package db

import (
  "context"
  "database/sql"
  "fmt"
  "log"
  "net"
  "os"

  "cloud.google.com/go/cloudsqlconn"
  "github.com/go-sql-driver/mysql"
  gmysql "gorm.io/driver/mysql"
  "gorm.io/gorm"
)

var DB *gorm.DB

type Model struct {
  gorm.Model
}

func mustGetenv(k string) string {
  v := os.Getenv(k)
  if v == "" {
    log.Fatalf("Fatal Error in connect_connector.go: %s environment variable not set.", k)
  }
  return v
}

func InitDB() {

  var (
    dbUser                 = mustGetenv("DB_USER")                  // e.g. 'my-db-user'
    dbPwd                  = mustGetenv("DB_PASS")                  // e.g. 'my-db-password'
    dbName                 = mustGetenv("DB_NAME")                  // e.g. 'my-database'
    instanceConnectionName = mustGetenv("INSTANCE_CONNECTION_NAME") // e.g. 'project:region:instance'
    usePrivate             = os.Getenv("PRIVATE_IP")
  )
  d, err := cloudsqlconn.NewDialer(context.Background())
  if err != nil {
    fmt.Errorf("cloudsqlconn.NewDialer: %w", err)
    return
  }
  var opts []cloudsqlconn.DialOption
  if usePrivate != "" {
    opts = append(opts, cloudsqlconn.WithPrivateIP())
  }
  mysql.RegisterDialContext("cloudsqlconn",
    func(ctx context.Context, addr string) (net.Conn, error) {
      return d.Dial(ctx, instanceConnectionName, opts...)
    })

  dbURI := fmt.Sprintf("%s:%s@cloudsqlconn(localhost:3306)/%s?parseTime=true",
    dbUser, dbPwd, dbName)

  sqlDB, err := sql.Open("mysql", dbURI)
  if err != nil {
    log.Fatalf("sql.Open: %v", err)
  }

  // Open a connection to the database using the gorm package
  DB, err = gorm.Open(gmysql.New(gmysql.Config{
    Conn: sqlDB,
  }), &gorm.Config{})

  if err != nil {
    log.Fatalf("gorm.Open: %v", err)
  }

  fmt.Println("データベースに接続しました")
}