// Package app 装配 user-service 的 gRPC 入口、领域服务、repository 和健康检查。
package app

import (
	"context"
	"errors"
	"net"
	"sync"
	"time"

	userv1 "hyapp.local/api/proto/user/v1"
	"hyapp/pkg/grpchealth"
	"hyapp/pkg/idgen"
	"hyapp/pkg/logx"
	"hyapp/services/user-service/internal/config"
	authservice "hyapp/services/user-service/internal/service/auth"
	hostservice "hyapp/services/user-service/internal/service/host"
	userservice "hyapp/services/user-service/internal/service/user"
	mysqlstorage "hyapp/services/user-service/internal/storage/mysql"
	grpcserver "hyapp/services/user-service/internal/transport/grpc"

	"google.golang.org/grpc"
	healthgrpc "google.golang.org/grpc/health/grpc_health_v1"
)

// App 装配 user-service gRPC 入口和底座依赖。
type App struct {
	// server 承载 AuthService、UserService、UserIdentityService 和 gRPC health。
	server *grpc.Server
	// listener 是 user-service 的唯一网络入口。
	listener net.Listener
	// health 是标准 gRPC health 的 serving/draining 状态来源。
	health *grpchealth.ServingChecker
	// mysqlRepo 持有用户主数据、认证身份、session 和短号事务的唯一运行时存储。
	mysqlRepo *mysqlstorage.Repository
	// userSvc 持有用户主数据用例，后台 region rebuild worker 复用它消费任务。
	userSvc *userservice.Service
	// cfg 保存 worker 运行参数，避免 Run 阶段重新读配置。
	cfg config.Config
	// workerCtx 统一控制后台 worker 生命周期。
	workerCtx context.Context
	// workerCancel 停止 region rebuild worker。
	workerCancel context.CancelFunc
	// workerWG 等待后台 worker 当前批次安全退出。
	workerWG sync.WaitGroup
	// closeOnce 防止信号退出和 Serve 异常同时触发重复关闭。
	closeOnce sync.Once
}

// New 初始化 user-service 应用。
func New(cfg config.Config) (*App, error) {
	// userRepository 只表达用户主数据用例，authRepository 只表达认证用例；MySQL 实现同时满足两者。
	startupCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	// user-service 的登录、注册、短号和 session 都必须落 MySQL；空 DSN 直接启动失败。
	mysqlRepo, err := mysqlstorage.Open(startupCtx, cfg.MySQLDSN)
	if err != nil {
		return nil, err
	}
	// listener 在 New 阶段创建，端口占用会作为启动失败返回。
	listener, err := net.Listen("tcp", cfg.GRPCAddr)
	if err != nil {
		if mysqlRepo != nil {
			_ = mysqlRepo.Close()
		}
		return nil, err
	}

	server := grpc.NewServer(grpc.UnaryInterceptor(logx.UnaryServerInterceptor("user-service")))
	thirdPartyVerifier := authservice.NewRoutedThirdPartyVerifier(
		authservice.NewFirebaseThirdPartyVerifier(authservice.FirebaseVerifierConfig{
			ProjectID:              cfg.ThirdParty.Firebase.ProjectID,
			AllowedSignInProviders: cfg.ThirdParty.Firebase.AllowedSignInProviders,
			CertsURL:               cfg.ThirdParty.Firebase.CertsURL,
		}),
		authservice.NewStaticThirdPartyVerifier(cfg.ThirdParty.AllowedProviders),
	)
	authRepo := mysqlRepo.AuthRepository()
	appRepo := mysqlRepo.AppRepository()
	userRepo := mysqlRepo.UserRepository()
	identityRepo := mysqlRepo.IdentityRepository()
	regionRepo := mysqlRepo.RegionRepository()
	hostRepo := mysqlRepo.HostRepository()

