sharee.bike-App/TINKLib/ViewModel/FeesAndBikes/HelpContactViewModel.cs

using System.ComponentModel;
using Xamarin.Forms;
using TINK.Services.CopriApi.ServerUris;
using System;

namespace TINK.ViewModel.Contact
{
    public class HelpContactViewModel : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

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

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

        /// <summary> Constructs view model.</summary>
        /// <param name="isSiteCachingOn">Set of user permissions</param>
        /// <param name="resourceProvider">Delegate to get an an embedded html ressource. Used as fallback if download from web page does not work and cache is empty.</param>
        public HelpContactViewModel(
            string hostName,
            bool isSiteCachingOn,
            Func<string, string> resourceProvider)
        {
            HostName = hostName;
            IsSiteCachingOn = isSiteCachingOn;
            
            ResourceProvider = resourceProvider
                ?? throw new ArgumentException($"Can not instantiate {typeof(HelpContactViewModel)}-object. No ressource provider availalbe.");

        }

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

        /// <summary> Called when page is shown. </summary>
        public async void OnAppearing()
        {
            RentBikeText = new HtmlWebViewSource
            {
                Html = HostName.GetIsCopri()
                    ? ResourceProvider("HtmlResouces.V02.InfoRentBike.html")
                    : await ViewModelHelper.GetSource($"https://{HostName}/{CopriHelper.SHAREE_SILTEFOLDERNAME}/tariff_info_1.html", IsSiteCachingOn)                
            };

            TypesOfBikesText = new HtmlWebViewSource 
            {
                Html = HostName.GetIsCopri()
                    ? ResourceProvider("HtmlResouces.V02.InfoTypesOfBikes.html")
                    : await ViewModelHelper.GetSource($"https://{HostName}/{CopriHelper.SHAREE_SILTEFOLDERNAME}/bike_info.html", IsSiteCachingOn)                 
            };
        }

        private HtmlWebViewSource rentBikeText;

        private HtmlWebViewSource typesOfBikesText;

        public HtmlWebViewSource RentBikeText
        {
            get => rentBikeText;
            set
            {
                rentBikeText = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(RentBikeText)));
            }
        }

        public HtmlWebViewSource TypesOfBikesText
        {
            get => typesOfBikesText;
            set
            {
                typesOfBikesText = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(TypesOfBikesText)));
            }
        }
    }
}