using System;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEngine;

public class ReplaceMobileShaders
{
    private static ShaderReplace[] _shaderReplace;
    
    [MenuItem("ResourceTool/Replace Mobile Shaders")]
    public static void ReplaceMobile()
    {
        if (_shaderReplace == null)
        {
            _shaderReplace = new []
            {
                new ShaderReplace("Mobile/Particles/Additive", "Particles/Additive", true),
                new ShaderReplace("Mobile/Particles/Additive Culled", "Particles/Additive", false),
                new ShaderReplace("Mobile/Particles/Additive Alpha", "Particles/Alpha Blended", false),
                new ShaderReplace("Mobile/Particles/Alpha Blended", "Particles/Alpha Blended", true),
            };
        }
        var allMaterials = from assetPath in AssetDatabase.GetAllAssetPaths()
            let extension = Path.GetExtension(assetPath)
            where !string.IsNullOrEmpty(extension) && extension.Equals(".mat", StringComparison.OrdinalIgnoreCase)
            select assetPath;
        foreach (var assetPath in allMaterials)
        {
            var material = AssetDatabase.LoadAssetAtPath<Material>(assetPath);
            var shaderName = material.shader == null ? string.Empty : material.shader.name;
            for(var i = 0; i < _shaderReplace.Length; i++)
                if (shaderName.Equals(_shaderReplace[i].originName, StringComparison.OrdinalIgnoreCase))
                {
                    const string tintColorName = "_TintColor";
                    var sourceColor = Color.white;
                    var replace = _shaderReplace[i];
                    if (replace.halfColor)
                        sourceColor = material.HasProperty(tintColorName) ? material.GetColor(tintColorName) : Color.white;
                    material.shader = replace.shader;
                    if (replace.halfColor)
                        material.SetColor(tintColorName, sourceColor * 0.5f);
                    EditorUtility.SetDirty(material);
                }
        }
    }
    
    private class ShaderReplace
    {
        public readonly string originName;
        public readonly Shader shader;
        public readonly bool halfColor;
        
        public ShaderReplace(string origin, string target, bool useHalf)
        {
            originName = origin;
            shader = Shader.Find(target);
            halfColor = useHalf;
        }
    }
}