sorting images by date; acquiring metadata

media.go

@@ -77,13 +77,13 @@ func (ch *CaddyHugo) serveMediaPage(w http.ResponseWriter, r *http.Request) (int
 	<div style="display: inline-block; width: 100%; height: 10vh;"></div>
 	`)
 	if ch.Media != nil {
-		media, err := ch.Media.Walk()
+		mm, err := ch.Media.Walk()
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return 500, nil
 		}
 
-		for _, m := range media {
+		for _, m := range media.Set(mm).ByDate() {
 
 			src, size, err := ch.Media.ThumbMax(*m, 100)
 			if err != nil {

media/media.go

@@ -9,18 +9,23 @@ import (
 	"path"
 	"path/filepath"
 	"regexp"
+	"sort"
 	"strconv"
+	"time"
 
 	// for processing images
 	_ "image/gif"
 	_ "image/png"
 
 	"github.com/nfnt/resize"
+	"github.com/tajtiattila/metadata"
 )
 
 type MediaSource struct {
 	StorageDir string
 	ThumbDir   string
+
+	set Set
 }
 
 func (ms *MediaSource) LocationOrig(m Media) string {
@@ -49,6 +54,8 @@ func (ms *MediaSource) ThumbFilename(m Media, size image.Rectangle) string {
 }
 
 func (ms *MediaSource) ReceiveNewMedia(name string, r io.Reader) error {
+	ms.set = nil
+
 	dest := path.Join(ms.StorageDir, name)
 	f, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE, 0644)
 	if err != nil {
@@ -67,6 +74,47 @@ type Media struct {
 	Type     string
 	Name     string
 	Size     image.Rectangle
+	FullName string
+
+	metadata *metadata.Metadata
+}
+
+func (m *Media) Date() time.Time {
+	m.getMetadata()
+
+	if m.metadata != nil {
+		raw := m.metadata.Get(metadata.DateTimeOriginal)
+		if raw != "" {
+			d, err := time.Parse("2006-01-02T15:04:05", raw)
+			if err == nil {
+				return d
+			}
+		}
+	}
+
+	fi, err := os.Stat(m.FullName)
+	if err == nil {
+		return fi.ModTime()
+	}
+
+	return time.Time{}
+}
+
+func (m *Media) getMetadata() error {
+	if m.metadata != nil {
+		return nil
+	}
+
+	f, err := os.Open(m.FullName)
+	if err != nil {
+		return err
+	}
+	md, err := metadata.Parse(f)
+	if err != nil {
+		return err
+	}
+	m.metadata = md
+	return nil
 }
 
 func (ms *MediaSource) Size(name string) (image.Rectangle, error) {
@@ -136,11 +184,13 @@ func (ms *MediaSource) HasThumb(m Media, size image.Rectangle) bool {
 
 func (ms *MediaSource) ByName(name string) *Media {
 	size, _ := ms.Size(path.Join(ms.StorageDir, name))
-	return &Media{
+	m := Media{
 		Type: "image",
 		Name: name,
 		Size: size,
 	}
+	m.FullName = ms.LocationOrig(m)
+	return &m
 }
 
 func (ms *MediaSource) Thumb(m Media, size image.Rectangle) (string, error) {
@@ -187,6 +237,7 @@ func (ms *MediaSource) ThumbImage(img image.Image, m Media, size image.Rectangle
 }
 
 func (ms *MediaSource) Walk() ([]*Media, error) {
+	if ms.set == nil {
 		var media []*Media
 
 		err := filepath.Walk(ms.StorageDir, func(name string, fi os.FileInfo, err error) error {
@@ -200,7 +251,23 @@ func (ms *MediaSource) Walk() ([]*Media, error) {
 			return nil
 		})
 
+		if err != nil {
 			return media, err
+		}
+
+		ms.set = media
+	}
+
+	return ms.set, nil
+}
+
+type Set []*Media
+
+func (s Set) ByDate() Set {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Date().After(s[j].Date())
+	})
+	return s
 }
 
 var (