#7: implement POP3 protocol server (RFC 1939, RFC 2449, STLS)

services/protocols/internal/application/usecase/pop3_session.go

@@ -0,0 +1,86 @@
+package usecase
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/alexedwards/argon2id"
+	"github.com/google/uuid"
+
+	"lambdamail/protocols/internal/application/port"
+)
+
+type Pop3SessionUseCase struct {
+	authRepo     port.AuthRepository
+	folderRepo   port.ImapFolderRepository
+	messageQuery port.MessageQueryRepository
+	blobReader   port.BlobReader
+	expungeRepo  port.ExpungeRepository
+}
+
+func NewPop3SessionUseCase(
+	authRepo port.AuthRepository,
+	folderRepo port.ImapFolderRepository,
+	messageQuery port.MessageQueryRepository,
+	blobReader port.BlobReader,
+	expungeRepo port.ExpungeRepository,
+) *Pop3SessionUseCase {
+	return &Pop3SessionUseCase{
+		authRepo:     authRepo,
+		folderRepo:   folderRepo,
+		messageQuery: messageQuery,
+		blobReader:   blobReader,
+		expungeRepo:  expungeRepo,
+	}
+}
+
+func (uc *Pop3SessionUseCase) Login(ctx context.Context, username, password string) (string, error) {
+	rec, err := uc.authRepo.FindByAddress(ctx, username)
+	if err != nil {
+		return "", fmt.Errorf("lookup mailbox %q: %w", username, err)
+	}
+	if rec == nil {
+		return "", ErrAuthFailed
+	}
+	match, err := argon2id.ComparePasswordAndHash(password, rec.PasswordHash)
+	if err != nil {
+		return "", fmt.Errorf("verify password hash: %w", err)
+	}
+	if !match {
+		return "", ErrAuthFailed
+	}
+	return rec.ID.String(), nil
+}
+
+func (uc *Pop3SessionUseCase) GetInbox(ctx context.Context, mailboxID string) (*port.ImapFolderRecord, []port.MessageRecord, error) {
+	folder, err := uc.folderRepo.FindByName(ctx, mailboxID, "INBOX")
+	if err != nil {
+		return nil, nil, fmt.Errorf("find INBOX for mailbox %s: %w", mailboxID, err)
+	}
+	if folder == nil {
+		return nil, nil, ErrNoSuchFolder
+	}
+	messages, err := uc.messageQuery.ListMessages(ctx, folder.ID)
+	if err != nil {
+		return nil, nil, fmt.Errorf("list messages for INBOX folder %s: %w", folder.ID, err)
+	}
+	return folder, messages, nil
+}
+
+func (uc *Pop3SessionUseCase) ReadBlob(ctx context.Context, blobID uuid.UUID) ([]byte, error) {
+	content, err := uc.blobReader.ReadByID(ctx, blobID)
+	if err != nil {
+		return nil, fmt.Errorf("read blob %s: %w", blobID, err)
+	}
+	return content, nil
+}
+
+func (uc *Pop3SessionUseCase) ExpungeMessages(ctx context.Context, folderID string, uids []uint32) error {
+	if len(uids) == 0 {
+		return nil
+	}
+	if err := uc.expungeRepo.Expunge(ctx, folderID, uids); err != nil {
+		return fmt.Errorf("expunge messages in folder %s: %w", folderID, err)
+	}
+	return nil
+}