#!/bin/sh
set -eu

BACKUP_DIR="${BACKUP_DIR:-/backups}"
INTERVAL_SECONDS="${BACKUP_INTERVAL_SECONDS:-86400}"
RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-7}"
COMPRESSION_LEVEL="${BACKUP_GZIP_LEVEL:-6}"
TIMESTAMP_FORMAT="${BACKUP_TIMESTAMP_FORMAT:-%Y-%m-%d_%H-%M-%S}"

mkdir -p "$BACKUP_DIR"

log() {
  printf '[backup] %s %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*"
}

backup_db() {
  host="$1"
  port="$2"
  db_name="$3"
  db_user="$4"
  db_password="$5"
  prefix="$6"

  if [ -z "$db_name" ] || [ -z "$db_user" ] || [ -z "$db_password" ]; then
    log "skip $prefix because DB credentials are incomplete"
    return 0
  fi

  timestamp="$(date +"$TIMESTAMP_FORMAT")"
  file_path="$BACKUP_DIR/${prefix}_${timestamp}.sql.gz"

  log "starting backup for $prefix ($db_name@$host:$port)"
  PGPASSWORD="$db_password" \
    pg_dump \
      --host="$host" \
      --port="$port" \
      --username="$db_user" \
      --dbname="$db_name" \
      --clean \
      --if-exists \
      --no-owner \
      --no-privileges | gzip "-$COMPRESSION_LEVEL" > "$file_path"

  log "backup created: $file_path"
}

cleanup_old_backups() {
  find "$BACKUP_DIR" -type f -name '*.sql.gz' -mtime +"$RETENTION_DAYS" -delete
  log "old backups cleanup completed (retention ${RETENTION_DAYS} days)"
}

run_cycle() {
  backup_db \
    "${POSTGRES_HOST:-postgres}" \
    "${POSTGRES_PORT:-5432}" \
    "${POSTGRES_DB:-}" \
    "${POSTGRES_USER:-}" \
    "${POSTGRES_PASSWORD:-}" \
    "main"

  if [ "${BACKUP_INCLUDE_CHAT_DB:-true}" = "true" ]; then
    backup_db \
      "${CHAT_POSTGRES_HOST:-chat-postgres}" \
      "${CHAT_POSTGRES_PORT:-5432}" \
      "${CHAT_POSTGRES_DB:-}" \
      "${CHAT_POSTGRES_USER:-}" \
      "${CHAT_POSTGRES_PASSWORD:-}" \
      "chat"
  fi

  cleanup_old_backups
}

log "auto-backup service started"

while true; do
  run_cycle
  log "sleeping for ${INTERVAL_SECONDS} seconds"
  sleep "$INTERVAL_SECONDS"
done