#!/bin/sh
set -e

CREDENTIALS="-h ${PGHOST:-postgres} -U ${PGUSER:-postgres}"
BACKUP_DIR=${BACKUP_DIR:-/backup}
RETENTION_DAYS=${RETENTION_DAYS:-7}

# 自动创建备份目录
mkdir -p "$BACKUP_DIR"

backup() {
  local filename="backup_$(date +%Y%m%d_%H%M%S).sql.gz"
  echo "[$(date +%Y-%m-%d\ %H:%M:%S)] Starting backup: $filename"
  pg_dumpall $CREDENTIALS | gzip > "$BACKUP_DIR/$filename"
  echo "[$(date +%Y-%m-%d\ %H:%M:%S)] Backup complete: $(du -h "$BACKUP_DIR/$filename" | cut -f1)"
}

cleanup() {
  local count=$(find "$BACKUP_DIR" -name "backup_*.sql.gz" -mtime +$RETENTION_DAYS | wc -l)
  if [ "$count" -gt 0 ]; then
    find "$BACKUP_DIR" -name "backup_*.sql.gz" -mtime +$RETENTION_DAYS -delete
    echo "[$(date +%Y-%m-%d\ %H:%M:%S)] Cleaned up $count backup(s) older than $RETENTION_DAYS days"
  fi
}

# Run immediately on startup
backup
cleanup

# Schedule: calculate seconds until next 2:00 AM, then run every 24h
while true; do
  now=$(date +%s)
  target=$(date -d "tomorrow 02:00" +%s)
  sleep_seconds=$((target - now))
  echo "[$(date +%Y-%m-%d\ %H:%M:%S)] Next backup scheduled at $(date -d @$target '+%Y-%m-%d %H:%M:%S')"
  sleep $sleep_seconds
  backup
  cleanup
done