Add Google OAuth authentication with configurable authorized emails (#29)

* Initial plan

* Add Google authentication with authorized email configuration

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Complete Google authentication implementation with documentation

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix CORS error by removing [Authorize] from auth user endpoint

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Add authorization attribute to ConfigurationController for security

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix JavaScript error in login button by correcting window.location.href usage

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix Google OAuth redirect URI configuration to resolve authentication error

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix OAuth state validation error by specifying authentication scheme in callback

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix OAuth state validation error by improving authentication configuration

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix authentication setup documentation with correct redirect URI

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Fix navigation buttons overlapping with authentication header

Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>

* Remove unused unsing

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: clayschaad <11883505+clayschaad@users.noreply.github.com>
Co-authored-by: Claudio Schaad <clayschaad@users.noreply.github.com>
Co-authored-by: Claudio Schaad <c.schaad@pog.ch>

Client/Pages/Index.razor.css

@@ -1,7 +1,7 @@
 /* Top navigation buttons */
 .top-nav-buttons {
     position: fixed;
-    top: 0;
+    top: 60px;
     right: 24px;
     display: flex;
     gap: 10px;

Client/Program.cs

@@ -1,3 +1,4 @@
+using Microsoft.AspNetCore.Components.Authorization;
 using Microsoft.AspNetCore.Components.Web;
 using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
 using ShiftScheduler.Client;
@@ -7,5 +8,7 @@ builder.RootComponents.Add<App>("#app");
 builder.RootComponents.Add<HeadOutlet>("head::after");
 
 builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
+builder.Services.AddAuthorizationCore();
+builder.Services.AddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
 
 await builder.Build().RunAsync();

Client/ServerAuthenticationStateProvider.cs

@@ -0,0 +1,55 @@
+using Microsoft.AspNetCore.Components.Authorization;
+using System.Net.Http.Json;
+using System.Security.Claims;
+
+namespace ShiftScheduler.Client
+{
+    public class ServerAuthenticationStateProvider : AuthenticationStateProvider
+    {
+        private readonly HttpClient _httpClient;
+
+        public ServerAuthenticationStateProvider(HttpClient httpClient)
+        {
+            _httpClient = httpClient;
+        }
+
+        public override async Task<AuthenticationState> GetAuthenticationStateAsync()
+        {
+            try
+            {
+                var userInfo = await _httpClient.GetFromJsonAsync<UserInfo>("api/auth/user");
+                
+                if (userInfo?.IsAuthenticated == true && !string.IsNullOrEmpty(userInfo.Email))
+                {
+                    var claims = new List<Claim>
+                    {
+                        new Claim(ClaimTypes.Name, userInfo.Email),
+                        new Claim(ClaimTypes.Email, userInfo.Email)
+                    };
+
+                    var identity = new ClaimsIdentity(claims, "Server authentication");
+                    var user = new ClaimsPrincipal(identity);
+
+                    return new AuthenticationState(user);
+                }
+            }
+            catch (HttpRequestException)
+            {
+                // User is not authenticated
+            }
+
+            return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
+        }
+
+        public void NotifyAuthenticationStateChanged()
+        {
+            NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
+        }
+    }
+
+    public class UserInfo
+    {
+        public string? Email { get; set; }
+        public bool IsAuthenticated { get; set; }
+    }
+}

Client/Shared/AuthHeader.razor

@@ -0,0 +1,32 @@
+@inject HttpClient Http
+@inject IJSRuntime JSRuntime
+
+<div class="auth-header">
+    <div class="user-info">
+        Welcome, @Email
+    </div>
+    <button class="btn btn-outline-danger logout-btn" @onclick="Logout">
+        Sign Out
+    </button>
+</div>
+
+@code {
+    [Parameter] public string Email { get; set; } = string.Empty;
+    [Parameter] public EventCallback OnLogout { get; set; }
+
+    private async Task Logout()
+    {
+        try
+        {
+            await Http.PostAsync("api/auth/logout", null);
+        }
+        catch (Exception)
+        {
+            // Ignore errors, just redirect
+        }
+        finally
+        {
+            await JSRuntime.InvokeVoidAsync("window.location.reload");
+        }
+    }
+}

Client/Shared/AuthHeader.razor.css

@@ -0,0 +1,19 @@
+.auth-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 10px 20px;
+    background-color: #f8f9fa;
+    border-bottom: 1px solid #dee2e6;
+    margin-bottom: 20px;
+}
+
+.user-info {
+    font-weight: 500;
+    color: #495057;
+}
+
+.logout-btn {
+    padding: 5px 15px;
+    font-size: 14px;
+}

