diff --git a/sunset-alarm b/sunset-alarm
index 56046f7..9d0d774 100755
--- a/sunset-alarm
+++ b/sunset-alarm
@@ -1,183 +1,140 @@
-#!/usr/bin/env python3
-"""Sunset Alarm — alert at a specified offset before sunset.
+#!/usr/bin/env bash
+# sunset-alarm — alert at a specified number of minutes before sunset
+# Usage: sunset-alarm (-l LAT:LONG | -t HH24:MI) (-m MINUTES) [-h]
+set -euo pipefail
 
-Usage:
-    sunset-alarm (-l LAT:LONG | -t HH24:MI) (-m MINUTES) [-h]
-"""
+SUNSET=""         # epoch seconds for today's sunset
+ALERT_EPOCH=""    # epoch when alert should fire (sunset - offset)
+OFFSET_MIN=0      # signed minute offset from sun -t/--hardcoded
+LAT="" LON=""     # coordinates  (-l/--location)
+HARDCODED_TIME="" # HH:MM string              (-t/--hardcoded)
 
-import argparse
-import json
-import subprocess
-import sys
-import time
-from datetime import datetime, timedelta
-from urllib.error import URLError
-from urllib.request import urlopen
+# ── helpers ────────────────────────────────────────────────────────
+usage() {
+    cat <<'EOF'
+Usage: sunset-alarm (-l LAT:LONG | -t HH24:MI) (-m MINUTES) [-h]
 
+Options:
+  -l LAT:LONG        Latitude and longitude (e.g. 32.123:-111.111)
+  -t HH24:MI         Hardcoded sunset time (ignored when combined with -l)
+  -m MINUTES         Minutes offset before (+) or after (-) sunset to alert
+  -h                 Show this help and exit
+EOF
+}
 
-def parse_coordinate(value):
-    """Parse 'lat:long' string into two floats."""
-    parts = value.split(":")
-    if len(parts) != 2:
-        raise argparse.ArgumentTypeError(
-            f"invalid coordinate format '{value}': expected LAT:LONG"
-        )
-    try:
-        lat, lon = float(parts[0]), float(parts[1])
-    except ValueError:
-        raise argparse.ArgumentTypeError(
-            f"invalid coordinate values in '{value}': must be numbers"
-        )
-    if not -90 <= lat <= 90:
-        raise argparse.ArgumentTypeError(f"latitude {lat} out of range [-90, 90]")
-    if not -180 <= lon <= 180:
-        raise argparse.ArgumentTypeError(f"longitude {lon} out of range [-180, 180]")
-    return lat, lon
+die() { echo "ERROR: $*" >&2; exit 1; }
 
+warn_reconnect() { echo "Network unavailable, retrying in 5 minutes…" >&2; }
 
-def parse_hardcoded_time(value):
-    """Parse 'HH:MM' string into a time object and validate."""
-    try:
-        t = datetime.strptime(value, "%H:%M").time()
-    except ValueError:
-        raise argparse.ArgumentTypeError(
-            f"invalid time format '{value}': expected HH24:MI"
-        )
-    return t
+# Query Open-Meteo for today's sunset epoch (local timezone).
+fetch_sunset_epoch() {
+    local lat="$1" lon="$2"
+    local json resp_code
+    # curl –silent + show HTTP code (-w) so we can detect server errors.
+    json=$(curl -sf -w '\n%{http_code}' \
+        "https://api.open-meteo.com/v1/forecast?latitude=${lat}&longitude=${lon}&current=sunset&timezone=auto" \
+        --connect-timeout 10 --max-time 30) || return 1
+    resp_code="${json##*$'\n'}"
+    json="${json%$'\n'*}"
+    [[ "$resp_code" == "200" ]] || return 2
+    # jq → "YYYY-MM-DDTHH:MM" (ISO-8601 local-time string for the sunset field)
+    local iso_ts
+    iso_ts=$(echo "$json" | jq -r '.current.sunset' | grep -v '^null$')
+    [[ -n "$iso_ts" ]] || return 3
+    # date -d parses ISO-8601 timestamps directly.
+    SUNSET=$(date -d "$iso_ts" +%s)
+}
 
+# Build today's sunset epoch from HH:MM when using the hardcoded path (-t).
+set_sunset_from_time() {
+    local hhmm="$1" hh mm
+    read -r hh mm <<< "$(echo "$hhmm" | tr ':' ' ')"
+    # Pad hours / minutes in case user passed "8:30" etc. (they won't via arg
+    # parsing, but defensive never hurts).
+    SUNSET=$(date -d "$(date +%Y-%m-%d) ${hh}:${mm}:00" +%s)
+}
 
-def fetch_sunset(lat, lon):
-    """Query Open-Meteo for today's sunrise/sunset and return a datetime.
+# Fire a desktop notification (best-effort).
+notify() {
+    local title="$1" body="$2"
+    notify-send -u normal "$title" "$body" 2>/dev/null || true
+    printf '%s — %s\n' "$(date '+%F %T')" "ALERT: $body"
+}
 
-    Uses the `current日出_sunset` parameter set which returns values in UTC.
-    """
-    url = (
-        f"https://api.open-meteo.com/v1/forecast?"
-        f"latitude={lat}&longitude={lon}"
-        f"&current=sunrise,sunset"
-        f"&timezone=auto"
-    )
-    with urlopen(url, timeout=30) as resp:
-        data = json.loads(resp.read().decode("utf-8"))
+# ── argument parsing ───────────────────────────────────────────────
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        -l)
+            [[ $# -ge 2 ]] || die "-l requires an argument (LAT:LONG)"
+            IFS=':' read -r LAT LON <<< "$2"
+            shift 2
+            ;;
+        -t)
+            [[ $# -ge 2 ]] || die "-t requires an argument (HH24:MI)"
+            HARDCODED_TIME="$2"
+            shift 2
+            ;;
+        -m)
+            [[ $# -ge 2 ]] || die "-m requires an argument (MINUTES)"
+            OFFSET_MIN="$2"
+            shift 2
+            ;;
+        -h|--help) usage; exit 0 ;;
+        *)         die "Unknown option: $1" ;;
+    esac
+done
 
-    sunrise_utc_str = data["current"]["sunrise"]  # e.g. '2026-10-17T04:23'
-    sunset_utc_str = data["current"]["sunset"]    # e.g. '2026-10-17T18:56'
+# ── guardrails ─────────────────────────────────────────────────────
+[[ $# -eq 0 ]] || die "extra arguments provided — see --help"
+(( OFFSET_MIN >= -60 )) || [[ $OFFSET_MIN -le 0 ]] 2>/dev/null \
+    1>/dev/null || die "-m must be ≥ -60 (or any value ≤ 0)"
 
-    sunset_dt = datetime.strptime(sunset_utc_str, "%Y-%m-%dT%H:%M")
-    return sunset_dt
+# Need either -l or -t.
+if [[ -z "$LAT" && -z "$HARDCODED_TIME" ]]; then
+    die "Need at least one of: -l LAT:LONG, -t HH24:MI"
+fi
 
+# ── Phase 1 — resolve today's sunset (epoch) ───────────────────────
+if [[ -n "$LAT" && -n "$LON" ]]; then
+    while true; do
+        fetch_sunset_epoch "$LAT" "$LON" && break
+        delay=$(( 5 * 60 ))
+        warn_reconnect; sleep "$delay" || warn_reconnect
+    done
+else
+    set_sunset_from_time "$HARDCODED_TIME"
+fi
 
-def notify_send(title, message):
-    """Send a desktop notification via notify-send."""
-    try:
-        subprocess.run(
-            ["notify-send", title, message],
-            check=False,
-            stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL,
-        )
-    except FileNotFoundError:
-        pass  # notify-send not available; fall through to stdout
+# ── Phase 2 — compute alert time and loop ──────────────────────────
+ALERT_EPOCH=$(( SUNSET - OFFSET_MIN * 60 ))
+now_epoch=$(date +%s)
 
+if (( now_epoch >= ALERT_EPOCH )); then
+    # Already past the window — fire once, exit.
+    notify "Sunset Alarm" \
+        "Triggered (offset: ${OFFSET_MIN:++}$(printf '%d' "$OFFSET_MIN")). Sunset at $(date -d @"$SUNSET" '+%H:%M')."
+    exit 0
+fi
 
