using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;

namespace AtomicEngine
{

public class AtomicNETRuntime
{
  [DllImport (Constants.LIBNAME, CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
  public static extern int csb_Atomic_Test (int id);

  public static void Startup()
  {
    //Console.WriteLine("AtomicNETRuntime Startup:" + csb_Atomic_Test(42));

    Atomic.Initialize();

  }
}

public static class Atomic
{

  static public void Initialize()
  {
    ContainerModule.Initialize ();
    CoreModule.Initialize ();
    MathModule.Initialize ();
    EngineModule.Initialize ();
    InputModule.Initialize ();
    IOModule.Initialize ();
    ResourceModule.Initialize ();
    AudioModule.Initialize ();
    GraphicsModule.Initialize ();
    SceneModule.Initialize ();
    Atomic2DModule.Initialize ();
    Atomic3DModule.Initialize ();
    NavigationModule.Initialize ();
    NetworkModule.Initialize ();
    PhysicsModule.Initialize ();
    EnvironmentModule.Initialize ();
    UIModule.Initialize ();
    AtomicPlayer.PlayerModule.Initialize ();
    initSubsystems();
  }

  static Dictionary<Type, RefCounted> subSystems = new Dictionary<Type, RefCounted>();

  static private void registerSubsystem (RefCounted subsystem)
  {
    subSystems[subsystem.GetType()] = subsystem;
  }

  static public T GetSubsystem<T>() where T : RefCounted
  {
    return (T) subSystems [typeof(T)];
  }

  static private void initSubsystems()
  {
    registerSubsystem (NativeCore.WrapNative<Graphics> (csb_AtomicEngine_GetSubsystem("Graphics")));
    registerSubsystem (NativeCore.WrapNative<Renderer> (csb_AtomicEngine_GetSubsystem("Renderer")));
    registerSubsystem (NativeCore.WrapNative<ResourceCache> (csb_AtomicEngine_GetSubsystem("ResourceCache")));
  }

  [DllImport (Constants.LIBNAME, CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
  private static extern IntPtr csb_AtomicEngine_GetSubsystem(string name);

}

public static partial class Constants
{
    public const string LIBNAME = "__Internal";
}

public partial class RefCounted
{

  public RefCounted()
  {
  }

  protected RefCounted (IntPtr native)
  {
    nativeInstance = native;
  }

  public IntPtr nativeInstance;

  [DllImport (Constants.LIBNAME, CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
  public static extern IntPtr csb_Atomic_RefCounted_GetClassID (IntPtr self);

}

static class NativeCore
{
  [DllImport (Constants.LIBNAME, CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
  private static extern void csb_AtomicEngine_ReleaseRef (IntPtr refCounted);

  // given an existing instance classID, construct the managed instance, with downcast support (ask for Component, get StaticModel for example)
  public static Dictionary<IntPtr, Func<IntPtr, RefCounted>> nativeClassIDToManagedConstructor = new Dictionary<IntPtr, Func<IntPtr, RefCounted>>();

  // weak references here, hold a ref native side
  public static Dictionary<IntPtr, WeakReference> nativeLookup = new Dictionary<IntPtr, WeakReference> ();

  // native engine types, instances of these types can be trivially recreated managed side
  private static Dictionary<Type, Type> nativeTypes = new Dictionary<Type, Type> ();

  public static bool GetNativeType (Type type)
  {
    return nativeTypes.ContainsKey (type);
  }

  public static void RegisterNativeType (Type type)
  {
    nativeTypes.Add (type, type);
  }

  public static void ReleaseExpiredNativeReferences()
  {
    List<IntPtr> released = null;

    foreach(KeyValuePair<IntPtr, WeakReference> entry in nativeLookup)
    {

      if (entry.Value.Target == null || !entry.Value.IsAlive)
      {
        if (released == null)
          released = new List<IntPtr> ();

        released.Add (entry.Key);
      }

    }

    if (released == null)
      return;

    foreach (IntPtr native in released) {
      nativeLookup.Remove (native);
      csb_AtomicEngine_ReleaseRef(native);
      //Console.WriteLine("Released: " + test);
    }

  }

  static IntPtr test = IntPtr.Zero;

  // called by native code
  public static void NETUpdate (float timeStep)
  {

    GC.Collect();
    GC.WaitForPendingFinalizers();
    GC.Collect();
    ReleaseExpiredNativeReferences();

    if (test == IntPtr.Zero || !nativeLookup.ContainsKey(test))
    {
      test = Atomic.GetSubsystem<Renderer>().GetDefaultZone().nativeInstance;
      //Console.WriteLine("Allocated: " + test);
    }

  }

  // called by native code for every refcounted deleted
  public static void RefCountedDeleted (IntPtr native)
  {
    // native side deleted, immediate remove, if we have a script reference still this is an error

    WeakReference w;

    if (nativeLookup.TryGetValue (native, out w)) {

        if ( w != null && w.IsAlive) {
          throw new System.InvalidOperationException("Native Refcounted was deleted with live managed instance");
        }
    }

    nativeLookup.Remove(native);
  }

  // register a newly created native
  public static IntPtr RegisterNative (IntPtr native, RefCounted r)
  {
    r.nativeInstance = native;

    var w = new WeakReference (r);
    NativeCore.nativeLookup [native] = w;
    // keep native side alive
    r.AddRef();

    return native;
  }

  // wraps an existing native instance, with downcast support
  public static T WrapNative<T> (IntPtr native) where T:RefCounted
  {
    if (native == IntPtr.Zero)
      return null;

    WeakReference w;

    // first see if we're already available
    if (nativeLookup.TryGetValue (native, out w)) {

      if (w.IsAlive) {

        // we're alive!
        return (T)w.Target;

      } else {

        // we were seen before, but have since been GC'd, remove!
        nativeLookup.Remove (native);
        csb_AtomicEngine_ReleaseRef(native);
      }
    }

    IntPtr classID = RefCounted.csb_Atomic_RefCounted_GetClassID (native);

    // and store, with downcast support for instance Component -> StaticModel
    // we never want to hit this path for script inherited natives

    RefCounted r = nativeClassIDToManagedConstructor[classID](native);
    w = new WeakReference (r);
    NativeCore.nativeLookup [native] = w;

    // store a ref, so native side will not be released while we still have a reference in managed code
    r.AddRef();

    return (T) r;

  }

}

public class InspectorAttribute : Attribute
{
  public InspectorAttribute(string defaultValue = "")
  {
    DefaultValue = defaultValue;
  }

  public string DefaultValue;
}


}