/**
 * Unit tests for calendar: dutiesByDate (including edge case end_at < start_at),
 * calendarEventsByDate.
 */

import { describe, it, expect, beforeAll, beforeEach } from "vitest";

beforeAll(() => {
  document.body.innerHTML =
    '<div id="calendar"></div><h2 id="monthTitle"></h2>' +
    '<div id="dutyList"></div><div id="loading"></div><div id="error"></div>' +
    '<div id="accessDenied"></div><div class="header"></div><div class="weekdays"></div>' +
    '<button id="prevMonth"></button><button id="nextMonth"></button>';
});

import { dutiesByDate, calendarEventsByDate, renderCalendar } from "./calendar.js";
import { state } from "./dom.js";

describe("dutiesByDate", () => {
  it("groups duty by single local day", () => {
    const duties = [
      {
        full_name: "Alice",
        start_at: "2025-02-25T09:00:00Z",
        end_at: "2025-02-25T18:00:00Z",
      },
    ];
    const byDate = dutiesByDate(duties);
    expect(byDate["2025-02-25"]).toHaveLength(1);
    expect(byDate["2025-02-25"][0].full_name).toBe("Alice");
  });

  it("spans duty across multiple days", () => {
    const duties = [
      {
        full_name: "Bob",
        start_at: "2025-02-25T00:00:00Z",
        end_at: "2025-02-27T23:59:59Z",
      },
    ];
    const byDate = dutiesByDate(duties);
    const keys = Object.keys(byDate).sort();
    expect(keys.length).toBeGreaterThanOrEqual(2);
    keys.forEach((k) => expect(byDate[k]).toHaveLength(1));
    expect(byDate[keys[0]][0].full_name).toBe("Bob");
  });

  it("skips duty when end_at < start_at (no infinite loop)", () => {
    const duties = [
      {
        full_name: "Bad",
        start_at: "2025-02-28T12:00:00Z",
        end_at: "2025-02-25T08:00:00Z",
      },
    ];
    const byDate = dutiesByDate(duties);
    expect(Object.keys(byDate)).toHaveLength(0);
  });

  it("does not iterate more than MAX_DAYS_PER_DUTY", () => {
    const start = "2025-01-01T00:00:00Z";
    const end = "2026-06-01T00:00:00Z";
    const duties = [{ full_name: "Long", start_at: start, end_at: end }];
    const byDate = dutiesByDate(duties);
    const keys = Object.keys(byDate).sort();
    expect(keys.length).toBeLessThanOrEqual(367);
  });

  it("handles empty duties", () => {
    expect(dutiesByDate([])).toEqual({});
  });
});

describe("calendarEventsByDate", () => {
  it("maps events to local date key by UTC date", () => {
    const events = [
      { date: "2025-02-25", summary: "Holiday" },
      { date: "2025-02-25", summary: "Meeting" },
      { date: "2025-02-26", summary: "Other" },
    ];
    const byDate = calendarEventsByDate(events);
    expect(byDate["2025-02-25"]).toEqual(["Holiday", "Meeting"]);
    expect(byDate["2025-02-26"]).toEqual(["Other"]);
  });

  it("skips events without summary", () => {
    const events = [{ date: "2025-02-25", summary: null }];
    const byDate = calendarEventsByDate(events);
    expect(byDate["2025-02-25"] || []).toHaveLength(0);
  });

  it("handles null or undefined events", () => {
    expect(calendarEventsByDate(null)).toEqual({});
    expect(calendarEventsByDate(undefined)).toEqual({});
  });
});

describe("renderCalendar", () => {
  beforeEach(() => {
    state.lang = "en";
  });

  it("renders 42 cells (6 weeks)", () => {
    renderCalendar(2025, 0, {}, {});
    const calendarEl = document.getElementById("calendar");
    const cells = calendarEl?.querySelectorAll(".day") ?? [];
    expect(cells.length).toBe(42);
  });

  it("sets data-date on each cell to YYYY-MM-DD", () => {
    renderCalendar(2025, 0, {}, {});
    const calendarEl = document.getElementById("calendar");
    const cells = Array.from(calendarEl?.querySelectorAll(".day") ?? []);
    const dates = cells.map((c) => c.getAttribute("data-date"));
    expect(dates.every((d) => /^\d{4}-\d{2}-\d{2}$/.test(d ?? ""))).toBe(true);
  });

  it("adds today class to cell matching today", () => {
    const today = new Date();
    renderCalendar(today.getFullYear(), today.getMonth(), {}, {});
    const calendarEl = document.getElementById("calendar");
    const todayKey =
      today.getFullYear() +
      "-" +
      String(today.getMonth() + 1).padStart(2, "0") +
      "-" +
      String(today.getDate()).padStart(2, "0");
    const todayCell = calendarEl?.querySelector('.day.today[data-date="' + todayKey + '"]');
    expect(todayCell).toBeTruthy();
  });

  it("sets month title from state.lang and given year/month", () => {
    state.lang = "en";
    renderCalendar(2025, 1, {}, {});
    const titleEl = document.getElementById("monthTitle");
    expect(titleEl?.textContent).toContain("2025");
    expect(titleEl?.textContent).toContain("February");
  });
});