Client/Shared/LoginDisplay.razor

@@ -0,0 +1,29 @@
+@inject IJSRuntime JSRuntime
+
+<div class="login-container">
+    <div class="login-card">
+        <h2>Welcome to Shift Scheduler</h2>
+        <p>Please sign in with your Google account to access the application.</p>
+        
+        @if (!string.IsNullOrEmpty(ErrorMessage))
+        {
+            <div class="alert alert-danger">
+                @ErrorMessage
+            </div>
+        }
+        
+        <button class="btn btn-primary login-btn" @onclick="Login">
+            <span class="google-icon">🔐</span>
+            Sign in with Google
+        </button>
+    </div>
+</div>
+
+@code {
+    [Parameter] public string? ErrorMessage { get; set; }
+
+    private async Task Login()
+    {
+        await JSRuntime.InvokeVoidAsync("eval", "window.location.href = '/api/auth/login'");
+    }
+}

Client/Shared/LoginDisplay.razor.css

@@ -0,0 +1,63 @@
+.login-container {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    min-height: 80vh;
+    padding: 20px;
+}
+
+.login-card {
+    background: white;
+    border: 1px solid #ddd;
+    border-radius: 8px;
+    padding: 30px;
+    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
+    text-align: center;
+    max-width: 400px;
+    width: 100%;
+}
+
+.login-card h2 {
+    color: #333;
+    margin-bottom: 15px;
+}
+
+.login-card p {
+    color: #666;
+    margin-bottom: 25px;
+}
+
+.login-btn {
+    background-color: #4285f4;
+    color: white;
+    border: none;
+    padding: 12px 24px;
+    border-radius: 4px;
+    font-size: 16px;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 10px;
+    width: 100%;
+}
+
+.login-btn:hover {
+    background-color: #3367d6;
+}
+
+.google-icon {
+    font-size: 18px;
+}
+
+.alert {
+    padding: 10px;
+    margin-bottom: 20px;
+    border-radius: 4px;
+}
+
+.alert-danger {
+    background-color: #f8d7da;
+    color: #721c24;
+    border: 1px solid #f5c6cb;
+}

Client/Shared/MainLayout.razor

@@ -1,9 +1,33 @@
 @inherits LayoutComponentBase
+@inject IJSRuntime JSRuntime
 
 <div class="page">
     <main>
+        <CascadingAuthenticationState>
+            <AuthorizeView>
+                <Authorized>
+                    <AuthHeader Email="@GetEmailFromContext(context)" />
                     <article class="content px-4">
                         @Body
                     </article>
+                </Authorized>
+                <NotAuthorized>
+                    <LoginDisplay ErrorMessage="@GetErrorMessage()" />
+                </NotAuthorized>
+            </AuthorizeView>
+        </CascadingAuthenticationState>
     </main>
 </div>
+
+@code {
+    private string GetEmailFromContext(AuthenticationState authState)
+    {
+        return authState.User?.FindFirst(System.Security.Claims.ClaimTypes.Email)?.Value ?? "Unknown";
+    }
+    
+    private string GetErrorMessage()
+    {
+        // Get error message from URL query parameters
+        return "";  // We'll handle this through JS if needed
+    }
+}

Client/ShiftScheduler.Client.csproj

@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="9.0.8" />
+    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Authentication" Version="9.0.8" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="9.0.8" PrivateAssets="all" />
   </ItemGroup>
 

Client/_Imports.razor

@@ -5,6 +5,7 @@
 @using Microsoft.AspNetCore.Components.Web
 @using Microsoft.AspNetCore.Components.Web.Virtualization
 @using Microsoft.AspNetCore.Components.WebAssembly.Http
+@using Microsoft.AspNetCore.Components.Authorization
 @using Microsoft.JSInterop
 @using ShiftScheduler.Client
 @using ShiftScheduler.Client.Shared

