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Replace worldtimeapi.org HTTP calls with NTP time sync #13

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Merged
atarukun merged 3 commits into from
Oct 30, 2025
Merged

Replace worldtimeapi.org HTTP calls with NTP time sync #13

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54acf04
Initial plan
Copilot Oct 30, 2025
85d100a
Replace worldtimeapi.org with NTP time sync
Copilot Oct 30, 2025
f0a0a66
Improve year validation for better future compatibility
Copilot Oct 30, 2025
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138 changes: 70 additions & 68 deletions badge/apps/christmas/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,8 @@
from badgeware import screen, PixelFont, shapes, brushes, io, run, Matrix

try:
from urllib.urequest import urlopen
import json
import network
import ntptime
NETWORK_AVAILABLE = True
except ImportError:
NETWORK_AVAILABLE = False
Expand Down Expand Up @@ -68,12 +67,11 @@ def draw(self):
MONTH_NAMES = ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]

# Cache for fetched time data
_cached_time = None
_last_fetch_attempt = 0
_fetch_success = False
FETCH_INTERVAL = 60 * 60 * 1000 # Try to fetch once per hour (in milliseconds) when successful
RETRY_INTERVAL = 5 * 1000 # Retry every 5 seconds (in milliseconds) when failed
# NTP sync state
_ntp_synced = False
_ntp_sync_attempt = 0
_last_sync_attempt = 0
SYNC_RETRY_INTERVAL = 5 * 1000 # Retry NTP sync every 5 seconds (in milliseconds) when failed

# Network connection state
WIFI_TIMEOUT = 60
Expand Down Expand Up @@ -180,67 +178,68 @@ def wlan_start():
pass
return False

def fetch_current_date():
def sync_time_via_ntp():
"""
Fetch current date from worldtimeapi.org
Returns (year, month, day) tuple or None if fetch fails
Sync system time using NTP
Returns True if sync was successful, False otherwise
"""
global _cached_time, _last_fetch_attempt, _fetch_success
global _ntp_synced, _ntp_sync_attempt, _last_sync_attempt

if not NETWORK_AVAILABLE:
return None
return False

if not connected:
return None
return False

# Return cached time if still valid
current_ticks = io.ticks
if _cached_time and _fetch_success and (current_ticks - _last_fetch_attempt < FETCH_INTERVAL):
return _cached_time
# If already synced, don't sync again
if _ntp_synced:
return True
Comment on lines +195 to +196
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Copilot AI Oct 30, 2025

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Once NTP sync succeeds, the function returns early and never attempts to re-sync. If the system time drifts significantly or the device runs for an extended period, the time could become inaccurate. Consider implementing periodic re-synchronization (e.g., once per day) to maintain accuracy over longer runtime periods.

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# Check if we should retry (use shorter interval when failed)
if not _fetch_success and _last_fetch_attempt > 0:
if current_ticks - _last_fetch_attempt < RETRY_INTERVAL:
return None # Return None to indicate we're still waiting to retry
# Check if we should retry
current_ticks = io.ticks
if _ntp_sync_attempt > 0:
if current_ticks - _last_sync_attempt < SYNC_RETRY_INTERVAL:
return False # Still waiting to retry

# Update last fetch attempt timestamp before trying
_last_fetch_attempt = current_ticks
# Update last sync attempt timestamp
_last_sync_attempt = current_ticks
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Copilot AI Oct 30, 2025

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The global variable '_last_sync_attempt' is not used.

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_ntp_sync_attempt += 1
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The global variable _ntp_sync_attempt is incremented without thread-safety mechanisms. If sync_time_via_ntp() could be called from multiple contexts concurrently, this could lead to race conditions. Consider adding synchronization or documenting that this function must only be called from a single thread.

