using System;
using System.IO;
using System.Linq;
using System.Reflection;

namespace BepInEx.Preloader
{
	internal static class Entrypoint
	{
		/// <summary>
		///     The main entrypoint of BepInEx, called from Doorstop.
		/// </summary>
		/// <param name="args">
		///     The arguments passed in from Doorstop. First argument is the path of the currently executing
		///     process.
		/// </param>
		public static void Main(string[] args)
		{
			EnvVars.LoadVars();

			string bepinPath = Path.GetDirectoryName(Path.GetDirectoryName(Path.GetFullPath(EnvVars.DOORSTOP_INVOKE_DLL_PATH)));

			Paths.SetExecutablePath(args[0], bepinPath, EnvVars.DOORSTOP_MANAGED_FOLDER_DIR);
			AppDomain.CurrentDomain.AssemblyResolve += LocalResolve;

			Preloader.Run();
		}

		/// <summary>
		///     A handler for <see cref="AppDomain.AssemblyResolve" /> to perform some special handling.
		///     <para>
		///         It attempts to check currently loaded assemblies (ignoring the version), and then checks the BepInEx/core path,
		///         BepInEx/patchers path and the BepInEx folder, all in that order.
		///     </para>
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="args"></param>
		/// <returns></returns>
		internal static Assembly LocalResolve(object sender, ResolveEventArgs args)
		{
			var assemblyName = new AssemblyName(args.Name);

			var foundAssembly = AppDomain.CurrentDomain.GetAssemblies()
										 .FirstOrDefault(x => x.GetName().Name == assemblyName.Name);

			if (foundAssembly != null)
				return foundAssembly;

			if (Utility.TryResolveDllAssembly(assemblyName, Paths.BepInExAssemblyDirectory, out foundAssembly)
				|| Utility.TryResolveDllAssembly(assemblyName, Paths.PatcherPluginPath, out foundAssembly)
				|| Utility.TryResolveDllAssembly(assemblyName, Paths.PluginPath, out foundAssembly))
				return foundAssembly;

			return null;
		}
	}
}