source

type Direction string

type Driver interface {
	// Open returns a new driver instance configured with parameters
	// coming from the URL string. Migrate will call this function
	// only once per instance.
	Open(url string, logger *log.Logger) (Driver, error)

	// Close closes the underlying source instance managed by the driver.
	// Migrate will call this function only once per instance.
	Close() error

	// Scan scans the local migration files
	Scan() error

	// Default Parser to be used for scanning the file system
	DefaultParser(Parser)

	// First returns the very first migration version available to the driver.
	// Migrate will call this function multiple times.
	// If there is no version available, it must return os.ErrNotExist.
	First() (version uint64, err error)

	// GetLocalVersion returns the latest version available in migrations folder
	GetLocalVersion() (version uint64, err error)

	// Get all unapplied migrations present in local directory
	GetUnappliedMigrations(version uint64) (versions []uint64)

	// Prev returns the previous version for a given version available to the driver.
	// Migrate will call this function multiple times.
	// If there is no previous version available, it must return os.ErrNotExist.
	Prev(version uint64) (prevVersion uint64, err error)

	// Next returns the next version for a given version available to the driver.
	// Migrate will call this function multiple times.
	// If there is no next version available, it must return os.ErrNotExist.
	Next(version uint64) (nextVersion uint64, err error)

	GetDirections(version uint64) map[Direction]bool

	// ReadUp returns the UP migration body and an identifier that helps
	// finding this migration in the source for a given version.
	// If there is no up migration available for this version,
	// it must return os.ErrNotExist.
	// Do not start reading, just return the ReadCloser!
	ReadUp(version uint64) (r io.ReadCloser, identifier string, fileName string, err error)

	// ReadUp returns the UP migration body and an identifier that helps
	// finding this migration in the source for a given version.
	// If there is no up migration available for this version,
	// it must return os.ErrNotExist.
	// Do not start reading, just return the ReadCloser!
	ReadMetaUp(version uint64) (r io.ReadCloser, identifier string, fileName string, err error)

	// ReadDown returns the DOWN migration body and an identifier that helps
	// finding this migration in the source for a given version.
	// If there is no down migration available for this version,
	// it must return os.ErrNotExist.
	// Do not start reading, just return the ReadCloser!
	ReadDown(version uint64) (r io.ReadCloser, identifier string, fileName string, err error)

	// ReadDown returns the DOWN migration body and an identifier that helps
	// finding this migration in the source for a given version.
	// If there is no down migration available for this version,
	// it must return os.ErrNotExist.
	// Do not start reading, just return the ReadCloser!
	ReadMetaDown(version uint64) (r io.ReadCloser, identifier string, fileName string, err error)

	// ReadName returns an name that helps
	// finding this migration in the source for a given version
	ReadName(version uint64) (name string)
}

type Migration struct {
	// Version is the version of this migration.
	Version uint64

	// Identifier can be any string that helps identifying
	// this migration in the source.
	Identifier string

	// Direction is either Up or Down.
	Direction Direction

	// Raw holds the raw location path to this migration in source.
	// ReadUp and ReadDown will use this.
	Raw string

	// Check if the file exists in a directory
	IsDir bool
}

type Migrations struct {
	Index      uint64Slice
	Migrations map[uint64]map[Direction]*Migration
}

type Parser func(raw string) (*Migration, error)