AuthoringGenerator.cs

using System;
using System.IO;
using System.Reflection;
using System.Text;
using Unity.Entities;
using UnityEditor;

/// <summary>
/// will create a new authring script based on an IComponentData
/// </summary>
public class AuthoringGenerator
{
    [MenuItem("Assets/Create Authoring")]
    private static void CreateAuthoring()
    {
        var selection = Selection.activeObject;
        if (selection.GetType() != typeof(MonoScript))
            return;

        var script = Selection.activeObject as MonoScript;
        var type = script.GetClass();

        if (type.GetInterface(nameof(IComponentData)) == null)
            return;

        Generate(type);
    }

    [MenuItem("Assets/Create Authoring", true)]
    private static bool CreateAuthoringValidator()
    {
        var selection = Selection.activeObject;
        if (selection.GetType() != typeof(MonoScript))
            return false;

        var script = Selection.activeObject as MonoScript;
        var type = script.GetClass();

        if (type.GetInterface(nameof(IComponentData)) == null)
            return false;

        return true;
    }


    private static void Generate(Type type)
    {
        const string accessibilityLevel = "public";
        StringBuilder generatedFields = new();
        StringBuilder assignedFields = new();

        var fields = type.GetFields();
        for (int i = 0; i < fields.Length; i++)
        {
            FieldInfo field = fields[i];

            if (i != 0)
                generatedFields.Append("\t\t");

            generatedFields.Append(accessibilityLevel);
            generatedFields.Append(" ");
            generatedFields.Append(GetFieldShortName(field));
            generatedFields.Append(" ");
            generatedFields.Append(field.Name);
            generatedFields.Append(";");
            generatedFields.AppendLine();

            if (i != 0)
                assignedFields.Append("\t\t\t\t\t");
            assignedFields.Append(field.Name);
            assignedFields.Append(" = ");
            assignedFields.Append("authoring.");
            assignedFields.Append(field.Name);
            if (i != fields.Length - 1)
            {
                assignedFields.Append(",");
                assignedFields.AppendLine();
            }
        }

        var fileName = $"{type.Name}_Authoring";
        string @namespace = string.IsNullOrEmpty(type.Namespace) ? "Authoring" : type.Namespace + ".Authoring";
        string source = $@"// <auto-generated/>
using Unity.Entities;
using UnityEngine;

namespace {@namespace}
{{
    public partial class {fileName} : MonoBehaviour
    {{
        {generatedFields.ToString()}
        private partial class Baker : Baker<{fileName}>
        {{
            public override void Bake({fileName} authoring)
            {{
                Entity e = GetEntity(TransformUsageFlags.Dynamic);
                AddComponent(e, new {type.Name}()
                {{
                    {assignedFields.ToString()}
                }});
            }}
        }}
    }}
}}

        ";

        var path = UnityEngine.Application.dataPath + $"/{fileName}.cs";

        if (!File.Exists(path))
        {
            var fs = File.Create(path);
            fs.Dispose();
            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();
        }
        
        File.WriteAllText(path, source);
        AssetDatabase.SaveAssets();
        AssetDatabase.Refresh();
    }

    private static string GetFieldShortName(FieldInfo field)
    {
        switch (field.FieldType)
        {
            case Type t when t == typeof(Boolean):
                return "bool";
            case Type t when t == typeof(Int32):
                return "int";
            case Type t when t == typeof(Single):
                return "float";
            case Type t when t == typeof(Double):
                return "double";
            case Type t when t == typeof(String):
                return "string";
            default:
                return field.FieldType.FullName;
        }
    }
}