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

import {
  feetToMeters,
  metersToFeet,
  formatNumber1dp,
  dimInFeet,
  dimInMeters,
} from '@/components/yachts/yacht-dimensions';

describe('yacht-dimensions: ft ↔ m conversions', () => {
  it('feetToMeters: returns null for non-finite inputs', () => {
    expect(feetToMeters(null)).toBeNull();
    expect(feetToMeters(undefined)).toBeNull();
    expect(feetToMeters('')).toBeNull();
    expect(feetToMeters('abc')).toBeNull();
    expect(feetToMeters(NaN)).toBeNull();
  });

  it('metersToFeet: returns null for non-finite inputs', () => {
    expect(metersToFeet(null)).toBeNull();
    expect(metersToFeet(undefined)).toBeNull();
    expect(metersToFeet('')).toBeNull();
    expect(metersToFeet('abc')).toBeNull();
    expect(metersToFeet(NaN)).toBeNull();
  });

  it('feetToMeters: matches 1 ft = 0.3048 m within 1e-4', () => {
    // 1 / 3.28084 = 0.304800061... vs the SI definition 0.3048 m
    expect(feetToMeters(1)).toBeCloseTo(0.3048, 4);
    expect(feetToMeters(12.5)).toBeCloseTo(3.81, 2);
    expect(feetToMeters(50)).toBeCloseTo(15.24, 2);
  });

  it('metersToFeet: produces inverse of feetToMeters within float precision', () => {
    expect(metersToFeet(0.3048)).toBeCloseTo(1, 4);
    expect(metersToFeet(3.81)).toBeCloseTo(12.5, 2);
    expect(metersToFeet(15.24)).toBeCloseTo(50, 2);
  });

  describe('round-trip is lossless within helper precision', () => {
    const cases = [1, 5, 12.5, 25, 50, 120, 250];
    cases.forEach((ft) => {
      it(`${ft} ft → m → ft preserves value`, () => {
        const m = feetToMeters(ft)!;
        const backToFt = metersToFeet(m)!;
        expect(backToFt).toBeCloseTo(ft, 6);
      });
    });
    const mCases = [0.5, 1, 3.81, 7.62, 15.24, 36.58];
    mCases.forEach((m) => {
      it(`${m} m → ft → m preserves value`, () => {
        const ft = metersToFeet(m)!;
        const backToM = feetToMeters(ft)!;
        expect(backToM).toBeCloseTo(m, 6);
      });
    });
  });

  describe('formatNumber1dp', () => {
    it('strips trailing .0', () => {
      expect(formatNumber1dp(12)).toBe('12');
      expect(formatNumber1dp(12.5)).toBe('12.5');
      expect(formatNumber1dp(3.812)).toBe('3.8');
      expect(formatNumber1dp(null)).toBeNull();
    });
  });

  describe('form-shape round-trip (4dp + trimZero, mirrors yacht-form.tsx)', () => {
    // The form persists string values, so we model the same shape the
    // input fields see. trimZero strips trailing zeros after the dot.
    const trimZero = (s: string) => (!s.includes('.') ? s : s.replace(/\.?0+$/, ''));
    const ftToM = (v: string): string => {
      const m = feetToMeters(v);
      return m === null ? '' : trimZero(m.toFixed(4));
    };
    const mToFt = (v: string): string => {
      const ft = metersToFeet(v);
      return ft === null ? '' : trimZero(ft.toFixed(4));
    };

    it('round-trip 1 ft → m → ft is lossless', () => {
      const m = ftToM('1');
      expect(mToFt(m)).toBe('1');
    });
    it('round-trip 12.5 ft ↔ 3.81 m ↔ 12.5 ft', () => {
      const m = ftToM('12.5');
      const ft = mToFt(m);
      // 12.5 / 3.28084 = 3.80999961... → "3.81" → 3.81 * 3.28084 = 12.4999... → "12.5"
      expect(ft).toBe('12.5');
    });
    it('round-trip 50 ft → 15.24 m → 50 ft', () => {
      expect(mToFt(ftToM('50'))).toBe('50');
    });
    it('round-trip 0.5 m → ft → 0.5 m', () => {
      expect(ftToM(mToFt('0.5'))).toBe('0.5');
    });
    it('empty string returns empty', () => {
      expect(ftToM('')).toBe('');
      expect(mToFt('')).toBe('');
    });
    it('non-numeric returns empty', () => {
      expect(ftToM('abc')).toBe('');
      expect(mToFt('abc')).toBe('');
    });
  });

  describe('dimInFeet / dimInMeters: derive missing unit from sibling', () => {
    it('returns ft value when set', () => {
      expect(dimInFeet({ ft: 12.5, m: 3.81 })).toBe('12.5');
    });
    it('derives ft from m when ft is null', () => {
      expect(dimInFeet({ ft: null, m: 3.81 })).toBe('12.5');
    });
    it('returns m value when set', () => {
      expect(dimInMeters({ ft: 12.5, m: 3.81 })).toBe('3.8');
    });
    it('derives m from ft when m is null', () => {
      expect(dimInMeters({ ft: 12.5, m: null })).toBe('3.8');
    });
    it('returns null when both null', () => {
      expect(dimInFeet({ ft: null, m: null })).toBeNull();
      expect(dimInMeters({ ft: null, m: null })).toBeNull();
    });
  });
});
