box

type BaseBox interface {
	// Location returns some information where the box is located.
	// Format is dependent of the box.
	Location() string

	// GetZettel retrieves a specific zettel.
	GetZettel(ctx context.Context, zid id.Zid) (zettel.Zettel, error)

	// AllowRenameZettel returns true, if box will not disallow renaming the zettel.
	AllowRenameZettel(ctx context.Context, zid id.Zid) bool

	// RenameZettel changes the current Zid to a new Zid.
	RenameZettel(ctx context.Context, curZid, newZid id.Zid) error

	// CanDeleteZettel returns true, if box could possibly delete the given zettel.
	CanDeleteZettel(ctx context.Context, zid id.Zid) bool

	// DeleteZettel removes the zettel from the box.
	DeleteZettel(ctx context.Context, zid id.Zid) error
}

type Box interface {
	BaseBox
	WriteBox

	// FetchZids returns the set of all zettel identifer managed by the box.
	FetchZids(ctx context.Context) (id.Set, error)

	// GetMeta returns the metadata of the zettel with the given identifier.
	GetMeta(context.Context, id.Zid) (*meta.Meta, error)

	// SelectMeta returns a list of metadata that comply to the given selection criteria.
	// If `metaSeq` is `nil`, the box assumes metadata of all available zettel.
	SelectMeta(ctx context.Context, metaSeq []*meta.Meta, q *query.Query) ([]*meta.Meta, error)

	// GetAllZettel retrieves a specific zettel from all managed boxes.
	GetAllZettel(ctx context.Context, zid id.Zid) ([]zettel.Zettel, error)

	// Refresh the data from the box and from its managed sub-boxes.
	Refresh(context.Context) error

	// ReIndex one zettel to update its index data.
	ReIndex(context.Context, id.Zid) error
}

type Enricher interface {
	// Enrich computes additional properties and updates the given metadata.
	// It is typically called by zettel reading methods.
	Enrich(ctx context.Context, m *meta.Meta, boxNumber int)
}

type ErrInvalidZid struct{ Zid string }

type ErrNotAllowed struct {
	Op   string
	User *meta.Meta
	Zid  id.Zid
}

type ErrZettelNotFound struct{ Zid id.Zid }

type ManagedBox interface {
	BaseBox

	// HasZettel returns true, if box conains zettel with given identifier.
	HasZettel(context.Context, id.Zid) bool

	// Apply identifier of every zettel to the given function, if predicate returns true.
	ApplyZid(context.Context, ZidFunc, query.RetrievePredicate) error

	// Apply metadata of every zettel to the given function, if predicate returns true.
	ApplyMeta(context.Context, MetaFunc, query.RetrievePredicate) error

	// ReadStats populates st with box statistics
	ReadStats(st *ManagedBoxStats)
}

type ManagedBoxStats struct {
	// ReadOnly indicates that the content of a box cannot change.
	ReadOnly bool

	// Zettel is the number of zettel managed by the box.
	Zettel int
}

type Manager interface {
	Box
	StartStopper
	Subject

	// ReadStats populates st with box statistics
	ReadStats(st *Stats)

	// Dump internal data to a Writer.
	Dump(w io.Writer)
}

type MetaFunc func(*meta.Meta)

type Refresher interface {
	// Refresh the box data.
	Refresh(context.Context)
}

type StartState uint8

type StartStopper interface {
	// State the current status of the box.
	State() StartState

	// Start the box. Now all other functions of the box are allowed.
	// Starting a box, which is not in state StartStateStopped is not allowed.
	Start(ctx context.Context) error

	// Stop the started box. Now only the Start() function is allowed.
	Stop(ctx context.Context)
}

type Stats struct {
	// ReadOnly indicates that boxes cannot be modified.
	ReadOnly bool

	// NumManagedBoxes is the number of boxes managed.
	NumManagedBoxes int

	// Zettel is the number of zettel managed by the box, including
	// duplicates across managed boxes.
	ZettelTotal int

	// LastReload stores the timestamp when a full re-index was done.
	LastReload time.Time

	// DurLastReload is the duration of the last full re-index run.
	DurLastReload time.Duration

	// IndexesSinceReload counts indexing a zettel since the full re-index.
	IndexesSinceReload uint64

	// ZettelIndexed is the number of zettel managed by the indexer.
	ZettelIndexed int

	// IndexUpdates count the number of metadata updates.
	IndexUpdates uint64

	// IndexedWords count the different words indexed.
	IndexedWords uint64

	// IndexedUrls count the different URLs indexed.
	IndexedUrls uint64
}

type Subject interface {
	// RegisterObserver registers an observer that will be notified
	// if one or all zettel are found to be changed.
	RegisterObserver(UpdateFunc)
}

type UpdateFunc func(UpdateInfo)

type UpdateInfo struct {
	Box    BaseBox
	Reason UpdateReason
	Zid    id.Zid
}

type UpdateReason uint8

type WriteBox interface {
	// CanCreateZettel returns true, if box could possibly create a new zettel.
	CanCreateZettel(ctx context.Context) bool

	// CreateZettel creates a new zettel.
	// Returns the new zettel id (and an error indication).
	CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error)

	// CanUpdateZettel returns true, if box could possibly update the given zettel.
	CanUpdateZettel(ctx context.Context, zettel zettel.Zettel) bool

	// UpdateZettel updates an existing zettel.
	UpdateZettel(ctx context.Context, zettel zettel.Zettel) error
}

type ZidFunc func(id.Zid)