package mdb

type WALStatus struct {
	MaxID        uint64 // TODO: WALMaxSeqNum
	MaxAppliedID uint64 // TODO: KVMaxSeqNum
}

type itemIndex[T any] interface {
	load(m map[uint64]*T) error
	insert(*T)
	update(old, new *T) // Old and new MUST have the same ID.
	delete(*T)
}

type itemUniqueIndex[T any] interface {
	load(m map[uint64]*T) error
	name() string
	lock(*T)
	unlock(*T)
	insertConflict(*T) bool
	updateConflict(*T) bool
}

type dbCollection interface {
	loadData()
	onStore(string, uint64, []byte) // For WAL following.
	onDelete(string, uint64)        // For WAL following.
}