#!/bin/bash
# Disk-space guardrail. Alerts via Telegram BEFORE the root filesystem fills up
# and crashes Postgres/Listmonk (as happened 2026-06-27 when an orphaned 15GB
# forgejo-dump.zip + uncapped Docker logs pushed / to 100% and Postgres
# crash-looped on "No space left on device"). Silent on healthy days.
#
# Also proactively cleans the two things that caused that outage:
#   1. orphaned /tmp/forgejo-dump.zip left behind by an interrupted backup
#   2. Docker build cache (safe, fully regenerable)
# ...but ONLY once usage crosses a soft threshold, so normal days are untouched.
#
# Schedule: every 15 min via cron (see infra/cron/pw-disk-space-alert).
set -uo pipefail

ENV_FILE=/opt/performancewest/.env
WARN_PCT=${PW_DISK_WARN_PCT:-90}    # Telegram warning at/above this %
CRIT_PCT=${PW_DISK_CRIT_PCT:-94}    # auto-cleanup kicks in at/above this %
MOUNT=/

BOT=$(grep -E '^TELEGRAM_BOT_TOKEN=' "$ENV_FILE" 2>/dev/null | head -1 | cut -d= -f2-)
CHAT=$(grep -E '^TELEGRAM_CHAT_ID=' "$ENV_FILE" 2>/dev/null | head -1 | cut -d= -f2-)
tg() {
  [ -n "${BOT:-}" ] && [ -n "${CHAT:-}" ] || return 0
  curl -s --max-time 10 "https://api.telegram.org/bot${BOT}/sendMessage" \
    --data-urlencode "chat_id=${CHAT}" --data-urlencode "text=$1" >/dev/null 2>&1
}

usage_pct() { df --output=pcent "$MOUNT" | tail -1 | tr -dc '0-9'; }

PCT=$(usage_pct)
[ -n "$PCT" ] || exit 0

if [ "$PCT" -lt "$WARN_PCT" ]; then
  exit 0   # healthy, stay silent
fi

FREED=""
if [ "$PCT" -ge "$CRIT_PCT" ]; then
  # 1. Drop any orphaned forgejo dump still sitting in the container's /tmp.
  if docker exec performancewest-forgejo test -f /tmp/forgejo-dump.zip 2>/dev/null; then
    docker exec performancewest-forgejo rm -f /tmp/forgejo-dump.zip 2>/dev/null \
      && FREED="${FREED}orphaned forgejo-dump.zip; "
  fi
  # 2. Reclaim Docker build cache (safe, regenerable).
  RECLAIMED=$(docker builder prune -af 2>/dev/null | grep -oE 'Total reclaimed space: .*' | head -1)
  [ -n "$RECLAIMED" ] && FREED="${FREED}build-cache (${RECLAIMED#Total reclaimed space: }); "
fi

NEWPCT=$(usage_pct)
AVAIL=$(df -h "$MOUNT" | tail -1 | awk '{print $4}')
TOPDIRS=$(sudo du -shx /var/lib/docker /opt/backups /var/log 2>/dev/null | sort -rh | head -3 | awk '{printf "%s %s; ", $1, $2}')

LEVEL="⚠️ WARNING"; [ "$NEWPCT" -ge "$CRIT_PCT" ] && LEVEL="🔴 CRITICAL"

MSG=$(printf '%s Performance West disk space\n\nRoot %s: %s%% used (%s free)\n%s\nTop: %s' \
  "$LEVEL" "$MOUNT" "$NEWPCT" "$AVAIL" \
  "${FREED:+Auto-freed: ${FREED}now ${NEWPCT}%}" "$TOPDIRS")
tg "$MSG"

# Mirror to the same report log the warmup check uses, for history.
echo "[$(date '+%F %T')] disk ${PCT}% -> ${NEWPCT}% (free ${AVAIL}) ${FREED:+freed: $FREED}" \
  >> /opt/performancewest/logs/pw-disk-space-alert.log 2>&1