#if UGX_BRIDGE || UNITY_EDITOR
using System;
using Uigenx.Protocol;

namespace Uigenx.Bridge
{
    /// <summary>Reports the screen stack to the studio whenever it changes.</summary>
    public sealed class UgxScreenStateHandler : IDisposable
    {
        readonly UgxBridgeClient _client;
        UgxScreenManager _manager;
        bool _disposed;

        public UgxScreenStateHandler(UgxBridgeClient client)
        {
            _client = client ?? throw new ArgumentNullException(nameof(client));
            Rebind();
        }

        /// <summary>Main thread. Picks up a manager created after the bridge started.</summary>
        public void Tick()
        {
            if (_disposed || ReferenceEquals(_manager, UgxScreenManager.Instance)) return;
            Rebind();
            SendState();
        }

        public void SendState()
        {
            var state = new UgxScreenState();
            var manager = _manager;
            if (manager != null)
            {
                var stack = manager.Stack;
                for (int i = 0; i < stack.Count; i++)
                    state.Stack.Add(new UgxScreenStateEntry
                    {
                        Screen = stack[i].Key,
                        Layer = stack[i].Layer.ToWireName(),
                    });
            }
            _client.Send(UgxMessageTypes.ScreenState, state);
        }

        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;
            if (_manager != null) _manager.StackChanged -= SendState;
            _manager = null;
        }

        void Rebind()
        {
            if (_manager != null) _manager.StackChanged -= SendState;
            _manager = UgxScreenManager.Instance;
            if (_manager != null) _manager.StackChanged += SendState;
        }
    }
}
#endif