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

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

namespace UnityEditor.Rendering.HighDefinition
{
    /// <summary>
    /// The UI block that represents Transparency properties for materials.
    /// </summary>
    public class TransparencyUIBlock : MaterialUIBlock
    {
        /// <summary>Transparency UI Block features. Use this to select which field you want to show.</summary>
        [Flags]
        public enum Features
        {
            /// <summary>Hides all the fields.</summary>
            None = 0,
            /// <summary>Displays the distortion fields.</summary>
            Distortion = 1 << 0,
            /// <summary>Displays the refraction fields.</summary>
            Refraction = 1 << 1,
            /// <summary>Displays all the fields.</summary>
            All = ~0
        }

        internal class Styles
        {
            public const string header = "Transparency Inputs";
        }

        ExpandableBit m_ExpandableBit;
        Features m_Features;
        MaterialUIBlockList m_TransparencyBlocks;

        /// <summary>
        /// Constructs a TransparencyUIBlock based on the parameters.
        /// </summary>
        /// <param name="expandableBit">Bit index used to store the foldout state.</param>
        /// <param name="features">Features of the Transparency block.</param>
        public TransparencyUIBlock(ExpandableBit expandableBit, Features features = Features.All)
        {
            m_ExpandableBit = expandableBit;
            m_Features = features;

            m_TransparencyBlocks = new MaterialUIBlockList(parent);
            if ((features & Features.Refraction) != 0)
                m_TransparencyBlocks.Add(new RefractionUIBlock(1));  // This block will not be used in by a layered shader so we can safely set the layer count to 1
            if ((features & Features.Distortion) != 0)
                m_TransparencyBlocks.Add(new DistortionUIBlock());
        }

        /// <summary>
        /// Loads the material properties for the block.
        /// </summary>
        public override void LoadMaterialProperties() {}

        /// <summary>
        /// Renders the properties in the block.
        /// </summary>
        public override void OnGUI()
        {
            // Disable the block if one of the materials is not transparent:
            if (materials.Any(material => material.GetSurfaceType() != SurfaceType.Transparent))
                return;

            // If refraction model is not enabled in SG, we don't show the section
            var shader = materials[0].shader;
            if (shader.IsShaderGraph())
            {
                var defaultRefractionModel = shader.GetPropertyDefaultFloatValue(shader.FindPropertyIndex(kRefractionModel));
                if (defaultRefractionModel == 0)
                    return;
            }

            using (var header = new MaterialHeaderScope(Styles.header, (uint)m_ExpandableBit, materialEditor))
            {
                if (header.expanded)
                {
                    m_TransparencyBlocks.OnGUI(materialEditor, properties);
                }
            }
        }
    }
}