using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Threading.Tasks;
using System.Windows.Input;
using Plugin.Messaging;
using Serilog;
using TINK.Model.Station;
using TINK.MultilingualResources;
using TINK.View;
using Xamarin.Essentials;
using Xamarin.Forms;

namespace TINK.ViewModel.Info
{
	/// <summary> View model for contact page.</summary>
	public class ContactPageViewModel : INotifyPropertyChanged
	{
		/// <summary>
		/// Mail address for app related support.
		/// </summary>
		public const string APPSUPPORTMAILADDRESS = "hotline@sharee.bike";

		/// <summary> Reference on view service to show modal notifications and to perform navigation. </summary>
		private IViewService ViewService { get; }

		/// <summary> Station selected by user. </summary>
		private IStation SelectedStation { get; set; } = new NullStation();

		/// <summary> Holds the name of the app (sharee.bike, Mein konrad, ...)</summary>
		string AppFlavorName { get; }

		/// <summary> Holds a reference to the external trigger service. </summary>
		private Action OpenUrlInExternalBrowser { get; }

		Func<string> CreateAttachment { get; }

		/// <summary> Notifies view about changes. </summary>
		public event PropertyChangedEventHandler PropertyChanged;

		/// <summary> Constructs a contact page view model. </summary>
		/// <param name="appFlavorName">Holds the name of the app.</param>
		/// <param name="openUrlInExternalBrowser">Action to open an external browser.</param>
		/// <param name="viewService">View service to notify user.</param>
		public ContactPageViewModel(
			string appFlavorName,
			Func<string> createAttachment,
			Action openUrlInExternalBrowser,
			IViewService viewService)
		{
			AppFlavorName = !string.IsNullOrEmpty(appFlavorName)
				? appFlavorName
				: throw new ArgumentException("Can not instantiate contact page view model- object. No app name availalbe.");

			CreateAttachment = createAttachment
				?? throw new ArgumentException("Can not instantiate contact page view model- object. No create attachment provider available.");

			ViewService = viewService
				?? throw new ArgumentException("Can not instantiate contact page view model- object. No user view service available.");

			OpenUrlInExternalBrowser = openUrlInExternalBrowser
				?? throw new ArgumentException("Can not instantiate contact page view model- object. No user external browse service available.");
		}

		/// <summary> Is invoked when page is shown. </summary>
		public async Task OnAppearing(
			IStation selectedStation)
		{
			if (SelectedStation?.Id == selectedStation?.Id)
			{
				// Nothing to do because either both are null or of same id.
				return;
			}

			SelectedStation = selectedStation;

			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(MailAddressText)));
			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(OfficeHoursText)));
			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(PhoneNumberText)));
			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ProviderNameText)));
			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsOperatorInfoAvaliable)));

			await Task.CompletedTask;
		}

		/// <summary> Command object to bind mail button to view model. </summary>
		public ICommand OnMailToOperatorRequest
			=> new Command(
					async () => await DoSendMailToOperator(),
					() => IsSendMailAvailable);

		/// <summary> Command object to bind mail app releated button to model. </summary>
		public ICommand OnMailAppRelatedRequest
			=> new Command(
					async () => await DoSendMailAppRelated(),
					() => IsSendMailAvailable);

		/// <summary>True if sending mail is possible.</summary>
		public bool IsSendMailAvailable =>
			CrossMessaging.Current.EmailMessenger.CanSendEmail;


		/// <summary>cTrue if doing a phone call is possible.</summary>
		public bool IsDoPhoncallAvailable
			=> CrossMessaging.Current.PhoneDialer.CanMakePhoneCall;

		/// <summary>Holds the mail address to mail to.</summary>
		public string MailAddressText
			=> SelectedStation?.OperatorData?.MailAddressText ?? string.Empty;

		/// <summary>Holds the mail address to send mail to.</summary>
		public string PhoneNumberText
			=> SelectedStation?.OperatorData?.PhoneNumberText ?? string.Empty;

