package db

import (
	"database/sql"
	"fmt"
	"log"
	"os"
	"time"

	_ "github.com/lib/pq"
)

var DB *sql.DB

// Config 数据库配置
type Config struct {
	Host     string
	Port     int
	User     string
	Password string
	DBName   string
	SSLMode  string
}

// DefaultConfig 从环境变量读取默认配置
func DefaultConfig() Config {
	return Config{
		Host:     getEnv("DB_HOST", "localhost"),
		Port:     getEnvInt("DB_PORT", 5432),
		User:     getEnv("DB_USER", "postgres"),
		Password: getEnv("DB_PASSWORD", ""),
		DBName:   getEnv("DB_NAME", "gpt_manager"),
		SSLMode:  getEnv("DB_SSLMODE", "disable"),
	}
}

// Connect 连接数据库
func Connect(cfg Config) (*sql.DB, error) {
	dsn := fmt.Sprintf(
		"host=%s port=%d user=%s password=%s dbname=%s sslmode=%s",
		cfg.Host, cfg.Port, cfg.User, cfg.Password, cfg.DBName, cfg.SSLMode,
	)

	db, err := sql.Open("postgres", dsn)
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	// 配置连接池
	db.SetMaxOpenConns(25)
	db.SetMaxIdleConns(5)
	db.SetConnMaxLifetime(5 * time.Minute)

	// 测试连接
	if err := db.Ping(); err != nil {
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	log.Println("Database connected successfully")
	return db, nil
}

// Init 初始化全局数据库连接
func Init() error {
	cfg := DefaultConfig()
	db, err := Connect(cfg)
	if err != nil {
		return err
	}
	DB = db
	return nil
}

// Close 关闭数据库连接
func Close() error {
	if DB != nil {
		return DB.Close()
	}
	return nil
}

// getEnv 获取环境变量，带默认值
func getEnv(key, defaultVal string) string {
	if val := os.Getenv(key); val != "" {
		return val
	}
	return defaultVal
}

// getEnvInt 获取整数类型环境变量
func getEnvInt(key string, defaultVal int) int {
	if val := os.Getenv(key); val != "" {
		var i int
		if _, err := fmt.Sscanf(val, "%d", &i); err == nil {
			return i
		}
	}
	return defaultVal
}