using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using JetBrains.Annotations;
using Unity.Collections;
using Unity.Simulation;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Profiling;
using UnityEngine.UI;

#if HDRP_PRESENT
using UnityEngine.Rendering.HighDefinition;
#endif

namespace UnityEngine.Perception.GroundTruth
{
    /// <summary>
    /// Labeler which generates a semantic segmentation image each frame. Each object is rendered to the semantic segmentation
    /// image using the color associated with it based on the given <see cref="SemanticSegmentationLabelConfig"/>.
    /// Semantic segmentation images are saved to the dataset in PNG format.
    ///
    /// Only one SemanticSegmentationLabeler can render at once across all cameras.
    /// </summary>
    [Serializable]
    public sealed class SemanticSegmentationLabeler : CameraLabeler
    {
        const string k_SemanticSegmentationDirectory = "SemanticSegmentation";
        const string k_SegmentationFilePrefix = "segmentation_";

        /// <summary>
        /// The id to associate with semantic segmentation annotations in the dataset.
        /// </summary>
        [Tooltip("The id to associate with semantic segmentation annotations in the dataset.")]
        public string annotationId = "12f94d8d-5425-4deb-9b21-5e53ad957d66";
        /// <summary>
        /// The SemanticSegmentationLabelConfig which maps labels to pixel values.
        /// </summary>
        public SemanticSegmentationLabelConfig labelConfig;

        /// <summary>
        /// Event information for <see cref="SemanticSegmentationLabeler.imageReadback"/>
        /// </summary>
        public struct ImageReadbackEventArgs
        {
            /// <summary>
            /// The <see cref="Time.frameCount"/> on which the image was rendered. This may be multiple frames in the past.
            /// </summary>
            public int frameCount;
            /// <summary>
            /// Color pixel data.
            /// </summary>
            public NativeArray<Color32> data;
            /// <summary>
            /// The source image texture.
            /// </summary>
            public RenderTexture sourceTexture;
        }

        /// <summary>
        /// Event which is called each frame a semantic segmentation image is read back from the GPU.
        /// </summary>
        public event Action<ImageReadbackEventArgs> imageReadback;

        /// <summary>
        /// The RenderTexture on which semantic segmentation images are drawn. Will be resized on startup to match
        /// the camera resolution.
        /// </summary>
        public RenderTexture targetTexture => m_TargetTextureOverride;

        [Tooltip("(Optional) The RenderTexture on which semantic segmentation images will be drawn. Will be reformatted on startup.")]
        [SerializeField]
        RenderTexture m_TargetTextureOverride;

        AnnotationDefinition m_SemanticSegmentationAnnotationDefinition;
        RenderTextureReader<Color32> m_SemanticSegmentationTextureReader;

#if HDRP_PRESENT
        SemanticSegmentationPass m_SemanticSegmentationPass;
#endif

        Dictionary<int, AsyncAnnotation> m_AsyncAnnotations;

        private float segmentTransparency = 0.8f;
        private float backgroundTransparency = 0.0f;

        /// <summary>
        /// Creates a new SemanticSegmentationLabeler. Be sure to assign <see cref="labelConfig"/> before adding to a <see cref="PerceptionCamera"/>.
        /// </summary>
        public SemanticSegmentationLabeler() { }

        /// <summary>
        /// Creates a new SemanticSegmentationLabeler with the given <see cref="SemanticSegmentationLabelConfig"/>.
        /// </summary>
        /// <param name="labelConfig">The label config associating labels with colors.</param>
        /// <param name="targetTextureOverride">Override the target texture of the labeler. Will be reformatted on startup.</param>
        public SemanticSegmentationLabeler(SemanticSegmentationLabelConfig labelConfig, RenderTexture targetTextureOverride = null)
        {
            this.labelConfig = labelConfig;
            this.m_TargetTextureOverride = targetTextureOverride;
        }

        [SuppressMessage("ReSharper", "InconsistentNaming")]
        struct SemanticSegmentationSpec
        {
            [UsedImplicitly]
            public string label_name;
            [UsedImplicitly]
            public Color pixel_value;
        }

        struct AsyncSemanticSegmentationWrite
        {
            public NativeArray<Color32> data;
            public int width;
            public int height;
            public string path;
        }

        int camWidth = 0;
        int camHeight = 0;

        private GameObject segCanvas;
        private GameObject segVisual = null;
        private RawImage segImage = null;

