#!/bin/sh
# ─────────────────────────────────────────────────────────────────────────────
# Single Postgres backup: pg_dump -> gzip -> N-day rotation.
# Run by scripts/backup-loop.sh inside the `backup` compose service.
# Env: DB_USER, DB_PASSWORD, DB_NAME, BACKUP_DIR, RETENTION_DAYS
# ─────────────────────────────────────────────────────────────────────────────
set -eu

BACKUP_DIR="${BACKUP_DIR:-/backups}"
RETENTION_DAYS="${RETENTION_DAYS:-14}"
TS=$(date -u +%Y%m%d_%H%M%S)
OUT="${BACKUP_DIR}/flux_db_${TS}.sql.gz"

mkdir -p "$BACKUP_DIR"
export PGPASSWORD="$DB_PASSWORD"

echo "[backup] $(date -u +%Y-%m-%dT%H:%M:%SZ) starting pg_dump -> ${OUT}"

# --no-owner/--no-privileges keep the dump portable across roles on restore.
if pg_dump -h postgres -U "$DB_USER" -d "$DB_NAME" --no-owner --no-privileges | gzip -9 > "$OUT"; then
  SIZE=$(du -h "$OUT" | cut -f1)
  echo "[backup] OK: ${OUT} (${SIZE})"
else
  echo "[backup] FAILED: pg_dump returned non-zero; removing partial file"
  rm -f "$OUT"
  exit 1
fi

# Rotation — drop dumps older than RETENTION_DAYS.
DELETED=$(find "$BACKUP_DIR" -name 'flux_db_*.sql.gz' -mtime +"$RETENTION_DAYS" -print -delete 2>/dev/null | wc -l || echo 0)
echo "[backup] rotation: kept last ${RETENTION_DAYS} days, pruned ${DELETED} old dump(s)"