using System.Linq;
using Serilog;
using ShareeBike.Model.Device;
using Xamarin.Forms;

namespace ShareeBike.View
{
	public static class WebViewHelper
	{
		/// <summary> Rountes request to browser if internal URI was detected or displays link in app otherwise. </summary>
		/// <param name="sender">Sender of the event.</param>
		/// <param name="eventArgs">Event arguments</param>
		public static void SelectDisplayTarget(object sender, WebNavigatingEventArgs eventArgs)
		{
			if (!eventArgs.Url.ToUpper().StartsWith("HTTP"))
			{
				// An internal link was detected.
				// Stay inside WebView
				eventArgs.Cancel = false;
				return;
			}

			// Do not navigate outside the document on web view.
			eventArgs.Cancel = true;
			// Open external link in browser.
			DependencyService.Get<IExternalBrowserService>().OpenUrl(eventArgs.Url);
		}

		/// <summary> Routes request to broswer to download pdf- documents or displays link in app otherwise. </summary>
		/// <param name="sender">Sender of the event.</param>
		/// <param name="eventArgs">Event arguments</param>
		public static void SetBusyAndDisplayOrDownload(object sender, WebNavigatingEventArgs eventArgs)
		{
			if (!eventArgs.Url.ToUpper().EndsWith(".PDF"))
			{
				// Stay inside web view except for downloading pdf- files.
				SetBusy(sender);
				eventArgs.Cancel = false;
				return;
			}

			// Do not navigate outside the document on web view.
			eventArgs.Cancel = true;
			// Open external link in browser.
			DependencyService.Get<IExternalBrowserService>().OpenUrl(eventArgs.Url);
		}

		/// <summary>
		/// Disables WebView and shows ActivityIndicator.
		/// </summary>
		/// <remarks>
		/// Prerequisites: Both WebView and ActivityInicator must be located on the same Grid object.
		/// </remarks>
		/// <param name="sender"></param>
		private static void SetBusy(object sender)
		{
			if (!(sender is WebView webView))
			{
				// Nothing to do if sender is not a web view.
				Log.Error($"Unexpected call of {nameof(SetBusy)} detected. Argument must not be of type {sender.GetType()}.");
				return;
			}

			if (!(webView.Parent is Grid grid))
			{
				// Nothing to do if web view is not located on grid.
				Log.Error($"Unexpected call of {nameof(SetBusy)} detected. Parent of argument must not be of type {webView.Parent.GetType()}.");
				return;
			}

			grid.IsEnabled = false;

			var indicator = grid.Children.OfType<ActivityIndicator>().FirstOrDefault();
			if (indicator == null)
			{
				// Nothing to do if there is not activity indicator.
				Log.Error($"Unexpected call of {nameof(SetBusy)} detected. No activity indicator found.");
				return;
			}

			indicator.IsVisible = true;
			indicator.IsRunning = true;
		}

		/// <summary>
		/// Enables WebView and hides ActivityIndicator and sets error text to WebView in case an error occurred.
		/// </summary>
		/// <remarks>
		/// Prerequisites: Both WebView and ActivityInicator must be located on the same Grid object.
		/// </remarks>
		/// <param name="htmlErrorMessage">HTML showing an error message.</param>
		public static void SetIdleAndHandleError(
			object sender,
			WebNavigatedEventArgs eventArgs,
			string htmlErrorMessage)
		{
			if (!(sender is WebView webView))
			{
				// Nothing to do if sender is not a web view.
				Log.Error($"Unexpected call of {nameof(SetIdleAndHandleError)} detected. Argument must not be of type {sender.GetType()}.");
				return;
			}

			if (!(webView.Parent is Grid grid))
			{
				// Nothing to do if web view is not located on grid.
				Log.Error($"Unexpected call of {nameof(SetIdleAndHandleError)} detected. Parent of argument must not be of type {webView.Parent.GetType()}.");
				return;
			}

			var indicator = grid.Children.OfType<ActivityIndicator>().FirstOrDefault();
			if (indicator == null)
			{
				// Nothing to do if there is not activity indicator.
				Log.Error($"Unexpected call of {nameof(SetIdleAndHandleError)} detected. No activity indicator found.");
			}

			if (eventArgs.Result == WebNavigationResult.Success)
			{
				// Uri could be loaded successfully.
				grid.IsEnabled = true;
				if (indicator != null)
				{
					indicator.IsVisible = false;
					indicator.IsRunning = false;
				}
				return;
			}

			// Navigation failed.
			Log.Error("Navigation did not succeed.{@Event}{@Sender}", eventArgs, sender);
			webView.Source = new HtmlWebViewSource
			{
				Html = !string.IsNullOrEmpty(htmlErrorMessage) ? htmlErrorMessage : $"Navigation to {eventArgs.Url} failed."
			};

			grid.IsEnabled = true;
			if (indicator != null)
			{
				indicator.IsVisible = false;
				indicator.IsRunning = false;
			}
		}

		/// <summary>
		/// Sets error text to WebView in case an error occurred.
		/// </summary>
		/// <param name="htmlErrorMessage">HTML showing an error message.</param>
		public static void HandleError(
			object sender,
			WebNavigatedEventArgs eventArgs,
			string htmlErrorMessage)
		{
			if (eventArgs.Result == WebNavigationResult.Success)
			{
				// Uri could be loaded successfully.
				return;
			}

			if (!(sender is WebView webView))
			{
				// Nothing to do if sender is not a web view.
				Log.Error($"Unexpected call of {nameof(HandleError)} detected. Argument must not be of type {sender.GetType()}.");
				return;
			}

			// Navigation failed.
			Log.Error("Navigation did not succeed.{@Event}{@Sender}", eventArgs, sender);
			webView.Source = new HtmlWebViewSource
			{
				Html = !string.IsNullOrEmpty(htmlErrorMessage) ? htmlErrorMessage : $"Navigation to {eventArgs.Url} failed."
			};
		}
	}
}