//
// This file is part of the Tremble package by Tiny Goose.
// Copyright (c) 2024-2026 TinyGoose Ltd., All Rights Reserved.
//

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace TinyGoose.Tremble
{
	public static class EntityClassWriter
	{
		public static void WriteCSharp(this FgdClass fgdClass, string file, List<FgdClass> allBaseClasses = null, string namespaceName = null)
		{
			if (fgdClass.Type == FgdClassType.Base)
			{
				WriteCSharpInterface(fgdClass, file, namespaceName);
			}
			else
			{
				WriteCSharpClass(fgdClass, file, allBaseClasses, namespaceName);
			}
		}

		private static void WriteCSharpClass(this FgdClass fgdClass, string file, List<FgdClass> allBaseClasses = null, string namespaceName = null)
		{
			using FileStream classFile = new(file, FileMode.Create, FileAccess.Write);
			using StreamWriter writer = new(classFile);

			writer.WriteLine($"// Class '{fgdClass.Name}'");
			writer.WriteLine($"// Generated by Tremble v{TrembleConsts.VERSION_STRING}");
			writer.WriteLine();

			writer.WriteLine("using UnityEngine;");
			writer.WriteLine("using TinyGoose.Tremble;");
			writer.WriteLine();

			writer.WriteLine("// Disable 'Field is assigned but its value is never used' warning");
			writer.WriteLine("#pragma warning disable CS0414");
			writer.WriteLine();

			bool hasNamespace = !namespaceName.IsNullOrEmpty();

			if (hasNamespace)
			{
				writer.WriteLine($"namespace {namespaceName}");
				writer.WriteLine("{");
			}

			if (!fgdClass.Description.IsNullOrEmpty())
			{
				writer.WriteLine($"\t// \"{fgdClass.Description}\"");
			}

			{
				fgdClass.Name.Split('_', out string category, out string classname);

				if (fgdClass.Type == FgdClassType.Brush)
				{
					if (hasNamespace)
					{
						writer.Write("\t");
					}
					writer.Write("[BrushEntity(");
				}
				else
				{
					if (hasNamespace)
					{
						writer.Write("\t");
					}
					writer.Write("[PointEntity(");
				}

				writer.Write($"\"{classname}\"");

				if (category.IsNullOrEmpty())
				{
					writer.Write($", category: \"\" /* empty category - gross, but necessary */");
				}
				else
				{
					writer.Write($", category: \"{category}\"");
				}

				if (fgdClass.Type == FgdClassType.Brush && fgdClass.Name.ContainsInvariant("trigger"))
				{
					writer.Write($", type: BrushType.Trigger");
				}

				writer.WriteLine(")]");

				string csharpClassname = classname.ToNamingConvention(NamingConvention.UpperCamelCase);
				if (!category.IsNullOrEmpty()
				    && !category.EqualsInvariant("misc")
				    && !category.EqualsInvariant("func"))
				{
					csharpClassname += category.ToNamingConvention(NamingConvention.UpperCamelCase);
				}

				if (csharpClassname.EqualsInvariant("light"))
				{
					// Hack: you can't call a MonoBehaviour "Light" in Unity, but Quake for example
					// has an entity called "light" - let's call it LightEntity
					csharpClassname = "LightEntity";
				}

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.Write($"public class {csharpClassname} : MonoBehaviour");

				foreach (string baseClass in fgdClass.BaseClassNames)
				{
					// Not the Tremble ones!
					if (baseClass.EqualsInvariant(FgdConsts.CLASS_MAP_BASE, caseSensitive: true)
					    || baseClass.EqualsInvariant(FgdConsts.CLASS_MAP_POINT_BASE, caseSensitive: true))
						continue;

					writer.Write($", I{baseClass}");
				}
				writer.WriteLine();

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.WriteLine("{");

				if (fgdClass.AllFields.Count > 0)
				{
					writer.WriteIndent(hasNamespace ? 2 : 1);
					writer.WriteLine("// Fields:");

					foreach (FgdFieldBase field in fgdClass.AllFields)
					{
						field.WriteCSharpClass(writer, hasNamespace ? 2 : 1);
					}

					writer.WriteLine();
				}

				if (fgdClass.AllSpawnFlags.Count > 0)
				{
					writer.WriteIndent(hasNamespace ? 2 : 1);
					writer.WriteLine("// Spawnflags: ");
					foreach (FgdSpawnFlagField spawnFlagField in fgdClass.AllSpawnFlags)
					{
						spawnFlagField.WriteCSharpClass(writer, hasNamespace ? 2 : 1);
					}

					writer.WriteLine();
				}

				// Write base class fields
				if (allBaseClasses != null)
				{
					List<string> writtenBaseClasses = new(64);
					List<string> writtenFields = new(64);

					foreach (string baseClassName in fgdClass.BaseClassNames)
					{
						AddBaseClassFields(fgdClass, writer, hasNamespace, baseClassName, writtenBaseClasses, writtenFields, allBaseClasses);
					}
				}

