package connection

import (
	"context"
	"fmt"
	"sync"
	"time"

	"dbview/service/internal/common/databases"
	"dbview/service/internal/common/databases/drivers"
	"dbview/service/internal/common/databases/meta"
	"dbview/service/internal/common/response"
)

// PooledConnection 池化连接，包装数据库连接和元数据
type PooledConnection struct {
	DbConn   databases.Connection   // 数据库连接
	LastUsed time.Time              // 最后使用时间
	Type     string                 // 数据库类型
	Version  string                 // 数据库版本
	DbConfig *meta.ConnectionConfig // 连接配置

	closeChan chan struct{}      // 关闭通知通道
	ctx       context.Context    // 上下文
	cancel    context.CancelFunc // 取消函数
}

// ConnectionPool 连接池管理器
type ConnectionPool struct {
	pools         map[string]*PooledConnection
	mu            sync.RWMutex
	cleanupCtx    context.Context
	cleanupCancel context.CancelFunc
	cleanupTicker *time.Ticker
}

// PoolStats 描述连接池中单个连接的运行状态快照
type PoolStats struct {
	LastUsed     time.Time
	Type         string
	Version      string
	IsConnected  bool
	MaxIdleTime  time.Duration
	MaxLifetime  time.Duration
	MaxOpenConns int
	MaxIdleConns int
}

// NewConnectionPool 创建新的连接池管理器
func NewConnectionPool(ctx context.Context) *ConnectionPool {
	cleanupCtx, cleanupCancel := context.WithCancel(ctx)
	pool := &ConnectionPool{
		pools:         make(map[string]*PooledConnection),
		cleanupCtx:    cleanupCtx,
		cleanupCancel: cleanupCancel,
	}

	// 启动定期清理协程
	go pool.periodicCleanup()

	return pool
}

// RegisterConnectionWithConfig 使用新的配置结构注册连接
func (cp *ConnectionPool) RegisterConnectionWithConfig(connID string, dbType, dbVersion string, config *meta.ConnectionConfig) error {
	cp.mu.Lock()
	defer cp.mu.Unlock()

	// 检查连接ID是否已存在
	if _, exists := cp.pools[connID]; exists {
		return nil
	}

	ctx, cancel := context.WithCancel(cp.cleanupCtx)

	// 立即创建数据库执行器
	executor, err := drivers.Connect(dbType, dbVersion, config)
	if err != nil {
		cancel()
		return fmt.Errorf("创建数据库连接失败: %v", err)
	}

	// 测试连接
	if err := executor.Ping(context.Background()); err != nil {
		executor.Close()
		cancel()
		return fmt.Errorf("数据库连接失败: %v", err)
	}

	cp.pools[connID] = &PooledConnection{
		DbConn:    executor,
		LastUsed:  time.Now(),
		Type:      dbType,
		Version:   dbVersion,
		DbConfig:  config,
		closeChan: make(chan struct{}),
		ctx:       ctx,
		cancel:    cancel,
	}

	return nil
}

// RegisterConnection 注册一个新的数据库连接配置
func (cp *ConnectionPool) RegisterConnection(
	connID string,
	dbType string,
	dbVersion string,
	host string,
	port int,
	username string,
	password string,
	dbName string,
	schema string,
	extraParams map[string]string,
	maxIdleTime time.Duration,
	maxLifetime time.Duration,
	maxOpenConns int,
	maxIdleConns int,
) error {
	cp.mu.Lock()
	defer cp.mu.Unlock()

	// 检查连接ID是否已存在
	if _, exists := cp.pools[connID]; exists {
		//return fmt.Errorf("连接ID %s 已存在", connID)
		return nil
	}

	ctx, cancel := context.WithCancel(cp.cleanupCtx)

