import { describe, expect, it } from "vitest";
import {
  languageAlternates,
  localeOfPath,
  pathFor,
  routeRequest,
  sitemapEntries,
  switchPath,
} from "./routes";

describe("pathFor", () => {
  it("serves German at the root, with German names for the legal pages", () => {
    expect(pathFor("home", "de")).toBe("/");
    expect(pathFor("imprint", "de")).toBe("/impressum");
    expect(pathFor("privacy", "de")).toBe("/datenschutz");
  });

  it("serves English under /en", () => {
    expect(pathFor("home", "en")).toBe("/en");
    expect(pathFor("imprint", "en")).toBe("/en/imprint");
    expect(pathFor("privacy", "en")).toBe("/en/privacy");
  });
});

describe("languageAlternates", () => {
  it("names both languages of a page and German as the fallback", () => {
    expect(languageAlternates("home")).toEqual({
      de: "/",
      en: "/en",
      "x-default": "/",
    });
    expect(languageAlternates("privacy")).toEqual({
      de: "/datenschutz",
      en: "/en/privacy",
      "x-default": "/datenschutz",
    });
  });
});

describe("localeOfPath", () => {
  it.each([
    ["/", "de"],
    ["/impressum", "de"],
    ["/en", "en"],
    ["/en/", "en"],
    ["/en/imprint", "en"],
    ["/en/anything/else", "en"],
    // Only a whole first segment counts.
    ["/energy", "de"],
    ["/dev/en", "de"],
    ["", "de"],
  ] as const)("%s is %s", (pathname, locale) => {
    expect(localeOfPath(pathname)).toBe(locale);
  });
});

describe("switchPath", () => {
  it("leads to the same page in the other language", () => {
    expect(switchPath("/", "en")).toBe("/en");
    expect(switchPath("/en", "de")).toBe("/");
    expect(switchPath("/impressum", "en")).toBe("/en/imprint");
    expect(switchPath("/en/imprint", "de")).toBe("/impressum");
    expect(switchPath("/datenschutz", "en")).toBe("/en/privacy");
    expect(switchPath("/en/privacy", "de")).toBe("/datenschutz");
  });

  it("stays on the page when the language is already the requested one", () => {
    expect(switchPath("/en/imprint", "en")).toBe("/en/imprint");
    expect(switchPath("/datenschutz", "de")).toBe("/datenschutz");
  });

  it("ignores a trailing slash", () => {
    expect(switchPath("/en/", "de")).toBe("/");
    expect(switchPath("/impressum/", "en")).toBe("/en/imprint");
  });

  it("leads to the homepage from an address that is not a page", () => {
    expect(switchPath("/nothing-here", "en")).toBe("/en");
    expect(switchPath("/en/nothing-here", "de")).toBe("/");
    // A German page name under /en is not an English page.
    expect(switchPath("/en/impressum", "de")).toBe("/");
  });
});

const german = { cookie: undefined, acceptLanguage: "de-DE,de;q=0.9,en;q=0.8" };
const english = { cookie: undefined, acceptLanguage: "en-US,en;q=0.9" };
const unknown = { cookie: undefined, acceptLanguage: undefined };

describe("routeRequest", () => {
  describe("addresses without a language", () => {
    it.each([
      ["/", "/de"],
      ["/impressum", "/de/imprint"],
      ["/datenschutz", "/de/privacy"],
    ])("shows %s in German to a German browser", (pathname, to) => {
      expect(routeRequest({ pathname, ...german })).toEqual({
        kind: "rewrite",
        to,
        negotiated: true,
      });
    });

    it("shows German when nothing is known about the visitor, as for a search engine", () => {
      expect(routeRequest({ pathname: "/", ...unknown })).toEqual({
        kind: "rewrite",
        to: "/de",
        negotiated: true,
      });
    });

    it.each([
      ["/", "/en"],
      ["/impressum", "/en/imprint"],
      ["/datenschutz", "/en/privacy"],
    ])(
      "sends an English browser from %s to %s, not permanently",
      (pathname, to) => {
        expect(routeRequest({ pathname, ...english })).toEqual({
          kind: "redirect",
          to,
          permanent: false,
          negotiated: true,
        });
      },
    );

    it("leaves an English browser on German once German was chosen", () => {
      expect(routeRequest({ pathname: "/", ...english, cookie: "de" })).toEqual(
        { kind: "rewrite", to: "/de", negotiated: true },
      );
    });

    it("sends a German browser to English once English was chosen", () => {
      expect(routeRequest({ pathname: "/", ...german, cookie: "en" })).toEqual({
        kind: "redirect",
        to: "/en",
        permanent: false,
        negotiated: true,
      });
    });

    it("treats a trailing slash like the page itself", () => {
      expect(routeRequest({ pathname: "/impressum/", ...english })).toEqual({
        kind: "redirect",
        to: "/en/imprint",
        permanent: false,
        negotiated: true,
      });
      expect(routeRequest({ pathname: "/impressum/", ...german })).toEqual({
        kind: "rewrite",
        to: "/de/imprint",
        negotiated: true,
      });
      expect(routeRequest({ pathname: "/impressum//", ...german })).toEqual({
        kind: "rewrite",
        to: "/de/imprint",
        negotiated: true,
      });
    });

