#if UNITY_EDITOR
using UnityEditor;
#endif
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using UnityEngine.XR;

namespace Golems.RenderFeatures
{
    /// <summary>
    /// A base class for RenderFeatures that take a source and do some operation on it and put
    /// the result into some destination.
    /// This base class provides settings for the source and destination textures via
    /// RenderFeatures.TextureSourceType, allowing the named temporary texture name to be given
    /// if need (named textures are provided by TemporaryCameraCopyTextureRenderFeature).
    /// Can also set a named textures as a temporary copy texture if the source and destination
    /// are the same.
    /// </summary>
    public abstract class SourceToDestinationBlitRenderFeature : ScriptableRendererFeature
    {
        /// <summary>
        /// The texture source type of the source of the pass.
        /// Camera colour or named temporary texture.
        /// </summary>
        [Header("Source and Destination")]
        [SerializeField]
        protected RenderFeatures.TextureSourceType m_SourceTextureSourceType = RenderFeatures.TextureSourceType.CameraColour;

        /// <summary>
        /// If the source is a named texture then this is its name.
        /// </summary>
        [SerializeField]
        private string m_SourceNamedTemporaryName;

        protected int m_SourceNamedTemporaryNameHash;

        /// <summary>
        /// The texture source type of the destination of the pass.
        /// Camera colour or named temporary texture.
        /// </summary>
        [SerializeField]
        protected RenderFeatures.TextureSourceType m_DestinationTextureSourceType = RenderFeatures.TextureSourceType.CameraColour;

        /// <summary>
        /// If the destination is a named texture then this is its name.
        /// </summary>
        [SerializeField]
        private string m_DestinationNamedTemporaryName;
        
        protected int m_DestinationNamedTemporaryNameHash;
        
        /// <summary>
        /// If the source and destination are the same then this named texture can be used as
        /// the temporary copy location.
        /// If not set then a the pass will create its own temporary texture.
        /// </summary>
        [SerializeField]
        private string m_TempCopyNamedTemporaryName;
        
        protected int m_TempCopyNamedTemporaryNameHash;
        
        /// <summary>
        /// When to insert the pass
        /// </summary>
        [Header("What stage")]
        [SerializeField] 
        protected RenderPassEvent m_WhenToInsert = RenderPassEvent.BeforeRenderingPostProcessing;

        /// <summary>
        /// Gets the hashes of the named texture names.
        ///
        /// NOTE: this should be called in the Create() of sub-classes.
        /// </summary>
        protected void DoCreate()
        {
            SetTextureNameHashes();
        }

        /// <summary>
        /// Determine if the source and destination are the same.
        /// </summary>
        /// <returns></returns>
        protected bool IsSourceAndDestinationSame()
        {
            if (m_SourceTextureSourceType == TextureSourceType.CameraColour &&
                m_DestinationTextureSourceType == TextureSourceType.CameraColour)
            {
                return true;
            }

            if (m_SourceTextureSourceType == TextureSourceType.NameTemporary &&
                     m_DestinationTextureSourceType == TextureSourceType.NameTemporary)
            {
                //
                // Both using a named temporary texture, are they the same
                //
                return m_SourceNamedTemporaryNameHash == m_DestinationNamedTemporaryNameHash;
            }

            return false;
        }

        /// <summary>
        /// Set the texture name hashes from the current name values.
        /// </summary>
        protected void SetTextureNameHashes()
        {
            m_SourceNamedTemporaryNameHash =
                TemporaryCameraCopyTextureRenderFeature.GetNameHash(m_SourceNamedTemporaryName);
            m_DestinationNamedTemporaryNameHash =
                TemporaryCameraCopyTextureRenderFeature.GetNameHash(m_DestinationNamedTemporaryName);
            m_TempCopyNamedTemporaryNameHash =
                TemporaryCameraCopyTextureRenderFeature.GetNameHash(m_TempCopyNamedTemporaryName);
        }
        
