#!/usr/bin/env bash
set -euo pipefail

# 支持两种模式：
# 1) 本机 mysql/mysqldump：
#    MYSQL_HOST MYSQL_PORT MYSQL_USER MYSQL_PASSWORD MYSQL_DATABASE
# 2) 容器内执行（推荐在无本地 mysql 客户端时使用）：
#    MYSQL_CONTAINER=<container_name>

MYSQL_HOST="${MYSQL_HOST:-127.0.0.1}"
MYSQL_PORT="${MYSQL_PORT:-3306}"
MYSQL_USER="${MYSQL_USER:-root}"
MYSQL_PASSWORD="${MYSQL_PASSWORD:-}"
MYSQL_DATABASE="${MYSQL_DATABASE:-wx_service}"
MYSQL_CONTAINER="${MYSQL_CONTAINER:-}"

BACKUP_DIR="${BACKUP_DIR:-/var/backups/wx_service}"
KEEP_DAYS="${KEEP_DAYS:-7}"
OPS_ALERT_WEBHOOK="${OPS_ALERT_WEBHOOK:-}"
ALERT_TITLE="${ALERT_TITLE:-[wx_service] 数据备份失败}"

send_alert() {
  local message="$1"
  if [[ -z "${OPS_ALERT_WEBHOOK}" ]]; then
    echo "ALERT: ${message}" >&2
    return
  fi
  curl -fsS -X POST "${OPS_ALERT_WEBHOOK}" \
    -H "Content-Type: application/json" \
    -d "{\"title\":\"${ALERT_TITLE}\",\"message\":\"${message}\"}" >/dev/null || true
}

dump_cmd() {
  if [[ -n "${MYSQL_CONTAINER}" ]]; then
    if [[ -n "${MYSQL_PASSWORD}" ]]; then
      docker exec "${MYSQL_CONTAINER}" mysqldump -h127.0.0.1 -P"${MYSQL_PORT}" -u"${MYSQL_USER}" "-p${MYSQL_PASSWORD}" --single-transaction --quick --set-gtid-purged=OFF "${MYSQL_DATABASE}"
    else
      docker exec "${MYSQL_CONTAINER}" mysqldump -h127.0.0.1 -P"${MYSQL_PORT}" -u"${MYSQL_USER}" --single-transaction --quick --set-gtid-purged=OFF "${MYSQL_DATABASE}"
    fi
    return
  fi

  if [[ -n "${MYSQL_PASSWORD}" ]]; then
    mysqldump -h"${MYSQL_HOST}" -P"${MYSQL_PORT}" -u"${MYSQL_USER}" "-p${MYSQL_PASSWORD}" --single-transaction --quick --set-gtid-purged=OFF "${MYSQL_DATABASE}"
  else
    mysqldump -h"${MYSQL_HOST}" -P"${MYSQL_PORT}" -u"${MYSQL_USER}" --single-transaction --quick --set-gtid-purged=OFF "${MYSQL_DATABASE}"
  fi
}

mkdir -p "${BACKUP_DIR}"
timestamp="$(date +%Y%m%d_%H%M%S)"
outfile="${BACKUP_DIR}/${MYSQL_DATABASE}_${timestamp}.sql.gz"

if ! dump_cmd | gzip -9 > "${outfile}"; then
  send_alert "MySQL 备份失败，数据库=${MYSQL_DATABASE}"
  exit 1
fi

find "${BACKUP_DIR}" -type f -name "${MYSQL_DATABASE}_*.sql.gz" -mtime +"${KEEP_DAYS}" -delete || true
echo "backup created: ${outfile}"