package config

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sync"
)

var (
	instance *Config
	once     sync.Once
)

type Config struct {
	ServerPort    string
	DatabasePath  string
	JWTSecret     string
	EncryptionKey string // 独立加密密钥，必须与JWT_SECRET分离
	DataDir       string
	KubeDir       string
	LogLevel      string // 新增：日志级别 debug/info/warn/error
	HostKeyDir    string // 新增：SSH主机密钥存储目录
}

func GetConfig() *Config {
	once.Do(func() {
		dataDir := getEnv("DATA_DIR", "./data")

		jwtSecret := os.Getenv("JWT_SECRET")
		encKey := os.Getenv("ENCRYPTION_KEY")

		// 生产环境强制校验：JWT_SECRET和ENCRYPTION_KEY必须设置
		if jwtSecret == "" {
			log.Fatal("[SECURITY] JWT_SECRET environment variable is required. Please set a strong random secret.")
		}
		if encKey == "" {
			log.Fatal("[SECURITY] ENCRYPTION_KEY environment variable is required. Please set a strong 32-byte random key (base64 or hex encoded).")
		}

		// ENCRYPTION_KEY 长度校验：至少32字节（256位）
		if len(encKey) < 32 {
			log.Fatal(fmt.Sprintf("[SECURITY] ENCRYPTION_KEY must be at least 32 bytes, got %d bytes", len(encKey)))
		}

		instance = &Config{
			ServerPort:    getEnv("SERVER_PORT", "8080"),
			DatabasePath:  databasePath(dataDir),
			JWTSecret:     jwtSecret,
			EncryptionKey: encKey,
			DataDir:       dataDir,
			KubeDir:       filepath.Join(dataDir, "kubeconfigs"),
			LogLevel:      getEnv("LOG_LEVEL", "info"),
			HostKeyDir:    filepath.Join(dataDir, "known_hosts"),
		}

		_ = os.MkdirAll(instance.KubeDir, 0700)
		_ = os.MkdirAll(instance.HostKeyDir, 0700)
	})
	return instance
}

func getEnv(key, defaultVal string) string {
	if val := os.Getenv(key); val != "" {
		return val
	}
	return defaultVal
}

// databasePath 新名优先;历史命名的数据文件存在且新文件不存在时沿用旧文件
// (数据平滑迁移,不搬移文件、零丢失风险)
func databasePath(dataDir string) string {
	newPath := filepath.Join(dataDir, "lokistack.json")
	if _, err := os.Stat(newPath); err == nil {
		return newPath
	}
	for _, legacy := range []string{"opsxloki.json", "lokideploy.json"} {
		legacyPath := filepath.Join(dataDir, legacy)
		if _, err := os.Stat(legacyPath); err == nil {
			return legacyPath
		}
	}
	return newPath
}