        GUIStyle labelStyle = null;
        GUIStyle sliderStyle = null;

        /// <inheritdoc/>
        protected override bool supportsVisualization => true;

        /// <inheritdoc/>
        protected override void Setup()
        {
            var myCamera = perceptionCamera.GetComponent<Camera>();
            camWidth = myCamera.pixelWidth;
            camHeight = myCamera.pixelHeight;

            if (labelConfig == null)
            {
                throw new InvalidOperationException(
                    "SemanticSegmentationLabeler's LabelConfig must be assigned");
            }

            m_AsyncAnnotations = new Dictionary<int, AsyncAnnotation>();

            if (targetTexture != null)
            {
                if (targetTexture.sRGB)
                {
                    Debug.LogError("targetTexture supplied to SemanticSegmentationLabeler must be in Linear mode. Disabling labeler.");
                    this.enabled = false;
                }
                var renderTextureDescriptor = new RenderTextureDescriptor(camWidth, camHeight, GraphicsFormat.R8G8B8A8_UNorm, 8);
                targetTexture.descriptor = renderTextureDescriptor;
            }
            else
                m_TargetTextureOverride = new RenderTexture(camWidth, camHeight, 8, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);

            targetTexture.Create();
            targetTexture.name = "Labeling";

#if HDRP_PRESENT
            var gameObject = perceptionCamera.gameObject;
            var customPassVolume = gameObject.GetComponent<CustomPassVolume>() ?? gameObject.AddComponent<CustomPassVolume>();
            customPassVolume.injectionPoint = CustomPassInjectionPoint.BeforeRendering;
            customPassVolume.isGlobal = true;
            m_SemanticSegmentationPass = new SemanticSegmentationPass(myCamera, targetTexture, labelConfig)
            {
                name = "Labeling Pass"
            };
            customPassVolume.customPasses.Add(m_SemanticSegmentationPass);
#endif
#if URP_PRESENT
            perceptionCamera.AddScriptableRenderPass(new SemanticSegmentationUrpPass(myCamera, targetTexture, labelConfig));
#endif

            var specs = labelConfig.labelEntries.Select((l) => new SemanticSegmentationSpec()
            {
                label_name = l.label,
                pixel_value = l.color
            }).ToArray();

            m_SemanticSegmentationAnnotationDefinition = DatasetCapture.RegisterAnnotationDefinition(
                "semantic segmentation",
                specs,
                "pixel-wise semantic segmentation label",
                "PNG",
                id: Guid.Parse(annotationId));

            m_SemanticSegmentationTextureReader = new RenderTextureReader<Color32>(targetTexture, myCamera,
                (frameCount, data, tex) => OnSemanticSegmentationImageRead(frameCount, data));

            visualizationEnabled = supportsVisualization;
        }

        private void SetupVisualizationElements()
        {
            segmentTransparency = 0.8f;
            backgroundTransparency = 0.0f;

            segVisual = GameObject.Instantiate(Resources.Load<GameObject>("SegmentTexture"));

            segImage = segVisual.GetComponent<RawImage>();
            segImage.material.SetFloat("_SegmentTransparency", segmentTransparency);
            segImage.material.SetFloat("_BackTransparency", backgroundTransparency);
            segImage.texture = targetTexture;

            var rt = segVisual.transform as RectTransform;
            rt.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, camWidth);
            rt.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, camHeight);

            if (segCanvas == null)
            {
                segCanvas = new GameObject(perceptionCamera.gameObject.name + "_segmentation_canvas");
                segCanvas.AddComponent<RectTransform>();
                var canvas = segCanvas.AddComponent<Canvas>();
                canvas.renderMode = RenderMode.ScreenSpaceOverlay;
                segCanvas.AddComponent<CanvasScaler>();