#if UNITY_EDITOR
        private bool m_EditorTextureHashesFoldout;
        protected virtual void EditorOnInspectorGUIAfterBase()
        {
            EditorGUILayout.LabelField("Info", EditorStyles.boldLabel);
            
            var origIndent = EditorGUI.indentLevel;
            EditorGUI.indentLevel += 1;
            m_EditorTextureHashesFoldout = EditorGUILayout.Foldout(m_EditorTextureHashesFoldout, "Texture hashes");
            if (m_EditorTextureHashesFoldout)
            {
                EditorGUI.BeginDisabledGroup(true);

                EditorGUI.indentLevel += 1;
                EditorTextureNameAndHash("Source", m_SourceNamedTemporaryName, m_SourceNamedTemporaryNameHash);

                EditorTextureNameAndHash("Destination", m_DestinationNamedTemporaryName,
                    m_DestinationNamedTemporaryNameHash);

                EditorTextureNameAndHash("Source", m_SourceNamedTemporaryName, m_SourceNamedTemporaryNameHash);
                EditorGUI.EndDisabledGroup();
            }

            EditorGUI.indentLevel = origIndent;

            EditorGUILayout.LabelField("Controls", EditorStyles.boldLabel);
            
            //
            // NOTE:
            // This button is not actually needed as the Create() of the render feature is called
            // if the exposed settings are changed.
            //
            if (GUILayout.Button("Update temp texture hashes"))
            {
                SetTextureNameHashes();
            }
        }

        private static void EditorTextureNameAndHash(string label, string namedTemporaryName, int namedTemporaryNameHash)
        {
            EditorGUILayout.TextField(label);
            EditorGUI.indentLevel += 1;
            if (!string.IsNullOrEmpty(namedTemporaryName))
            {
                EditorGUILayout.IntField(namedTemporaryName, namedTemporaryNameHash);
            }
            else
            {
                EditorGUILayout.IntField("null name", namedTemporaryNameHash);
            }
            EditorGUI.indentLevel -= 1;
        }

        [CustomEditor(typeof(SourceToDestinationBlitRenderFeature), true)]
        private class SourceToDestinationBlitRenderFeatureEditor : Editor
        {
            public override void OnInspectorGUI()
            {
                base.OnInspectorGUI();

                var me = target as SourceToDestinationBlitRenderFeature;
                if (me != null)
                {
                    me.EditorOnInspectorGUIAfterBase();
                }
            }
        }
#endif
    }


    /// <summary>
    /// The RenderPass for things that take a source, do some operation on it and put the
    /// result in some destination.
    ///
    /// NOTE:
    /// If the source and destination are different then the execute must at least copy the
    /// source to the destination (as long as m_GoodToExecute is true) otherwise later
    /// passes may not see the correct texture contents.
    /// </summary>
    public abstract class SourceToDestinationBlitRenderPass : ScriptableRenderPass
    {
        /// <summary>
        /// If this pass needs to create a temporary texture (when the source and destination
        /// are the same) then is id is used.
        /// </summary>
        protected readonly int m_ScreenCopyID = Shader.PropertyToID("_ScreenCopy");

        protected RenderFeatures.TextureSourceType m_SourceTextureSourceType;
        protected int m_SourceNamedTemporaryNameHash;

        protected RenderFeatures.TextureSourceType m_DestinationTextureSourceType;
        protected int m_DestinationNamedTemporaryNameHash;

        protected int m_SameSourceDestNamedTemporaryNameHash;

        protected bool m_SourceAndDestinationSame;

        /// <summary>
        /// If this is true then Execute() can happen, if false something went wrong in the pass setup
        /// so the Execute() should do nothing.
        /// </summary>
        protected bool m_GoodToExecute;

        protected RenderTargetIdentifier m_CameraColourTargetIdentifier;
        protected RenderTargetIdentifier m_SourceTargetIdentifier;
        protected RenderTargetIdentifier m_DestinationTargetIdentifier;
        protected RenderTargetIdentifier m_TempCopyTargetIdentifier;

