type Go struct {
	// We used an explicit bool instead of relying on a pointer because registered funcs may be nil.
	// These are still valid Go and versioned migrations, but they are just empty.
	//
	// For example: goose.AddMigration(nil, nil)
	UseTx bool

	// Only one of these func pairs will be set:
	UpFn, DownFn func(context.Context, *sql.Tx) error
	// -- or --
	UpFnNoTx, DownFnNoTx func(context.Context, *sql.DB) error
}

type Migration struct {
	// Fullpath is the full path to the migration file.
	//
	// Example: /path/to/migrations/123_create_users_table.go
	Fullpath string
	// Version is the version of the migration.
	Version int64
	// Type is the type of migration.
	Type MigrationType
	// A migration is either a Go migration or a SQL migration, but never both.
	//
	// Note, the SQLParsed field is used to determine if the SQL migration has been parsed. This is
	// an optimization to avoid parsing the SQL migration if it is never required. Also, the
	// majority of the time migrations are incremental, so it is likely that the user will only want
	// to run the last few migrations, and there is no need to parse ALL prior migrations.
	//
	// Exactly one of these fields will be set:
	Go *Go
	// -- or --
	SQLParsed bool
	SQL       *SQL
}

type MigrationType int

const (
	TypeGo MigrationType = iota + 1
	TypeSQL
)

type SQL struct {
	UseTx          bool
	UpStatements   []string
	DownStatements []string
}