CaritasPWA/Shared/Services/MasterDataService.cs

using CaritasPWA.Shared.Models;
using Microsoft.JSInterop;
using System;
using System.Threading.Tasks;

namespace CaritasPWA.Shared.Services {
    public class MasterDataService {

        private ILFBicycleRest _lFBicycleRest;
        private const string KeyNameColors = "colors";
        private const string KeyNameBcTypes = "bicycleTypes";

        private readonly IJSRuntime _jsRuntime;
        private bool _initializedColors;
        private bool _initializedBcTypes;
        private ColorItem[] _colors = new ColorItem[] { };
        private BicycleType[] _bicycleTypes = new BicycleType[] { };

        public ColorItem[] Colors {
            get => _colors;
            set => _colors = value;
        }

        public BicycleType[] BicycleTypes {
            get => _bicycleTypes;
            set => _bicycleTypes = value;
        }

        public event EventHandler Changed;

        public MasterDataService(IJSRuntime jsRuntime, ILFBicycleRest lFBicycleRest) {
            _jsRuntime = jsRuntime;
            _lFBicycleRest = lFBicycleRest;
        }

        public async Task SynchronizeMasterdata() {
            await SynchronizeColors();
            await SynchronizeBcTypes();
        }

        public async Task SynchronizeColors() {
            Colors = _lFBicycleRest.GetColors().ToArray();
            if (Colors != null && Colors.Length > 0) {
                await SaveColorsToStorage();
            };
        }

        public async Task SynchronizeBcTypes() {
            BicycleTypes = _lFBicycleRest.GetBicycleTypes().ToArray();
            if (BicycleTypes != null && BicycleTypes.Length > 0) {
                await SaveBcTypesToStorage();
            }
        }

        public async Task<ColorItem[]> GetColors() {
            ColorItem[] colors = await GetColorsFromStorage();
            Colors = (colors != null && colors.Length > 0) ? colors : Defaults.ColorItems;
            return Colors;
        }

        public async Task<BicycleType[]> GetBicycleTypes() {
            BicycleType[] bicycleTypes = await GetBicycleTypesFromStorage();
            BicycleTypes = (bicycleTypes != null && bicycleTypes.Length > 0) ? bicycleTypes : Defaults.BycicleTypes;
            return BicycleTypes;
        }

        private async ValueTask<ColorItem[]> GetColorsFromStorage() {

            // Register the Storage event handler. This handler calls OnStorageUpdated when the storage changed.
            // This way, you can reload the settings when another instance of the application (tab / window) save the settings
            if (!_initializedColors) {
                // Create a reference to the current object, so the JS function can call the public method "OnStorageUpdated"
                var reference = DotNetObjectReference.Create(this);
                await _jsRuntime.InvokeVoidAsync("BlazorRegisterStorageEvent", reference);
                _initializedColors = true;
            }

            // Read the JSON string that contains the data from the local storage
            ColorItem[] result;
            var str = await _jsRuntime.InvokeAsync<string>("BlazorGetLocalStorage", KeyNameColors);
            if (str != null) {
                result = System.Text.Json.JsonSerializer.Deserialize<ColorItem[]>(str) ?? new ColorItem[] { };
            } else {
                result = new ColorItem[] { };
            }
            _colors = result;
            return result;
        }

        private async ValueTask<BicycleType[]> GetBicycleTypesFromStorage() {

            // Register the Storage event handler. This handler calls OnStorageUpdated when the storage changed.
            // This way, you can reload the settings when another instance of the application (tab / window) save the settings
            if (!_initializedBcTypes) {
                // Create a reference to the current object, so the JS function can call the public method "OnStorageUpdated"
                var reference = DotNetObjectReference.Create(this);
                await _jsRuntime.InvokeVoidAsync("BlazorRegisterStorageEvent", reference);
                _initializedBcTypes = true;
            }

            // Read the JSON string that contains the data from the local storage
            BicycleType[] result;
            var str = await _jsRuntime.InvokeAsync<string>("BlazorGetLocalStorage", KeyNameBcTypes);
            if (str != null) {
                result = System.Text.Json.JsonSerializer.Deserialize<BicycleType[]>(str) ?? new BicycleType[] { };
            } else {
                result = new BicycleType[] { };
            }
            _bicycleTypes = result;
            return result;
        }

        private async Task SaveColorsToStorage() {
            var json = System.Text.Json.JsonSerializer.Serialize(_colors);
            await _jsRuntime.InvokeVoidAsync("BlazorSetLocalStorage", KeyNameColors, json);
        }

        private async Task SaveBcTypesToStorage() {
            var json = System.Text.Json.JsonSerializer.Serialize(_bicycleTypes);
            await _jsRuntime.InvokeVoidAsync("BlazorSetLocalStorage", KeyNameBcTypes, json);
        }

        // This method is called from BlazorRegisterStorageEvent when the storage changed
        [JSInvokable]
        public void OnStorageUpdated(string key) {
            // Reset the settings. The next call to Get will reload the data
            if (key == KeyNameColors) {
                _colors = null;
                Changed?.Invoke(this, EventArgs.Empty);
            } else if (key == KeyNameBcTypes) {
                _bicycleTypes = null;
                Changed?.Invoke(this, EventArgs.Empty);
            }
        }
    }
}