import log4js from "logger";
import nodemailer from "nodemailer";

type CommentEmailConfig = {
  enabled: boolean;
  fromEmail: string;
  smtpHost: string;
  smtpPort: number;
  smtpSecure: boolean;
  smtpUser: string;
  smtpPass: string;
};

const logger = log4js.getLogger("COMMENT_EMAIL_TEST");
const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

export class CommentEmailTestValidationError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "CommentEmailTestValidationError";
  }
}

function hasValue(value: string): boolean {
  return value.trim().length > 0;
}

export function assertCommentEmailConfigReadyForTest(config: CommentEmailConfig): void {
  if (!config.enabled) {
    throw new CommentEmailTestValidationError("评论邮件通知总开关未开启");
  }
  if (!hasValue(config.fromEmail) || !hasValue(config.smtpHost) || !hasValue(config.smtpUser) || !hasValue(config.smtpPass)) {
    throw new CommentEmailTestValidationError("邮件配置不完整，请先填写发件人、SMTP 主机、用户名和密码");
  }
  if (!Number.isInteger(config.smtpPort) || config.smtpPort < 1 || config.smtpPort > 65535) {
    throw new CommentEmailTestValidationError("SMTP 端口不合法");
  }
}

export function assertAdminEmailReady(adminEmail: string | null | undefined): asserts adminEmail is string {
  if (!adminEmail || adminEmail.trim().length === 0) {
    throw new CommentEmailTestValidationError("当前管理员账号未配置邮箱，无法接收测试邮件");
  }
  if (!EMAIL_REGEX.test(adminEmail.trim())) {
    throw new CommentEmailTestValidationError("当前管理员账号邮箱格式不合法");
  }
}

export async function sendCommentEmailTestMail(input: {
  toEmail: string;
  requestedBy: string;
  config: CommentEmailConfig;
}) {
  assertCommentEmailConfigReadyForTest(input.config);
  assertAdminEmailReady(input.toEmail);

  const transporter = nodemailer.createTransport({
    host: input.config.smtpHost,
    port: input.config.smtpPort,
    secure: input.config.smtpSecure,
    connectionTimeout: 10_000,
    greetingTimeout: 10_000,
    socketTimeout: 15_000,
    auth: {
      user: input.config.smtpUser,
      pass: input.config.smtpPass,
    },
  });

  await transporter.sendMail({
    from: input.config.fromEmail,
    to: input.toEmail.trim(),
    subject: "[Person Panel] 评论邮件配置测试",
    text: `你好，${input.requestedBy}。\n\n这是一封评论邮件配置测试邮件，若你收到该邮件，说明 SMTP 配置可用。\n\n发送时间：${new Date().toISOString()}\n`,
  });

  logger.info("comment email test message sent to admin account");
}