	// 创建连接配置
	config := &meta.ConnectionConfig{
		Host:     host,
		Port:     port,
		Username: username,
		Password: password,
		Database: dbName,
		Schema:   schema,
		//ExtraParams:  extraParams,
		MaxOpenConns: maxOpenConns,
		MaxIdleConns: maxIdleConns,
		MaxIdleTime:  int(maxIdleTime.Seconds()),
		MaxLifetime:  int(maxLifetime.Seconds()),
	}

	// 立即创建数据库执行器
	executor, err := drivers.Connect(dbType, dbVersion, config)
	if err != nil {
		cancel()
		return fmt.Errorf("创建数据库连接失败: %v", err)
	}

	// 测试连接
	if err := executor.Ping(context.Background()); err != nil {
		executor.Close()
		cancel()
		return fmt.Errorf("数据库连接失败: %v", err)
	}

	cp.pools[connID] = &PooledConnection{
		DbConn:    executor,
		LastUsed:  time.Now(),
		Type:      dbType,
		Version:   dbVersion,
		DbConfig:  config,
		closeChan: make(chan struct{}),
		ctx:       ctx,
		cancel:    cancel,
	}

	return nil
}

// GetConnection 获取已注册的数据库连接
func (cp *ConnectionPool) GetConnection(connID string) (*PooledConnection, error) {
	cp.mu.RLock()
	pooledConn, exists := cp.pools[connID]
	cp.mu.RUnlock()

	if !exists {
		// 返回可用于错误匹配的已导出哨兵错误
		return nil, fmt.Errorf("%w: %s", response.ErrConnNotExist, connID)
	}

	// 检查连接是否已被关闭
	select {
	case <-pooledConn.ctx.Done():
		return nil, fmt.Errorf("连接 %s 已关闭", connID)
	default:
	}

	// 检查连接是否已初始化
	if pooledConn.DbConn == nil {
		cp.mu.Lock()
		defer cp.mu.Unlock()

		// 再次检查是否已初始化（并发情况下）
		if pooledConn.DbConn == nil {
			// 创建新执行器
			executor, err := drivers.Connect(pooledConn.Type, pooledConn.Version, pooledConn.DbConfig)
			if err != nil {
				return nil, fmt.Errorf("创建数据库执行器失败: %v", err)
			}

			// 测试连接
			if err := executor.Ping(context.Background()); err != nil {
				executor.Close()
				return nil, fmt.Errorf("测试数据库连接失败: %v", err)
			}

			// 保存执行器
			pooledConn.DbConn = executor
			pooledConn.LastUsed = time.Now()
		}
	}

	// 检查连接是否已过期
	maxLifetime := time.Duration(pooledConn.DbConfig.MaxLifetime) * time.Second
	if maxLifetime > 0 && time.Since(pooledConn.LastUsed) > maxLifetime {
		cp.mu.Lock()
		defer cp.mu.Unlock()

		// 再次检查（并发情况下）
		if maxLifetime > 0 && time.Since(pooledConn.LastUsed) > maxLifetime {
			// 关闭旧连接
			pooledConn.DbConn.Close()

			// 创建新执行器
			executor, err := drivers.Connect(pooledConn.Type, pooledConn.Version, pooledConn.DbConfig)
			if err != nil {
				return nil, fmt.Errorf("创建数据库执行器失败: %v", err)
			}

			// 测试连接
			if err := executor.Ping(context.Background()); err != nil {
				executor.Close()
				return nil, fmt.Errorf("测试数据库连接失败: %v", err)
			}

			// 更新执行器
			pooledConn.DbConn = executor
			pooledConn.LastUsed = time.Now()
		}
	} else {
		// 更新最后使用时间
		pooledConn.LastUsed = time.Now()
	}

	return pooledConn, nil
}

// CloseConnection 关闭并移除连接
func (cp *ConnectionPool) CloseConnection(connID string) error {
	cp.mu.Lock()
	defer cp.mu.Unlock()

	if pooledConn, exists := cp.pools[connID]; exists {
		// 标记连接为已关闭
		pooledConn.cancel()

