using System;
using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering;

// This script is for combining multiple GraphicsStateCollection files into one.
// Select multiple GraphicsStateCollection files in the ProjectView,
// and right click to combine the contents into one.
// The first selected file will be the result file.
public static class GraphicsStateCollectionCombiner
{
    private static GraphicsStateCollection[] s_Selected;
    private const string k_RightClickMenu = "Assets/Combine GraphicsStateCollections";

    // Enable the menu option if there are more than 1 GraphicsStateCollection files selected.
    [MenuItem(k_RightClickMenu, true)]
    private static bool ShowRightClickOption()
    {
        s_Selected = Selection.GetFiltered<GraphicsStateCollection>(SelectionMode.Assets);
        return s_Selected.Length > 1;
    }

    // Combine the selected GraphicsStateCollections files.
    [MenuItem(k_RightClickMenu)]
    private static void DoCombine()
    {
        int addedVariantCount = 0;
        int addedGfxStateCount = 0;
        int combinedCollectionCount = 0;

        // Selection.activeObject is the first selected object, so use it as the result file.
        GraphicsStateCollection result = Selection.activeObject as GraphicsStateCollection;

        // In case it is null, use the first one.
        if (result == null)
        {
            result = s_Selected[0];
        }

        string resultPath = AssetDatabase.GetAssetPath(result);

        for (int i = 0; i < s_Selected.Length; i++)
        {
            GraphicsStateCollection collection = s_Selected[i];

            // Skip the result file itself.
            if (collection == result)
            {
                continue;
            }

            // Skip this collection file if any setting does not match.
            if (collection.runtimePlatform != result.runtimePlatform ||
                collection.graphicsDeviceType != result.graphicsDeviceType ||
                collection.qualityLevelName != result.qualityLevelName)
            {
                string collectionPath = AssetDatabase.GetAssetPath(collection);
                Debug.LogError(String.Concat("Skip combining ", ColorString(collectionPath), " into ",
                    ColorString(resultPath), " because platform or gfx api or quality level does not match."), collection);
                continue;
            }

            // Add the variants and graphics states into the result collection file.
            List<GraphicsStateCollection.ShaderVariant> variants = new();
            collection.GetVariants(variants);
            foreach (GraphicsStateCollection.ShaderVariant v in variants)
            {
                Shader shader = v.shader;
                PassIdentifier passId = v.passId;
                LocalKeyword[] keywords = v.keywords;

                // Add the variant.
                if (result.AddVariant(shader, passId, keywords))
                {
                    addedVariantCount++;
                }

                // Also add the graphics states from the variant.
                List<GraphicsStateCollection.GraphicsState> states = new();
                collection.GetGraphicsStatesForVariant(v, states);
                foreach (GraphicsStateCollection.GraphicsState s in states)
                {
                    if (result.AddGraphicsStateForVariant(shader, passId, keywords, s))
                    {
                        addedGfxStateCount++;
                    }
                }
            }

            // Delete the collection file.
            string path = AssetDatabase.GetAssetPath(collection);
            AssetDatabase.DeleteAsset(path);
            combinedCollectionCount++;
        }

        // Save the result collection file.
        result.SaveToFile(resultPath);

        Debug.Log(String.Concat(
            "Combined ", ColorString(combinedCollectionCount.ToString()),
            " GraphicsStateCollections into ", ColorString(resultPath),
            ". Added ", ColorString(addedVariantCount.ToString()),
            " variants and ", ColorString(addedGfxStateCount.ToString()),
            " graphics states."), result);
    }

    private static string ColorString(string text)
    {
        return String.Concat("<color=#00ffff>", text, "</color>");
    }
}