// Package app 负责把 room-service 的领域服务、存储、路由目录和 gRPC 入口装配成进程。
package app

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

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	healthgrpc "google.golang.org/grpc/health/grpc_health_v1"
	activityv1 "hyapp.local/api/proto/activity/v1"
	roomv1 "hyapp.local/api/proto/room/v1"
	"hyapp/pkg/grpchealth"
	"hyapp/pkg/logx"
	"hyapp/pkg/tencentim"
	"hyapp/services/room-service/internal/config"
	"hyapp/services/room-service/internal/healthcheck"
	"hyapp/services/room-service/internal/integration"
	roomservice "hyapp/services/room-service/internal/room/service"
	"hyapp/services/room-service/internal/router"
	mysqlstorage "hyapp/services/room-service/internal/storage/mysql"
	grpcserver "hyapp/services/room-service/internal/transport/grpc"
)

// App 负责装配 room-service 运行时依赖。
type App struct {
	// cfg 保留启动配置，便于后续扩展后台 worker 时复用。
	cfg config.Config
	// grpcServer 承载 RoomCommandService、RoomGuardService 和标准 gRPC health。
	grpcServer *grpc.Server
	// service 是 Room Cell 领域入口，后台 presence worker 复用它执行清理命令。
	service *roomservice.Service
	// listener 是 room-service 的唯一网络入口。
	listener net.Listener
	// walletConn 是 SendGift 同步扣费依赖。
	walletConn *grpc.ClientConn
	// activityConn 是 room outbox 事实投递到 activity-service 的 best-effort 通道。
	activityConn *grpc.ClientConn
	// repository 是 MySQL 持久化实现，保存 meta、command log、snapshot 和 outbox。
	repository *mysqlstorage.Repository
	// redisClose 关闭 Redis client，Redis directory 本身不拥有额外生命周期。
	redisClose func() error
	// health 汇总 gRPC、runtime、MySQL 和 Redis lease 探测状态。
	health *healthcheck.State
	// workerCtx 统一控制本节点后台 worker，关闭时必须先停止 worker 再释放 MySQL/Redis。
	workerCtx context.Context
	// workerCancel 停止 presence stale 和 outbox 补偿 worker。
	workerCancel context.CancelFunc
	// workerWG 等待后台 worker 当前事件或当前扫描批次安全退出。
	workerWG sync.WaitGroup
	// closeOnce 防止信号退出和 Serve 错误同时触发重复关闭。
	closeOnce sync.Once
}

// New 初始化 room-service 应用。
func New(cfg config.Config) (*App, error) {
	normalized, err := config.Normalize(cfg)
	if err != nil {
		return nil, err
	}
	cfg = normalized

	// wallet-service 是 SendGift 主链路依赖，连接对象创建失败时不能启动。
	walletConn, err := grpc.Dial(cfg.WalletServiceAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		return nil, err
	}
	activityConn, err := grpc.Dial(cfg.ActivityServiceAddr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		_ = walletConn.Close()
		return nil, err
	}

	startupCtx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()

	// MySQL 是房间恢复的持久来源，启动阶段必须确认连接池可用。
	repository, err := mysqlstorage.Open(startupCtx, cfg.MySQLDSN, cfg.MySQLMaxOpenConns, cfg.MySQLMaxIdleConns)
	if err != nil {
		_ = activityConn.Close()
		_ = walletConn.Close()
		return nil, err
	}

	if cfg.MySQLAutoMigrate {
		// 本地和测试环境可自动建表，线上应通过显式迁移控制结构变更。
		if err := repository.Migrate(startupCtx); err != nil {
			_ = repository.Close()
			_ = activityConn.Close()
			_ = walletConn.Close()
			return nil, err
		}
	}

	// Redis directory 保存 room owner lease，是单房间单活的运行时仲裁来源。
	redisClient, err := router.NewRedisClient(startupCtx, cfg.RedisAddr, cfg.RedisPassword, cfg.RedisDB)
	if err != nil {
		_ = repository.Close()
		_ = activityConn.Close()
		_ = walletConn.Close()
		return nil, err
	}

	directory := router.NewRedisDirectory(redisClient)
	roomPublisher := integration.NewNoopRoomEventPublisher()
	outboxPublisher := integration.NewNoopOutboxPublisher()
	if cfg.TencentIM.Enabled {
		// 腾讯云 IM 替代自研 IM；room-service 只负责服务端 REST 群消息桥接。
		tencentClient, err := tencentim.NewRESTClient(cfg.TencentIM.RESTConfig())
		if err != nil {
			_ = repository.Close()
			_ = activityConn.Close()
			_ = walletConn.Close()
			_ = redisClient.Close()
			return nil, err
		}
		tencentPublisher := integration.NewTencentIMPublisher(tencentClient)
		roomPublisher = tencentPublisher
		outboxPublisher = tencentPublisher
	}