		/// <summary>Holds the mail address to send mail to.</summary>
		public string OfficeHoursText
			=> SelectedStation?.OperatorData?.Hours ?? string.Empty;

		/// <summary> Gets whether any operator support info is avaliable. </summary>
		public bool IsOperatorInfoAvaliable
			=> MailAddressText.Length > 0 || PhoneNumberText.Length > 0;

		/// <returns> Returns true if eithe mail was sent or if no mailer available.</returns>
		public async Task DoSendMailToOperator()
		{
			try
			{
				if (!IsSendMailAvailable)
				{
					// Nothing to do because email can not be sent.
					return;
				}

				// Ask whether mail is operator or app specific.
				var operatorRelatedMail = await ViewService.DisplayAlert(
						AppResources.QuestionTitle,
						string.Format(AppResources.QuestionSupportmailSubject, AppFlavorName),
						string.Format(AppResources.QuestionSupportmailAnswerOperator, AppFlavorName),
						string.Format(AppResources.QuestionSupportmailAnswerApp, AppFlavorName));

				if (operatorRelatedMail)
				{
					// Send operator related support mail to operator.
					await Email.ComposeAsync(new EmailMessage
					{
						To = new List<string> { MailAddressText },
						Subject = string.Format(AppResources.SupportmailSubjectOperatormail, AppFlavorName)
					});
					return;
				}

				// Send app-related related support mail to operator.
				await Email.ComposeAsync(new EmailMessage
				{
					To = new List<string> { MailAddressText },
					Cc = APPSUPPORTMAILADDRESS.ToUpper() != MailAddressText.ToUpper() ? new List<string> { APPSUPPORTMAILADDRESS } : new List<string>(),
					Subject = string.Format(AppResources.SupportmailSubjectAppmail, AppFlavorName)
				});

				return;
			}
			catch (Exception exception)
			{
				Log.Error("An unexpected error occurred sending mail to operator. {@Exception}", exception);
				await ViewService.DisplayAdvancedAlert(
					AppResources.MessageWaring,
					AppResources.ErrorSupportmailMailingFailed,
					exception.Message,
					AppResources.MessageAnswerOk);
				return;
			}
		}

		/// <summary> Request to send a app related mail. </summary>
		public async Task DoSendMailAppRelated()
		{
			try
			{
				// Ask for permission to append diagnostics.    
				var appendFile = false;
				appendFile = await ViewService.DisplayAlert(
					AppResources.QuestionSupportmailTitle,
					AppResources.QuestionSupportmailAttachment,
					AppResources.QuestionAnswerYes,
					AppResources.QuestionSupportmailAnswerNo);

				var message = new EmailMessage
				{
					To = new List<string> { APPSUPPORTMAILADDRESS },
					Subject = string.Format(AppResources.SupportmailSubjectAppmail, AppFlavorName)
				};

				if (appendFile == false)
				{
					// Send without attachment
					await Email.ComposeAsync(message);
					return;
				}

				// Send with attachment.
				var logFileName = string.Empty;
				try
				{
					logFileName = CreateAttachment();
				}
				catch (Exception exception)
				{
					await ViewService.DisplayAdvancedAlert(
						AppResources.MessageWaring,
						AppResources.ErrorSupportmailCreateAttachment,
						exception.Message,
						AppResources.MessageAnswerOk);

					Log.ForContext<ContactPageViewModel>().Error("An error occurred creating attachment for app mail. {@Exception)", exception);
				}

				if (!string.IsNullOrEmpty(logFileName))
				{
					message.Attachments.Add(new Xamarin.Essentials.EmailAttachment(logFileName));
				}

				// Send a tink app related mail
				await Email.ComposeAsync(message);
			}
			catch (Exception exception)
			{
				Log.ForContext<ContactPageViewModel>().Error("An unexpected error occurred sending mail. {@Exception}", exception);
				await ViewService.DisplayAdvancedAlert(
					AppResources.MessageWaring,
					AppResources.ErrorSupportmailMailingFailed,
					exception.Message,
					AppResources.MessageAnswerOk);
				return;
			}
		}

