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

describe("describeTimezoneArea", () => {
  it("keeps the zone's own label", () => {
    expect(describeTimezoneArea("Asia/Manila")).toEqual({ area: "Manila" });
  });

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

  it("turns underscores into spaces", () => {
    expect(describeTimezoneArea("America/New_York")).toEqual({ area: "New York" });
  });

  it("drops the continent grouping, which answers a question nobody asked", () => {
    // "Asia" beside a locale region of "Philippines" reads as two answers to
    // the same question.
    expect(describeTimezoneArea("Asia/Manila")).not.toHaveProperty("region");
  });

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

describe("localeRegion", () => {
  it("reads the region the user configured, rather than inferring one", () => {
    expect(localeRegion("en-PH")).toEqual({ code: "PH", name: "Philippines" });
  });

  it("handles other regions", () => {
    expect(localeRegion("de-DE")?.name).toBe("Germany");
    expect(localeRegion("en-US")?.code).toBe("US");
  });

  it("has nothing to say for a locale with no region", () => {
    expect(localeRegion("en")).toBeUndefined();
  });

  it("does not throw on a malformed locale", () => {
    expect(localeRegion("not a locale")).toBeUndefined();
    expect(localeRegion("")).toBeUndefined();
  });
});

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.utcOffset).toContain("+08:00");
    expect(context.locale.length).toBeGreaterThan(0);
    // The zone's label is reported as such, never as the user's city.
    expect(context.timezoneArea).toBe("Manila");
    expect(context).not.toHaveProperty("city");
  });

  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");
  });

  it("carries the configured place through verbatim", () => {
    const context = getLocationContext(new Date(), "Asia/Manila", "  Cebu City, Philippines  ");
    expect(context.place).toBe("Cebu City, Philippines");
  });

  it("treats an empty or whitespace place as unset", () => {
    expect(getLocationContext(new Date(), "Asia/Manila", "").place).toBeUndefined();
    expect(getLocationContext(new Date(), "Asia/Manila", "   ").place).toBeUndefined();
    expect(getLocationContext(new Date(), "Asia/Manila").place).toBeUndefined();
  });
});