dates are now stored in UTC and displayed in local time

TODO

@@ -1,7 +1,8 @@
-- conflict detection
-  - note title and content changes are not in audit_log table
 - deleting cloned nodes ends with 500 (probably only on folders)
 - what links here
 - recent changes - link to note should lead to the revision
 - db upgrade / migration
-- dates should be stored in UTC to work correctly with time zones
+- dates should be stored in UTC to work correctly with time zones
+  - we should also record timezone info so that we display the date correctly with respect to the local date at the time of recording it
+- modularize frontend
+  - unify handling of global variables

src/notes_api.py

@@ -12,6 +12,7 @@ from sql import delete
 from sql import execute, insert, commit
 from sql import getResults, getSingleResult, getOption, addAudit, deleteRecentAudits
 
+import utils
 import audit_category
 
 notes_api = Blueprint('notes_api', __name__)
@@ -44,7 +45,7 @@ def updateNote(note_id):
 
     note = request.get_json(force=True)
 
-    now = math.floor(time.time())
+    now = utils.nowTimestamp()
 
     history_snapshot_time_interval = float(getOption('history_snapshot_time_interval'))
 
@@ -154,7 +155,7 @@ def createChild(parent_note_id):
 
     addAudit(audit_category.CREATE_NOTE, request, noteId)
 
-    now = math.floor(time.time())
+    now = utils.nowTimestamp()
 
     insert("notes", {
         'note_id': noteId,

src/sql.py

@@ -4,6 +4,8 @@ import sqlite3
 import math
 import time
 
+import utils
+
 conn = None
 
 def dict_factory(cursor, row):
@@ -36,7 +38,7 @@ def getOption(name):
     return getSingleResult("SELECT opt_value FROM options WHERE opt_name = ?", [name])['opt_value']
 
 def addAudit(category, request = None, note_id = None, change_from = None, change_to = None, comment = None):
-    now = math.floor(time.time())
+    now = utils.nowTimestamp()
 
     browser_id = None
 
@@ -49,7 +51,7 @@ def addAudit(category, request = None, note_id = None, change_from = None, chang
 def deleteRecentAudits(category, request, note_id):
     browser_id = request.headers['x-browser-id']
 
-    delete_cutoff = math.floor(time.time()) - 10 * 60;
+    delete_cutoff = utils.nowTimestamp() - 10 * 60;
 
     execute("DELETE FROM audit_log WHERE category = ? AND browser_id = ? AND note_id = ? AND date_modified > ?",
             [category, browser_id, note_id, delete_cutoff])

src/tree_api.py

@@ -7,6 +7,7 @@ from flask import Blueprint, jsonify
 from flask_login import login_required
 
 from sql import getResults, getSingleResult, getOption
+import utils
 
 tree_api = Blueprint('tree_api', __name__)
 
@@ -50,6 +51,6 @@ def getTree():
     retObject['encrypted_data_key'] = getOption('encrypted_data_key')
     retObject['encryption_session_timeout'] = getOption('encryption_session_timeout')
     retObject['browser_id'] = base64.b64encode(os.urandom(8))
-    retObject['full_load_time'] = math.floor(time.time())
+    retObject['full_load_time'] = utils.nowTimestamp()
 
     return jsonify(retObject)

src/utils.py

@@ -0,0 +1,5 @@
+from datetime import datetime
+import time
+
+def nowTimestamp():
+    return time.mktime(datetime.utcnow().timetuple())

static/js/init.js

@@ -15,6 +15,16 @@ $(document).bind('keydown', 'alt+s', function() {
     $("input[name=search]").focus();
 });
 
+function getDateFromTS(timestamp) {
+    // Date accepts number of milliseconds since epoch so UTC timestamp works without any extra handling
+    // see https://stackoverflow.com/questions/4631928/convert-utc-epoch-to-local-date-with-javascript
+    const utcDate = new Date(timestamp * 1000);
+
+    const localDate = new Date(utcDate.getTime() - utcDate.getTimezoneOffset() * 60 * 1000);
+
+    return localDate;
+}
+
 function formatTime(date) {
     return (date.getHours() <= 9 ? "0" : "") + date.getHours() + ":" + (date.getMinutes() <= 9 ? "0" : "") + date.getMinutes();
 }

static/js/note_history.js

@@ -17,7 +17,7 @@ $(document).bind('keydown', 'alt+h', function() {
             globalHistoryItems = result;
 
             for (const row of result) {
-                const dateModified = new Date(row.date_modified * 1000);
+                const dateModified = getDateFromTS(row.date_modified);
 
                 $("#noteHistoryList").append($('<option>', {
                     value: row.id,

static/js/recent_changes.js

@@ -21,7 +21,7 @@ $(document).bind('keydown', 'alt+r', function() {
                     }
                 }
 
-                const dateModified = new Date(row.date_modified * 1000);
+                const dateModified = getDateFromTS(row.date_modified);
                 const formattedDate = formatDate(dateModified);
 
                 if (!groupedByDate[formattedDate]) {
@@ -41,7 +41,7 @@ $(document).bind('keydown', 'alt+r', function() {
                 const dayEl = $('<div>').append($('<b>').html(formattedDay)).append(changesListEl);
 
                 for (const dayChanges of groupedByDate[formattedDay]) {
-                    const formattedTime = formatTime(new Date(dayChanges.date_modified * 1000));
+                    const formattedTime = formatTime(getDateFromTS(dayChanges.date_modified));
 
                     const noteLink = $("<a>", {
                        href: 'app#' + dayChanges.note_id,