Add support for setting user timezone

app/routes.py

@@ -4,6 +4,7 @@ from io import StringIO
 import io
 from flask import Blueprint, Response, make_response, render_template, redirect, request, send_file, url_for, flash
 import humanize
+from pytz import timezone, utc
 from sqlalchemy import func
 from werkzeug.security import generate_password_hash, check_password_hash
 from werkzeug.http import http_date
@@ -177,10 +178,15 @@ def dashboard():
     # Fetch readings
     readings = readings_query.order_by(Reading.timestamp.desc()).all()
 
-    # Add relative timestamps to readings
+    # Fetch the user's timezone (default to 'UTC' if none is set)
+    user_timezone = current_user.profile.timezone if current_user.profile and current_user.profile.timezone else 'UTC'
+    local_tz = timezone(user_timezone)
+
+    # Add relative & local timestamps to readings
     now = datetime.utcnow()
     for reading in readings:
         reading.relative_timestamp = humanize.naturaltime(now - reading.timestamp)
+        reading.local_timestamp = utc.localize(reading.timestamp).astimezone(local_tz)
 
     # Calculate weekly summary and progress badges
     systolic_avg, diastolic_avg, heart_rate_avg = calculate_weekly_summary(readings)
@@ -248,10 +254,20 @@ def edit_reading(reading_id):
     if reading.user_id != current_user.id:
         flash('You are not authorized to edit this reading.', 'danger')
         return redirect(url_for('main.dashboard'))
+    
+    # Fetch the user's timezone (default to 'UTC' if none is set)
+    user_timezone = current_user.profile.timezone if current_user.profile and current_user.profile.timezone else 'UTC'
+    local_tz = timezone(user_timezone)
+
+    reading.local_timestamp = utc.localize(reading.timestamp).astimezone(local_tz)
 
     form = ReadingForm(obj=reading)  # Populate form with existing reading data
+    form.timestamp.data = reading.local_timestamp
     if form.validate_on_submit():
-        reading.timestamp = form.timestamp.data
+        # Convert the local timestamp back to UTC for saving
+        local_timestamp = form.timestamp.data
+        reading.timestamp = user_timezone.localize(local_timestamp).astimezone(utc)
+
         reading.systolic = form.systolic.data
         reading.diastolic = form.diastolic.data
         reading.heart_rate = form.heart_rate.data
@@ -306,6 +322,7 @@ def profile():
         profile.systolic_threshold = form.systolic_threshold.data or profile.systolic_threshold
         profile.diastolic_threshold = form.diastolic_threshold.data or profile.diastolic_threshold
         profile.dark_mode = form.dark_mode.data
+        profile.timezone = form.timezone.data
 
         # Handle profile picture upload
         if form.profile_pic.data: