Meta: Add const, func, and struct comments for easier troubleshooting

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/meta/data.go

@@ -9,6 +9,7 @@ import (
 	"github.com/photoprism/photoprism/pkg/rnd"
 )
 
+// Extended image type constants extracted from vendor-specific metadata.
 const (
 	ImageTypeHDR = 3 // see https://exiftool.org/TagNames/Apple.html
 )

internal/meta/docs.go

@@ -1,5 +1,6 @@
 package meta
 
+// Docs lists external references for metadata standards PhotoPrism relies on.
 var Docs = [][]string{
 	{"Exiftool", "https://exiftool.org/TagNames/EXIF.html"},
 	{"Exiftool XMP", "https://exiftool.org/TagNames/XMP.html"},

internal/meta/exif_parser.go

@@ -16,6 +16,8 @@ import (
 	"github.com/photoprism/photoprism/pkg/fs"
 )
 
+// RawExif extracts the raw EXIF block from the given media file, optionally falling back to a
+// brute-force search when native parsers fail.
 func RawExif(fileName string, fileFormat fs.Type, bruteForce bool) (rawExif []byte, err error) {
 	defer func() {
 		if e := recover(); e != nil {

internal/meta/gps.go

@@ -10,14 +10,18 @@ import (
 	"github.com/photoprism/photoprism/pkg/clean"
 )
 
+// Latitude/Longitude bounds used when clamping map coordinates.
 const (
 	LatMax = 90
 	LngMax = 180
 )
 
-var GpsCoordsRegexp = regexp.MustCompile("[0-9\\.]+")
-var GpsRefRegexp = regexp.MustCompile("[NSEW]+")
-var GpsFloatRegexp = regexp.MustCompile("[+\\-]?(?:(?:0|[1-9]\\d*)(?:\\.\\d*)?|\\.\\d+)")
+// Regular expressions used to extract GPS coordinate components from EXIF strings.
+var (
+	GpsCoordsRegexp = regexp.MustCompile("[0-9\\.]+")
+	GpsRefRegexp    = regexp.MustCompile("[NSEW]+")
+	GpsFloatRegexp  = regexp.MustCompile("[+\\-]?(?:(?:0|[1-9]\\d*)(?:\\.\\d*)?|\\.\\d+)")
+)
 
 // GpsToLatLng returns the GPS latitude and longitude as float point number.
 func GpsToLatLng(s string) (lat, lng float64) {

internal/meta/json_exiftool.go

@@ -21,8 +21,11 @@ import (
 	"github.com/photoprism/photoprism/pkg/txt"
 )
 
-const MimeVideoMp4 = "video/mp4"
-const MimeQuicktime = "video/quicktime"
+// Common MIME types used to detect video contexts in ExifTool sidecars.
+const (
+	MimeVideoMp4  = "video/mp4"
+	MimeQuicktime = "video/quicktime"
+)
 
 // Exiftool parses JSON sidecar data as created by Exiftool.
 func (data *Data) Exiftool(jsonData []byte, originalName string) (err error) {

internal/meta/json_gphotos.go

@@ -9,6 +9,7 @@ import (
 	"github.com/photoprism/photoprism/pkg/time/tz"
 )
 
+// GPhoto represents the photo-level fields exported by Google Photos JSON sidecars.
 type GPhoto struct {
 	Title       string `json:"title"`
 	Description string `json:"description"`
@@ -19,18 +20,22 @@ type GPhoto struct {
 	UpdatedAt   GTime  `json:"modificationTime"`
 }
 
+// GetTitle returns the sanitized Google Photos title.
 func (m GPhoto) GetTitle() string {
 	return SanitizeTitle(m.Title)
 }
 
+// GetCaption returns the sanitized Google Photos description.
 func (m GPhoto) GetCaption() string {
 	return SanitizeCaption(m.Description)
 }
 
+// GMeta wraps album metadata embedded in Google Photos sidecars.
 type GMeta struct {
 	Album GAlbum `json:"albumData"`
 }
 
+// GAlbum contains album-level information from Google Photos exports.
 type GAlbum struct {
 	Title       string `json:"title"`
 	Description string `json:"description"`
@@ -40,29 +45,35 @@ type GAlbum struct {
 	Geo         GGeo   `json:"geoData"`
 }
 
+// Exists reports whether the album entry has meaningful data.
 func (m GAlbum) Exists() bool {
 	return m.Title != ""
 }
 
+// GGeo holds geolocation data provided by Google Photos.
 type GGeo struct {
 	Lat      float64 `json:"latitude"`
 	Lng      float64 `json:"longitude"`
 	Altitude float64 `json:"altitude"`
 }
 
+// Exists reports whether the geolocation entry has usable coordinates.
 func (m GGeo) Exists() bool {
 	return m.Lat != 0.0 && m.Lng != 0.0
 }
 
+// GTime stores Unix timestamps used in Google Photos metadata.
 type GTime struct {
 	Unix      int64  `json:"timestamp,string"`
 	Formatted string `json:"formatted"`
 }
 
+// Exists reports whether the timestamp is set.
 func (m GTime) Exists() bool {
 	return m.Unix > 0
 }
 
+// Time returns the timestamp as a UTC time.Time.
 func (m GTime) Time() time.Time {
 	return time.Unix(m.Unix, 0).UTC()
 }

internal/meta/keywords.go

@@ -8,6 +8,7 @@ import (
 	"github.com/photoprism/photoprism/pkg/txt"
 )
 
+// Built-in keyword slugs inferred from metadata.
 const (
 	KeywordFlash           = "flash"
 	KeywordHdr             = "hdr"
@@ -24,6 +25,7 @@ func (w Keywords) String() string {
 	return strings.Join(w, ", ")
 }
 
+// AutoKeywords lists keywords we automatically infer from descriptions or EXIF flags.
 var AutoKeywords = []string{KeywordHdr, KeywordBurst, KeywordPanorama, KeywordEquirectangular}
 
 // AddKeywords appends keywords.

internal/meta/sanitize.go

@@ -10,6 +10,7 @@ import (
 	"github.com/photoprism/photoprism/pkg/txt"
 )
 
+// UnwantedStrings lists boilerplate captions we strip during import.
 var UnwantedStrings = map[string]bool{
 	"Created by Imlib":         true, // Apps
 	"iClarified":               true,
@@ -60,6 +61,7 @@ var UnwantedStrings = map[string]bool{
 	"Digital Camera":           true,
 }
 
+// LowerCaseRegexp matches lower-case tokens in generated filenames.
 var LowerCaseRegexp = regexp.MustCompile("[a-z\\d_\\-]+")
 
 // SanitizeUnicode returns the string as valid Unicode with whitespace trimmed.

internal/meta/video.go

@@ -4,10 +4,13 @@ import (
 	"github.com/photoprism/photoprism/pkg/media/video"
 )
 
-const CodecUnknown = ""
-const CodecJpeg = "jpeg"
-const CodecHeic = "heic"
-const CodecXMP = "xmp"
+// Common codec labels encountered in metadata.
+const (
+	CodecUnknown = ""
+	CodecJpeg    = "jpeg"
+	CodecHeic    = "heic"
+	CodecXMP     = "xmp"
+)
 
 // CodecAvc returns true if the video codec is AVC.
 func (data Data) CodecAvc() bool {