#!/bin/sh
# Dumps the database once at start, every day at BACKUP_TIME (HH:MM, container time zone), and whenever
# the api asks for one through /requests (it does so before every database upgrade).
set -eu
: "${BACKUP_TIME:=02:30}"
: "${BACKUP_KEEP_DAYS:=30}"
mkdir -p /backups /requests
chmod 1777 /requests
rm -f /tmp/first-backup-done

dump() {
  file="/backups/budget_$(date +%Y%m%d_%H%M%S)${1:-}.sql.gz"
  if pg_dump --no-owner --clean --if-exists | gzip > "$file.tmp"; then
    mv "$file.tmp" "$file"
    echo "$(date -Iseconds) backup written: $file"
    find /backups -name 'budget_*.sql.gz' -mtime +"$BACKUP_KEEP_DAYS" -delete
    return 0
  fi
  rm -f "$file.tmp"
  echo "$(date -Iseconds) backup FAILED" >&2
  return 1
}

answer_requests() {
  for request in /requests/*.request; do
    [ -e "$request" ] || continue
    id=$(basename "$request" .request)
    echo "$(date -Iseconds) backup requested: $(cat "$request" 2>/dev/null)"
    if dump _before_upgrade; then echo ok > "/requests/$id.done"; else echo failed > "/requests/$id.done"; fi
    rm -f "$request"
  done
  # answers nobody picked up
  find /requests -name '*.done' -mmin +60 -delete 2>/dev/null || true
}

until pg_isready -q; do sleep 2; done
dump || true
touch /tmp/first-backup-done
while true; do
  now=$(date +%s)
  next=$(date -d "$(date +%Y-%m-%d) $BACKUP_TIME" +%s 2>/dev/null || date -D '%Y-%m-%d %H:%M' -d "$(date +%Y-%m-%d) $BACKUP_TIME" +%s)
  [ "$next" -le "$now" ] && next=$((next + 86400))
  while [ "$(date +%s)" -lt "$next" ]; do
    answer_requests
    sleep 5
  done
  dump || true
done