#!/bin/bash
# Follower-box sync of the canonical TG list.
#
# Pulls the master list from the svxportal master (its public /tglist.php) into
# the LOCAL /etc/svxlink/tglist.json, so every local program reads ONE identical
# list: svxdr (Lastheard TG name/Location) and the box's own /tglist.php (TG
# Monitor) both read that local file. No extra daemon — a plain curl run by a
# systemd timer.
#
# Master and fully-standalone boxes OWN the file locally (web editor) and must
# NOT run this — leave UPSTREAM empty there (the timer is a no-op / not enabled).
set -euo pipefail
: "${UPSTREAM:=}"
: "${DEST:=/etc/svxlink/tglist.json}"

# Empty UPSTREAM = this box owns its list; nothing to sync.
[ -n "$UPSTREAM" ] || { echo "UPSTREAM empty — this box owns its TG list, skipping sync"; exit 0; }

tmp="$(mktemp)"; out="$(mktemp)"
trap 'rm -f "$tmp" "$out"' EXIT

curl -fsS -m 20 "$UPSTREAM" -o "$tmp"

# Keep ONLY the canonical shape {tgs:[...],requests:[]}. Refuse to overwrite the
# live file with anything that is not a valid list (a 404/HTML/partial body must
# never blank the TG names) — last good copy then simply stays.
python3 - "$tmp" "$out" <<'PY'
import json, sys
d = json.load(open(sys.argv[1]))
tgs = d.get("tgs")
if not isinstance(tgs, list) or not tgs:
    raise SystemExit("upstream has no tgs list — refusing to overwrite")
json.dump({"tgs": tgs, "requests": []}, open(sys.argv[2], "w"), indent=2)
PY

# www-data owns it so the web can still read it; atomic replace via install.
install -o www-data -g www-data -m 0664 "$out" "$DEST"
echo "TG list synced from $UPSTREAM -> $DEST"