feat(PROJ-9): implement labels backend - DB schema, labelstore, API handlers, Xapian integration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/api/server.go

@@ -25,6 +25,7 @@ import (
 	"github.com/archivmail/internal/auth"
 	imapstore "github.com/archivmail/internal/imap"
 	"github.com/archivmail/internal/index"
+	"github.com/archivmail/internal/labelstore"
 	ldapcfg "github.com/archivmail/internal/ldapconfig"
 	pop3store "github.com/archivmail/internal/pop3"
 	"github.com/archivmail/internal/smtpd"
@@ -79,6 +80,7 @@ type Server struct {
 	pop3Store     *pop3store.Store
 	pop3Importer  *pop3store.Importer
 	uploadJobs    sync.Map // jobID → *UploadJob
+	labels        *labelstore.Store         // PROJ-9: label management
 	ldapStore         *ldapcfg.Store
 	tenantStore       *tenantstore.Store
 	tenantLdapStore   *ldapcfg.TenantStore   // PROJ-23: per-tenant LDAP config
@@ -600,6 +602,7 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 	dateToStr := r.URL.Query().Get("date_to")
 	sortParam := r.URL.Query().Get("sort") // "relevance", "date_asc", "date_desc"
 	hasAttachStr := r.URL.Query().Get("has_attachment") // "true" or "false"
+	labelIDStr := r.URL.Query().Get("label_id")       // PROJ-9: filter by label
 	pageStr := r.URL.Query().Get("page")
 	pageSizeStr := r.URL.Query().Get("page_size")
 
@@ -616,6 +619,13 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 		Page:     page,
 	}
 
+	// PROJ-9: Parse label_id filter.
+	if labelIDStr != "" {
+		if lid, err := strconv.ParseInt(labelIDStr, 10, 64); err == nil && lid > 0 {
+			req.LabelID = &lid
+		}
+	}
+
 	if hasAttachStr == "true" {
 		v := true
 		req.HasAttachment = &v
@@ -691,6 +701,25 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	// PROJ-9: Post-filter by label_id when the label store is available.
+	if req.LabelID != nil && s.labels != nil && len(result.Hits) > 0 {
+		labelEmailIDs, lErr := s.labels.GetEmailIDsByLabel(r.Context(), *req.LabelID)
+		if lErr == nil {
+			allowed := make(map[string]struct{}, len(labelEmailIDs))
+			for _, id := range labelEmailIDs {
+				allowed[id] = struct{}{}
+			}
+			filtered := result.Hits[:0]
+			for _, h := range result.Hits {
+				if _, ok := allowed[h.ID]; ok {
+					filtered = append(filtered, h)
+				}
+			}
+			result.Hits = filtered
+			result.Total = len(filtered)
+		}
+	}
+
 	sess := sessionFromCtx(r.Context())
 	s.audlog.Log(audit.Entry{
 		EventType: audit.EventSearch,
@@ -710,7 +739,19 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 		Date           string  `json:"date,omitempty"`
 		Size           int64   `json:"size,omitempty"`
 		HasAttachments bool    `json:"has_attachments"`
+		LabelIDs       []int64 `json:"label_ids,omitempty"` // PROJ-9
 	}
+
+	// PROJ-9: Batch-load label IDs for all hits.
+	var labelMap map[string][]int64
+	if s.labels != nil && len(result.Hits) > 0 {
+		emailIDs := make([]string, len(result.Hits))
+		for i, h := range result.Hits {
+			emailIDs[i] = h.ID
+		}
+		labelMap, _ = s.labels.GetLabelsForEmails(r.Context(), emailIDs)
+	}
+
 	enriched := make([]enrichedHit, 0, len(result.Hits))
 	for _, h := range result.Hits {
 		eh := enrichedHit{ID: h.ID, Score: h.Score}
@@ -728,6 +769,9 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 				eh.HasAttachments = len(pm.Attachments) > 0
 			}
 		}
+		if labelMap != nil {
+			eh.LabelIDs = labelMap[h.ID]
+		}
 		enriched = append(enriched, eh)
 	}