	// 领域服务只依赖接口，App 层负责选择 MySQL/Redis/gRPC 具体实现。
	svc := roomservice.New(roomservice.Config{
		NodeID:             cfg.NodeID,
		LeaseTTL:           cfg.LeaseTTL,
		RankLimit:          cfg.RankLimit,
		SnapshotEveryN:     cfg.SnapshotEveryN,
		PresenceStaleAfter: cfg.PresenceStaleAfter,
		MicPublishTimeout:  cfg.MicPublishTimeout,
	}, directory, repository, integration.NewGRPCWalletClient(walletConn), roomPublisher, outboxPublisher)
	svc.SetEventPublisher(integration.NewActivityOutboxPublisher(activityv1.NewRoomEventConsumerServiceClient(activityConn), time.Second))

	server := grpc.NewServer(grpc.UnaryInterceptor(logx.UnaryServerInterceptor("room-service")))
	// 命令服务处理房间状态变更，守卫服务给腾讯云 IM 回调或 gateway 做发言和进群校验。
	roomv1.RegisterRoomCommandServiceServer(server, grpcserver.NewServer(svc))
	roomv1.RegisterRoomGuardServiceServer(server, grpcserver.NewServer(svc))
	roomv1.RegisterRoomQueryServiceServer(server, grpcserver.NewServer(svc))
	healthState := healthcheck.NewState(cfg.NodeID, svc, repository, directory)
	healthgrpc.RegisterHealthServer(server, grpchealth.NewServer(healthState))

	// listener 在 New 阶段创建，可以把端口占用作为启动失败暴露。
	listener, err := net.Listen("tcp", cfg.GRPCAddr)
	if err != nil {
		_ = activityConn.Close()
		_ = walletConn.Close()
		_ = repository.Close()
		_ = redisClient.Close()
		return nil, err
	}
	workerCtx, workerCancel := context.WithCancel(context.Background())

	return &App{
		cfg:          cfg,
		grpcServer:   server,
		service:      svc,
		listener:     listener,
		walletConn:   walletConn,
		activityConn: activityConn,
		repository:   repository,
		redisClose:   redisClient.Close,
		health:       healthState,
		workerCtx:    workerCtx,
		workerCancel: workerCancel,
	}, nil
}

// Run 启动 gRPC 服务。
func (a *App) Run() error {
	// health 先标记 serving，再进入 Serve，ready 才能在监听开始后通过。
	a.health.MarkGRPCServing()
	defer func() {
		if a.workerCancel != nil {
			a.workerCancel()
		}
		a.workerWG.Wait()
	}()
	if a.cfg.PresenceStaleScanInterval > 0 {
		// presence worker 只清理本节点已装载 Cell，命令仍走 Room Cell 持久化链路。
		a.workerWG.Go(func() {
			a.service.RunPresenceStaleWorker(a.workerCtx, a.cfg.PresenceStaleScanInterval)
		})
	}
	if a.cfg.MicPublishScanInterval > 0 {
		// MicUp 只代表业务占麦；后台 worker 负责释放未确认 RTC 发流的 pending_publish 麦位。
		a.workerWG.Go(func() {
			a.service.RunMicPublishTimeoutWorker(a.workerCtx, a.cfg.MicPublishScanInterval)
		})
	}
	if a.cfg.OutboxWorker.Enabled {
		a.workerWG.Go(func() {
			a.service.RunOutboxWorker(a.workerCtx, roomservice.OutboxWorkerOptions{
				PollInterval:   a.cfg.OutboxWorker.PollInterval,
				BatchSize:      a.cfg.OutboxWorker.BatchSize,
				PublishTimeout: a.cfg.OutboxWorker.PublishTimeout,
				RetryStrategy:  a.cfg.OutboxWorker.RetryStrategy,
			})
		})
	}

	err := a.grpcServer.Serve(a.listener)
	a.health.MarkGRPCStopped()
	if errors.Is(err, grpc.ErrServerStopped) {
		// GracefulStop 触发的退出不是故障。
		return nil
	}

	return err
}

// Close 关闭底层 gRPC 服务。
func (a *App) Close() {
	a.closeOnce.Do(func() {
		// 先进入 draining，避免下线中的节点继续接管房间 lease 或接收新命令。
		a.health.MarkDraining()
		if a.service != nil {
			a.service.MarkDraining()
		}
		if a.workerCancel != nil {
			// 先停后台 worker 并等待当前投递结果落库，再关闭 gRPC/MySQL/Redis。
			a.workerCancel()
		}
		a.workerWG.Wait()
		// GracefulStop 让已进入的 gRPC 请求自然结束。
		a.grpcServer.GracefulStop()
		if a.walletConn != nil {
			_ = a.walletConn.Close()
		}
		if a.activityConn != nil {
			_ = a.activityConn.Close()
		}
		if a.repository != nil {
			// MySQL 连接池最后释放，保证 GracefulStop 期间仍可完成持久化。
			_ = a.repository.Close()
		}
		if a.redisClose != nil {
			// Redis client 关闭后本节点不再续约或接管房间。
			_ = a.redisClose()
		}
	})
}