From ef2f231d5b2debbc4325bc2ac048021995dbc857 Mon Sep 17 00:00:00 2001
From: Michael Mayer <michael@lastzero.net>
Date: Mon, 25 Jan 2021 21:41:57 +0100
Subject: [PATCH] Indexer: Improve taken date fallback when other metadata is
 missing #930

---
 internal/entity/photo.go               | 22 ++++++++++++++++++++--
 internal/entity/photo_test.go          | 19 +++++++++++++++++++
 internal/photoprism/index_mediafile.go | 11 ++++++-----
 3 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/internal/entity/photo.go b/internal/entity/photo.go
index 1c1d27e2f..129e9a1c9 100644
--- a/internal/entity/photo.go
+++ b/internal/entity/photo.go
@@ -857,19 +857,34 @@ func (m *Photo) SetTakenAt(taken, local time.Time, zone, source string) {
 		return
 	}
 
-	m.TakenAt = taken.Round(time.Second).UTC()
+	// Round times to avoid jitter.
+	taken = taken.Round(time.Second).UTC()
+	local = local.Round(time.Second)
+
+	// Don't update older date.
+	if SrcPriority[source] <= SrcPriority[SrcName] && !m.TakenAt.IsZero() && taken.After(m.TakenAt) {
+		return
+	}
+
+	m.TakenAt = taken
 	m.TakenSrc = source
 
 	if local.IsZero() || local.Year() < 1000 {
 		m.TakenAtLocal = m.TakenAt
 	} else {
-		m.TakenAtLocal = local.Round(time.Second)
+		m.TakenAtLocal = local
 	}
 
+	// Set time zone.
 	if zone != "" {
 		m.TimeZone = zone
 	}
 
+	// Apply time zone.
+	if m.TimeZone != "" {
+		m.TakenAt = m.GetTakenAt()
+	}
+
 	m.UpdateDateFields()
 }
 
@@ -883,7 +898,10 @@ func (m *Photo) SetTimeZone(zone, source string) {
 		return
 	}
 
+	// Set time zone.
 	m.TimeZone = zone
+
+	// Apply time zone.
 	m.TakenAt = m.GetTakenAt()
 }
 
diff --git a/internal/entity/photo_test.go b/internal/entity/photo_test.go
index 6233e09ad..222822732 100644
--- a/internal/entity/photo_test.go
+++ b/internal/entity/photo_test.go
@@ -557,11 +557,30 @@ func TestPhoto_SetTakenAt(t *testing.T) {
 		m := PhotoFixtures.Get("Photo15")
 		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAt)
 		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAtLocal)
+
 		m.SetTakenAt(time.Date(2019, 12, 11, 9, 7, 18, 0, time.UTC),
 			time.Date(2019, 12, 11, 10, 7, 18, 0, time.UTC), "", SrcMeta)
+
 		assert.Equal(t, time.Date(2019, 12, 11, 9, 7, 18, 0, time.UTC), m.TakenAt)
 		assert.Equal(t, time.Date(2019, 12, 11, 10, 7, 18, 0, time.UTC), m.TakenAtLocal)
 	})
+	t.Run("fallback and time zone", func(t *testing.T) {
+		m := PhotoFixtures.Get("Photo15")
+		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAt)
+		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAtLocal)
+
+		m.SetTakenAt(time.Date(2019, 12, 11, 9, 7, 18, 0, time.UTC),
+			time.Date(2019, 12, 11, 10, 7, 18, 0, time.UTC), "", SrcName)
+
+		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAt)
+		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAtLocal)
+
+		m.SetTakenAt(time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC),
+			time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), "Europe/Berlin", SrcName)
+
+		assert.Equal(t, time.Date(2013, 11, 11, 8, 7, 18, 0, time.UTC), m.TakenAt)
+		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAtLocal)
+	})
 	t.Run("time > max year", func(t *testing.T) {
 		m := PhotoFixtures.Get("Photo15")
 		assert.Equal(t, time.Date(2013, 11, 11, 9, 7, 18, 0, time.UTC), m.TakenAt)
diff --git a/internal/photoprism/index_mediafile.go b/internal/photoprism/index_mediafile.go
index 3d2dcd556..3d741e20b 100644
--- a/internal/photoprism/index_mediafile.go
+++ b/internal/photoprism/index_mediafile.go
@@ -521,6 +521,12 @@ func (ind *Index) MediaFile(m *MediaFile, o IndexOptions, originalName string) (
 		}
 	}
 
+	// Try to set taken date based on file mod time or name if other metadata is missing:
+	if m.IsMedia() && (photo.TakenSrc == entity.SrcAuto || photo.TakenSrc == entity.SrcName) {
+		takenUtc, takenSrc := m.TakenAt()
+		photo.SetTakenAt(takenUtc, takenUtc, "", takenSrc)
+	}
+
 	// file obviously exists: remove deleted and missing flags
 	file.DeletedAt = nil
 	file.FileMissing = false
@@ -588,11 +594,6 @@ func (ind *Index) MediaFile(m *MediaFile, o IndexOptions, originalName string) (
 			photo.PhotoExposure = m.Exposure()
 		}
 
-		if photo.TakenSrc == entity.SrcAuto || photo.TakenSrc == entity.SrcName {
-			takenUtc, takenSrc := m.TakenAt()
-			photo.SetTakenAt(takenUtc, takenUtc, "", takenSrc)
-		}
-
 		var locLabels classify.Labels
 
 		locKeywords, locLabels = photo.UpdateLocation()