refactor: consolidate specid <-> filesystem mapping and always use abs paths (#309)

server/ctrlsubsonic/specidpaths/specidpaths.go

@@ -0,0 +1,77 @@
+package specidpaths
+
+import (
+	"errors"
+	"path/filepath"
+	"strings"
+
+	"go.senan.xyz/gonic/db"
+	"go.senan.xyz/gonic/server/ctrlsubsonic/specid"
+)
+
+var ErrNotAbs = errors.New("not abs")
+var ErrNotFound = errors.New("not found")
+
+type Result interface {
+	SID() *specid.ID
+	AbsPath() string
+}
+
+// Locate maps a specid to its location on the filesystem
+func Locate(dbc *db.DB, podcastsPath string, id specid.ID) (Result, error) {
+	switch id.Type {
+	case specid.Track:
+		var track db.Track
+		if err := dbc.Preload("Album").Where("id=?", id.Value).Find(&track).Error; err == nil {
+			return &track, nil
+		}
+	case specid.PodcastEpisode:
+		var pe db.PodcastEpisode
+		if err := dbc.Where("id=?", id.Value).Find(&pe).Error; err == nil {
+			pe.AbsP = filepath.Join(podcastsPath, pe.Path)
+			return &pe, err
+		}
+	}
+	return nil, ErrNotFound
+}
+
+// Locate maps a location on the filesystem to a specid
+func Lookup(dbc *db.DB, musicPaths []string, podcastsPath string, path string) (Result, error) {
+	if !filepath.IsAbs(path) {
+		return nil, ErrNotAbs
+	}
+
+	if strings.HasPrefix(path, podcastsPath) {
+		path, _ = filepath.Rel(podcastsPath, path)
+		var pe db.PodcastEpisode
+		if err := dbc.Where(`path=?`, path).First(&pe).Error; err == nil {
+			return &pe, nil
+		}
+		return nil, ErrNotFound
+	}
+
+	var musicPath string
+	for _, mp := range musicPaths {
+		if strings.HasPrefix(path, mp) {
+			musicPath = mp
+		}
+	}
+	if musicPath == "" {
+		return nil, ErrNotFound
+	}
+
+	relPath, _ := filepath.Rel(musicPath, path)
+	relDir, filename := filepath.Split(relPath)
+	leftPath, rightPath := filepath.Split(filepath.Clean(relDir))
+
+	q := dbc.
+		Where(`albums.root_dir=? AND albums.left_path=? AND albums.right_path=? AND tracks.filename=?`, musicPath, leftPath, rightPath, filename).
+		Joins(`JOIN albums ON tracks.album_id=albums.id`).
+		Preload("Album")
+
+	var track db.Track
+	if err := q.First(&track).Error; err == nil {
+		return &track, nil
+	}
+	return nil, ErrNotFound
+}