WIP

BudgetApp/Program.cs

@@ -1,3 +1,4 @@
+using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.EntityFrameworkCore;
 using BudgetApp.Components;
@@ -34,6 +35,47 @@ builder.Services.ConfigureApplicationCookie(options =>
     options.LogoutPath = "/logout";
 });
 
+// External authentication providers (only registered when configured)
+var authBuilder = builder.Services.AddAuthentication();
+
+var googleSection = builder.Configuration.GetSection("Authentication:Google");
+if (!string.IsNullOrEmpty(googleSection["ClientId"]) && !string.IsNullOrEmpty(googleSection["ClientSecret"]))
+{
+    authBuilder.AddGoogle(options =>
+    {
+        options.ClientId = googleSection["ClientId"]!;
+        options.ClientSecret = googleSection["ClientSecret"]!;
+    });
+}
+
+var microsoftSection = builder.Configuration.GetSection("Authentication:Microsoft");
+if (!string.IsNullOrEmpty(microsoftSection["ClientId"]) && !string.IsNullOrEmpty(microsoftSection["ClientSecret"]))
+{
+    authBuilder.AddMicrosoftAccount(options =>
+    {
+        options.ClientId = microsoftSection["ClientId"]!;
+        options.ClientSecret = microsoftSection["ClientSecret"]!;
+    });
+}
+
+var githubSection = builder.Configuration.GetSection("Authentication:GitHub");
+if (!string.IsNullOrEmpty(githubSection["ClientId"]) && !string.IsNullOrEmpty(githubSection["ClientSecret"]))
+{
+    authBuilder.AddOAuth("GitHub", "GitHub", options =>
+    {
+        options.ClientId = githubSection["ClientId"]!;
+        options.ClientSecret = githubSection["ClientSecret"]!;
+        options.AuthorizationEndpoint = "https://github.com/login/oauth/authorize";
+        options.TokenEndpoint = "https://github.com/login/oauth/access_token";
+        options.UserInformationEndpoint = "https://api.github.com/user";
+        options.CallbackPath = "/signin-github";
+        options.Scope.Add("user:email");
+        options.ClaimActions.MapJsonKey(System.Security.Claims.ClaimTypes.NameIdentifier, "id");
+        options.ClaimActions.MapJsonKey(System.Security.Claims.ClaimTypes.Name, "login");
+        options.ClaimActions.MapJsonKey(System.Security.Claims.ClaimTypes.Email, "email");
+    });
+}
+
 // Application services
 builder.Services.AddScoped<AccountService>();
 builder.Services.AddScoped<TransactionService>();
@@ -75,4 +117,62 @@ app.MapStaticAssets();
 app.MapRazorComponents<App>()
     .AddInteractiveServerRenderMode();
 
+// External authentication endpoints
+app.MapPost("/api/auth/external-login", (HttpContext context) =>
+{
+    var provider = context.Request.Form["provider"].ToString();
+    var returnUrl = context.Request.Form["returnUrl"].ToString();
+    if (string.IsNullOrEmpty(returnUrl)) returnUrl = "/";
+
+    var redirectUrl = $"/api/auth/external-callback?returnUrl={Uri.EscapeDataString(returnUrl)}";
+    var properties = new Microsoft.AspNetCore.Authentication.AuthenticationProperties { RedirectUri = redirectUrl };
+    return Results.Challenge(properties, [provider]);
+});
+
+app.MapGet("/api/auth/external-callback", async (
+    HttpContext context,
+    SignInManager<ApplicationUser> signInManager,
+    UserManager<ApplicationUser> userManager,
+    string? returnUrl) =>
+{
+    returnUrl ??= "/";
+    var info = await signInManager.GetExternalLoginInfoAsync();
+    if (info is null)
+        return Results.Redirect("/login");
+
+    var signInResult = await signInManager.ExternalLoginSignInAsync(
+        info.LoginProvider, info.ProviderKey, isPersistent: false);
+
+    if (signInResult.Succeeded)
+        return Results.Redirect(returnUrl);
+
+    // Auto-register: create user from external claims
+    var email = info.Principal.FindFirst(System.Security.Claims.ClaimTypes.Email)?.Value;
+    var userName = email ?? info.Principal.FindFirst(System.Security.Claims.ClaimTypes.Name)?.Value
+        ?? $"{info.LoginProvider}_{info.ProviderKey}";
+
+    var user = new ApplicationUser { UserName = userName, Email = email };
+    var createResult = await userManager.CreateAsync(user);
+    if (createResult.Succeeded)
+    {
+        await userManager.AddLoginAsync(user, info);
+        await signInManager.SignInAsync(user, isPersistent: false);
+        return Results.Redirect(returnUrl);
+    }
+
+    // If the email is already taken, try linking
+    if (email is not null)
+    {
+        var existingUser = await userManager.FindByEmailAsync(email);
+        if (existingUser is not null)
+        {
+            await userManager.AddLoginAsync(existingUser, info);
+            await signInManager.SignInAsync(existingUser, isPersistent: false);
+            return Results.Redirect(returnUrl);
+        }
+    }
+
+    return Results.Redirect("/login");
+});
+
 app.Run();