using System;
using System.Collections.Generic;

namespace OpenMacroBoard.SDK.Internals
{
    internal sealed class DeviceContextInternal : IDeviceContext
    {
        private readonly MergedDeviceListener mergedDeviceListener = new();
        private readonly List<IDisposable> disposeWithContext = new();
        private readonly List<KnownDeviceInternal> knownDevices = new();

        public DeviceContextInternal()
        {
            KnownDevices = knownDevices.AsReadOnly();

            DeviceStateReports = mergedDeviceListener;
            KnownDevices = mergedDeviceListener.KnownDevices;
        }

        public IReadOnlyList<IKnownDevice> KnownDevices { get; }
        public IObservable<DeviceStateReport> DeviceStateReports { get; }

        public void Dispose()
        {
            foreach (var disposable in disposeWithContext)
            {
                disposable.Dispose();
            }
        }

        public IDeviceContext AddListener(IObservable<DeviceStateReport> deviceListener)
        {
            return AddListener(deviceListener, true);
        }

        public IDeviceContext AddListener(IObservable<DeviceStateReport> deviceListener, bool disposeWithContext)
        {
            var subscription = deviceListener.Subscribe(mergedDeviceListener);
            this.disposeWithContext.Add(subscription);

            if (disposeWithContext && deviceListener is IDisposable disposableListener)
            {
                this.disposeWithContext.Add(disposableListener);
            }

            return this;
        }

        public IDeviceContext AddListener<TListener>()
            where TListener : IObservable<DeviceStateReport>, new()
        {
            var listener = new TListener();
            return AddListener(listener, true);
        }
    }
}