ANTOOZA-BACKEND/Infrastructure/DependencyInjection.cs

using Application.Abstractions.Authentication;
using Application.Abstractions.Cache;
using Application.Abstractions.Chat;
using Application.Abstractions.Crypto;
using Application.Abstractions.Data;
using Application.Abstractions.Hub;
using Application.Abstractions.Identity;
using Application.Abstractions.Forum;
using Application.Abstractions.Messaging.Email;
using Application.Abstractions.Notification;
using Application.Abstractions.Payment;
using Application.Abstractions.YouTube;
using Infrastructure.Authentication;
using Infrastructure.Crypto;
using Infrastructure.Payment;
using Infrastructure.Forum;
using Infrastructure.Cache;
using Infrastructure.Chat;
using Infrastructure.Messaging.Email;
using Infrastructure.Persistence;
using Infrastructure.Persistence.Identity;
using Infrastructure.Storage;
using Infrastructure.YouTube;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Diagnostics;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using SharedKernel;
using SharedKernel.Storage;
using StackExchange.Redis;
using System.Text;

namespace Infrastructure;

public static class DependencyInjection
{
    // SQL Server
    private static IServiceCollection AddDatabase(this IServiceCollection services, IConfiguration configuration)
    {
        var dbConn = configuration.GetConnectionString("DefaultConnection");
        if (string.IsNullOrWhiteSpace(dbConn))
        {
            throw new InvalidOperationException("Connection string 'DefaultConnection' is not configured.");
        }

        // Pooling: 매 request 마다 새 DbContext 생성 비용 제거. ChangeTracker 등 내부 상태는 풀 반환 시 자동 reset
        // ConfigureWarnings: EF 9+의 PendingModelChangesWarning을 무시 (snapshot 일관성 문제로 false-positive 발생, 마이그레이션은 별도 관리)
        services.AddDbContextPool<AppDbContext>(options => options
            .UseSqlServer(dbConn)
            .ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning)), poolSize: 128);
        services.AddDbContextPool<IdentityDbContext>(options => options
            .UseSqlServer(dbConn)
            .ConfigureWarnings(w => w.Ignore(RelationalEventId.PendingModelChangesWarning)), poolSize: 64);

        services.AddScoped<IAppDbContext>(sp => sp.GetRequiredService<AppDbContext>());

        return services;
    }

    // Redis Server
    public static IServiceCollection AddRedis(this IServiceCollection services, IConfiguration configuration)
    {
        var settings = configuration.Get<AppSettings>()!;
        var redis = ConnectionMultiplexer.Connect(settings.Redis.DefaultConnection);

        services.AddSingleton<IConnectionMultiplexer>(redis);
        services.AddDataProtection()
            .SetApplicationName(settings.App.Name)
            .PersistKeysToStackExchangeRedis(redis, settings.Redis.DataProtectionKey)
            .ProtectKeysWithDpapi(protectToLocalMachine: true) // key를 암호화하여 저장 (로컬 머신에서만 복호화 가능, 서버간 공유 불가)
            .SetDefaultKeyLifetime(settings.Redis.DefaultKeyLifetime); // 기본 90일 주기

        // Distributed Cache 설정
        services.AddStackExchangeRedisCache(options =>
        {
            options.Configuration = settings.Redis.DefaultConnection;
            options.InstanceName = settings.Redis.CachePrefix;
        });

        return services;
    }

    private static IServiceCollection AddHealthChecks(this IServiceCollection services, IConfiguration configuration)
    {
        var settings = configuration.Get<AppSettings>()!;

        services.AddHealthChecks().AddSqlServer(settings.ConnectionStrings.DefaultConnection).AddRedis(settings.Redis.DefaultConnection);

        return services;
    }

    // Admin/Api 둘 다 필요한 공용 서비스 (singleton/transient/scoped, HttpClient)
    private static IServiceCollection AddCommonServices(this IServiceCollection services, IConfiguration configuration)
    {
        // 파일 저장 위치 옵션 (deploy 영향 받지 않는 외부 경로 권장)
        services.Configure<StorageOptions>(configuration.GetSection(StorageOptions.SectionName));