                segVisual.transform.SetParent(segCanvas.transform, false);
            }

            labelStyle = new GUIStyle(GUI.skin.label) {padding = {left = 10}};
            sliderStyle = new GUIStyle(GUI.skin.horizontalSlider) {margin = {left = 12}};
        }

        void OnSemanticSegmentationImageRead(int frameCount, NativeArray<Color32> data)
        {
            if (!m_AsyncAnnotations.TryGetValue(frameCount, out var annotation))
                return;

            var datasetRelativePath = $"{k_SemanticSegmentationDirectory}/{k_SegmentationFilePrefix}{frameCount}.png";
            var localPath = $"{Manager.Instance.GetDirectoryFor(k_SemanticSegmentationDirectory)}/{k_SegmentationFilePrefix}{frameCount}.png";

            annotation.ReportFile(datasetRelativePath);

            var asyncRequest = Manager.Instance.CreateRequest<AsyncRequest<AsyncSemanticSegmentationWrite>>();

            imageReadback?.Invoke(new ImageReadbackEventArgs
            {
                data = data,
                frameCount = frameCount,
                sourceTexture = targetTexture
            });
            asyncRequest.data = new AsyncSemanticSegmentationWrite
            {
                data = new NativeArray<Color32>(data, Allocator.TempJob),
                width = targetTexture.width,
                height = targetTexture.height,
                path = localPath
            };
            asyncRequest.Enqueue((r) =>
            {
                Profiler.BeginSample("Encode");
                var pngBytes = ImageConversion.EncodeArrayToPNG(r.data.data.ToArray(), GraphicsFormat.R8G8B8A8_UNorm, (uint)r.data.width, (uint)r.data.height);
                Profiler.EndSample();
                Profiler.BeginSample("WritePng");
                File.WriteAllBytes(r.data.path, pngBytes);
                Manager.Instance.ConsumerFileProduced(r.data.path);
                Profiler.EndSample();
                r.data.data.Dispose();
                return AsyncRequest.Result.Completed;
            });
            asyncRequest.Execute();
        }

        /// <inheritdoc/>
        protected override void OnBeginRendering()
        {
            m_AsyncAnnotations[Time.frameCount] = perceptionCamera.SensorHandle.ReportAnnotationAsync(m_SemanticSegmentationAnnotationDefinition);
        }

        /// <inheritdoc/>
        protected override void Cleanup()
        {
            m_SemanticSegmentationTextureReader?.WaitForAllImages();
            m_SemanticSegmentationTextureReader?.Dispose();
            m_SemanticSegmentationTextureReader = null;

            Object.Destroy(segCanvas);
            segCanvas = null;

            if (m_TargetTextureOverride != null)
                m_TargetTextureOverride.Release();

            m_TargetTextureOverride = null;
        }

        /// <inheritdoc/>
        override protected void OnVisualizerEnabledChanged(bool enabled)
        {
            if (segVisual != null)
                segVisual.SetActive(enabled);
        }



        /// <inheritdoc/>
        protected override void OnVisualizeAdditionalUI()
        {
            if (segImage == null)
            {
                SetupVisualizationElements();
            }

            var rt = segVisual.transform as RectTransform;
            if (rt != null && camHeight != Screen.height)
            {
                camHeight = Screen.height;
                rt.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, camHeight);
            }

            if (rt != null && camWidth != Screen.width)
            {
                camWidth = Screen.width;
                rt.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, Screen.width);
            }

            GUILayout.Space(4);
            GUILayout.Label("Object Alpha:", labelStyle);
            segmentTransparency = GUILayout.HorizontalSlider(segmentTransparency, 0.0f, 1.0f, sliderStyle, GUI.skin.horizontalSliderThumb);
            GUILayout.Space(4);
            GUILayout.Label("Background Alpha:", labelStyle);
            backgroundTransparency = GUILayout.HorizontalSlider(backgroundTransparency, 0.0f, 1.0f, sliderStyle, GUI.skin.horizontalSliderThumb);
            GUI.skin.label.padding.left = 0;

            if (!GUI.changed) return;
            segImage.material.SetFloat("_SegmentTransparency", segmentTransparency);
            segImage.material.SetFloat("_BackTransparency", backgroundTransparency);

        }
    }
}