		/// <summary> Command object to bind login button to view model. </summary>
		public ICommand OnSelectStationRequest
#if USEFLYOUT
                => new Xamarin.Forms.Command(() => OpenSelectStationPage());
#else
				=> new Xamarin.Forms.Command(async () => await OpenSelectStationPageAsync());
#endif

		/// <summary> Opens login page. </summary>
#if USEFLYOUT
        public void OpenSelectStationPage()
#else
		public async Task OpenSelectStationPageAsync()
#endif
		{
			try
			{
				// Switch to map page

#if USEFLYOUT
                ViewService.PushAsync(ViewTypes.SelectStationPage);
#else
				await ViewService.PushAsync(ViewTypes.SelectStationPage);
#endif
			}
			catch (Exception p_oException)
			{
				Log.Error("Ein unerwarteter Fehler ist in der Klasse ContactPageViewModel aufgetreten. Kontext: Klick auf Hinweistext auf Station N- seite ohne Anmeldung. {@Exception}", p_oException);
				return;
			}
		}


		/// <summary> Command object to bind phone call button. </summary>
		public ICommand OnPhoneRequest
			=> new Command(
					async () => await DoPhoneCall(),
					() => IsDoPhoncallAvailable);

		/// <summary> Request to do a phone call. </summary>
		public async Task DoPhoneCall()
		{
			try
			{
				// Make Phone Call
				if (IsDoPhoncallAvailable)
				{
					CrossMessaging.Current.PhoneDialer.MakePhoneCall(PhoneNumberText);
				}
			}
			catch (Exception exception)
			{
				Log.Error("An unexpected error occurred doing a phone call. {@Exception}", exception);
				await ViewService.DisplayAdvancedAlert(
					AppResources.MessageWaring,
					AppResources.ErrorSupportmailPhoningFailed,
					exception.Message,
					AppResources.MessageAnswerOk);
				return;
			}
		}



		/// <summary> Text providing mail address and possilbe reasons to contact. </summary>
		public string ProviderNameText
			=> string.Format("Betreiber: {0}", SelectedStation?.OperatorData?.Name)
;
		/// <summary> Text providing mail address and possilbe reasons to contact. </summary>
		public FormattedString MailAddressAndMotivationsText
		{
			get
			{
				var hint = new FormattedString();
				hint.Spans.Add(new Span { Text = AppResources.MessageContactMail });
				return hint;
			}
		}

		/// <summary> Invitation to rate app.</summary>
		public FormattedString LikeTinkApp
		{
			get
			{
				var hint = new FormattedString();
				hint.Spans.Add(new Span { Text = string.Format(AppResources.MessageRateMail, AppFlavorName) });
				return hint;
			}
		}

		/// <summary> User clicks rate button.</summary>
		public ICommand OnRateRequest
			=> new Command(() => RegisterRequest());

		/// <summary> Opens login page.</summary>
		public void RegisterRequest()
		{
			try
			{
				OpenUrlInExternalBrowser();
			}
			catch (Exception p_oException)
			{
				Log.Error("Ein unerwarteter Fehler ist auf der Login Seite beim Öffnen eines Browsers, Seite {url}, aufgetreten. {@Exception}", p_oException);
				return;
			}
		}

		/// <summary> Invitation to rate app.</summary>
		public FormattedString PhoneContactText
		{
			get
			{
				var l_oHint = new FormattedString();
				l_oHint.Spans.Add(new Span
				{
					Text = string.Format(AppResources.MessagePhoneMail, AppFlavorName) + $"{(OfficeHoursText.Length > 0 ? $" {OfficeHoursText}" : string.Empty)}"
				});
				return l_oHint;
			}
		}
	}
}