using System;
using System.ComponentModel;
using System.Threading.Tasks;
using System.Windows.Input;
using ShareeBike.View;
using ShareeBike.ViewModel.LegalInformation;
using Xamarin.Forms;

namespace ShareeBike.ViewModel.WhatsNew.Gtc
{
	public class GtcViewModel : INotifyPropertyChanged
	{
		/// <summary> Fired whenever a property changed.</summary>
		public event PropertyChangedEventHandler PropertyChanged;

		/// <summary> Holds the name of the host.</summary>
		private string HostName { get; }

		/// <summary> Holds value whether site caching is on or off.</summary>
		bool IsSiteCachingOn { get; }

		/// <summary> Constructs AGB view model</summary>
		/// <param name="isSiteCachingOn">Holds value whether site caching is on or off.</param>
		/// <param name="uiIsoLangugageName">Two letter ISO language name.</param>
		/// <param name="resourceProvider">Delegate to get embedded html resource. Used as fallback if download from web page does not work and cache is empty.</param>
		/// <param name="viewService">View service to close page.</param>
		public GtcViewModel(
			string hostName,
			bool isSiteCachingOn,
			Func<string, string> resourceProvider,
			IViewService viewService)
		{
			HostName = hostName;
			IsSiteCachingOn = isSiteCachingOn;

			ViewService = viewService
				?? throw new ArgumentException($"Can not instantiate {typeof(WhatsNewViewModel)}-object. No view available.");

			ResourceProvider = resourceProvider
				?? throw new ArgumentException($"Can not instantiate {typeof(WhatsNewViewModel)}-object. No resource provider centered.");
		}

		/// <summary> Gets the platfrom specific prefix. </summary>
		private Func<string, string> ResourceProvider { get; set; }

		/// <summary> Agb information text.</summary>
		private HtmlWebViewSource gtcHtml;

		/// <summary> Agb information text.</summary>
		public HtmlWebViewSource GtcHtml
		{
			get => gtcHtml;
			set
			{
				gtcHtml = value;
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(GtcHtml)));
			}
		}

		/// <summary> Called when page is shown. </summary>
		public async Task OnAppearing()
		{
			GtcHtml = await LegalInformationPageViewModel.GetGtc(HostName, "agbResourcePath", IsSiteCachingOn);
		}

		/// <summary> User clicks OK button.</summary>
		public ICommand OnOk
		{
			get
			{
				return new Command(async () => await ViewService.PopModalAsync());
			}
		}

		/// <summary> Reference to view service object.</summary>
		private IViewService ViewService;
	}
}