#!/bin/bash

# LibrePortal WebUI Update Lock Check
# Guards against concurrent WebUI data refreshes.
#
# Echoes its verdict ("true" = a live lock is held, skip; "false" = clear to
# proceed) on stdout, and auto-clears a STALE lock. Callers must capture the
# echo — `result=$(webuiCheckUpdateLock)` runs the function in a subshell, so a
# global it set would never reach the caller (that was a real bug: the guard
# read an always-empty global and so never actually blocked anything).
#
# Staleness matters because the lock's remover (webuiRemoveUpdateLock) is itself
# a lazy-loaded function whose backing file can be transiently missing while the
# scripts tree is wiped+repopulated mid-deploy. If that removal is skipped once,
# the leftover lock would otherwise wedge EVERY future refresh. No single refresh
# runs anywhere near this long, so a lock older than the threshold is a leftover.
webuiCheckUpdateLock() {
    local lock_file="$containers_dir/libreportal/frontend/data/updater.lock"
    local stale_after=900   # seconds (15 min); far longer than any real refresh

    if [ ! -f "$lock_file" ]; then
        isNotice "No update lock file found" >&2
        echo "false"
        return 0
    fi

    local now lock_mtime age
    now=$(date +%s 2>/dev/null || echo 0)
    lock_mtime=$(stat -c '%Y' "$lock_file" 2>/dev/null || echo 0)
    age=$(( now - lock_mtime ))

    if (( now > 0 && lock_mtime > 0 && age >= stale_after )); then
        isNotice "Stale update lock (${age}s old ≥ ${stale_after}s) — clearing and continuing." >&2
        runFileOp rm -f "$lock_file" >/dev/null 2>&1
        echo "false"
        return 0
    fi

    isNotice "Update lock file exists: $lock_file" >&2
    echo "true"
    return 0
}