using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.HighDefinition;
using System.Linq;

// Include material common properties names
using static UnityEngine.Rendering.HighDefinition.HDMaterialProperties;

namespace UnityEditor.Rendering.HighDefinition
{
    /// <summary>
    /// The UI block that represents refraction properties.
    /// </summary>
    public class RefractionUIBlock : MaterialUIBlock
    {
        internal static class Styles
        {
            public static string refractionModelText = "Refraction Model";
            public static GUIContent refractionIorText = new GUIContent("Index Of Refraction", "Controls the index of refraction for this Material.");
            public static GUIContent refractionThicknessText = new GUIContent("Thickness", "Controls the thickness for rough refraction.\nFor a Sphere model, this is the diameter of the sphere.");
            public static GUIContent refractionThicknessMapText = new GUIContent("Thickness Map", "Specifies the Refraction Thickness Map (R) for this Material - This acts as a thickness multiplier map.");
            public static GUIContent refractionThicknessRemappingText = new GUIContent("Thickness Remapping", "Controls the maximum thickness for rough refraction.");
            public static GUIContent thicknessMapText = new GUIContent("Thickness Map", "Specifies the Thickness Map (R) for this Material - This map describes the thickness of the object. When subsurface scattering is enabled, low values allow some light to transmit through the object.");
            public static GUIContent transmittanceColorText = new GUIContent("Transmittance Color", "Specifies the Transmittance Color (RGB) for this Material.");
            public static GUIContent atDistanceText = new GUIContent("Transmittance Absorption Distance", "Sets the absorption distance reference in meters.");
            public static string refractionBlendModeWarning = "Refraction is only supported with the Blend Mode value Alpha. Please, set the Blend Mode to Alpha in the Surface Options to hide this mesage.";
            public static string refractionRenderingPassWarning = "Refraction is not supported with the rendering pass Pre-Refraction. Please, use a different rendering pass.";
        }

        MaterialProperty refractionModel = null;
        const string kRefractionModel = "_RefractionModel";
        MaterialProperty atDistance = null;
        const string kATDistance = "_ATDistance";
        MaterialProperty[] thickness = null;
        const string kThickness = "_Thickness";
        MaterialProperty[] thicknessRemap = null;
        const string kThicknessRemap = "_ThicknessRemap";
        MaterialProperty[] thicknessMap = null;
        const string kThicknessMap = "_ThicknessMap";
        MaterialProperty ior = null;
        const string kIor = "_Ior";
        MaterialProperty transmittanceColorMap = null;
        const string kTransmittanceColorMap = "_TransmittanceColorMap";
        MaterialProperty transmittanceColor = null;
        const string kTransmittanceColor = "_TransmittanceColor";
        MaterialProperty blendMode = null;

        int m_LayerCount;

        /// <summary>
        /// Constructs a RefractionUIBlock based on the parameters.
        /// </summary>
        /// <param name="layerCount">Current layer index. For non-layered shader, indicate 1.</param>
        public RefractionUIBlock(int layerCount)
        {
            m_LayerCount = layerCount;
        }

        /// <summary>
        /// Loads the material properties for the block.
        /// </summary>
        public override void LoadMaterialProperties()
        {
            refractionModel = FindProperty(kRefractionModel, false);
            atDistance = FindProperty(kATDistance, false);
            transmittanceColorMap = FindProperty(kTransmittanceColorMap, false);
            transmittanceColor = FindProperty(kTransmittanceColor, false);
            thicknessMap = FindPropertyLayered(kThicknessMap, m_LayerCount, false);
            thickness = FindPropertyLayered(kThickness, m_LayerCount, false);
            thicknessRemap = FindPropertyLayered(kThicknessRemap, m_LayerCount, false);
            blendMode = FindProperty(kBlendMode, false);
            ior = FindProperty(kIor, false);
        }

        /// <summary>
        /// Renders the properties in the block.
        /// </summary>
        public override void OnGUI()
        {
            if (refractionModel != null)
            {
                materialEditor.ShaderProperty(refractionModel, Styles.refractionModelText);
                var mode = (ScreenSpaceRefraction.RefractionModel)refractionModel.floatValue;
                switch (mode)
                {
                    case ScreenSpaceRefraction.RefractionModel.Box:
                    case ScreenSpaceRefraction.RefractionModel.Sphere:
                    {
                        if (ior != null)
                            materialEditor.ShaderProperty(ior, Styles.refractionIorText);

                        if (thicknessMap[0] != null)
                        {
                            if (thicknessMap[0].textureValue == null)
                            {
                                materialEditor.TexturePropertySingleLine(Styles.refractionThicknessText, thicknessMap[0], thickness[0]);
                            }
                            else
                            {
                                materialEditor.TexturePropertySingleLine(Styles.refractionThicknessMapText, thicknessMap[0]);
                                // Display the remap of texture values.
                                Vector2 remap = thicknessRemap[0].vectorValue;
                                EditorGUI.BeginChangeCheck();
                                EditorGUILayout.MinMaxSlider(Styles.refractionThicknessRemappingText, ref remap.x, ref remap.y, 0.0f, 1.0f);
                                if (EditorGUI.EndChangeCheck())
                                {
                                    thicknessRemap[0].vectorValue = remap;
                                }
                            }
                        }

                        if (transmittanceColorMap != null)
                        {
                            materialEditor.TexturePropertySingleLine(Styles.transmittanceColorText, transmittanceColorMap, transmittanceColor);
                            ++EditorGUI.indentLevel;
                            materialEditor.ShaderProperty(atDistance, Styles.atDistanceText);
                            atDistance.floatValue = Mathf.Max(atDistance.floatValue, 0);
                            --EditorGUI.indentLevel;
                        }
                    }
                    break;
                    case ScreenSpaceRefraction.RefractionModel.Thin:
                    {
                        if (ior != null)
                            materialEditor.ShaderProperty(ior, Styles.refractionIorText);
                        if (transmittanceColorMap != null)
                            materialEditor.TexturePropertySingleLine(Styles.transmittanceColorText, transmittanceColorMap, transmittanceColor);
                    }
                    break;
                    default:
                        break;
                }

                if (refractionModel.floatValue != 0 && blendMode != null)
                {
                    if (blendMode.floatValue != (int)BlendMode.Alpha)
                        EditorGUILayout.HelpBox(Styles.refractionBlendModeWarning, MessageType.Warning);

                    // Check for multi-selection render queue different values
                    if (materials.Length == 1 || materials.All(m => m.renderQueue == materials[0].renderQueue))
                    {
                        var renderQueueType = HDRenderQueue.GetTypeByRenderQueueValue(materials[0].renderQueue);

                        if (renderQueueType == HDRenderQueue.RenderQueueType.PreRefraction)
                            EditorGUILayout.HelpBox(Styles.refractionRenderingPassWarning, MessageType.Warning);
                    }
                }
            }
        }
    }
}