feat(api): add dbq→ref projection helpers

internal/api/convert.go

@@ -2,6 +2,8 @@ package api
 
 import (
 	"github.com/jackc/pgx/v5/pgtype"
+
+	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
 )
 
 // uuidToString renders a pgtype.UUID as a canonical hyphenated string.
@@ -65,3 +67,51 @@ func coverURL(albumID pgtype.UUID) string {
 func streamURL(trackID pgtype.UUID) string {
 	return "/api/tracks/" + uuidToString(trackID) + "/stream"
 }
+
+// artistRefFrom projects a dbq.Artist into an ArtistRef. albumCount must be
+// pre-computed by the caller (one query per artist in lists).
+func artistRefFrom(a dbq.Artist, albumCount int) ArtistRef {
+	return ArtistRef{
+		ID:         uuidToString(a.ID),
+		Name:       a.Name,
+		AlbumCount: albumCount,
+	}
+}
+
+// albumRefFrom projects a dbq.Album into an AlbumRef. artistName must be
+// pre-resolved because Album only carries artist_id. trackCount and
+// durationSec may be 0 when the caller does not compute them.
+func albumRefFrom(a dbq.Album, artistName string, trackCount, durationSec int) AlbumRef {
+	return AlbumRef{
+		ID:          uuidToString(a.ID),
+		Title:       a.Title,
+		ArtistID:    uuidToString(a.ArtistID),
+		ArtistName:  artistName,
+		Year:        yearFromDate(a.ReleaseDate),
+		TrackCount:  trackCount,
+		DurationSec: durationSec,
+		CoverURL:    coverURL(a.ID),
+	}
+}
+
+// trackRefFrom projects a dbq.Track into a TrackRef. Parent names must be
+// pre-resolved because Track only carries album_id and artist_id.
+func trackRefFrom(t dbq.Track, albumTitle, artistName string) TrackRef {
+	ref := TrackRef{
+		ID:          uuidToString(t.ID),
+		Title:       t.Title,
+		AlbumID:     uuidToString(t.AlbumID),
+		AlbumTitle:  albumTitle,
+		ArtistID:    uuidToString(t.ArtistID),
+		ArtistName:  artistName,
+		DurationSec: durationMsToSec(t.DurationMs),
+		StreamURL:   streamURL(t.ID),
+	}
+	if t.TrackNumber != nil {
+		ref.TrackNumber = int(*t.TrackNumber)
+	}
+	if t.DiscNumber != nil {
+		ref.DiscNumber = int(*t.DiscNumber)
+	}
+	return ref
+}