package dao

import (
	"database/sql"
	"fmt"
	"github.com/kratisto/mam-contract/configuration"

	_ "github.com/lib/pq" // Required to use the driver with database/sql
)

// Database is the interface for DB access
type Database interface {
	Ping() error
}

// DatabasePostgreSQL is the implementation of the Database interface for PostgreSQL
type DatabasePostgreSQL struct {
	session *sql.DB
	schema  string
}

// NewDatabasePostgreSQL returns an instance of the database
func NewDatabasePostgreSQL(config *configuration.Config) Database {
	var (
		dbSession *sql.DB
		err       error
	)

	connectionURI := fmt.Sprintf("postgresql://%s:%s@%s/%s?sslmode=disable", config.PostgresUser, config.PostgresPwd, config.PostgresHost, config.PostgresDBName)
	dbSession, err = sql.Open("postgres", connectionURI)
	if err != nil {
		return nil
	}

	err = dbSession.Ping()
	if err != nil {
		return nil
	}
	return &DatabasePostgreSQL{session: dbSession, schema: config.PostgresDBSchema}
}

// Ping doesn't use db.Ping because it doesn't Ping after the first time
// https://stackoverflow.com/a/41619206/3853913
func (db *DatabasePostgreSQL) Ping() error {
	_, err := db.session.Query("SELECT WHERE 1=0")
	return err
}