package dbx

import (
	"git.liteyuki.org/LiteyukiStudio/folium/osx"
	"gorm.io/gorm"
)

type DBDriverType string

const (
	Postgres DBDriverType = "postgres"
	MySQL    DBDriverType = "mysql"
	SQLite   DBDriverType = "sqlite"
)

// DBConfig 持有数据库连接配置，可以部分填写，未填写的字段会从环境变量读取默认值
type DBConfig struct {
	Driver   DBDriverType
	Host     string
	Port     string
	User     string
	Password string
	Sslmode  string
}

// NewDBConfigFromEnv 从环境变量构造默认配置
func NewDBConfigFromEnv() *DBConfig {
	return &DBConfig{
		Driver:   DBDriverType(osx.GetEnv("DB_DRIVER", string(Postgres))),
		Host:     osx.GetEnv("DB_HOST", "localhost"),
		Port:     osx.GetEnv("DB_PORT", "5432"),
		User:     osx.GetEnv("DB_USER", "user"),
		Password: osx.GetEnv("DB_PASSWORD", "password"),
		Sslmode:  osx.GetEnv("DB_SSLMODE", "disable"),
	}
}

// FillDefaultsFromEnv 对于为空的字段，用环境变量或默认值补全
func (c *DBConfig) FillDefaultsFromEnv() {
	if c == nil {
		c = &DBConfig{}
	}
	if c.Driver == "" {
		c.Driver = DBDriverType(osx.GetEnv("DB_DRIVER", string(Postgres)))
	}
	if c.Host == "" {
		c.Host = osx.GetEnv("DB_HOST", "localhost")
	}
	if c.Port == "" {
		c.Port = osx.GetEnv("DB_PORT", "5432")
	}
	if c.User == "" {
		c.User = osx.GetEnv("DB_USER", "user")
	}
	if c.Password == "" {
		c.Password = osx.GetEnv("DB_PASSWORD", "password")
	}
	if c.Sslmode == "" {
		c.Sslmode = osx.GetEnv("DB_SSLMODE", "disable")
	}
}

// GetDB 使用给定配置（或 DefaultDBConfig if nil）并返回对应的 *gorm.DB
// 如果 dbName 为空则使用配置中的 Name 字段（仍会从环境变量补全）
func GetDB(cfg *DBConfig, dbName string) *gorm.DB {
	if cfg == nil {
		cfg = NewDBConfigFromEnv()
	}
	cfg.FillDefaultsFromEnv()

	if dbName == "" {
		dbName = osx.GetEnv("DB_NAME", "database")
		if dbName == "" {
			panic("database name is not specified")
		}
	}

	switch cfg.Driver {
	case Postgres:
		return GetPostgresDB(cfg, dbName)
	case MySQL:
		return GetMySQLDB(cfg, dbName)
	case SQLite:
		return GetSQLiteDB(cfg, dbName)
	default:
		panic("unsupported database driver: " + string(cfg.Driver))
	}
}