From 4a595db3f53f23032ad0db5efededf74727fe7f1 Mon Sep 17 00:00:00 2001
From: Varun Patil <radialapps@gmail.com>
Date: Sun, 1 Oct 2023 09:34:48 -0700
Subject: [PATCH] metadata: fix display of dates without tz info

Signed-off-by: Varun Patil <radialapps@gmail.com>
---
 src/components/Metadata.vue       | 57 +++++++++++++++----------------
 src/components/modal/EditDate.vue | 14 ++------
 src/services/utils/date.ts        | 15 ++++++++
 3 files changed, 45 insertions(+), 41 deletions(-)

diff --git a/src/components/Metadata.vue b/src/components/Metadata.vue
index fd3e64eb..72d72993 100644
--- a/src/components/Metadata.vue
+++ b/src/components/Metadata.vue
@@ -208,41 +208,40 @@ export default defineComponent({
 
     /** Date taken info */
     dateOriginal(): DateTime | null {
-      const epoch = this.exif.DateTimeEpoch || this.baseInfo.datetaken;
-      let date = DateTime.fromSeconds(epoch);
-      if (!epoch || !date.isValid) return null;
+      // Try to get timezone info
+      let dateWithTz: DateTime | null = null;
+      const valid = () => dateWithTz?.isValid;
 
-      // The fallback to datetaken can be eventually removed
-      // and then this can be discarded
-      if (this.exif.DateTimeEpoch) {
-        const tzOffset = this.exif.OffsetTimeOriginal || this.exif.OffsetTime; // e.g. -05:00
-        const tzId = this.exif.LocationTZID; // e.g. America/New_York
+      // If we have an actual epoch, we can shift the date to the correct timezone
+      if (!valid() && this.exif.DateTimeEpoch) {
+        const date = DateTime.fromSeconds(this.exif.DateTimeEpoch);
+        if (date.isValid) {
+          const tzOffset = this.exif.OffsetTimeOriginal || this.exif.OffsetTime; // e.g. -05:00
+          const tzId = this.exif.LocationTZID; // e.g. America/New_York
 
-        let dateWithTz: DateTime | undefined = undefined;
+          // Use timezone offset if available
+          if (!valid() && tzOffset) {
+            dateWithTz = date.setZone('UTC' + tzOffset);
+          }
 
-        // If no timezone info is available, we will show the local time only
-        // In this case, everything happens in UTC
-        if (!tzOffset && !tzId) {
-          dateWithTz = date.setZone('UTC');
-        }
-
-        // Use timezone offset if available
-        if (!dateWithTz?.isValid && tzOffset) {
-          dateWithTz = date.setZone('UTC' + tzOffset);
-        }
-
-        // Fall back to tzId
-        if (!dateWithTz?.isValid && tzId) {
-          dateWithTz = date.setZone(tzId);
-        }
-
-        // Use the timezone only if the date is valid
-        if (dateWithTz?.isValid) {
-          date = dateWithTz;
+          // Fall back to tzId
+          if (!valid() && tzId) {
+            dateWithTz = date.setZone(tzId);
+          }
         }
       }
 
-      return date;
+      // If tz info is unavailable / wrong, we will show the local time only
+      // In this case, use the datetaken instead, which is guaranteed to be local, shifted to UTC
+      if (!valid() && this.baseInfo.datetaken) {
+        const date = DateTime.fromSeconds(this.baseInfo.datetaken);
+        if (date.isValid) {
+          dateWithTz = date.setZone('UTC');
+        }
+      }
+
+      // Return only if we found a valid date
+      return valid() ? dateWithTz : null;
     },
 
     dateOriginalStr(): string | null {
diff --git a/src/components/modal/EditDate.vue b/src/components/modal/EditDate.vue
index 3a18110b..2863404c 100644
--- a/src/components/modal/EditDate.vue
+++ b/src/components/modal/EditDate.vue
@@ -253,14 +253,14 @@ export default defineComponent({
       }
 
       if (this.sortedPhotos.length === 1) {
-        return this.getExifFormat(this.date);
+        return utils.getExifDateStr(this.date);
       }
 
       // Interpolate date
       const dT = this.date.getTime();
       const doT = this.origDateNewest.getTime();
       const offset = ((photo.datetaken ?? 0) * 1000 || doT) - doT;
-      return this.getExifFormat(new Date(dT + offset * this.scaleFactor));
+      return utils.getExifDateStr(new Date(dT + offset * this.scaleFactor));
     },
 
     newestChange(time = false) {
@@ -292,16 +292,6 @@ export default defineComponent({
       this.oldestDirty = true;
     },
 
-    getExifFormat(date: Date) {
-      const year = date.getUTCFullYear().toString().padStart(4, '0');
-      const month = (date.getUTCMonth() + 1).toString().padStart(2, '0');
-      const day = date.getUTCDate().toString().padStart(2, '0');
-      const hour = date.getUTCHours().toString().padStart(2, '0');
-      const minute = date.getUTCMinutes().toString().padStart(2, '0');
-      const second = date.getUTCSeconds().toString().padStart(2, '0');
-      return `${year}:${month}:${day} ${hour}:${minute}:${second}`;
-    },
-
     makeDate(yearS: string, monthS: string, dayS: string, hourS: string, minuteS: string, secondS: string) {
       const date = new Date();
       const year = parseInt(yearS, 10);
diff --git a/src/services/utils/date.ts b/src/services/utils/date.ts
index e5429a4a..d84e06a3 100644
--- a/src/services/utils/date.ts
+++ b/src/services/utils/date.ts
@@ -54,6 +54,21 @@ export function getMonthDateStr(date: Date) {
   });
 }
 
+/**
+ * Get the EXIF date string from a datetaken object
+ * @param date The datetaken value from photo metadata (UTC relative date)
+ * @returns YYYY:MM:DD HH:MM:SS
+ */
+export function getExifDateStr(date: Date) {
+  const year = date.getUTCFullYear().toString().padStart(4, '0');
+  const month = (date.getUTCMonth() + 1).toString().padStart(2, '0');
+  const day = date.getUTCDate().toString().padStart(2, '0');
+  const hour = date.getUTCHours().toString().padStart(2, '0');
+  const minute = date.getUTCMinutes().toString().padStart(2, '0');
+  const second = date.getUTCSeconds().toString().padStart(2, '0');
+  return `${year}:${month}:${day} ${hour}:${minute}:${second}`;
+}
+
 /** Get text like "5 years ago" from a date */
 export function getFromNowStr(date: Date) {
   // Get fromNow in correct locale