using System;
using System.Reflection;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using BadDog.Rendering.AreaLight;

namespace BadDog.Rendering.AreaLight.Samples
{
    /// <summary>
    /// AreaLight Test Panel for runtime testing and debugging
    /// </summary>
    public class AreaLightTestPanel : MonoBehaviour
    {
        [Header("UI Settings")]
        [SerializeField] private Rect panelRect = new Rect(10, 10, 800, 500);
        
        [Header("FPS Settings")]
        [SerializeField] private float fpsUpdateInterval = 0.5f;
        
        // FPS tracking
        private float m_LastFpsUpdate;
        private int m_FrameCount;
        private float m_CurrentFps;
        
        // GUI styles
        private GUIStyle m_WindowStyle;
        private GUIStyle m_LabelStyle;
        private GUIStyle m_ToggleStyle;
        private GUIStyle m_ButtonStyle;
        private bool m_StylesInitialized = false;
        
        // Shadow atlas resolution options
        private static readonly int[] k_ShadowAtlasResolutions = { 256, 512, 1024, 2048, 4096, 8192 };
        private static readonly string[] k_ShadowAtlasResolutionLabels = { "256", "512", "1024", "2048", "4096", "8192" };
        private int m_ShadowAtlasResolutionIndex = 2; // Default 1024

        private void Start()
        {
            InitializeFPSTracking();
            SetTargetFrameRate();
            InitializeShadowAtlasResolutionIndex();
        }

        private void Update()
        {
            UpdateFPS();
        }
        
        private void OnGUI()
        {
            InitializeStyles();
            // Fixed window that cannot be dragged
            panelRect = GUILayout.Window(95279529, panelRect, DrawTestPanel, "AreaLight Test Panel", m_WindowStyle, GUILayout.Width(panelRect.width), GUILayout.Height(panelRect.height));
        }
        
        private void InitializeFPSTracking()
        {
            m_LastFpsUpdate = Time.time;
            m_FrameCount = 0;
            m_CurrentFps = 0f;
        }
        
        private void SetTargetFrameRate()
        {
#if UNITY_ANDROID || UNITY_IOS
            // Set target frame rate to 60 for mobile platforms
            Application.targetFrameRate = 60;
#endif
        }
        
        private void UpdateFPS()
        {
            m_FrameCount++;
            float currentTime = Time.time;
            
            if (currentTime - m_LastFpsUpdate >= fpsUpdateInterval)
            {
                m_CurrentFps = m_FrameCount / (currentTime - m_LastFpsUpdate);
                m_FrameCount = 0;
                m_LastFpsUpdate = currentTime;
            }
        }
        
        private void InitializeStyles()
        {
            if (m_StylesInitialized)
            {
                return;
            }

            m_WindowStyle = new GUIStyle(GUI.skin.window) { fontSize = 38 };
            m_LabelStyle = new GUIStyle(GUI.skin.label) { fontSize = 32, wordWrap = true };
            m_ToggleStyle = new GUIStyle(GUI.skin.toggle) { fontSize = 32 };
            m_ButtonStyle = new GUIStyle(GUI.skin.button) { fontSize = 28 };
            
            m_StylesInitialized = true;
        }
        
        private void InitializeShadowAtlasResolutionIndex()
        {
            var areaLightInstance = GetActiveAreaLightInstance();
            if (areaLightInstance != null)
            {
                var shadowSettings = GetShadowSettings(areaLightInstance);
                if (shadowSettings != null)
                {
                    int currentResolution = shadowSettings.shadowAtlasResolution;
                    for (int i = 0; i < k_ShadowAtlasResolutions.Length; i++)
                    {
                        if (k_ShadowAtlasResolutions[i] == currentResolution)
                        {
                            m_ShadowAtlasResolutionIndex = i;
                            break;
                        }
                    }
                }
            }
        }
        
        private void DrawTestPanel(int windowID)
        {
            GUILayout.BeginVertical();
            GUILayout.Space(10);
            
            DrawPerformanceSection();
            DrawControlsSection();
            
            GUILayout.EndVertical();
        }
        
        private void DrawPerformanceSection()
        {
            GUILayout.Label("=== Performance ===", m_LabelStyle);
            
            Color originalColor = GUI.contentColor;
            SetFPSColor();
            GUILayout.Label($"FPS: {m_CurrentFps:F1}", m_LabelStyle);
            GUI.contentColor = originalColor;
            
            GUILayout.Space(10);
        }
        
        private void SetFPSColor()
        {
            if (m_CurrentFps >= 60f)
            {
                GUI.contentColor = Color.green;
            }
            else if (m_CurrentFps >= 30f)
            {
                GUI.contentColor = Color.yellow;
            }
            else
            {
                GUI.contentColor = Color.red;
            }
        }
        
        private void DrawControlsSection()
        {
            GUILayout.Label("=== AreaLight Controls ===", m_LabelStyle);
            
            // Get AreaLight instance from URP asset
            var areaLightInstance = GetActiveAreaLightInstance();
            if (areaLightInstance == null)
            {
                GUILayout.Label("AreaLight Feature not found", m_LabelStyle);
                return;
            }
            
            var lightSettings = GetLightSettings(areaLightInstance);
            var shadowSettings = GetShadowSettings(areaLightInstance);
            
            if (lightSettings == null || shadowSettings == null)
            {
                GUILayout.Label("Failed to access AreaLight settings", m_LabelStyle);
                return;
            }
            
