import { describe, expect, it } from "vitest";
import {
  formatBytes,
  formatDate,
  formatDurationMs,
  formatNumber,
  formatRelativeTime,
  initials,
  truncate,
} from "./formatters.js";

describe("formatBytes", () => {
  it("handles the spec edge cases", () => {
    expect(formatBytes(0)).toBe("0 B");
    expect(formatBytes(500)).toBe("500 B");
    expect(formatBytes(1)).toBe("1 B");
    expect(formatBytes(1023)).toBe("1023 B");
    expect(formatBytes(1024)).toBe("1 KB");
    expect(formatBytes(1536)).toBe("1.5 KB");
    expect(formatBytes(1048576)).toBe("1 MB");
  });

  it("uses 1024 steps with 1 decimal when <10", () => {
    expect(formatBytes(1.5 * 1024 * 1024)).toBe("1.5 MB");
    expect(formatBytes(9.9 * 1024)).toBe("9.9 KB");
    expect(formatBytes(10 * 1024)).toBe("10 KB");
    expect(formatBytes(1.2 * 1024 * 1024 * 1024)).toBe("1.2 GB");
    expect(formatBytes(2.5 * 1024 * 1024 * 1024)).toBe("2.5 GB");
    expect(formatBytes(1500 * 1024)).toBe("1.5 MB"); // 1500 KB → 1.4648 MB → 1.5 MB
  });

  it("clamps invalid input", () => {
    expect(formatBytes(-5)).toBe("0 B");
    expect(formatBytes(NaN)).toBe("0 B");
    expect(formatBytes(Infinity)).toBe("0 B");
  });
});

describe("formatNumber", () => {
  it("formats with the injected locale", () => {
    expect(formatNumber(1234567, "en-US")).toBe("1,234,567");
    expect(formatNumber(1234567, "de-DE")).toBe("1.234.567");
    expect(formatNumber(1.5, "en-US")).toBe("1.5");
  });
});

describe("formatRelativeTime (fixed now)", () => {
  const now = Date.parse("2025-06-01T12:00:00.000Z");

  it("just now / minutes / hours / days / date", () => {
    expect(formatRelativeTime("2025-06-01T11:59:30.000Z", now)).toBe("just now");
    expect(formatRelativeTime("2025-06-01T11:45:00.000Z", now)).toBe("15m ago");
    expect(formatRelativeTime("2025-06-01T11:55:00.000Z", now)).toBe("5m ago");
    expect(formatRelativeTime("2025-06-01T10:00:00.000Z", now)).toBe("2h ago");
    expect(formatRelativeTime("2025-05-29T12:00:00.000Z", now)).toBe("3d ago");
    // one ms short of 4 full days → still "3d ago" (floor)
    expect(formatRelativeTime("2025-05-28T12:00:00.001Z", now)).toBe("3d ago");
    // beyond 7 days → locale date, never "… ago"
    const out8d = formatRelativeTime("2025-05-24T12:00:00.000Z", now);
    expect(out8d.includes("ago")).toBe(false);
    expect(out8d.includes("2025")).toBe(true);
  });

  it("handles invalid ISO", () => {
    expect(formatRelativeTime("not-a-date", now)).toBe("");
  });
});

describe("formatDurationMs", () => {
  it("formats seconds and minutes", () => {
    expect(formatDurationMs(1200)).toBe("1.2s");
    expect(formatDurationMs(0)).toBe("0.0s");
    expect(formatDurationMs(1500)).toBe("1.5s");
    expect(formatDurationMs(12000)).toBe("12s");
    expect(formatDurationMs(184000)).toBe("3m 04s");
    expect(formatDurationMs(60_000)).toBe("1m 00s");
  });

  it("formats hours", () => {
    expect(formatDurationMs(3_723_000)).toBe("1h 02m 03s");
  });

  it("clamps invalid input", () => {
    expect(formatDurationMs(-100)).toBe("0s");
    expect(formatDurationMs(NaN)).toBe("0s");
  });
});

describe("initials", () => {
  it("two words → first letters", () => {
    expect(initials("Ada Lovelace")).toBe("AL");
    expect(initials("Ada   Lovelace")).toBe("AL");
  });

  it("single word → first two chars uppercased", () => {
    expect(initials("Grace")).toBe("GR");
    expect(initials("a")).toBe("A");
  });

  it("many words → only first two", () => {
    expect(initials("Ada King Olivia Lovelace")).toBe("AK");
  });

  it("empty / whitespace → empty string", () => {
    expect(initials("")).toBe("");
    expect(initials("   ")).toBe("");
  });
});

describe("truncate", () => {
  it("leaves short strings alone", () => {
    expect(truncate("abc", 5)).toBe("abc");
    expect(truncate("abc", 3)).toBe("abc");
  });
  it("adds ellipsis when longer", () => {
    expect(truncate("Hello world", 5)).toBe("Hello…");
    expect(truncate("abc", 0)).toBe("…");
  });
});

describe("formatDate", () => {
  it("includes all three parts and honors the injected locale", () => {
    const en = formatDate("2025-06-01T00:00:00.000Z", { locale: "en-US" });
    const de = formatDate("2025-06-01T00:00:00.000Z", { locale: "de-DE" });
    // locale-agnostic: day 1, June/06, year 2025 must all appear
    for (const out of [en, de]) {
      expect(out).toContain("2025");
      expect(out).toMatch(/1/);
      expect(out).toMatch(/(Jun|06)/);
    }
    expect(en).not.toBe(de); // locales actually differ
  });
  it("invalid → empty", () => {
    expect(formatDate("nope", { locale: "en-US" })).toBe("");
  });
});