AuthInbox/test/mime.test.ts

import { describe, expect, it } from "vitest";
import {
  decodeMimeHeader,
  decodeQuotedPrintable,
  extractMailBodies,
  isPromotionalEmail,
  stripHtmlTags,
} from "../src/services/mime";

describe("mime decoding", () => {
  it("decodes UTF-8 base64 body parts as Unicode text", () => {
    const rawEmail = [
      'Content-Type: multipart/alternative; boundary="mail-boundary"',
      "",
      "--mail-boundary",
      "Content-Type: text/plain; charset=UTF-8",
      "Content-Transfer-Encoding: base64",
      "",
      "5Lit5paH6aqM6K+B56CB77yaMTIzNDU2",
      "--mail-boundary--",
      "",
    ].join("\r\n");

    expect(extractMailBodies(rawEmail).textBody).toBe("中文验证码：123456");
  });

  it("decodes single-part base64 HTML emails", () => {
    const rawEmail = [
      "Content-Type: text/html; charset=utf-8",
      "Content-Transfer-Encoding: base64",
      "",
      "PGh0bWw+PGJvZHk+PHA+5Lit5paH6aqM6K+B56CB77yaMTIzNDU2PC9wPjwvYm9keT48L2h0bWw+",
      "",
    ].join("\r\n");

    const bodies = extractMailBodies(rawEmail);
    expect(bodies.htmlBody).toContain("中文验证码：123456");
    expect(bodies.textBody).toBe("中文验证码：123456");
  });

  it("decodes UTF-8 quoted-printable body parts as Unicode text", () => {
    expect(decodeQuotedPrintable("=E4=B8=AD=E6=96=87=E9=AA=8C=E8=AF=81=E7=A0=81=EF=BC=9A123456")).toBe(
      "中文验证码：123456",
    );
  });

  it("decodes RFC 2047 encoded subject headers", () => {
    expect(decodeMimeHeader("=?UTF-8?B?6aqM6K+B56CB?=")).toBe("验证码");
  });
});

describe("isPromotionalEmail", () => {
  it("does not flag transactional mail that carries List-Unsubscribe (Gmail/Yahoo bulk sender rules)", () => {
    const headers = new Headers({
      "List-Unsubscribe": "<mailto:x@unsubscribe.netflix.com>",
      "List-Unsubscribe-Post": "List-Unsubscribe=One-Click",
      Subject: "Your Netflix temporary access code",
    });
    expect(isPromotionalEmail(headers, "Subject: x\r\n\r\nbody")).toBe(false);
  });

  it("exempts RFC 2047 encoded CJK verification subjects", () => {
    const headers = new Headers({
      "List-Unsubscribe": "<mailto:x@example.com>",
      Subject: "=?UTF-8?B?6aqM6K+B56CB?=", // 验证码
    });
    expect(isPromotionalEmail(headers, "Subject: x\r\n\r\nbody")).toBe(false);
  });

  it("still flags List-Unsubscribe mail with a promotional subject", () => {
    const headers = new Headers({
      "List-Unsubscribe": "<mailto:x@example.com>",
      Subject: "Summer sale: 50% off everything this weekend!",
    });
    expect(isPromotionalEmail(headers, "Subject: x\r\n\r\nbody")).toBe(true);
  });

  it("keeps strong signals unconditional even when the subject looks transactional", () => {
    const listMail = new Headers({ "List-ID": "<dev.lists.example.com>", Subject: "your code" });
    expect(isPromotionalEmail(listMail, "Subject: x\r\n\r\nbody")).toBe(true);

    const bulkMail = new Headers({ Precedence: "bulk", Subject: "your verification code" });
    expect(isPromotionalEmail(bulkMail, "Subject: x\r\n\r\nbody")).toBe(true);

    const campaignMail = new Headers({ Subject: "your login code" });
    expect(
      isPromotionalEmail(campaignMail, "X-Campaign-ID: 42\r\nSubject: x\r\n\r\nbody"),
    ).toBe(true);
  });

  it("keeps plain mail without any bulk signal non-promotional", () => {
    const headers = new Headers({ Subject: "Hello" });
    expect(isPromotionalEmail(headers, "Subject: Hello\r\n\r\nbody")).toBe(false);
  });
});

describe("stripHtmlTags", () => {
  it("preserves anchor hrefs so button-only mails keep their link", () => {
    const html = '<p>Hi Thomas</p><a class="h5" href="https://www.netflix.com/verify?a=1&amp;b=2" style="x">Get Code</a>';
    expect(stripHtmlTags(html)).toContain("Get Code [https://www.netflix.com/verify?a=1&b=2]");
  });

  it("drops non-http hrefs but keeps the label", () => {
    expect(stripHtmlTags('<a href="mailto:x@y.com">contact us</a>')).toBe("contact us");
  });
});

describe("extractMailBodies single-part html", () => {
  it("treats a bare text/html fragment (no <html> wrapper) as the html body", () => {
    const rawEmail = [
      "Subject: code",
      "Content-Type: text/html; charset=utf-8",
      "Content-Transfer-Encoding: base64",
      "",
      Buffer.from('<div>Your code: <a href="https://x.com/v?t=1">Get Code</a></div>').toString("base64"),
      "",
    ].join("\r\n");

    const bodies = extractMailBodies(rawEmail);
    expect(bodies.htmlBody).toContain("https://x.com/v?t=1");
    expect(bodies.textBody).toContain("Get Code [https://x.com/v?t=1]");
  });
});