status-im/status-go

package mailserver

import (
    "encoding/binary"
    "errors"

    "github.com/status-im/status-go/eth-node/types"
)

const (
    // DBKeyLength is a size of the envelope key.
    DBKeyLength  = types.HashLength + timestampLength + types.TopicLength
    CursorLength = types.HashLength + timestampLength
)

var (
    // ErrInvalidByteSize is returned when DBKey can't be created
    // from a byte slice because it has invalid length.
    ErrInvalidByteSize = errors.New("byte slice has invalid length")
)

// DBKey key to be stored in a db.
type DBKey struct {
    raw []byte
}

// Bytes returns a bytes representation of the DBKey.
func (k *DBKey) Bytes() []byte {
    return k.raw
}

func (k *DBKey) Topic() types.TopicType {
    return types.BytesToTopic(k.raw[timestampLength+types.HashLength:])
}

func (k *DBKey) EnvelopeHash() types.Hash {
    return types.BytesToHash(k.raw[timestampLength : types.HashLength+timestampLength])
}

func (k *DBKey) Cursor() []byte {
    // We don't use the whole cursor for backward compatibility (also it's not needed)
    return k.raw[:CursorLength]
}

// NewDBKey creates a new DBKey with the given values.
func NewDBKey(timestamp uint32, topic types.TopicType, h types.Hash) *DBKey {
    var k DBKey
    k.raw = make([]byte, DBKeyLength)
    binary.BigEndian.PutUint32(k.raw, timestamp)
    copy(k.raw[timestampLength:], h[:])
    copy(k.raw[timestampLength+types.HashLength:], topic[:])
    return &k
}