Calendar_Frontend/lib/event-display.test.ts

import { describe, expect, it } from "vitest";
import { ApiError } from "@/lib/api";
import { describeApiError, isSessionExpired } from "@/lib/api-errors";
import { fromWallTime, toWallTime } from "@/lib/dates";
import { dateBlock, describeWhen, isPast, occurrence, repeatLabel, todayMarkerIndex } from "@/lib/event-display";
import { makeEvent } from "@/lib/test-fixtures";

const now = new Date("2026-09-27T10:00:00Z");

describe("dateBlock", () => {
  it("gives weekday, day and month in German, Berlin time", () => {
    // 23:30 UTC on 2 Oct is already Saturday 3 Oct in Berlin.
    expect(dateBlock(new Date("2026-10-02T23:30:00Z"))).toEqual({ weekday: "Sa", day: "3", month: "Okt" });
  });
});

describe("describeWhen", () => {
  it("shows a same-day time range", () => {
    expect(describeWhen(makeEvent(), now)).toBe("19:00–21:00 Uhr");
  });

  it("shows a multi-day timed event with both dates", () => {
    const event = makeEvent({ start: fromWallTime("2026-10-03", "19:00"), end: fromWallTime("2026-10-05", "12:00") });
    expect(describeWhen(event, now)).toBe("3. Okt., 19:00 – 5. Okt., 12:00");
  });

  it("shows whole-day events, with the range when they span days", () => {
    const oneDay = makeEvent({ wholeDay: true, start: fromWallTime("2026-10-03", "00:00"), end: fromWallTime("2026-10-03", "23:59") });
    const weekend = makeEvent({ wholeDay: true, start: fromWallTime("2026-10-17", "00:00"), end: fromWallTime("2026-10-19", "23:59") });
    expect(describeWhen(oneDay, now)).toBe("Ganztägig");
    expect(describeWhen(weekend, now)).toBe("Ganztägig · 17.–19. Okt.");
  });
});

describe("occurrence", () => {
  it("moves a birthday's start and end to this year's date together", () => {
    const birthday = makeEvent({
      wholeDay: true,
      repeatFrequency: "YEARLY",
      start: fromWallTime("1994-10-03", "00:00"),
      end: fromWallTime("1994-10-03", "23:59"),
    });
    const { start, end } = occurrence(birthday, now);
    expect(toWallTime(start)).toEqual({ date: "2026-10-03", time: "00:00" });
    expect(toWallTime(end)).toEqual({ date: "2026-10-03", time: "23:59" });
    expect(describeWhen(birthday, now)).toBe("Ganztägig");
  });
});

describe("isPast", () => {
  it("is true only for non-repeating events that ended before today", () => {
    const old = { start: fromWallTime("2026-07-18", "15:00"), end: fromWallTime("2026-07-18", "22:00") };
    expect(isPast(makeEvent(old), now)).toBe(true);
    expect(isPast(makeEvent({ ...old, repeatFrequency: "YEARLY" }), now)).toBe(false);
    expect(isPast(makeEvent(), now)).toBe(false);
  });
});

describe("todayMarkerIndex", () => {
  const past = makeEvent({ eventId: 1, start: fromWallTime("2026-07-18", "15:00"), end: fromWallTime("2026-07-18", "22:00") });
  const today = makeEvent({ eventId: 2, start: fromWallTime("2026-09-27", "08:00"), end: fromWallTime("2026-09-27", "09:00") });
  const later = makeEvent({ eventId: 3 });

  it("sits before the first event not yet over, ascending", () => {
    expect(todayMarkerIndex([past, today, later], "start_asc", now)).toBe(1);
  });

  it("sits before the first past event, descending", () => {
    expect(todayMarkerIndex([later, today, past], "start_desc", now)).toBe(2);
  });

  it("goes to the end or the start when everything is on one side", () => {
    expect(todayMarkerIndex([past], "start_asc", now)).toBe(1);
    expect(todayMarkerIndex([later], "start_asc", now)).toBe(0);
    expect(todayMarkerIndex([later], "start_desc", now)).toBe(1);
  });

  it("has no place in a list sorted by creation, or an empty one", () => {
    expect(todayMarkerIndex([past, later], "created_asc", now)).toBeNull();
    expect(todayMarkerIndex([], "start_asc", now)).toBeNull();
  });
});

describe("repeatLabel", () => {
  it("translates known frequencies and passes unknown ones through", () => {
    expect(repeatLabel("")).toBe("");
    expect(repeatLabel("YEARLY")).toBe("jährlich");
    expect(repeatLabel("HOURLY")).toBe("hourly");
  });
});

describe("describeApiError", () => {
  it("explains each kind of failure in German", () => {
    expect(describeApiError(new ApiError(0, {}))).toMatch(/Keine Verbindung/);
    expect(describeApiError(new ApiError(403, {}))).toMatch(/Berechtigung/);
    expect(describeApiError(new ApiError(500, {}))).toMatch(/\(500\)/);
    expect(describeApiError(new ApiError(200, {}, "Der Termin wurde nicht gespeichert."))).toBe(
      "Der Termin wurde nicht gespeichert.",
    );
    expect(describeApiError(new Error("x"))).toMatch(/Unerwarteter Fehler/);
  });

  it("recognises only 401 as an expired session", () => {
    expect(isSessionExpired(new ApiError(401, {}))).toBe(true);
    expect(isSessionExpired(new ApiError(403, {}))).toBe(false);
  });
});