            // Light Settings
            GUILayout.Label("--- Light Settings ---", m_LabelStyle);
            DrawIntSlider("Max Area Lights", ref lightSettings.maxAreaLights, 0, 8);
            
            GUILayout.Space(10);
            
            // Shadow Settings
            GUILayout.Label("--- Shadow Settings ---", m_LabelStyle);
            
            // Shadow Atlas Resolution (sync index first)
            int currentResolution = shadowSettings.shadowAtlasResolution;
            for (int i = 0; i < k_ShadowAtlasResolutions.Length; i++)
            {
                if (k_ShadowAtlasResolutions[i] == currentResolution)
                {
                    m_ShadowAtlasResolutionIndex = i;
                    break;
                }
            }
            
            GUILayout.Label("Shadow Atlas Resolution:", m_LabelStyle);
            int newIndex = GUILayout.SelectionGrid(m_ShadowAtlasResolutionIndex, k_ShadowAtlasResolutionLabels, 6, m_ButtonStyle);
            if (newIndex != m_ShadowAtlasResolutionIndex)
            {
                m_ShadowAtlasResolutionIndex = newIndex;
                shadowSettings.shadowAtlasResolution = k_ShadowAtlasResolutions[m_ShadowAtlasResolutionIndex];
            }
            
            DrawIntSlider("Max Shadow Casting Lights", ref shadowSettings.maxShadowCastingLights, 0, 8);
            
            GUILayout.Space(5);
            
            // Shadow Filter (enum dropdown simulation)
            GUILayout.Label("Shadow Filter:", m_LabelStyle);
            string[] filterOptions = { "Off", "PCF2x2", "Tent5x5", "Tent7x7", "PCSS" };
            int currentFilterIndex = (int)shadowSettings.shadowFilter;
            int newFilterIndex = GUILayout.SelectionGrid(currentFilterIndex, filterOptions, 5, m_ButtonStyle);
            if (newFilterIndex != currentFilterIndex)
            {
                shadowSettings.shadowFilter = (AreaLightShadowSettings.BGAreaLightShadowMode)newFilterIndex;
            }
            
            GUILayout.Space(5);
            
            // PCSS Settings (only show when PCSS is selected)
            if (shadowSettings.shadowFilter == AreaLightShadowSettings.BGAreaLightShadowMode.PCSS)
            {
                GUILayout.Label("--- PCSS Settings ---", m_LabelStyle);
                DrawSlider("PCSS Shadow Softness", ref shadowSettings.pcssShadowSoftness, 0f, 32f);
                DrawIntSlider("PCSS Blocker Sample Count", ref shadowSettings.pcssBlockerSampleCount, 4, 32);
                DrawIntSlider("PCSS Filter Sample Count", ref shadowSettings.pcssFilterSampleCount, 4, 32);
            }
        }
        
        private void DrawSlider(string label, ref float value, float min, float max)
        {
            GUILayout.Label($"{label}: {value:F2}", m_LabelStyle);
            // GUILayout.HorizontalSlider returns the current slider value
            // Ensure slider has enough width to be interactive
            value = GUILayout.HorizontalSlider(value, min, max, GUILayout.ExpandWidth(true), GUILayout.Height(20));
        }
        
        private void DrawIntSlider(string label, ref int value, int min, int max)
        {
            GUILayout.Label($"{label}: {value}", m_LabelStyle);
            // Ensure slider has enough width to be interactive
            float newValue = GUILayout.HorizontalSlider(value, min, max, GUILayout.ExpandWidth(true), GUILayout.Height(20));
            int intValue = Mathf.RoundToInt(newValue);
            // Clamp to ensure value stays within bounds
            value = Mathf.Clamp(intValue, min, max);
        }
        
        private AreaLighting GetActiveAreaLightInstance()
        {
            var urpAsset = GraphicsSettings.currentRenderPipeline as UniversalRenderPipelineAsset;
            if (urpAsset == null)
            {
                return null;
            }

            var scriptableRendererData = GetScriptableRendererData(urpAsset);
            if (scriptableRendererData == null)
            {
                return null;
            }

            if (scriptableRendererData.rendererFeatures != null)
            {
                foreach (var feature in scriptableRendererData.rendererFeatures)
                {
                    if (feature is AreaLighting areaLightFeature && feature.isActive)
                    {
                        return areaLightFeature;
                    }
                }
            }
            
            return null;
        }

        private ScriptableRendererData GetScriptableRendererData(UniversalRenderPipelineAsset urpAsset)
        {
            var property = typeof(UniversalRenderPipelineAsset).GetProperty("scriptableRendererData",
                BindingFlags.NonPublic | BindingFlags.Instance);

            if (property != null)
            {
                return property.GetValue(urpAsset) as ScriptableRendererData;
            }

            return null;
        }
        
        private AreaLightSettings GetLightSettings(AreaLighting areaLighting)
        {
            var field = typeof(AreaLighting).GetField("m_LightSettings",
                BindingFlags.NonPublic | BindingFlags.Instance);
            
            if (field != null)
            {
                return field.GetValue(areaLighting) as AreaLightSettings;
            }
            
            return null;
        }
        
        private AreaLightShadowSettings GetShadowSettings(AreaLighting areaLighting)
        {
            var field = typeof(AreaLighting).GetField("m_ShadowSettings",
                BindingFlags.NonPublic | BindingFlags.Instance);
            
            if (field != null)
            {
                return field.GetValue(areaLighting) as AreaLightShadowSettings;
            }
            
            return null;
        }
    }
}