package smtpserver

import (

"bytes"

"context"

"crypto/sha256"

"fmt"

"io"

"log/slog"

"os"

"github.com/mjl-/bstore"

"github.com/mjl-/mox/message"

"github.com/mjl-/mox/mlog"

"github.com/mjl-/mox/moxio"

"github.com/mjl-/mox/store"

)

// rejectPresent returns whether the message is already present in the rejects mailbox.

func rejectPresent(log mlog.Log, acc *store.Account, rejectsMailbox string, m *store.Message, f *os.File) (present bool, msgID string, hash []byte, rerr error) {

if p, err := message.Parse(log.Logger, false, store.FileMsgReader(m.MsgPrefix, f)); err != nil {

log.Infox("parsing reject message for message-id", err)

} else if header, err := p.Header(); err != nil {

log.Infox("parsing reject message header for message-id", err)

} else {

msgID, _, err = message.MessageIDCanonical(header.Get("Message-Id"))

if err != nil {

log.Debugx("parsing message-id for reject", err, slog.String("messageid", header.Get("Message-Id")))

}

}

// We must not read MsgPrefix, it will likely change for subsequent deliveries.

h := sha256.New()

if _, err := io.Copy(h, &moxio.AtReader{R: f}); err != nil {

log.Infox("copying reject message to hash", err)

} else {

hash = h.Sum(nil)

}

if msgID == "" && len(hash) == 0 {

return false, "", nil, fmt.Errorf("no message-id or hash for determining reject message presence")

}

var exists bool

var err error

acc.WithRLock(func() {

err = acc.DB.Read(context.TODO(), func(tx *bstore.Tx) error {

mb, err := acc.MailboxFind(tx, rejectsMailbox)

if err != nil {

return fmt.Errorf("looking for rejects mailbox: %w", err)

} else if mb == nil {

return nil

}

q := bstore.QueryTx[store.Message](tx)

q.FilterNonzero(store.Message{MailboxID: mb.ID})

q.FilterEqual("Expunged", false)

q.FilterFn(func(m store.Message) bool {

return msgID != "" && m.MessageID == msgID || len(hash) > 0 && bytes.Equal(m.MessageHash, hash)

})

exists, err = q.Exists()

return err

})

})

if err != nil {

return false, "", nil, fmt.Errorf("querying for presence of reject message: %w", err)

}

return exists, msgID, hash, nil

}