-def main():
-    parser = argparse.ArgumentParser(
-        description="Alert at a specified number of minutes before sunset.",
-    )
-    location_group = parser.add_mutually_exclusive_group(required=True)
-    location_group.add_argument(
-        "-l",
-        type=parse_coordinate,
-        metavar="LAT:LONG",
-        help="Latitude and longitude (e.g. 32.123:-111.111)",
-    )
-    location_group.add_argument(
-        "-t",
-        type=parse_hardcoded_time,
-        metavar="HH24:MI",
-        help="Hardcoded sunset time (e.g. 18:00)",
-    )
-    parser.add_argument(
-        "-m",
-        type=int,
-        required=True,
-        metavar="MINUTES",
-        help=(
-            "Minutes offset before/after sunset to trigger the alert. "
-            "Positive = before sunset; negative = after."
-        ),
-    )
-    parser.add_argument(
-        "-h",
-        action="help",
-        help="Show this help message and exit.",
-    )
-    args = parser.parse_args()
-
-    offset_minus = timedelta(minutes=args.m)
-
-    # --- Phase 1: resolve sunset time ---------------------------
-    while True:
-        try:
-            if args.l is not None:
-                lat, lon = args.l
-                sunset_dt = fetch_sunset(lat, lon)
-                print(f"Sunset fetched from Open-Meteo: {sunset_dt.isoformat()}")
-                break  # success — stop retry loop
-            else:
-                now = datetime.now()
-                today_date = today_date_naive = now.replace(hour=0, minute=0, second=0, microsecond=0)
-                sunset_today = datetime.combine(today_date_naive, args.t)
-                print(f"Using hardcoded sunset: {args.t}")
-                break  # no network needed for -t
-        except (URLError, OSError) as exc:
-            print(f"Network unavailable ({exc}), retrying in 5 minutes...", file=sys.stderr)
-            time.sleep(300)
-
-    # --- Phase 2: wait / loop and alert -------------------------
-    alert_threshold = sunset_dt - offset_minus
-
-    if alert_threshold <= datetime.now():
-        # Already past the alert window — fire once and exit.
-        notify_send(
-            "Sunset Alarm",
-            f"Alert triggered: {sunset_dt.strftime('%H:%M')} ({offset_minus.total_seconds()/60:+.0f} min from sunset)",
-        )
-        print(f"Alert: {alert_threshold.isoformat()} -> Now: {datetime.now().isoformat()}")
-        return
-
-    while True:
-        now = datetime.now()
-
-        if not (alert_threshold <= now < sunset_dt.replace(year=now.year + 1)):
-            # Normal path: only alert when within the window.
-            # Check again in 60 seconds.
-            time.sleep(60)
-            continue
-
-        if now.date() > sunset_dt.date():
-            # Day has passed — stop monitoring, wait until tomorrow.
-            print(f"Day {sunset_dt.date()} over; re-fetching for new day...", file=sys.stderr)
-            # Re-enter fetch loop
-            while True:
-                try:
-                    lat, lon = args.l
-                    sunset_dt = fetch_sunset(lat, lon)
-                    break
-                except (URLError, OSError) as exc:
-                    print(f"Network unavailable ({exc}), retrying in 5 minutes...", file=sys.stderr)
-                    time.sleep(300)
-            continue
-
-        # Within alert window — send notification.
-        notify_send(
-            "Sunset Alarm",
-            f"Alert triggered: {sunset_dt.strftime('%H:%M')} ({offset_minus.total_seconds()/60:+.0f} min from sunset)",
-        )
-        print(f"ALERT -> {alert_threshold.isoformat()} <= {now.isoformat()} < {sunset_dt.isoformat()}")
-
-        # Keep alerting (don't exit).
-
-
-if __name__ == "__main__":
-    main()
+while true; do
+    now_epoch=$(date +%s)
+    if (( ALERT_EPOCH <= now_epoch && now_epoch < SUNSET )); then
+        notify "Sunset Alarm" \
+            "Triggered (offset: ${OFFSET_MIN:++}$(printf '%d' "$OFFSET_MIN")). Sunset at $(date -d @"$SUNSET" '+%H:%M')."
+    elif (( now_epoch > SUNSET )); then
+        # Day is over — re-fetch for tomorrow (if we have -l).
+        if [[ -n "$LAT" && -n "$LON" ]]; then
+            warn_reconnect=true   # just print a quick line, don't sleep
+            while true; do
+                fetch_sunset_epoch "$LAT" "$LON" && break
+                delay=$(( 5 * 60 ))
+                warn_reconnect; sleep "$delay" || warn_reconnect
+            done
+        else
+            set_sunset_from_time "$HARDCODED_TIME"
+        fi
+        ALERT_EPOCH=$(( SUNSET - OFFSET_MIN * 60 ))
+        continue
+    fi
+    sleep 60
+done