using UnityEngine;
using UnityEngine.XR.ARFoundation;

#if UNITY_IOS && !UNITY_EDITOR
using Unity.iOS.Multipeer;
using UnityEngine.XR.ARKit;
#endif

[RequireComponent(typeof(ARSession))]
public class CollaborativeSession : MonoBehaviour
{
    [SerializeField]
    [Tooltip("The name for this network service. It should be 15 characters or less and can contain ASCII, lowercase letters, numbers, and hyphens.")]
    string m_ServiceType;

    /// <summary>
    /// The name for this network service.
    /// See <a href="https://developer.apple.com/documentation/multipeerconnectivity/mcnearbyserviceadvertiser">MCNearbyServiceAdvertiser</a>
    /// for the purpose of and restrictions on this name.
    /// </summary>
    public string serviceType
    {
        get { return m_ServiceType; }
        set { m_ServiceType = value; }
    }

    ARSession m_ARSession;

    void DisableNotSupported(string reason)
    {
        enabled = false;
        Logger.Log(reason);
    }

    void OnEnable()
    {
#if UNITY_IOS && !UNITY_EDITOR
        var subsystem = GetSubsystem();
        if (!ARKitSessionSubsystem.supportsCollaboration || subsystem == null)
        {
            DisableNotSupported("Collaborative sessions require iOS 13.");
            return;
        }

        subsystem.collaborationEnabled = true;
        m_MCSession.Enabled = true;
#else
        DisableNotSupported("Collaborative sessions are an ARKit 3 feature; This platform does not support them.");
#endif
    }

#if UNITY_IOS && !UNITY_EDITOR
    MCSession m_MCSession;

    ARKitSessionSubsystem GetSubsystem()
    {
        if (m_ARSession == null)
            return null;

        return m_ARSession.subsystem as ARKitSessionSubsystem;
    }

    void Awake()
    {
        m_ARSession = GetComponent<ARSession>();
        m_MCSession = new MCSession(SystemInfo.deviceName, m_ServiceType);
    }

    void OnDisable()
    {
        m_MCSession.Enabled = false;

        var subsystem = GetSubsystem();
        if (subsystem != null)
            subsystem.collaborationEnabled = false;
    }

    void Update()
    {
        var subsystem = GetSubsystem();
        if (subsystem == null)
            return;

        // Check for new collaboration data
        while (subsystem.collaborationDataCount > 0)
        {
            using (var collaborationData = subsystem.DequeueCollaborationData())
            {
                CollaborationNetworkingIndicator.NotifyHasCollaborationData();

                if (m_MCSession.ConnectedPeerCount == 0)
                    continue;

                using (var serializedData = collaborationData.ToSerialized())
                using (var data = NSData.CreateWithBytesNoCopy(serializedData.bytes))
                {
                    m_MCSession.SendToAllPeers(data, collaborationData.priority == ARCollaborationDataPriority.Critical
                        ? MCSessionSendDataMode.Reliable
                        : MCSessionSendDataMode.Unreliable);

                    CollaborationNetworkingIndicator.NotifyOutgoingDataSent();

                    // Only log 'critical' data as 'optional' data tends to come every frame
                    if (collaborationData.priority == ARCollaborationDataPriority.Critical)
                    {
                        Logger.Log($"Sent {data.Length} bytes of collaboration data.");
                    }
                }
            }
        }

        // Check for incoming data
        while (m_MCSession.ReceivedDataQueueSize > 0)
        {
            CollaborationNetworkingIndicator.NotifyIncomingDataReceived();

            using (var data = m_MCSession.DequeueReceivedData())
            using (var collaborationData = new ARCollaborationData(data.Bytes))
            {
                if (collaborationData.valid)
                {
                    subsystem.UpdateWithCollaborationData(collaborationData);
                    if (collaborationData.priority == ARCollaborationDataPriority.Critical)
                    {
                        Logger.Log($"Received {data.Bytes.Length} bytes of collaboration data.");
                    }
                }
                else
                {
                    Logger.Log($"Received {data.Bytes.Length} bytes from remote, but the collaboration data was not valid.");
                }
            }
        }
    }

    void OnDestroy()
    {
        m_MCSession.Dispose();
    }
#endif
}