Added custom google handler with prompt = 'select_account'

src/backend/src/FoodDiary.API/Authentication/AuthenticationExtensions.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Google;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace FoodDiary.API.Authentication;
+
+[SuppressMessage("ReSharper", "UnusedMethodReturnValue.Global")]
+public static class AuthenticationExtensions
+{
+    public static AuthenticationBuilder AddCustomGoogle(
+        this AuthenticationBuilder builder,
+        string authenticationScheme,
+        Action<GoogleOptions> configureOptions)
+    {
+        return builder.AddOAuth<GoogleOptions, CustomGoogleHandler>(
+            authenticationScheme,
+            GoogleDefaults.DisplayName,
+            configureOptions);
+    }
+}

src/backend/src/FoodDiary.API/Authentication/CustomGoogleHandler.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Google;
+using Microsoft.AspNetCore.Authentication.OAuth;
+using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using Microsoft.Extensions.Primitives;
+
+namespace FoodDiary.API.Authentication;
+
+public class CustomGoogleHandler(IOptionsMonitor<GoogleOptions> options, ILoggerFactory logger, UrlEncoder encoder)
+    : GoogleHandler(options, logger, encoder)
+{
+    protected override string BuildChallengeUrl(AuthenticationProperties properties, string redirectUri)
+    {
+        var query = QueryHelpers.ParseQuery(new Uri(base.BuildChallengeUrl(properties, redirectUri)).Query);
+
+        SetQueryParam(query, properties, OAuthChallengeProperties.ScopeKey, base.FormatScope, Options.Scope);
+        SetQueryParam(query, properties, GoogleChallengeProperties.AccessTypeKey, Options.AccessType);
+        SetQueryParam(query, properties, GoogleChallengeProperties.ApprovalPromptKey);
+        SetQueryParam(query, properties, GoogleChallengeProperties.PromptParameterKey, "select_account");
+        SetQueryParam(query, properties, GoogleChallengeProperties.LoginHintKey);
+        SetQueryParam(query, properties, GoogleChallengeProperties.IncludeGrantedScopesKey, v => v?.ToString(CultureInfo.InvariantCulture).ToLowerInvariant(), new bool?());
+
+        query["state"] = (StringValues) Options.StateDataFormat.Protect(properties);
+
+        return QueryHelpers.AddQueryString(Options.AuthorizationEndpoint, query);
+    }
+
+    private static void SetQueryParam<T>(
+        IDictionary<string, StringValues> queryStrings,
+        AuthenticationProperties properties,
+        string name,
+        Func<T, string> formatter,
+        T defaultValue)
+    {
+        var parameter = properties.GetParameter<T>(name);
+        string str;
+        if (parameter != null)
+            str = formatter(parameter);
+        else if (!properties.Items.TryGetValue(name, out str))
+            str = formatter(defaultValue);
+        properties.Items.Remove(name);
+        if (str == null)
+            return;
+        queryStrings[name] = (StringValues) str;
+    }
+
+    private static void SetQueryParam(
+        IDictionary<string, StringValues> queryStrings,
+        AuthenticationProperties properties,
+        string name,
+        string? defaultValue = null)
+    {
+        SetQueryParam(queryStrings, properties, name, (Func<string, string>) (x => x), defaultValue);
+    }
+}

src/backend/src/FoodDiary.API/Startup.cs

@@ -1,5 +1,6 @@
 using System.Reflection;
 using System.Threading.Tasks;
+using FoodDiary.API.Authentication;
 using FoodDiary.API.Extensions;
 using FoodDiary.API.Middlewares;
 using FoodDiary.API.Options;
@@ -58,7 +59,7 @@ public void ConfigureServices(IServiceCollection services)
                     return Task.CompletedTask;
                 };
             })
-            .AddGoogle(Constants.AuthenticationSchemes.OAuthGoogle, options =>
+            .AddCustomGoogle(Constants.AuthenticationSchemes.OAuthGoogle, options =>
             {
                 options.SignInScheme = Constants.AuthenticationSchemes.Cookie;
                 options.ClientId = _googleAuthOptions.ClientId;