        services.AddSingleton<IJwtTokenProvider, JwtTokenProvider>();
        services.AddSingleton<ILegacyPasswordVerifier, BcryptLegacyPasswordVerifier>();
        services.AddSingleton<ICacheService, RedisCacheService>();
        services.AddSingleton<IFieldEncryptor, AesGcmFieldEncryptor>();
        services.AddTransient<IEmailSender, IdentityEmailSender>();
        services.AddScoped<IFileStorage, LocalFileStorage>();
        services.AddScoped<IEditorImageService, EditorImageService>();
        services.AddScoped<IIdentityUserReader, IdentityUserReader>();
        services.AddScoped<IIdentityUserWriter, IdentityUserWriter>();
        services.AddScoped<IIdentityRoleReader, IdentityRoleReader>();
        services.AddScoped<IIdentityRoleWriter, IdentityRoleWriter>();
        services.AddSingleton<IChatMessageStore, RedisChatMessageStore>();
        services.AddSingleton<IChatConnectionTracker, RedisChatConnectionTracker>();
        services.AddSingleton<IChatLeaderboard, RedisChatLeaderboard>();
        services.AddSingleton<IPresenceTracker, Hubs.PresenceTracker>();
        services.AddSingleton<IVisitorTracker, Hubs.RedisVisitorTracker>();
        services.AddScoped<IBoardPermissionService, BoardPermissionService>();
        services.AddHttpClient<IGoogleTokenValidator, GoogleTokenValidator>();

        // YouTube & Google OAuth (HttpClients + singletons — Admin에서도 "API 키 테스트" 등에 쓰므로 공용)
        services.AddSingleton<IYouTubeApiKeyProvider, YouTubeApiKeyProvider>();
        services.AddTransient<YouTubeApiKeyHandler>();
        services.AddTransient<IYouTubeApiConnectionTester, YouTubeApiConnectionTester>();
        services.AddHttpClient("YouTubeApi", client =>
        {
            client.Timeout = TimeSpan.FromSeconds(15);
            client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
        })
        .AddHttpMessageHandler<YouTubeApiKeyHandler>();
        services.AddHttpClient("PubSubHub", client =>
        {
            client.Timeout = TimeSpan.FromSeconds(15);
        });
        services.AddHttpClient("YouTubeFeed", client =>
        {
            client.Timeout = TimeSpan.FromSeconds(10);
            client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/atom+xml"));
        });
        services.AddHttpClient<IGoogleOAuthService, GoogleOAuthService>();
        services.AddHttpClient<IDanalPayService, DanalPayService>();
        services.AddSingleton<IYouTubeApiService, YouTubeApiService>();
        services.AddSingleton<IYouTubeChannelCache, YouTubeChannelCache>();
        services.AddSingleton<IYouTubeLiveStateStore, YouTubeLiveStateStore>();
        services.AddSingleton<YouTubeLiveChatService>();
        services.AddSingleton<IYouTubeLiveChatService>(sp => sp.GetRequiredService<YouTubeLiveChatService>());
        services.AddSingleton<YouTubePubSubService>();
        services.AddSingleton<IYouTubePubSubService>(sp => sp.GetRequiredService<YouTubePubSubService>());
        services.AddSingleton<IYouTubeFeedPoller, YouTubeFeedPoller>();

        // Notification
        services.AddScoped<INotificationService, Notification.NotificationService>();

        // Feed broadcaster (SignalR)
        services.AddScoped<IFeedBroadcaster, Hubs.FeedBroadcaster>();

