uback

type Backup struct {
	// Snapshot from which this backup was created
	Snapshot

	// If nil, this backup is a full backup.
	// If not nil, this is an incremental backup whose base is BsaeSnapshot
	BaseSnapshot *Snapshot
}

type Destination interface {
	// List backups present on the source
	ListBackups() ([]Backup, error)

	// Remove a backup
	RemoveBackup(backup Backup) error

	// Store a backup whose data is `data`
	SendBackup(backup Backup, data io.Reader) error

	// Retrieve the content of a previously stored backup
	ReceiveBackup(backup Backup) (io.ReadCloser, error)
}

type KeyValuePair = [2]string

type Options struct {
	// All normal (non-"@"-prefixed) options
	String map[string]string

	// All noslice (non-"@"-prefixed) options
	// Keys have their "@" prefix stripped
	StrSlice map[string][]string
}

type ReadWriteCloser struct {
	io.ReadCloser
	io.WriteCloser
}

type RetentionPolicy struct {
	Interval int  // Minimum interval between two backups
	Count    int  // Maximum number of retained backups
	FullOnly bool // If true, only retain full backups
}

type RetentionPolicySubject interface {
	Time() (time.Time, error)
	IsFull() bool
	Name() string
}

type Snapshot string

type Source interface {
	// Get all snapshots that can be used as a base snapshot for incremental backups
	ListSnapshots() ([]Snapshot, error)

	// Remove a snapshot
	RemoveSnapshot(snapshot Snapshot) error

	// Create a backup from a base snapshot (if supported by the source), or nil for a full snapshot.
	// Returns the name of the created backup, and a reader to the backup data.
	// The returned backup can be full even if baseSnapshot is not nil, but cannot
	// be an incremental backup if baseSnapshot is nil.
	CreateBackup(baseSnapshot *Snapshot) (Backup, io.ReadCloser, error)

	// Restore a backup whose name is `backup` and data is `data` onto the `target` directory.
	// If `backup` is an incremental backup, his base is guaranteed to already have been restored.
	RestoreBackup(target string, backup Backup, data io.Reader) error
}