import { describe, expect, it } from 'vitest'
import {
  cmFromDisplay,
  cmFromFtIn,
  cmFromMeters,
  cmFromSpacing,
  displayFromCm,
  formatCm,
  formatDimensions,
  formatSpacing,
  spacingFromCm,
} from './units'

describe('cm conversions', () => {
  // Every cm column is REAL, so entry is exact — no whole-cm quantization. A 1 ft
  // grid is 30.48 cm, not 30, or the error accumulates across the garden (#47).
  it('feet+inches → exact cm', () => {
    expect(cmFromFtIn(1)).toBe(30.48)
    expect(cmFromFtIn(4)).toBe(121.92)
    expect(cmFromFtIn(8)).toBe(243.84)
    expect(cmFromFtIn(4, 6)).toBe(137.16)
  })

  it('meters → exact cm', () => {
    expect(cmFromMeters(10)).toBe(1000)
    expect(cmFromMeters(1.22)).toBe(122)
    expect(cmFromMeters(0.305)).toBe(30.5)
  })

  it('rounds away float dust, not precision', () => {
    // 12 × 2.54 is 30.479999999999997 in IEEE-754; 1 ft must read as 30.48.
    expect(cmFromFtIn(0, 12)).toBe(30.48)
    expect(cmFromSpacing(12, 'imperial')).toBe(30.48)
    expect(cmFromSpacing(1, 'imperial')).toBe(2.54)
  })

  it('round-trips display → cm → display at display precision', () => {
    const imperial = [0.5, 1, 2.5, 4, 8, 12.5, 24]
    for (const ft of imperial) {
      expect(displayFromCm(cmFromDisplay(ft, 'imperial'), 'imperial')).toBe(ft)
    }
    const metric = [0.15, 1, 1.22, 3.05, 10, 24.5]
    for (const m of metric) {
      expect(displayFromCm(cmFromDisplay(m, 'metric'), 'metric')).toBe(m)
    }
  })
})

describe('displayFromCm', () => {
  it('metric keeps cm precision', () => {
    expect(displayFromCm(1000, 'metric')).toBe(10)
    expect(displayFromCm(122, 'metric')).toBe(1.22)
  })

  it('imperial rounds to 0.1 ft so integers stay clean', () => {
    expect(displayFromCm(122, 'imperial')).toBe(4) // not 4.0026
    expect(displayFromCm(244, 'imperial')).toBe(8) // not 8.01
  })
})

describe('formatCm', () => {
  it('metric shows meters', () => {
    expect(formatCm(122, 'metric')).toBe('1.22 m')
    expect(formatCm(1000, 'metric')).toBe('10 m')
  })

  it('imperial shows feet and inches, carrying 12″ up', () => {
    expect(formatCm(122, 'imperial')).toBe('4′ 0″')
    expect(formatCm(244, 'imperial')).toBe('8′ 0″')
    expect(formatCm(137, 'imperial')).toBe('4′ 6″')
  })

  it('formats width × height', () => {
    expect(formatDimensions(122, 244, 'imperial')).toBe('4′ 0″ × 8′ 0″')
  })
})

describe('plant spacing (small scale)', () => {
  it('formats cm in metric, whole inches in imperial', () => {
    expect(formatSpacing(15, 'metric')).toBe('15 cm')
    expect(formatSpacing(15, 'imperial')).toBe('6″') // 15/2.54 = 5.9 → 6
    expect(formatSpacing(30, 'imperial')).toBe('12″')
  })

  it('parses an entered value back to exact cm', () => {
    expect(cmFromSpacing(15, 'metric')).toBe(15)
    expect(cmFromSpacing(6, 'imperial')).toBe(15.24)
  })

  it('prefills an input from cm', () => {
    expect(spacingFromCm(15, 'metric')).toBe(15)
    expect(spacingFromCm(30, 'imperial')).toBe(11.8) // 30/2.54 = 11.81 → 11.8
    expect(spacingFromCm(30.48, 'imperial')).toBe(12) // an exactly-12in grid reads back as 12
  })
})