/**
 * earth-now.co
 * Author:  Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 * File:    packages/counter/test/format.test.ts
 * Purpose: Formatting tests — sigFigs honesty cap, locales, rates, fallback on non-finite values
 */

import { describe, expect, it } from "vitest";
import {
  formatCompact,
  formatRate,
  formatUncertainty,
  formatValue,
  roundToSigFigs,
} from "../src/index";

describe("roundToSigFigs", () => {
  it("caps significant digits", () => {
    expect(roundToSigFigs(8_231_456_789, 7)).toBe(8_231_457_000);
    expect(roundToSigFigs(426.912345, 5)).toBeCloseTo(426.91, 9);
    expect(roundToSigFigs(0.0012349, 3)).toBeCloseTo(0.00123, 12);
    expect(roundToSigFigs(-1234, 2)).toBe(-1200);
    expect(roundToSigFigs(0, 3)).toBe(0);
  });
});

describe("formatValue", () => {
  it("applies sigFigs then decimals", () => {
    const s = formatValue(8_231_456_789, { decimals: 0, sigFigs: 7, unit: "people" });
    expect(s).toBe("8,231,457,000");
  });

  it("keeps full precision when applySigFigs=false (animated ticker)", () => {
    const s = formatValue(8_231_456_789, { decimals: 0, sigFigs: 7, unit: "people" }, {
      applySigFigs: false,
    });
    expect(s).toBe("8,231,456,789");
  });

  it("honors locale", () => {
    const s = formatValue(1234.5, { decimals: 1, unit: "t" }, { locale: "fr" });
    // fr uses narrow no-break space grouping and comma decimal.
    expect(s).toMatch(/1[\s  ]234,5/);
  });

  it("falls back on non-finite values (never NaN on screen)", () => {
    expect(formatValue(Number.NaN, { decimals: 0, unit: "x" })).toBe("—");
    expect(formatValue(Infinity, { decimals: 0, unit: "x" })).toBe("—");
  });
});

describe("formatRate", () => {
  it("chooses a human cadence", () => {
    expect(formatRate(4.2, { decimals: 0, unit: "people" })).toBe("4.2/s");
    expect(formatRate(0.5, { decimals: 0, unit: "people" })).toBe("30/min");
    expect(formatRate(0.002, { decimals: 0, unit: "people" })).toBe("7.2/h");
  });

  it("applies the display scale in every cadence band", () => {
    // 1027 MWh/s with scale 1e-6 → 0.001027 TWh/s → shown per hour: 3.7 TWh/h.
    expect(formatRate(1027, { decimals: 2, unit: "TWh", scale: 0.000001 })).toBe("3.7/h");
    // 500 m/s with scale 1e-3 → 0.5 km/s → per minute: 30 km/min.
    expect(formatRate(500, { decimals: 0, unit: "km", scale: 0.001 })).toBe("30/min");
  });
});

describe("formatCompact", () => {
  it("compacts axis-tick values with scale and sigFigs cap", () => {
    expect(formatCompact(8_310_000_000, { decimals: 0, sigFigs: 3, unit: "people" })).toBe(
      "8.31B",
    );
    expect(
      formatCompact(23_400_000_000, { decimals: 0, sigFigs: 4, unit: "Gt", scale: 1e-9 }),
    ).toBe("23.4");
    expect(formatCompact(Number.NaN, { decimals: 0, unit: "x" })).toBe("—");
  });
});

describe("formatUncertainty", () => {
  it("renders a CI range", () => {
    const s = formatUncertainty(8.1e9, 8.3e9, { decimals: 0, sigFigs: 3, unit: "people" });
    expect(s).toBe("8,100,000,000 – 8,300,000,000");
  });
});