        /// <summary>
        /// Sets up the named textures and/or the camera colour texture and determines if the
        /// source and destination are the same.
        ///
        /// NOTE:
        /// Call this from whatever setup type method the sub-class implements.
        /// </summary>
        protected void DoSetup(RenderPassEvent whenToRender, RenderTargetIdentifier cameraColourTargetIdentifier,
            RenderFeatures.TextureSourceType sourceSourceType, int tempSourceTextureHash,
            RenderFeatures.TextureSourceType destinationSourceType, int tempDestinationTextureHash,
            int sameSourceDestTextureHash)
        {
            renderPassEvent = whenToRender;
            m_CameraColourTargetIdentifier = cameraColourTargetIdentifier;

            m_SourceTextureSourceType = sourceSourceType;
            m_SourceNamedTemporaryNameHash = tempSourceTextureHash;

            m_DestinationTextureSourceType = destinationSourceType;
            m_DestinationNamedTemporaryNameHash = tempDestinationTextureHash;

            m_SameSourceDestNamedTemporaryNameHash = sameSourceDestTextureHash;

            m_SourceAndDestinationSame = false;

            if (m_SourceTextureSourceType == TextureSourceType.CameraColour &&
                m_DestinationTextureSourceType == TextureSourceType.CameraColour)
            {
                m_SourceAndDestinationSame = true;
            }
            else if (m_SourceTextureSourceType == TextureSourceType.NameTemporary &&
                     m_DestinationTextureSourceType == TextureSourceType.NameTemporary)
            {
                //
                // Both using a named temporary texture, are they the same
                //
                m_SourceAndDestinationSame = (m_SourceNamedTemporaryNameHash == m_DestinationNamedTemporaryNameHash);
            }
        }
        
        /// <summary>
        /// Gets the named textures and works out if all textures are available meaning that
        /// execution of the pass can go ahead.
        /// This create the local temporary copy texture if that is required.
        /// This sets up the RenderTargetIdentifiers the Execute() can then use. 
        /// </summary>
        protected void DoOnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
        {
            m_GoodToExecute = false;
            if (m_SourceTextureSourceType == TextureSourceType.CameraColour)
            {
                m_SourceTargetIdentifier = m_CameraColourTargetIdentifier;
            }
            else if (!TemporaryCameraCopyTextureRenderFeature.TryGetTempTextureIdentifier(m_SourceNamedTemporaryNameHash, out m_SourceTargetIdentifier))
            {
                return;
            }
            
            if (m_DestinationTextureSourceType == TextureSourceType.CameraColour)
            {
                m_DestinationTargetIdentifier = m_CameraColourTargetIdentifier;
            }
            else if (!TemporaryCameraCopyTextureRenderFeature.TryGetTempTextureIdentifier(m_DestinationNamedTemporaryNameHash, out m_DestinationTargetIdentifier))
            {
                return;
            }

            if (m_SourceAndDestinationSame)
            {
                //
                // need some texture to use as a copy
                //
                if (m_SameSourceDestNamedTemporaryNameHash != TemporaryCameraCopyTextureRenderFeature.k_InvalidNameHash)
                {
                    if (!TemporaryCameraCopyTextureRenderFeature.TryGetTempTextureIdentifier(m_SameSourceDestNamedTemporaryNameHash, out m_TempCopyTargetIdentifier))
                    {
                        return;
                    }
                }
                else
                {
                    //
                    // Use our own temporary texture
                    //
#if ENABLE_VR
                    var renderTextureDescriptor = XRSettings.enabled ? XRSettings.eyeTextureDesc : renderingData.cameraData.cameraTargetDescriptor;
#else
                    var renderTextureDescriptor = renderingData.cameraData.cameraTargetDescriptor;
#endif
                    cmd.GetTemporaryRT(m_ScreenCopyID, renderTextureDescriptor);
                    m_TempCopyTargetIdentifier = new RenderTargetIdentifier(m_ScreenCopyID);
                }
            }

            m_GoodToExecute = true;
        }
    }
}