s4

type AddressRange struct {
	// MinAddress (inclusive).
	MinAddress *utils.Big
	// MaxAddress (inclusive).
	MaxAddress *utils.Big
}

type Constraints struct {
	MaxPayloadSizeBytes    uint   `json:"maxPayloadSizeBytes"`
	MaxSlotsPerUser        uint   `json:"maxSlotsPerUser"`
	MaxExpirationLengthSec uint64 `json:"maxExpirationLengthSec"`
}

type Envelope struct {
	Address    []byte `json:"address"`
	SlotID     uint   `json:"slotid"`
	Payload    []byte `json:"payload"`
	Version    uint64 `json:"version"`
	Expiration int64  `json:"expiration"`
}

type Key struct {
	// Address is a user address
	Address common.Address
	// SlotId is a slot number
	SlotId uint
	// Version is a data version
	Version uint64
}

type Metadata struct {
	// Confirmed turns true once consensus is reached.
	Confirmed bool
	// Signature contains the original user signature.
	Signature []byte
}

type ORM interface {
	// Get reads a row for the given address and slotId combination.
	// If such row does not exist, ErrNotFound is returned.
	// There is no filter on Expiration.
	Get(address *utils.Big, slotId uint, qopts ...pg.QOpt) (*Row, error)

	// Update inserts or updates the row identified by (Address, SlotId) pair.
	// When updating, the new row must have greater or equal version,
	// otherwise ErrVersionTooLow is returned.
	// UpdatedAt field value is ignored.
	Update(row *Row, qopts ...pg.QOpt) error

	// DeleteExpired deletes any entries having Expiration < utcNow,
	// up to the given limit.
	// Returns the number of deleted rows.
	DeleteExpired(limit uint, utcNow time.Time, qopts ...pg.QOpt) (int64, error)

	// GetSnapshot selects all non-expired row versions for the given addresses range.
	// For the full address range, use NewFullAddressRange().
	GetSnapshot(addressRange *AddressRange, qopts ...pg.QOpt) ([]*SnapshotRow, error)

	// GetUnconfirmedRows selects all non-expired, non-confirmed rows ordered by UpdatedAt.
	// The number of returned rows is limited to the given limit.
	GetUnconfirmedRows(limit uint, qopts ...pg.QOpt) ([]*Row, error)
}

type Record struct {
	// Arbitrary user data
	Payload []byte
	// Expiration timestamp assigned by user (unix time in milliseconds)
	Expiration int64
}

type Row struct {
	Address    *utils.Big
	SlotId     uint
	Payload    []byte
	Version    uint64
	Expiration int64
	Confirmed  bool
	Signature  []byte
}

type SnapshotRow struct {
	Address    *utils.Big
	SlotId     uint
	Version    uint64
	Expiration int64
	Confirmed  bool
}

type Storage interface {
	// Constraints returns a copy of Constraints struct specified during service creation.
	// The implementation is thread-safe.
	Constraints() Constraints

	// Get returns a copy of record (with metadata) associated with the specified key.
	// The returned Record & Metadata are always a copy.
	Get(ctx context.Context, key *Key) (*Record, *Metadata, error)

	// Put creates (or updates) a record identified by the specified key.
	// For signature calculation see envelope.go
	Put(ctx context.Context, key *Key, record *Record, signature []byte) error

	// List returns a snapshot for the specified address.
	// Slots having no data are not returned.
	List(ctx context.Context, address common.Address) ([]*SnapshotRow, error)
}