package postgres

import (
	"fmt"

	"git.nonahob.net/jacob/golibs/datastores/sql/migrate"
)

var _ migrate.Dialect = Dialect{}

// Dialect implements migrate.Dialect for PostgreSQL.
type Dialect struct{}

// Placeholder returns PostgreSQL's positional bind parameter ($1, $2, …).
func (Dialect) Placeholder(n int) string { return fmt.Sprintf("$%d", n) }

// TableExistsQuery returns a query that checks whether a table exists in
// PostgreSQL using information_schema.
func (Dialect) TableExistsQuery() string {
	return "SELECT EXISTS (SELECT FROM information_schema.tables WHERE table_name = $1)"
}