        // Channel status broadcaster (라이브 시작/종료/시청자 수 → AppHub 브로드캐스트)
        services.AddSingleton<IChannelStatusBroadcaster, Hubs.ChannelStatusBroadcaster>();

        return services;
    }

    // Web.Api 전용 백그라운드 서비스 (Admin에서 중복 실행되면 quota 2배/폴링 2번 문제)
    // appsettings.json BackgroundJobs 섹션으로 개별 토글 (기본 모두 true). 진단용 A/B 테스트에 사용
    private static IServiceCollection AddBackgroundServices(this IServiceCollection services, IConfiguration configuration)
    {
        // Features:Channel OFF → YouTube/채널 백그라운드 서비스 전체 미등록 (코드 보존, 기능 노출 0)
        var features = configuration.GetSection("Features").Get<AppSettings.FeaturesSection>() ?? new AppSettings.FeaturesSection();
        if (!features.Channel)
        {
            return services;
        }

        var bg = configuration.GetSection("BackgroundJobs").Get<AppSettings.BackgroundJobsSection>() ?? new AppSettings.BackgroundJobsSection();

        if (bg.LiveChat)
        {
            services.AddHostedService(sp => sp.GetRequiredService<YouTubeLiveChatService>());
        }
        if (bg.PubSubRenewal)
        {
            services.AddHostedService<YouTubePubSubRenewalService>();
        }
        if (bg.FeedPolling)
        {
            services.AddHostedService<YouTubeFeedPollingService>();
        }
        if (bg.LiveViewerPoller)
        {
            services.AddHostedService<YouTubeLiveViewerPoller>();
        }
        if (bg.ChannelCacheRefresh)
        {
            services.AddHostedService<YouTubeChannelCacheRefreshService>();
        }
        if (bg.YouTubeDailyAggregator)
        {
            services.AddHostedService<YouTubeDailyAggregatorService>();
        }
        if (bg.YouTubeStaleDataPurge)
        {
            services.AddHostedService<YouTubeStaleDataPurgeService>();
        }

        return services;
    }

    /**
     * ========================================================================================================================================================================================================
     * ========================================================================================================================================================================================================
     */

    // Admin 전용 — 백그라운드 서비스는 포함하지 않음 (Web.Api에서만 돌아야 함)
    // 메일은 즉시 SMTP 발송 (DirectMailService)
    public static IServiceCollection AddAdminInfrastructure(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddScoped<IMailService, DirectMailService>();
        return services.AddDatabase(configuration).AddRedis(configuration).AddCommonServices(configuration).AddHealthChecks(configuration);
    }

    /**
     * ========================================================================================================================================================================================================
     * ========================================================================================================================================================================================================
     */

    // API 전용 — 공용 서비스 + 백그라운드 서비스 모두 포함
    // 메일은 EmailLog 큐에 적재 (QueuedMailService) — MailWorker가 별도로 폴링하여 SMTP 송신
    public static IServiceCollection AddApiInfrastructure(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddScoped<IMailService, QueuedMailService>();
        return services.AddDatabase(configuration).AddRedis(configuration).AddApiAuthentication(configuration).AddCommonServices(configuration).AddBackgroundServices(configuration).AddHealthChecks(configuration);
    }

    private static IServiceCollection AddApiAuthentication(this IServiceCollection services, IConfiguration configuration)
    {
        var settings = configuration.Get<AppSettings>()!;

        // 인증 정책- JWT Bearer
        services.AddAuthentication(options =>
        {
            options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
            options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        })
        .AddJwtBearer(options =>
        {
            options.RequireHttpsMetadata = false;
            options.MapInboundClaims = false;
            options.TokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuer = true,
                ValidateAudience = true,
                ValidateLifetime = true,
                ValidateIssuerSigningKey = true,
                ValidIssuer = settings.JWT.Issuer,
                ValidAudience = settings.JWT.Audience,
                IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(settings.JWT.SecretKey)),
                ClockSkew = TimeSpan.Zero
            };

            options.Events = new JwtBearerEvents
            {
                OnMessageReceived = context =>
                {
                    var accessToken = context.Request.Query["access_token"];
                    var path = context.HttpContext.Request.Path;

                    if (!string.IsNullOrEmpty(accessToken) && path.StartsWithSegments("/hubs"))
                    {
                        context.Token = accessToken;
                    }

                    return Task.CompletedTask;
                }
            };
        });

        services.AddAuthorization();

        // Identity Core (Admin Handler의 UserManager/RoleManager 의존 해소용)
        services.AddIdentityCore<ApplicationUser>().AddRoles<IdentityRole>().AddEntityFrameworkStores<IdentityDbContext>();

        return services;
    }
}