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.WriteLine("}");
			}

			if (hasNamespace)
			{
				writer.WriteLine("}");
			}

			writer.WriteLine();
			writer.WriteLine("#pragma warning restore CS0414");
		}

		private static void AddBaseClassFields(FgdClass thisClass, StreamWriter writer, bool hasNamespace, string baseClassName, List<string> writtenBaseClasses, List<string> writtenFields, List<FgdClass> allBaseClasses)
		{
			// Find the base class and add!
			FgdClass baseClass = allBaseClasses.FirstOrDefault(bc => bc.Name.EqualsInvariant(baseClassName, caseSensitive: true));
			if (baseClass == null)
				return;

			if (baseClass.AllFields.Count + baseClass.AllSpawnFlags.Count == 0)
				return;

			if (writtenBaseClasses.Contains(baseClassName))
				return;

			writtenBaseClasses.Add(baseClassName);

			foreach (string baseBaseClassName in baseClass.BaseClassNames)
			{
				AddBaseClassFields(thisClass, writer, hasNamespace, baseBaseClassName, writtenBaseClasses, writtenFields, allBaseClasses);
			}

			writer.WriteLine();
			writer.WriteIndent(hasNamespace ? 2 : 1);
			writer.WriteLine($"// From Base Class '{baseClassName}':");

			foreach (FgdFieldBase field in baseClass.AllFields)
			{
				if (writtenFields.Contains(field.FieldName))
				{
					writer.WriteIndent(hasNamespace ? 2 : 1);
					writer.WriteLine($"// Skipped '{field.FieldName}' - already defined by a base class!");
					continue;
				}

				writtenFields.Add(field.FieldName);

				bool overridden = thisClass.AllFields.Any(m => m.FieldName.EqualsInvariant(field.FieldName, caseSensitive: true));
				if (overridden)
				{
					writer.WriteLine("/* (overriden by subclass)");
				}

				field.WriteCSharpClass(writer, hasNamespace ? 2 : 1);

				if (overridden)
				{
					writer.WriteLine("(overriden by subclass) */");
				}
			}

			foreach (FgdSpawnFlagField spawnFlag in baseClass.AllSpawnFlags)
			{
				bool overridden = thisClass.AllSpawnFlags.Any(m => m.FieldName.EqualsInvariant(spawnFlag.FieldName, caseSensitive: true));
				if (overridden)
				{
					writer.WriteLine("/* (overriden by subclass)");
				}

				spawnFlag.WriteCSharpClass(writer, hasNamespace ? 2 : 1);

				if (overridden)
				{
					writer.WriteLine("(overriden by subclass) */");
				}
			}
		}


		private static void WriteCSharpInterface(this FgdClass fgdClass, string file, string namespaceOrNull)
		{
			using FileStream classFile = new(file, FileMode.Create, FileAccess.Write);
			using StreamWriter writer = new(classFile);

			writer.WriteLine($"// Interface 'I{fgdClass.Name}'");
			writer.WriteLine($"// Generated by Tremble v{TrembleConsts.VERSION_STRING}");
			writer.WriteLine();

			writer.WriteLine("using UnityEngine;");
			writer.WriteLine("using TinyGoose.Tremble;");
			writer.WriteLine();

			bool hasNamespace = !namespaceOrNull.IsNullOrEmpty();

			if (hasNamespace)
			{
				writer.WriteLine($"namespace {namespaceOrNull}");
				writer.WriteLine("{");
			}

			{
				fgdClass.Name.Split('_', out string _, out string classname);
				string csharpClassname = classname.ToNamingConvention(NamingConvention.UpperCamelCase);

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.WriteLine($"public interface I{csharpClassname} : ITrembleBaseClass");

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.WriteLine("{");

				if (fgdClass.AllFields.Count > 0)
				{
					if (hasNamespace)
					{
						writer.Write("\t");
					}
					writer.WriteLine("\t// Fields:");

					foreach (FgdFieldBase field in fgdClass.AllFields)
					{
						field.WriteCSharpInterface(writer, hasNamespace ? 2 : 1);
					}
				}

				if (fgdClass.AllSpawnFlags.Count > 0)
				{
					if (hasNamespace)
					{
						writer.Write("\t");
					}
					writer.WriteLine("\t// Spawnflags: ");
					foreach (FgdSpawnFlagField spawnFlagField in fgdClass.AllSpawnFlags)
					{
						spawnFlagField.WriteCSharpInterface(writer, hasNamespace ? 2 : 1);
					}
				}

				if (hasNamespace)
				{
					writer.Write("\t");
				}
				writer.WriteLine("}");
			}

			if (hasNamespace)
			{
				writer.WriteLine("}");
			}
		}
	}
}