Server/Controllers/AuthController.cs

@@ -0,0 +1,55 @@
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Google;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using System.Security.Claims;
+
+namespace ShiftScheduler.Server.Controllers
+{
+    [ApiController]
+    [Route("api/[controller]")]
+    public class AuthController : ControllerBase
+    {
+        private readonly List<string> _authorizedEmails;
+
+        public AuthController(List<string> authorizedEmails)
+        {
+            _authorizedEmails = authorizedEmails;
+        }
+
+        [HttpGet("login")]
+        public IActionResult Login()
+        {
+            return Challenge(new AuthenticationProperties
+            {
+                RedirectUri = "/"
+            }, GoogleDefaults.AuthenticationScheme);
+        }
+
+        [HttpPost("logout")]
+        [Authorize]
+        public async Task<IActionResult> Logout()
+        {
+            await HttpContext.SignOutAsync();
+            return Ok();
+        }
+
+        [HttpGet("user")]
+        public IActionResult GetUser()
+        {
+            if (User.Identity?.IsAuthenticated == true)
+            {
+                var emailClaim = User.FindFirst(ClaimTypes.Email) ??
+                               User.FindFirst("email");
+                
+                // Verify the user is in the authorized emails list
+                if (emailClaim?.Value != null && _authorizedEmails.Contains(emailClaim.Value))
+                {
+                    return Ok(new { Email = emailClaim.Value, IsAuthenticated = true });
+                }
+            }
+            
+            return Ok(new { Email = (string?)null, IsAuthenticated = false });
+        }
+    }
+}

Server/Controllers/ConfigurationController.cs

@@ -1,3 +1,4 @@
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using ShiftScheduler.Services;
 using ShiftScheduler.Shared;
@@ -7,6 +8,7 @@ namespace ShiftScheduler.Server.Controllers
 {
     [ApiController]
     [Route("api/[controller]")]
+    [Authorize(Policy = "AllowedEmails")]
     public class ConfigurationController : ControllerBase
     {
         private readonly IConfigurationService _configurationService;

Server/Controllers/ShiftController.cs

@@ -1,3 +1,4 @@
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using ShiftScheduler.Services;
 using ShiftScheduler.Shared;
@@ -6,6 +7,7 @@ namespace ShiftScheduler.Server.Controllers
 {
     [ApiController]
     [Route("api/[controller]")]
+    [Authorize(Policy = "AllowedEmails")]
     public class ShiftController : ControllerBase
     {
         private readonly IcsExportService _icsService;

Server/Program.cs

@@ -1,3 +1,7 @@
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Authentication.Google;
+using Microsoft.AspNetCore.Authorization;
+using System.Security.Claims;
 using ShiftScheduler.Services;
 using ShiftScheduler.Shared;
 
@@ -6,6 +10,7 @@ var builder = WebApplication.CreateBuilder(args);
 // Load configurations from appsettings.json
 var shifts = builder.Configuration.GetSection("Shifts").Get<List<Shift>>() ?? new();
 var transportConfig = builder.Configuration.GetSection("Transport").Get<TransportConfiguration>() ?? new();
+var authorizedEmails = builder.Configuration.GetSection("Authentication:AuthorizedEmails").Get<List<string>>() ?? new();
 
 // Create application configuration
 var appConfiguration = new ApplicationConfiguration
@@ -15,6 +20,7 @@ var appConfiguration = new ApplicationConfiguration
 };
 
 // Register services
+builder.Services.AddSingleton(authorizedEmails);
 builder.Services.AddSingleton<IConfigurationService>(new ConfigurationService(appConfiguration));
 builder.Services.AddMemoryCache();
 builder.Services.AddHttpClient<TransportApiService>();
@@ -23,6 +29,60 @@ builder.Services.AddSingleton<PdfExportService>();
 builder.Services.AddSingleton<ITransportApiService, TransportApiService>();
 builder.Services.AddSingleton<ITransportService, TransportService>();
 
+// Configure authentication
+builder.Services.AddAuthentication(options =>
+{
+    options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
+    options.DefaultChallengeScheme = GoogleDefaults.AuthenticationScheme;
+})
+.AddCookie(options =>
+{
+    options.LoginPath = "/api/auth/login";
+    options.LogoutPath = "/api/auth/logout";
+    options.AccessDeniedPath = "/";
+    options.ExpireTimeSpan = TimeSpan.FromDays(7);
+    options.SlidingExpiration = true;
+    options.Cookie.SameSite = SameSiteMode.Lax;
+    options.Cookie.SecurePolicy = CookieSecurePolicy.SameAsRequest;
+})
+.AddGoogle(googleOptions =>
+{
+    googleOptions.ClientId = builder.Configuration["Authentication:Google:ClientId"] ?? "";
+    googleOptions.ClientSecret = builder.Configuration["Authentication:Google:ClientSecret"] ?? "";
+    googleOptions.CallbackPath = "/signin-google";
+    googleOptions.SaveTokens = true;
+    googleOptions.Events.OnTicketReceived = async context =>
+    {
+        var emailClaim = context.Principal?.FindFirst(ClaimTypes.Email) ??
+                        context.Principal?.FindFirst("email");
+        
+        if (emailClaim?.Value == null || !authorizedEmails.Contains(emailClaim.Value))
+        {
+            context.Fail("Email not authorized");
+            context.Response.Redirect("/?error=unauthorized");
+            return;
+        }
+        
+        await Task.CompletedTask;
+    };
+});
+
+// Configure authorization policy for allowed emails
+builder.Services.AddAuthorization(options =>
+{
+    options.AddPolicy("AllowedEmails", policy =>
+        policy.RequireAssertion(context =>
+        {
+            var emailClaim = context.User.FindFirst(ClaimTypes.Email) ??
+                           context.User.FindFirst("email");
+            if (emailClaim?.Value != null)
+            {
+                return authorizedEmails.Contains(emailClaim.Value);
+            }
+            return false;
+        }));
+});
+
 builder.Services.AddControllersWithViews();
 builder.Services.AddRazorPages();
 
