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

archive_path="${1:-}"
passphrase_file="${DATA_BACKUP_PASSPHRASE_FILE:-}"

fail() {
  echo "错误：$*" >&2
  exit 2
}

[[ -n "${archive_path}" ]] || fail "用法：DATA_BACKUP_PASSPHRASE_FILE=/安全路径/密钥 $0 /备份/mysql-all-*.enc"
[[ "${archive_path}" == /* && ! -L "${archive_path}" && -f "${archive_path}" ]] || fail "备份必须是现有绝对路径，且不能是符号链接"
[[ "${passphrase_file}" == /* && ! -L "${passphrase_file}" && -f "${passphrase_file}" && -r "${passphrase_file}" ]] || fail "缺少安全、可读的 DATA_BACKUP_PASSPHRASE_FILE"

archive_path="$(realpath -e -- "${archive_path}")"
passphrase_file="$(realpath -e -- "${passphrase_file}")"
checksum_file="${archive_path}.sha256"
[[ ! -L "${checksum_file}" && -f "${checksum_file}" ]] || fail "缺少安全的校验文件：${checksum_file}"

expected="$(awk 'NR==1 {print $1}' "${checksum_file}")"
[[ "${expected}" =~ ^[0-9a-fA-F]{64}$ ]] || fail "SHA-256校验文件格式错误"
if command -v sha256sum >/dev/null 2>&1; then
  actual="$(sha256sum "${archive_path}" | awk '{print $1}')"
else
  actual="$(shasum -a 256 "${archive_path}" | awk '{print $1}')"
fi
if [[ "${actual,,}" != "${expected,,}" ]]; then
  echo "备份 SHA-256 校验失败" >&2
  exit 1
fi

openssl enc -d -aes-256-cbc -pbkdf2 -iter 200000 \
  -pass "file:${passphrase_file}" -in "${archive_path}" | gzip -t

echo "备份加密、SHA-256校验和与压缩结构验证通过。"
echo "生产环境仍应定期恢复到隔离MySQL实例进行完整恢复演练。"