#!/bin/bash
# GoChat Database Backup Script
# Reference: Chatwoot uses pg_dump for backup in production deployments
# Usage: ./scripts/db_backup.sh [env]

set -euo pipefail

ENV="${1:-production}"
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
BACKUP_DIR="${GOCHAT_BACKUP_DIR:-/var/backups/gochat}"
DSN="${GOCHAT_DATABASE_DSN:-}"
RETENTION_DAYS="${GOCHAT_BACKUP_RETENTION_DAYS:-30}"

if [[ -z "$DSN" ]]; then
    echo "[$(date)] ERROR: GOCHAT_DATABASE_DSN is not set"
    exit 1
fi

# Parse DSN: postgres://user:password@host:port/dbname?sslmode=...
DB_USER=$(echo "$DSN" | sed 's|.*://||; s|:.*||')
DB_PASS=$(echo "$DSN" | sed 's|.*://[^:]*:||; s|@.*||')
DB_HOST=$(echo "$DSN" | sed 's|.*@||; s|:.*||')
DB_PORT=$(echo "$DSN" | sed 's|.*@.*:||; s|/.*||')
DB_NAME=$(echo "$DSN" | sed 's|.*/||; s|\?.*||')

mkdir -p "${BACKUP_DIR}"

BACKUP_FILE="${BACKUP_DIR}/${DB_NAME}_${TIMESTAMP}.sql.gz"

echo "[$(date)] Starting backup of ${DB_NAME} on ${DB_HOST}:${DB_PORT}"

# pg_dump with compression — mirrors Chatwoot backup approach
PGPASSWORD="${DB_PASS}" pg_dump \
    -h "${DB_HOST}" \
    -p "${DB_PORT}" \
    -U "${DB_USER}" \
    -d "${DB_NAME}" \
    --format=custom \
    --compress=9 \
    | gzip > "${BACKUP_FILE}"

BACKUP_SIZE=$(du -h "${BACKUP_FILE}" | cut -f1)
echo "[$(date)] Backup complete: ${BACKUP_FILE} (${BACKUP_SIZE})"

# Prune old backups beyond retention period
find "${BACKUP_DIR}" -name "*.sql.gz" -mtime +"${RETENTION_DAYS}" -delete
echo "[$(date)] Pruned backups older than ${RETENTION_DAYS} days"

# Verify backup integrity
gunzip -t "${BACKUP_FILE}" && echo "[$(date)] Backup integrity verified" || {
    echo "[$(date)] ERROR: Backup integrity check failed!"
    rm -f "${BACKUP_FILE}"
    exit 1
}