using System.Runtime.InteropServices;
using UnityEngine;

namespace IDFATracking
{
    public enum Status
    {
        NotDetermined, //No requests have been made, status unknown
        Restricted, //User has explicitly blocked tracking requests from ALL apps via device settings
        Denied, //Request has been made and user denied tracking
        Authorized, //Request has been made and user allowed tracking
    }

    public delegate void RequestDelegate(Status status);

    internal interface IDFAPlatform
    {
        void RequestTracking(RequestDelegate on_complete);
        Status GetCurrentStatus();
    }

    public static class IDFATracking
    {
        public static void RequestTracking(RequestDelegate on_complete)
        {
            GetPlatform().RequestTracking(on_complete);
        }

        public static Status GetCurrentStatus()
        {
            return GetPlatform().GetCurrentStatus();
        }

        static IDFAPlatform impl;

        static IDFAPlatform GetPlatform()
        {
            if (impl != null)
                return impl;

            if (Application.platform == RuntimePlatform.IPhonePlayer)
                impl = new IDFAPlatformIOS();
            else
                impl = new IDFAPlatformMock();

            return impl;
        }
    }

    internal class IDFAPlatformMock : IDFAPlatform
    {
        public void RequestTracking(RequestDelegate on_complete)
        {
            on_complete?.Invoke(GetCurrentStatus());
        }

        public Status GetCurrentStatus()
        {
            return Status.Authorized;
        }
    }

    internal class IDFAPlatformIOS : IDFAPlatform
    {
        const string IOS_ATTrackingManagerAuthorizationStatusNotDetermined = "0";
        const string IOS_ATTrackingManagerAuthorizationStatusRestricted = "1";
        const string IOS_ATTrackingManagerAuthorizationStatusDenied = "2";
        const string IOS_ATTrackingManagerAuthorizationStatusAuthorized = "3";
        const string IOS_CustomUnsupportedVersion = "UnsupportedVersion";

        RequestDelegate pending_request;
        IDFAPlatformIOSImpl impl;

        public void RequestTracking(RequestDelegate on_complete)
        {
            pending_request = on_complete;
            GetImpl().Request();
        }

        IDFAPlatformIOSImpl GetImpl()
        {
            if (impl != null)
                return impl;

            var impl_go = new GameObject();
            impl = impl_go.AddComponent<IDFAPlatformIOSImpl>();
            impl.OnNewAuthStatus += OnNewAuthStatus;

            impl_go.name = impl.GetType().Name;
            UnityEngine.Object.DontDestroyOnLoad(impl_go);

            return impl;
        }

        void OnNewAuthStatus(string os_status)
        {
            Status status = FromOSStatus(os_status);
            pending_request?.Invoke(status);
        }

        static Status FromOSStatus(string os_status)
        {
            if (os_status == IOS_ATTrackingManagerAuthorizationStatusNotDetermined)
                return Status.NotDetermined;

            if (os_status == IOS_ATTrackingManagerAuthorizationStatusRestricted)
                return Status.Restricted;

            if (os_status == IOS_ATTrackingManagerAuthorizationStatusDenied)
                return Status.Denied;

            if (os_status == IOS_ATTrackingManagerAuthorizationStatusAuthorized ||
                os_status == IOS_CustomUnsupportedVersion)
                return Status.Authorized;

            return Status.NotDetermined;
        }

        public Status GetCurrentStatus()
        {
            string os_status = GetImpl().GetCurrentStatus();
            return FromOSStatus(os_status);
        }
    }

    internal class IDFAPlatformIOSImpl : MonoBehaviour
    {
        public System.Action<string> OnNewAuthStatus;

        public void OnTrackingAuthorizationComplete(string status)
        {
            OnNewAuthStatus?.Invoke(status);
        }

        public void Request()
        {
#if UNITY_IOS
            IDFATrackingRequestAuthorization();
#endif
        }

        public string GetCurrentStatus()
        {
#if UNITY_IOS
            return IDFATRackingGetCurrentStatus();
#else
            return "0";
#endif

        }

#if UNITY_IOS
  [DllImport("__Internal")]
  private static extern void IDFATrackingRequestAuthorization();

  [DllImport("__Internal")]
  private static extern string IDFATRackingGetCurrentStatus();
#endif
    }
}