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

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

namespace UnityEditor.Rendering.HighDefinition
{
    // A Material can be authored from the shader graph or by hand. When written by hand we need to provide an inspector.
    // Such a Material will share some properties between it various variant (shader graph variant or hand authored variant).
    // HDShaderGUI is here to provide a support for setup material keyword and pass function. It will allow the GUI
    // to setup the material properties needed for rendering when switching shaders on a material. For the GUI part
    // of the material you must use Material UI Blocks, examples of doing so can be found in the classes UnlitGUI,
    // LitGUI or LayeredLitGUI.

    /// <summary>
    /// Use this class to build your custom Shader GUI for HDRP.
    /// You can use a class that inherits from HDShaderGUI in the Shader Graph Custom EditorGUI field.
    /// </summary>
    public abstract class HDShaderGUI : ShaderGUI
    {
        /// <summary>
        /// Sets up the keywords and passes for the material you pass in as a parameter.
        /// </summary>
        /// <param name="material">Target material.</param>
        [Obsolete("SetupMaterialKeywordsAndPass has been renamed ValidateMaterial", false)]
        protected virtual void SetupMaterialKeywordsAndPass(Material material)
        {
            ValidateMaterial(material);
        }

        /// <summary>
        /// Unity calls this function when it displays the GUI. This method is sealed so you cannot override it. To implement your custom GUI, use OnMaterialGUI instead.
        /// </summary>
        /// <param name="materialEditor">Material editor instance.</param>
        /// <param name="props">The list of properties in the inspected material(s).</param>
        public sealed override void OnGUI(MaterialEditor materialEditor, MaterialProperty[] props)
        {
            if (!(RenderPipelineManager.currentPipeline is HDRenderPipeline))
            {
                CoreEditorUtils.DrawFixMeBox("Editing HDRP materials is only supported when an HDRP asset is assigned in the Graphics Settings", MessageType.Warning, "Open",
                    () => SettingsService.OpenProjectSettings("Project/Graphics"));
            }
            else
            {
                OnMaterialGUI(materialEditor, props);
            }
        }

        /// <summary>
        /// Implement your custom GUI in this function. To display a UI similar to HDRP shaders, use a MaterialUIBlockList.
        /// </summary>
        /// <param name="materialEditor">The current material editor.</param>
        /// <param name="props">The list of properties in the inspected material(s).</param>
        protected abstract void OnMaterialGUI(MaterialEditor materialEditor, MaterialProperty[] props);

        /// <summary>
        /// Override the material preview GUI.
        /// </summary>
        /// <param name="materialEditor">The current material editor.</param>
        /// <param name="r">Preview rect.</param>
        /// <param name="background">Style for the background.</param>
        public override void OnMaterialPreviewGUI(MaterialEditor materialEditor, Rect r, GUIStyle background)
        {
            using (ListPool<DiffusionProfileSettings>.Get(out var overrides))
            {
                Material material = materialEditor.target as Material;
                foreach (var nameID in HDMaterial.GetShaderDiffusionProfileProperties(material.shader))
                {
                    if (!material.HasProperty(nameID))
                        continue;

                    var diffusionProfile = HDMaterial.GetDiffusionProfileAsset(material, nameID);
                    if (diffusionProfile != null)
                        overrides.Add(diffusionProfile);
                    if (overrides.Count >= DiffusionProfileConstants.DIFFUSION_PROFILE_COUNT - 1)
                        break;
                }

                EditorGraphicsSettings.TryGetRenderPipelineSettingsForPipeline<HDRPDefaultVolumeProfileSettings, HDRenderPipeline>(out var settings);
                if (settings == null || settings.volumeProfile == null)
                {
                    EditorGUI.HelpBox(r, $"The current {nameof(VolumeProfile)} is null, please assign one on Graphics Settings > HDRP", MessageType.Error);
                }
                else
                {
                    var diffusionProfileList = VolumeUtils.GetOrCreateDiffusionProfileList(settings.volumeProfile);

                    var profiles = diffusionProfileList.ToArray();
                    diffusionProfileList.ReplaceWithArray(overrides.ToArray());

                    materialEditor.DefaultPreviewGUI(r, background);

                    diffusionProfileList.ReplaceWithArray(profiles);
                }
            }
        }

        /// <summary>
        /// Override the material interactive preview GUI.
        /// </summary>
        /// <param name="materialEditor">The current material editor.</param>
        /// <param name="r">Preview rect.</param>
        /// <param name="background">Style for the background.</param>
        public override void OnMaterialInteractivePreviewGUI(MaterialEditor materialEditor, Rect r, GUIStyle background)
        {
            OnMaterialPreviewGUI(materialEditor, r, background);
        }
    }
}