using System;
using System.IO;
using System.Runtime.InteropServices;
using UnityEngine;

public class UniQuake: MonoBehaviour
{
#if UNITY_EDITOR
    private const string DllPath = "Plugins/windows/x86_64/uniquake.dll";
#elif UNITY_STANDALONE_WIN
    #if UNITY_64
    private const string DllPath = "Plugins/x86_64/uniquake.dll";
    #else
    private const string DllPath = "Plugins/x86/uniquake.dll";
    #endif
#endif

    private const int MemSize = 0x4000000;  // 64 MB of heap space

    private IntPtr libraryHandle;

    private QuakeParms quakeParms;
    private SystemModule systemModule;
    private RenderModule renderModule;

    private bool initialized = false;
    private double startTime;

    /// <summary>
    /// Time since startup for this particular instance of Quake
    /// </summary>
    public double CurrentTime => Time.timeAsDouble - startTime;

    void Start()
    {
        systemModule = new SystemModule(this);
        renderModule = new RenderModule(this);

        LoadLibrary();

        string[] arguments = 
        {
            "",
            "-window",
            "-width", "1440",
            "-height", "1080",
            "+developer", "1",
        };

        quakeParms = new QuakeParms
        {
            baseDir = Application.persistentDataPath,
            cacheDir = null,
        };
        quakeParms.SetArguments(arguments);
        quakeParms.AllocateMemory(MemSize);

        startTime = Time.timeAsDouble;

        try
        {
            UniQuake_SetFmodSystem(AudioManager.Instance.FmodSystem.handle);
            UniQuake_Init(quakeParms, systemModule.ToIntPtr, renderModule.ToIntPtr);
            initialized = true;
        }
        catch (QuakeException ex)
        {
            if (ex.ExitCode == 0)
                Debug.Log(ex.Message);
            else
                Debug.LogException(ex);

            Shutdown();
        }
        catch (Exception ex)
        {
            Debug.LogException(ex);
            Shutdown();
        }
    }

    void Update()
    {
        if (!initialized)
            return;

        try
        {
            UniQuake_Update(Time.deltaTime);
        }
        catch (QuakeException ex)
        {
            if (ex.ExitCode == 0)
                Debug.Log(ex.Message);
            else
                Debug.LogException(ex);

            Shutdown();
        }
        catch (Exception ex)
        {
            Debug.LogException(ex);
            Shutdown();
        }
    }

    private void Shutdown()
    {
        initialized = false;
        UniQuake_Shutdown();
        Destroy(this);
    }

    private void OnDestroy()
    {
        renderModule.Destroy();
        systemModule.Destroy();

        if (quakeParms != null)
        {
            quakeParms.Destroy();
            quakeParms = null;
        }

        FreeLibrary();
    }

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void UniQuake_InitFunc(QuakeParms parms, IntPtr sysCalls, IntPtr modCalls);
    private UniQuake_InitFunc UniQuake_Init;

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void UniQuake_UpdateFunc(float deltaTime);
    private UniQuake_UpdateFunc UniQuake_Update;

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void UniQuake_ShutdownFunc();
    private UniQuake_ShutdownFunc UniQuake_Shutdown;

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate void UniQuake_SetFmodSystemFunc(IntPtr fmodSystem);

    private UniQuake_SetFmodSystemFunc UniQuake_SetFmodSystem;

    private void LoadLibrary()
    {
        string dllFile = Path.Combine(Application.dataPath, DllPath);
        libraryHandle = SystemLibrary.LoadLibrary(dllFile);
        if (libraryHandle == IntPtr.Zero)
        {
            throw new DllNotFoundException($"Failed to load UniQuake library from path: {dllFile}, last error = {Marshal.GetLastWin32Error()}");
        }

        UniQuake_Init = LoadLibraryFunction<UniQuake_InitFunc>("UniQuake_Init");
        UniQuake_Update = LoadLibraryFunction<UniQuake_UpdateFunc>("UniQuake_Update");
        UniQuake_Shutdown = LoadLibraryFunction<UniQuake_ShutdownFunc>("UniQuake_Shutdown");
        UniQuake_SetFmodSystem = LoadLibraryFunction<UniQuake_SetFmodSystemFunc>("UniQuake_SetFmodSystem");
    }

    private TDelegate LoadLibraryFunction<TDelegate>(string name)
    {
        IntPtr procAddress = SystemLibrary.GetProcAddress(libraryHandle, name);
        if (procAddress == IntPtr.Zero)
        {
            throw new DllNotFoundException($"Could not find library function: {name}");
        }

        return Marshal.GetDelegateForFunctionPointer<TDelegate>(procAddress);
    }

    private void FreeLibrary()
    {
        if (libraryHandle != IntPtr.Zero)
        {
            SystemLibrary.FreeLibrary(libraryHandle);
            libraryHandle = IntPtr.Zero;
        }
    }
}

public class QuakeException: Exception
{
    public int ExitCode { get; }

    public QuakeException(string message, int exitCode = 0)
        : base(message)
    {
        ExitCode = exitCode;
    }
}