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

namespace TINK.ViewModel.Settings
{
    /// <summary> ViewModel for an active service plus a list of services which are not active.</summary>
    /// <remarks> 
    /// Example for services are lock services, geolocation services, ..., 
    /// </remarks>
    public class ServicesViewModel : INotifyPropertyChanged
    {
        /// <summary> Active service. </summary>
        private string active;

        /// <summary> Holds the dictionary which maps services to service display texts.</summary>
        private IDictionary<string, string> ServiceToText { get; }

        /// <summary> Holds the dictionary which maps service display texts to services.</summary>
        private IDictionary<string, string> TextToService { get; }

        /// <summary>Constructs view model ensuring consistency. </summary>
        /// <param name="services">List of available services.</param>
        /// <param name="serviceToText"> Dictionary holding display text for services as values.</param>
        /// <param name="active">Active service.</param>
        public ServicesViewModel(
            IEnumerable<string> services,
            IDictionary<string, string> serviceToText,
            string active)
        {
            if (!services.Contains(active))
                throw new ArgumentException($"Can not instantiate {typeof(ServicesViewModel).Name}- object. Active lock service {active} must be contained in [{String.Join(",", services)}].");

            ServiceToText = services.Distinct().ToDictionary(
                x => x,
                x => serviceToText.ContainsKey(x) ? serviceToText[x] : x);

            TextToService = ServiceToText.ToDictionary(x => x.Value, x => x.Key);
            Active = active;
        }

        /// <summary> Fired whenever active service changes.</summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary> Holds active service.</summary>
        public string Active
        {
            get => active;
            set
            {
                if (active == value)
                    return;

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

        /// <summary> List of display texts of services.</summary>
        public IList<string> ServicesTextList  => ServiceToText.Select(x => x.Value).OrderBy(x => x).ToList(); 

        /// <summary> Active locks service.</summary>
        public string ActiveText
        {
            get => ServiceToText[Active];
            set
            {
                if (!TextToService.ContainsKey(value))
                {
                    Log.ForContext<ServicesViewModel>().Error($"Can not set service {value} to services view model. List of services {{{string.Join(";", TextToService)}}} does not hold machting element.");
                    throw new ArgumentException($"Can not set service {value} to services view model. List of services {{{string.Join(";", TextToService)}}} does not hold machting element.");
                }

                Active = TextToService[value];
            }
        }
    }
}