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

import {
  DAY_MS,
  enumerateUtcDays,
  hasOverlap,
  isPublicAllowedByDefaultPolicy,
  isWeekendUtcDay,
  normalizeUtcDayStart,
  parseIsoDate,
} from "@/lib/booking";

describe("parseIsoDate", () => {
  it("accepts ISO YYYY-MM-DD", () => {
    const d = parseIsoDate("2026-06-15");
    expect(d).toBeInstanceOf(Date);
    expect(d?.toISOString().startsWith("2026-06-15")).toBe(true);
  });

  it("returns null for garbage input", () => {
    expect(parseIsoDate("not a date")).toBeNull();
    expect(parseIsoDate(null)).toBeNull();
    expect(parseIsoDate(undefined)).toBeNull();
    expect(parseIsoDate(123)).toBeNull();
  });
});

describe("normalizeUtcDayStart", () => {
  it("zeroes out time components", () => {
    const d = new Date("2026-06-15T17:30:45.123Z");
    const n = normalizeUtcDayStart(d);
    expect(n.getUTCHours()).toBe(0);
    expect(n.getUTCMinutes()).toBe(0);
    expect(n.getUTCSeconds()).toBe(0);
    expect(n.getUTCMilliseconds()).toBe(0);
    expect(n.toISOString().slice(0, 10)).toBe("2026-06-15");
  });
});

describe("hasOverlap", () => {
  const d = (iso: string) => new Date(iso);

  it("detects partial overlap", () => {
    expect(
      hasOverlap(d("2026-06-10"), d("2026-06-15"), d("2026-06-13"), d("2026-06-20")),
    ).toBe(true);
  });

  it("returns false for adjacent intervals (touching)", () => {
    expect(
      hasOverlap(d("2026-06-10"), d("2026-06-15"), d("2026-06-15"), d("2026-06-20")),
    ).toBe(false);
  });

  it("returns false for fully separate", () => {
    expect(
      hasOverlap(d("2026-06-01"), d("2026-06-05"), d("2026-06-10"), d("2026-06-15")),
    ).toBe(false);
  });

  it("returns true when one contains the other", () => {
    expect(
      hasOverlap(d("2026-06-01"), d("2026-06-30"), d("2026-06-10"), d("2026-06-15")),
    ).toBe(true);
  });
});

describe("enumerateUtcDays", () => {
  it("enumerates each day between start and end (exclusive)", () => {
    const days = enumerateUtcDays(new Date("2026-06-10"), new Date("2026-06-13"));
    expect(days.length).toBe(3);
    expect(days[0].toISOString().slice(0, 10)).toBe("2026-06-10");
    expect(days[2].toISOString().slice(0, 10)).toBe("2026-06-12");
  });

  it("returns empty when start === end", () => {
    const days = enumerateUtcDays(new Date("2026-06-10"), new Date("2026-06-10"));
    expect(days).toEqual([]);
  });
});

describe("isWeekendUtcDay", () => {
  it("flags Saturday (2026-06-13)", () => {
    expect(isWeekendUtcDay(new Date("2026-06-13"))).toBe(true);
  });
  it("flags Sunday (2026-06-14)", () => {
    expect(isWeekendUtcDay(new Date("2026-06-14"))).toBe(true);
  });
  it("rejects Monday (2026-06-15)", () => {
    expect(isWeekendUtcDay(new Date("2026-06-15"))).toBe(false);
  });
});

describe("isPublicAllowedByDefaultPolicy", () => {
  it("blocks weekends by default (CE-priority policy)", () => {
    expect(isPublicAllowedByDefaultPolicy(new Date("2026-06-13"))).toBe(false);
  });
  it("allows weekdays", () => {
    expect(isPublicAllowedByDefaultPolicy(new Date("2026-06-15"))).toBe(true);
  });
});

describe("DAY_MS constant", () => {
  it("equals 86_400_000", () => {
    expect(DAY_MS).toBe(86_400_000);
  });
});