using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using BepInEx.Bootstrap;
using BepInEx.Configuration;
using BepInEx.Logging;
using BepInEx.Preloader.Core;
using BepInEx.Preloader.Core.Logging;
using BepInEx.Preloader.Core.Patching;
using BepInEx.Preloader.RuntimeFixes;
using MonoMod.Utils;

namespace BepInEx.Preloader.Unity;

/// <summary>
///     The main entrypoint of BepInEx, and initializes all patchers and the chainloader.
/// </summary>
internal static class UnityPreloader
{
    #region Config

    internal static readonly ConfigEntry<bool> ConfigApplyRuntimePatches = ConfigFile.CoreConfig.Bind(
     "Preloader", "ApplyRuntimePatches",
     true,
     "Enables or disables runtime patches.\nThis should always be true, unless you cannot start the game due to a Harmony related issue (such as running .NET Standard runtime) or you know what you're doing.");

    #endregion

    /// <summary>
    ///     The log writer that is specific to the preloader.
    /// </summary>
    private static PreloaderConsoleListener PreloaderLog { get; set; }

    private static ManualLogSource Log => PreloaderLogger.Log;

    public static bool IsPostUnity2017 { get; } =
        File.Exists(Path.Combine(Paths.ManagedPath, "UnityEngine.CoreModule.dll"));

    public static void Run()
    {
        try
        {
            HarmonyBackendFix.Initialize();

            ConsoleManager.Initialize(false);
            AllocateConsole();

            Utility.TryDo(() =>
            {
                if (ConfigApplyRuntimePatches.Value)
                    UnityPatches.Apply();
            }, out var runtimePatchException);

            Logger.Sources.Add(new HarmonyLogSource());
            Logger.Sources.Add(TraceLogSource.CreateSource());

            PreloaderLog = new PreloaderConsoleListener();
            Logger.Listeners.Add(PreloaderLog);

            ChainloaderLogHelper.PrintLogInfo(Log);

            Log.Log(LogLevel.Info, $"Running under Unity v{GetUnityVersion()}");
            Log.Log(LogLevel.Info, $"CLR runtime version: {Environment.Version}");
            Log.Log(LogLevel.Info, $"Supports SRE: {Utility.CLRSupportsDynamicAssemblies}");

            Log.Log(LogLevel.Debug, $"Game executable path: {Paths.ExecutablePath}");
            Log.Log(LogLevel.Debug, $"Unity Managed directory: {Paths.ManagedPath}");
            Log.Log(LogLevel.Debug, $"BepInEx root path: {Paths.BepInExRootPath}");

            if (runtimePatchException != null)
                Log.Log(LogLevel.Warning,
                        $"Failed to apply runtime patches for Mono. See more info in the output log. Error message: {runtimePatchException.Message}");

            Log.Log(LogLevel.Message, "Preloader started");

            TypeLoader.SearchDirectories.UnionWith(Paths.DllSearchPaths);

            using (var assemblyPatcher = new AssemblyPatcher())
            {
                assemblyPatcher.AddPatchersFromDirectory(Paths.BepInExAssemblyDirectory);
                assemblyPatcher.AddPatchersFromDirectory(Paths.PatcherPluginPath);

                Log.Log(LogLevel.Info,
                        $"{assemblyPatcher.PatcherContext.PatcherPlugins.Count} patcher plugin{(assemblyPatcher.PatcherContext.PatcherPlugins.Count == 1 ? "" : "s")} loaded");

                assemblyPatcher.LoadAssemblyDirectories(Paths.DllSearchPaths);

                Log.Log(LogLevel.Info,
                        $"{assemblyPatcher.PatcherContext.AvailableAssemblies.Count} assemblies discovered");

                assemblyPatcher.PatchAndLoad();
            }

            Log.Log(LogLevel.Message, "Preloader finished");
            Logger.Listeners.Remove(PreloaderLog);
            PreloaderLog.Dispose();
        }
        catch (Exception ex)
        {
            try
            {
                Log.Log(LogLevel.Fatal, "Could not run preloader!");
                Log.Log(LogLevel.Fatal, ex);

                if (!ConsoleManager.ConsoleActive)
                {
                    //if we've already attached the console, then the log will already be written to the console
                    AllocateConsole();
                    Console.Write(PreloaderLog);
                }
            }
            catch { }

            var log = string.Empty;

            try
            {
                // We could use platform-dependent newlines, however the developers use Windows so this will be easier to read :)

                log = string.Join("\r\n", PreloaderConsoleListener.LogEvents.Select(x => x.ToString()).ToArray());
                log += "\r\n";

                PreloaderLog?.Dispose();
                PreloaderLog = null;
            }
            catch { }

            File.WriteAllText(
                              Path.Combine(Paths.GameRootPath, $"preloader_{DateTime.Now:yyyyMMdd_HHmmss_fff}.log"),
                              log + ex);
        }
    }

    /// <summary>
    ///     Allocates a console window for use by BepInEx safely.
    /// </summary>
    public static void AllocateConsole()
    {
        if (!ConsoleManager.ConsoleEnabled)
            return;

        try
        {
            ConsoleManager.CreateConsole();
            Logger.Listeners.Add(new ConsoleLogListener());
        }
        catch (Exception ex)
        {
            Log.LogError("Failed to allocate console!");
            Log.LogError(ex);
        }
    }

    public static string GetUnityVersion()
    {
        if (PlatformHelper.Is(Platform.Windows))
            return FileVersionInfo.GetVersionInfo(Paths.ExecutablePath).FileVersion;

        return $"Unknown ({(IsPostUnity2017 ? "post" : "pre")}-2017)";
    }
}