btc_overnight_message.py

#!/usr/bin/env python3
import json
import sys
from datetime import datetime, timedelta
from zoneinfo import ZoneInfo

# Reads jsonl from stdin or a file path arg; prints a short message
# comparing the most recent sample to the most recent 5pm sample.

tz = ZoneInfo('America/Edmonton')

path = sys.argv[1] if len(sys.argv) > 1 else None
fh = open(path, 'r', encoding='utf-8') if path else sys.stdin

recs = []
for line in fh:
    line = line.strip()
    if not line:
        continue
    recs.append(json.loads(line))

if path:
    fh.close()

if not recs:
    print('No BTC samples yet.')
    sys.exit(0)

recs.sort(key=lambda r: int(r['ts']))
latest = recs[-1]
latest_dt = datetime.fromtimestamp(int(latest['ts']), tz)

# Find latest 5pm (hour==17) sample strictly before latest, else any 5pm sample.
prev_5pm = None
for r in reversed(recs[:-1]):
    dt = datetime.fromtimestamp(int(r['ts']), tz)
    if dt.hour == 17:
        prev_5pm = r
        break

# If latest itself is a 5pm sample, compare to previous day's 5pm.
if latest_dt.hour == 17:
    prev_5pm = None
    for r in reversed(recs[:-1]):
        dt = datetime.fromtimestamp(int(r['ts']), tz)
        if dt.hour == 17 and dt.date() < latest_dt.date():
            prev_5pm = r
            break

btc_usd = float(latest['btc_usd'])
btc_cad = float(latest['btc_cad'])
usd_cad = float(latest['usd_cad'])

lines = []
lines.append(f"BTC snapshot ({latest_dt:%Y-%m-%d %H:%M} MST)")
lines.append(f"- BTC/USD: ${btc_usd:,.0f}")
lines.append(f"- BTC/CAD: C${btc_cad:,.0f}")
lines.append(f"- USD/CAD: {usd_cad:.4f}")

if prev_5pm:
    pdt = datetime.fromtimestamp(int(prev_5pm['ts']), tz)
    p_usd = float(prev_5pm['btc_usd'])
    p_cad = float(prev_5pm['btc_cad'])
    d_usd = btc_usd - p_usd
    d_cad = btc_cad - p_cad
    pct = (d_usd / p_usd) * 100 if p_usd else 0.0
    lines.append(f"Overnight vs last 5pm ({pdt:%Y-%m-%d %H:%M}): {d_usd:+,.0f} USD ({pct:+.2f}%) / {d_cad:+,.0f} CAD")

print("\n".join(lines))