#!/usr/bin/env bash
#
# Daily DB backup. Cron-friendly. Detects SQLite vs Postgres from DATABASE_URL.
#
# Example crontab:
#   15 3 * * * /path/to/scripts/backup_db.sh >> /var/log/trumpsignal-backup.log 2>&1
#
# Retention: keeps the last RETAIN_DAYS daily backups (default 14).
# Storage:   writes to $BACKUP_DIR (default ./backups/).
#
# DATABASE_URL must be available in env. Loads .env if present.

set -euo pipefail

cd "$(dirname "$0")/.."

# Load .env if it exists (so cron jobs without inherited env still work)
if [[ -f .env ]]; then
  set -a
  # shellcheck disable=SC1091
  source .env
  set +a
fi

: "${DATABASE_URL:?DATABASE_URL not set — refusing to back up nothing}"
BACKUP_DIR="${BACKUP_DIR:-./backups}"
RETAIN_DAYS="${RETAIN_DAYS:-14}"
TS="$(date -u +%Y%m%d_%H%M%S)"

mkdir -p "$BACKUP_DIR"

if [[ "$DATABASE_URL" == sqlite* ]]; then
  # Extract path from sqlite+aiosqlite:///./trumpsignal.db
  DB_PATH="$(echo "$DATABASE_URL" | sed -E 's#^sqlite(\+[^:]+)?:///+##')"
  if [[ ! -f "$DB_PATH" ]]; then
    echo "[backup] SQLite file not found: $DB_PATH" >&2
    exit 1
  fi
  OUT="$BACKUP_DIR/sqlite_${TS}.db"
  # sqlite3 .backup is online-safe (uses backup API, not a raw copy).
  # Fall back to cp if sqlite3 CLI isn't installed.
  if command -v sqlite3 >/dev/null 2>&1; then
    sqlite3 "$DB_PATH" ".backup '$OUT'"
  else
    cp "$DB_PATH" "$OUT"
  fi
  gzip -f "$OUT"
  echo "[backup] wrote $OUT.gz ($(du -h "$OUT.gz" | cut -f1))"
elif [[ "$DATABASE_URL" == postgres* ]] || [[ "$DATABASE_URL" == postgresql* ]]; then
  OUT="$BACKUP_DIR/pg_${TS}.sql.gz"
  # pg_dump reads DATABASE_URL natively if we strip the driver prefix.
  PG_URL="${DATABASE_URL/+asyncpg/}"
  PG_URL="${PG_URL/+psycopg2/}"
  pg_dump "$PG_URL" --no-owner --no-privileges | gzip > "$OUT"
  echo "[backup] wrote $OUT ($(du -h "$OUT" | cut -f1))"
else
  echo "[backup] unsupported DATABASE_URL scheme: $DATABASE_URL" >&2
  exit 1
fi

# Prune backups older than RETAIN_DAYS days
find "$BACKUP_DIR" -name "*.gz" -mtime "+$RETAIN_DAYS" -print -delete