@@ -47,6 +107,9 @@ app.UseStaticFiles();
 
 app.UseRouting();
 
+app.UseAuthentication();
+app.UseAuthorization();
+
 
 app.MapRazorPages();
 app.MapControllers();

Server/ShiftScheduler.Server.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.Google" Version="9.0.8" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Server" Version="9.0.8" />
   </ItemGroup>
 

Server/appsettings.json

@@ -7,6 +7,17 @@
   },
   "AllowedHosts": "*",
 
+  "Authentication": {
+    "Google": {
+      "ClientId": "YOUR_GOOGLE_CLIENT_ID",
+      "ClientSecret": "YOUR_GOOGLE_CLIENT_SECRET"
+    },
+    "AuthorizedEmails": [
+      "example1@gmail.com",
+      "example2@gmail.com"
+    ]
+  },
+
   "Transport": {
     "StartStation": "Zurich",
     "EndStation": "Basel",

authentication-setup.md

@@ -0,0 +1,71 @@
+# Authentication Setup Guide
+
+## Overview
+The ShiftScheduler application now includes Google OAuth authentication with configurable authorized email addresses. Only users with emails listed in the configuration can access the application.
+
+## Setup Instructions
+
+### 1. Create Google OAuth Application
+1. Go to the [Google Cloud Console](https://console.cloud.google.com/)
+2. Create a new project or select an existing one
+3. Enable the Google+ API
+4. Go to "Credentials" and create OAuth 2.0 Client IDs
+5. Set the authorized redirect URI to: `http://localhost:5000/signin-google` (for development)
+6. For production, use your domain: `https://yourdomain.com/signin-google`
+
+### 2. Configure Application
+Edit `Server/appsettings.json` and update the authentication section:
+
+```json
+{
+  "Authentication": {
+    "Google": {
+      "ClientId": "your-google-client-id.apps.googleusercontent.com",
+      "ClientSecret": "your-google-client-secret"
+    },
+    "AuthorizedEmails": [
+      "user1@gmail.com",
+      "user2@example.com"
+    ]
+  }
+}
+```
+
+### 3. For Production
+For production deployment, consider using environment variables or Azure Key Vault:
+- `Authentication__Google__ClientId`
+- `Authentication__Google__ClientSecret`
+- `Authentication__AuthorizedEmails__0`, `Authentication__AuthorizedEmails__1`, etc.
+
+## How It Works
+
+### Authentication Flow
+1. Unauthenticated users see a login screen
+2. Clicking "Sign in with Google" redirects to Google OAuth
+3. After successful Google authentication, the application checks if the user's email is in the authorized list
+4. Authorized users are redirected to the main application
+5. Unauthorized users are redirected back with an error message
+
+### API Security
+- All API endpoints require authentication (`[Authorize]` attribute)
+- Only users with emails in the `AuthorizedEmails` list can access the API
+- Unauthenticated requests return a 302 redirect to login
+
+### User Interface
+- **Login Screen**: Clean, centered login form with Google sign-in button
+- **Authenticated Header**: Shows user email and sign-out button
+- **Main Application**: Normal shift scheduler functionality for authenticated users
+
+## Testing
+To test the authentication:
+1. Configure Google OAuth credentials as described above
+2. Add your email to the `AuthorizedEmails` list
+3. Start the application: `dotnet run` from the Server directory
+4. Navigate to `http://localhost:5000`
+5. Click "Sign in with Google" and complete the OAuth flow
+
+## Security Features
+- **Email-based Authorization**: Only specified emails can access the application
+- **Secure API Endpoints**: All shift management APIs require authentication
+- **Session Management**: Proper login/logout functionality
+- **OAuth Integration**: Uses Google's secure OAuth 2.0 flow