import { describe, expect, it } from "vitest";
import { describeTimezone, getLocationContext, utcOffsetLabel, weekdayName } from "../lib/location";

describe("describeTimezone", () => {
  it("splits a simple zone into region and city", () => {
    expect(describeTimezone("Asia/Manila")).toEqual({ region: "Asia", city: "Manila" });
  });

  it("handles zones with more than two segments", () => {
    expect(describeTimezone("America/Argentina/Salta")).toEqual({ region: "America", city: "Salta" });
  });

  it("underscores become spaces", () => {
    expect(describeTimezone("America/New_York")).toEqual({ region: "America", city: "New York" });
  });

  it("returns nothing for a bare zone like UTC", () => {
    expect(describeTimezone("UTC")).toEqual({});
  });
});

describe("utcOffsetLabel", () => {
  it("renders a GMT offset for a fixed zone", () => {
    const date = new Date("2026-01-02T03:04:05Z");
    expect(utcOffsetLabel(date, "Asia/Manila")).toContain("+08:00");
  });

  it("reflects daylight saving rather than a fixed offset", () => {
    const winter = utcOffsetLabel(new Date("2026-01-15T12:00:00Z"), "America/New_York");
    const summer = utcOffsetLabel(new Date("2026-07-15T12:00:00Z"), "America/New_York");

    expect(winter).not.toBe(summer);
    expect(winter).toContain("-05:00");
    expect(summer).toContain("-04:00");
  });
});

describe("weekdayName", () => {
  it("names the weekday in the requested zone", () => {
    // 2026-01-02T03:04:05Z is a Friday in UTC.
    expect(weekdayName(new Date("2026-01-02T03:04:05Z"), "UTC")).toBe("Friday");
  });

  it("respects the zone when the local date differs from UTC", () => {
    // 2026-01-02T23:30Z is still Friday in UTC but already Saturday in Manila.
    const late = new Date("2026-01-02T23:30:00Z");
    expect(weekdayName(late, "UTC")).toBe("Friday");
    expect(weekdayName(late, "Asia/Manila")).toBe("Saturday");
  });
});

describe("getLocationContext", () => {
  it("reports the requested zone with its parts", () => {
    const context = getLocationContext(new Date("2026-01-02T03:04:05Z"), "Asia/Manila");

    expect(context.timezone).toBe("Asia/Manila");
    expect(context.city).toBe("Manila");
    expect(context.region).toBe("Asia");
    expect(context.utcOffset).toContain("+08:00");
    expect(context.locale.length).toBeGreaterThan(0);
  });

  it("still returns a usable context for an unknown zone", () => {
    const context = getLocationContext(new Date("2026-01-02T03:04:05Z"), "Not/AReal_Zone");
    expect(context.timezone).toBe("Not/AReal_Zone");
    expect(context.utcOffset).toBe("UTC");
  });
});