxMs) * rect.width;
        float gpuWidth = Mathf.Clamp01(gpuMs / maxMs) * rect.width;

        EditorGUI.DrawRect(new Rect(rect.x, rect.y, cpuWidth, rect.height / 2), new Color(0.3f, 0.6f, 1f));
        EditorGUI.DrawRect(new Rect(rect.x, rect.y + rect.height / 2, gpuWidth, rect.height / 2), new Color(1f, 0.4f, 0.4f));

        EditorGUI.DropShadowLabel(rect, $"CPU {cpuMs:F2} ms | GPU {gpuMs:F2} ms");
    }

    private void DrawGraph(Rect rect, Queue<float> cpuData, Queue<float> gpuData)
    {
        Handles.BeginGUI();
        GUI.Box(rect, GUIContent.none);

        if (cpuData.Count > 1 && gpuData.Count > 1)
        {
            float[] cpuArray = cpuData.ToArray();
            float[] gpuArray = gpuData.ToArray();
            int count = Mathf.Min(cpuArray.Length, gpuArray.Length);

            float maxVal = 0f;
            for (int i = 0; i < count; i++)
                maxVal = Mathf.Max(maxVal, Mathf.Max(cpuArray[i], gpuArray[i]));

            if (maxVal < 16.67f)
                maxVal = 16.67f; // ensure ~60 fps baseline is visible

            Vector3 prevCpu = Vector3.zero;
            Vector3 prevGpu = Vector3.zero;
            for (int i = 0; i < count; i++)
            {
                float x = Mathf.Lerp(rect.x, rect.xMax, i / (float)(count - 1));
                float cpuY = Mathf.Lerp(rect.yMax, rect.y, cpuArray[i] / maxVal);
                float gpuY = Mathf.Lerp(rect.yMax, rect.y, gpuArray[i] / maxVal);

                Vector3 cpuPoint = new Vector3(x, cpuY, 0);
                Vector3 gpuPoint = new Vector3(x, gpuY, 0);

                if (i > 0)
                {
                    Handles.color = new Color(0.3f, 0.6f, 1f);
                    Handles.DrawLine(prevCpu, cpuPoint);

                    Handles.color = new Color(1f, 0.4f, 0.4f);
                    Handles.DrawLine(prevGpu, gpuPoint);
                }

                prevCpu = cpuPoint;
                prevGpu = gpuPoint;
            }
        }

        Handles.EndGUI();
    }
}