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package imap
import (
"slices"
"sync"
"git.sr.ht/~rjarry/aerc/lib/log"
)
type SeqMap struct {
lock sync.Mutex
// map of IMAP sequence numbers to message UIDs
m []uint32
}
// Initialize sets the initial seqmap of the mailbox
func (s *SeqMap) Initialize(uids []uint32) {
s.lock.Lock()
s.m = make([]uint32, len(uids))
copy(s.m, uids)
s.sort()
s.lock.Unlock()
}
func (s *SeqMap) Size() int {
s.lock.Lock()
size := len(s.m)
s.lock.Unlock()
return size
}
// Get returns the UID of the given seqnum
func (s *SeqMap) Get(seqnum uint32) (uint32, bool) {
if int(seqnum) > s.Size() || seqnum < 1 {
return 0, false
}
s.lock.Lock()
uid := s.m[seqnum-1]
s.lock.Unlock()
return uid, true
}
// Put adds a UID to the slice. Put should only be used to add new messages
// into the slice
func (s *SeqMap) Put(uid uint32) {
s.lock.Lock()
if slices.Contains(s.m, uid) {
// We already have this UID, don't insert it.
s.lock.Unlock()
return
}
s.m = append(s.m, uid)
s.sort()
s.lock.Unlock()
}
// Take a snapshot of the SequenceNumber=>UID mappings for the given UIDs,
// remove those UIDs from the SeqMap, and return the snapshot it to the caller,
// as well as the loweest sequence number it contains.
func (s *SeqMap) Snapshot(uids []uint32) (map[uint32]uint32, uint32) {
// Take the snapshot.
snapshot := make(map[uint32]uint32)
var minSequenceNum uint32 = 0
var snapshotSeqNums []uint32
s.lock.Lock()
for num, uid := range s.m {
if slices.Contains(uids, uid) {
// IMAP sequence numbers start at 1
seqNum := uint32(num) + 1
snapshotSeqNums = append(snapshotSeqNums, seqNum)
if minSequenceNum == 0 {
minSequenceNum = seqNum
}
snapshot[seqNum] = uid
}
}
s.lock.Unlock()
// Remove the snapshotted mappings from the sequence; we need to do it from
// the highest to the lowest key since a SeqMap.Pop moves all the items on
// the right of the popped sequence number by one position to the left.
for i := len(snapshotSeqNums) - 1; i >= 0; i-- {
_, ok := s.Pop(snapshotSeqNums[i])
if !ok {
log.Errorf("Unable to pop %d from SeqMap", snapshotSeqNums[i])
}
}
return snapshot, minSequenceNum
}
// Pop removes seqnum from the SeqMap. seqnum must be a valid seqnum, ie
// [1:size of mailbox]
func (s *SeqMap) Pop(seqnum uint32) (uint32, bool) {
s.lock.Lock()
defer s.lock.Unlock()
if int(seqnum) > len(s.m) || seqnum < 1 {
return 0, false
}
uid := s.m[seqnum-1]
s.m = append(s.m[:seqnum-1], s.m[seqnum:]...)
return uid, true
}
// sort sorts the slice in ascending UID order. See:
// https://datatracker.ietf.org/doc/html/rfc3501#section-2.3.1.2
func (s *SeqMap) sort() {
// Always be sure the SeqMap is sorted
slices.Sort(s.m)
}
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