#!/usr/bin/env bash
# scripts/backup-db.sh — nightly Postgres dump for loreal-prod-tracker
#
# Runs on the HOST (not inside the app container), driving pg_dump
# through the db service's compose project. Writes a gzipped SQL
# file to $BACKUP_DIR and prunes anything older than $RETAIN_DAYS.
#
# Intended to run from cron at midnight — see DEPLOY.md for the
# crontab entry. Safe to run manually at any time.
#
# Env vars (all optional, sensible defaults for optical-dev):
#   BACKUP_DIR      where to write dumps  (default /srv/backups/loreal-prod-tracker)
#   RETAIN_DAYS     days to keep dumps    (default 30)
#   COMPOSE_PROJECT compose project name  (default loreal-prod-tracker)
#   COMPOSE_DIR     dir containing docker-compose.yml  (default /opt/loreal-prod-tracker)
#   PGDATABASE      database name         (default loreal_prod_tracker)
#   PGUSER          postgres user         (default postgres)
#
# Exit codes: 0 ok, non-zero = failure (cron will mail root on non-zero).

set -euo pipefail

BACKUP_DIR="${BACKUP_DIR:-/srv/backups/loreal-prod-tracker}"
RETAIN_DAYS="${RETAIN_DAYS:-30}"
COMPOSE_PROJECT="${COMPOSE_PROJECT:-loreal-prod-tracker}"
COMPOSE_DIR="${COMPOSE_DIR:-/opt/loreal-prod-tracker}"
PGDATABASE="${PGDATABASE:-loreal_prod_tracker}"
PGUSER="${PGUSER:-postgres}"

TIMESTAMP=$(date +%Y-%m-%d_%H%M%S)
OUT_FILE="${BACKUP_DIR}/loreal-prod-tracker_${TIMESTAMP}.sql.gz"

mkdir -p "$BACKUP_DIR"

echo "[backup] $(date -Iseconds) starting dump → $OUT_FILE"

# Stream pg_dump output straight through gzip to disk without buffering
# the whole dump in memory. `exec -T` keeps the TTY disabled so this
# works from cron. We `cd` into the compose dir because compose reads
# its project definition from the working dir.
(
  cd "$COMPOSE_DIR"
  docker compose -p "$COMPOSE_PROJECT" exec -T db \
    pg_dump -U "$PGUSER" --format=plain --clean --if-exists "$PGDATABASE"
) | gzip > "$OUT_FILE"

SIZE=$(du -h "$OUT_FILE" | cut -f1)
echo "[backup] wrote $OUT_FILE ($SIZE)"

# Prune anything older than RETAIN_DAYS. `-mtime +N` is "modified more
# than N days ago" — older dumps get deleted. Fails gracefully if the
# dir is empty.
find "$BACKUP_DIR" -maxdepth 1 -type f -name 'loreal-prod-tracker_*.sql.gz' \
  -mtime +"$RETAIN_DAYS" -print -delete || true

echo "[backup] $(date -Iseconds) done"