		// 关闭通道通知
		close(pooledConn.closeChan)

		// 关闭实际连接
		if pooledConn.DbConn != nil {
			if closer, ok := pooledConn.DbConn.(interface{ Close() error }); ok {
				if err := closer.Close(); err != nil {
					return fmt.Errorf("关闭数据库连接失败: %v", err)
				}
			}
			pooledConn.DbConn = nil
		}

		// 从池中移除
		delete(cp.pools, connID)
	}

	return nil
}

// CloseAllConnections 关闭所有连接
func (cp *ConnectionPool) CloseAllConnections() error {
	cp.mu.Lock()
	defer cp.mu.Unlock()

	// 停止清理协程
	if cp.cleanupTicker != nil {
		cp.cleanupTicker.Stop()
	}
	cp.cleanupCancel()

	var firstError error
	for connID, pooledConn := range cp.pools {
		// 标记连接为已关闭
		pooledConn.cancel()

		// 关闭通道通知
		close(pooledConn.closeChan)

		// 关闭实际连接
		if pooledConn.DbConn != nil {
			if closer, ok := pooledConn.DbConn.(interface{ Close() error }); ok {
				if err := closer.Close(); err != nil {
					if firstError == nil {
						firstError = fmt.Errorf("关闭连接 %s 失败: %v", connID, err)
					}
				}
			}
			pooledConn.DbConn = nil
		}
	}

	cp.pools = make(map[string]*PooledConnection)
	return firstError
}

// periodicCleanup 定期清理空闲连接
func (cp *ConnectionPool) periodicCleanup() {
	// 默认每5分钟检查一次
	if cp.cleanupTicker == nil {
		cp.cleanupTicker = time.NewTicker(5 * time.Minute)
	}

	for {
		select {
		case <-cp.cleanupTicker.C:
			cp.mu.Lock()
			now := time.Now()

			for connID, pooledConn := range cp.pools {
				// 检查连接是否需要清理
				// 这里可以根据需要添加清理逻辑
				_ = connID
				_ = pooledConn
				_ = now
			}

			cp.mu.Unlock()

		case <-cp.cleanupCtx.Done():
			return
		}
	}
}

// GetConnectionStats 获取连接池状态统计
func (cp *ConnectionPool) GetConnectionStats() map[string]PoolStats {
	cp.mu.RLock()
	defer cp.mu.RUnlock()

	stats := make(map[string]PoolStats)

	for connID, pooledConn := range cp.pools {
		stats[connID] = cp.buildPoolStatsLocked(pooledConn)
	}

	return stats
}

// GetConnectionStat 返回指定连接的状态快照
func (cp *ConnectionPool) GetConnectionStat(connID string) (PoolStats, bool) {
	cp.mu.RLock()
	defer cp.mu.RUnlock()

	pooledConn, exists := cp.pools[connID]
	if !exists {
		return PoolStats{}, false
	}

	return cp.buildPoolStatsLocked(pooledConn), true
}

// buildPoolStatsLocked 在持有读写锁的前提下构建连接状态
func (cp *ConnectionPool) buildPoolStatsLocked(pooledConn *PooledConnection) PoolStats {
	maxIdleTime := time.Duration(pooledConn.DbConfig.MaxIdleTime) * time.Second
	maxLifetime := time.Duration(pooledConn.DbConfig.MaxLifetime) * time.Second

	return PoolStats{
		LastUsed:     pooledConn.LastUsed,
		Type:         pooledConn.Type,
		Version:      pooledConn.Version,
		IsConnected:  pooledConn.DbConn != nil,
		MaxIdleTime:  maxIdleTime,
		MaxLifetime:  maxLifetime,
		MaxOpenConns: pooledConn.DbConfig.MaxOpenConns,
		MaxIdleConns: pooledConn.DbConfig.MaxIdleConns,
	}
}