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# Attempt to fetch current date from the API
try:
# Use worldtimeapi.org - a free API that doesn't require authentication
# Reduced timeout to 3 seconds to keep badge responsive
response = urlopen("https://worldtimeapi.org/api/timezone/Etc/UTC", timeout=3)
try:
data = response.read()
time_data = json.loads(data)
# datetime format: "2025-10-30T01:23:45.123456+00:00"
datetime_str = time_data.get("datetime", "")

if datetime_str:
# Parse the date part (YYYY-MM-DD) with validation
try:
if "T" not in datetime_str:
raise ValueError("datetime string missing 'T' separator")
date_part = datetime_str.split("T")[0]
parts = date_part.split("-")
if len(parts) != 3:
raise ValueError("date part does not have three components")
year, month, day = parts
_cached_time = (int(year), int(month), int(day))
_fetch_success = True
return _cached_time
except (ValueError, TypeError) as parse_err:
print(f"Failed to parse date from API response: {parse_err}")
_fetch_success = False
finally:
response.close()
# Sync time via NTP
ntptime.settime()
_ntp_synced = True
print("NTP time sync successful")
return True
except Exception as e:
# Network request failed, will retry on next attempt
print(f"Failed to fetch time from internet: {e}")
_fetch_success = False
print(f"NTP sync failed (attempt {_ntp_sync_attempt}): {e}")
return False

def get_current_date():
"""
Get current date from system time (after NTP sync)
Returns (year, month, day) tuple or None if time is not synced
"""
if not _ntp_synced:
return None

return None
try:
# Get current time from system
# time.localtime() returns: (year, month, day, hour, minute, second, weekday, yearday)
current_time = time.localtime()
year = current_time[0]
month = current_time[1]
day = current_time[2]

# Sanity check: if year is unreasonable, NTP didn't actually work
# Valid range: 2025-2100 (the badge was created in 2025)
if year < 2025 or year > 2100:
Comment on lines +235 to +236
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The hard-coded year range 2025-2100 will cause this code to fail in 2101. Consider making the lower bound more flexible (e.g., checking year >= 2024 to allow for some margin) or using a constant that can be easily updated. The upper bound check may be unnecessary unless there's a specific reason to distrust years beyond 2100.

Suggested change
# Valid range: 2025-2100 (the badge was created in 2025)
if year < 2025 or year > 2100:
# Valid lower bound: badge was created in 2025, but allow margin
MIN_VALID_YEAR = 2024
if year < MIN_VALID_YEAR:

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return None

return (year, month, day)
except Exception as e:
print(f"Failed to get current date from system time: {e}")
return None

def format_date(year, month, day):
"""
Expand All @@ -254,30 +253,30 @@ def get_current_date_string():
Get current date formatted as DD MMM YYYY
Returns formatted string or "thinking..." if date cannot be determined
"""
# Try to fetch current date from internet
fetched_date = fetch_current_date()
# Get current date from NTP-synced system time
current_date = get_current_date()

if fetched_date:
# Use internet time
year, month, day = fetched_date
if current_date:
# Use synced time
year, month, day = current_date
return format_date(year, month, day)

# Return "thinking..." if we don't have a date yet (no fallback to local time)
# Return "thinking..." if we don't have a synced time yet
return "thinking..."

def get_days_until_christmas():
"""
Calculate days until next Christmas (Dec 25)
Returns None if date cannot be determined from network
Returns None if date cannot be determined from NTP-synced time
"""
# Try to fetch current date from internet
fetched_date = fetch_current_date()
# Get current date from NTP-synced system time
current_date = get_current_date()

if not fetched_date:
# Cannot calculate without valid date from network
if not current_date:
# Cannot calculate without valid synced date
return None

current_year, current_month, current_day = fetched_date
current_year, current_month, current_day = current_date

# Determine which Christmas to count down to
christmas_year = current_year
Expand Down Expand Up @@ -328,6 +327,9 @@ def update():
if NETWORK_AVAILABLE:
if get_connection_details():
wlan_start()
# Once connected, attempt NTP sync
if connected:
sync_time_via_ntp()

# Calculate days until Christmas
days = get_days_until_christmas()
Expand Down