using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;

namespace TINK.Services
{
    /// <summary> Container of service objects (locks , geolocation, ...) where one service is active. </summary>
    /// <remarks> All service objects must be of different type. </remarks>
    public class ServicesContainerMutable<T>: IEnumerable<T>, INotifyPropertyChanged
    {
        private readonly Dictionary<string, T> serviceDict;

        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary> Constructs object on startup of app.</summary>
        /// <param name="services">Fixed list of service- objects .</param>
        /// <param name="activeName">LocksService name which is activated on startup of app.</param>
        public ServicesContainerMutable(
            IEnumerable<T> services,
            string activeName) 
        {
            serviceDict = services.Distinct().ToDictionary(x => x.GetType().FullName);

            if (!serviceDict.ContainsKey(activeName))
            {
                throw new ArgumentException($"Can not instantiate {typeof(T).Name}- object. Active lock service {activeName} must be contained in [{String.Join(",", serviceDict)}].");
            }

            Active = serviceDict[activeName];
        }

        /// <summary> Active locks service.</summary>
        public T Active { get; private set; }

        /// <summary> Sets a lock service as active locks service by name. </summary>
        /// <param name="active">Name of the new locks service.</param>
        public void SetActive(string active)
        {
            if (!serviceDict.ContainsKey(active))
            {
                throw new ArgumentException($"Can not set active lock service {active}. Service must be contained in [{String.Join(",", serviceDict)}].");
            }

            Active = serviceDict[active];

            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Active)));
        }

        public IEnumerator<T> GetEnumerator()
            => serviceDict.Values.GetEnumerator();

        IEnumerator IEnumerable.GetEnumerator()
            => serviceDict.Values.GetEnumerator();
    }
}