    // The legal pages used to live here in English; search engines know those addresses.
    it.each([
      ["/imprint", "/en/imprint"],
      ["/privacy", "/en/privacy"],
      ["/privacy/", "/en/privacy"],
    ])(
      "moves the English page name %s to %s for good, whatever the browser says",
      (pathname, to) => {
        for (const visitor of [german, english, unknown]) {
          expect(routeRequest({ pathname, ...visitor })).toEqual({
            kind: "redirect",
            to,
            permanent: true,
            negotiated: false,
          });
        }
      },
    );

    it("shows the German error page for an unknown address, whatever the browser says", () => {
      expect(routeRequest({ pathname: "/nothing-here", ...english })).toEqual({
        kind: "rewrite",
        to: "/de/nothing-here",
        negotiated: false,
      });
      expect(routeRequest({ pathname: "/a/b", ...german })).toEqual({
        kind: "rewrite",
        to: "/de/a/b",
        negotiated: false,
      });
    });
  });

  describe("English addresses", () => {
    it.each([
      ["/en", "/en"],
      ["/en/", "/en"],
      ["/en/imprint", "/en/imprint"],
      ["/en/privacy", "/en/privacy"],
    ])("shows %s in English to everyone", (pathname, to) => {
      for (const visitor of [german, english, { ...english, cookie: "de" }]) {
        expect(routeRequest({ pathname, ...visitor })).toEqual({
          kind: "rewrite",
          to,
          negotiated: false,
        });
      }
    });

    it.each([
      ["/en/impressum", "/en/imprint"],
      ["/en/datenschutz", "/en/privacy"],
      ["/en/datenschutz/", "/en/privacy"],
    ])(
      "moves the German page name %s to the English one for good",
      (pathname, to) => {
        expect(routeRequest({ pathname, ...german })).toEqual({
          kind: "redirect",
          to,
          permanent: true,
          negotiated: false,
        });
      },
    );

    it("shows the English error page for an unknown English address", () => {
      expect(routeRequest({ pathname: "/en/nothing-here", ...german })).toEqual(
        { kind: "rewrite", to: "/en/nothing-here", negotiated: false },
      );
    });
  });

  describe("addresses with the internal German prefix", () => {
    it.each([
      ["/de", "/"],
      ["/de/", "/"],
      ["/de/impressum", "/impressum"],
      ["/de/datenschutz", "/datenschutz"],
      ["/de/imprint", "/impressum"],
      ["/de/privacy", "/datenschutz"],
      ["/de/nothing-here", "/nothing-here"],
    ])(
      "moves %s to %s for good, so that each page has one address",
      (pathname, to) => {
        expect(routeRequest({ pathname, ...english })).toEqual({
          kind: "redirect",
          to,
          permanent: true,
          negotiated: false,
        });
      },
    );

    it("only treats a whole segment as a prefix", () => {
      expect(routeRequest({ pathname: "/design", ...german })).toEqual({
        kind: "rewrite",
        to: "/de/design",
        negotiated: false,
      });
      expect(routeRequest({ pathname: "/energy", ...german })).toEqual({
        kind: "rewrite",
        to: "/de/energy",
        negotiated: false,
      });
    });
  });
});

describe("sitemapEntries", () => {
  it("lists every language of the given pages, each with all its alternates", () => {
    const languages = {
      de: "https://example.com/",
      en: "https://example.com/en",
      "x-default": "https://example.com/",
    };
    expect(sitemapEntries("https://example.com", ["home"])).toEqual([
      { url: "https://example.com/", alternates: { languages } },
      { url: "https://example.com/en", alternates: { languages } },
    ]);
  });

  it("keeps the order of the pages", () => {
    expect(
      sitemapEntries("https://example.com", ["privacy", "home"]).map(
        (entry) => entry.url,
      ),
    ).toEqual([
      "https://example.com/datenschutz",
      "https://example.com/en/privacy",
      "https://example.com/",
      "https://example.com/en",
    ]);
  });

  it("is empty without pages", () => {
    expect(sitemapEntries("https://example.com", [])).toEqual([]);
  });
});