	// auth service 负责登录、session 和 token；用户主数据和短号事务仍通过各自领域存储完成。
	authSvc := authservice.New(authservice.Config{
		Issuer:             cfg.JWT.Issuer,
		AccessTokenTTLSec:  cfg.JWT.AccessTokenTTLSec,
		RefreshTokenTTLSec: cfg.JWT.RefreshTokenTTLSec,
		SigningAlg:         cfg.JWT.SigningAlg,
		SigningSecret:      cfg.JWT.SigningSecret,
	},
		authservice.WithAuthRepository(authRepo),
		authservice.WithUserRepository(userRepo),
		authservice.WithIdentityRepository(identityRepo),
		authservice.WithCountryRegionRepository(regionRepo),
		authservice.WithIDGenerator(idgen.NewInt64Generator(cfg.IDGenerator.NodeID)),
		authservice.WithDisplayUserIDAllocateMaxAttempts(cfg.DisplayUserID.AllocateMaxAttempts),
		authservice.WithThirdPartyVerifier(thirdPartyVerifier),
	)
	// user service 负责用户主状态和 display_user_id/靓号用例，不进入房间高频流程。
	userSvc := userservice.New(userRepo,
		userservice.WithAppRegistryRepository(appRepo),
		userservice.WithIdentityRepository(identityRepo),
		userservice.WithCountryRegionRepository(regionRepo),
		userservice.WithCountryAdminRepository(regionRepo),
		userservice.WithRegionAdminRepository(regionRepo),
		userservice.WithRegionRebuildRepository(regionRepo),
		userservice.WithIDGenerator(idgen.NewInt64Generator(cfg.IDGenerator.NodeID)),
		userservice.WithDisplayUserIDPolicy(cfg.DisplayUserID.AllocateMaxAttempts, time.Duration(cfg.DisplayUserID.ChangeCooldownSec)*time.Second),
	)
	hostSvc := hostservice.New(hostRepo,
		hostservice.WithIDGenerator(idgen.NewInt64Generator(cfg.IDGenerator.NodeID)),
	)
	userServer := grpcserver.NewServer(authSvc, userSvc, hostSvc)
	// 多个 protobuf service 共用一个 Server 适配器，领域逻辑仍拆在 auth/user/host service。
	userv1.RegisterAuthServiceServer(server, userServer)
	userv1.RegisterUserServiceServer(server, userServer)
	userv1.RegisterAppRegistryServiceServer(server, userServer)
	userv1.RegisterUserIdentityServiceServer(server, userServer)
	userv1.RegisterCountryAdminServiceServer(server, userServer)
	userv1.RegisterCountryQueryServiceServer(server, userServer)
	userv1.RegisterRegionAdminServiceServer(server, userServer)
	userv1.RegisterUserHostServiceServer(server, userServer)
	userv1.RegisterUserHostAdminServiceServer(server, userServer)

	health := grpchealth.NewServingChecker("user-service")
	// user-service 目前使用简单 serving checker，存储探测由后续专用 health 可扩展。
	healthgrpc.RegisterHealthServer(server, grpchealth.NewServer(health))
	workerCtx, workerCancel := context.WithCancel(context.Background())

	return &App{
		server:       server,
		listener:     listener,
		health:       health,
		mysqlRepo:    mysqlRepo,
		userSvc:      userSvc,
		cfg:          cfg,
		workerCtx:    workerCtx,
		workerCancel: workerCancel,
	}, nil
}

// Run 启动 gRPC 服务。
func (a *App) Run() error {
	// 只有 listener 进入 Serve 后才标记 serving，避免健康检查提前放行。
	a.health.MarkServing()
	defer func() {
		if a.workerCancel != nil {
			a.workerCancel()
		}
		a.workerWG.Wait()
	}()
	if a.cfg.RegionRebuildWorker.Enabled {
		a.workerWG.Add(1)
		go func() {
			defer a.workerWG.Done()
			a.userSvc.RunRegionRebuildWorker(a.workerCtx, userservice.RegionRebuildWorkerOptions{
				WorkerID:     a.cfg.NodeID,
				PollInterval: time.Duration(a.cfg.RegionRebuildWorker.PollIntervalSec) * time.Second,
				LockTTL:      time.Duration(a.cfg.RegionRebuildWorker.LockTTLSec) * time.Second,
				BatchSize:    a.cfg.RegionRebuildWorker.BatchSize,
			})
		}()
	}
	err := a.server.Serve(a.listener)
	a.health.MarkStopped()
	if errors.Is(err, grpc.ErrServerStopped) {
		// GracefulStop 触发的退出不是故障。
		return nil
	}

	return err
}

// Close 关闭 gRPC 服务和底层持久化连接。
func (a *App) Close() {
	a.closeOnce.Do(func() {
		// draining 会让 health 立即失败，避免下线进程继续接新 RPC。
		a.health.MarkDraining()
		if a.workerCancel != nil {
			a.workerCancel()
		}
		a.workerWG.Wait()
		// GracefulStop 等待已进入的 RPC 结束，避免 token/session 写入被硬切。
		a.server.GracefulStop()
		if a.mysqlRepo != nil {
			// MySQL 连接池最后关闭，保证 GracefulStop 期间 repository 仍可用。
			_ = a.mysqlRepo.Close()
		}
	})
}