import { describe, expect, it } from 'vitest'
import { flatten, roll, sample, times, without } from '@/utils'

describe('array utils', () => {
  it('flatten', () => {
    expect(flatten([])).toEqual([])
    expect(flatten([[]])).toEqual([])
    expect(flatten([[1, 2], [3], [4, 5, 6]])).toEqual([1, 2, 3, 4, 5, 6])
  })

  it('roll', () => {
    const arr = [0, 1, 2]
    const right = roll(arr, 1)
    const left = roll(arr, -1)

    expect(arr).toEqual([0, 1, 2])
    expect(right).toEqual([2, 0, 1])
    expect(left).toEqual([1, 2, 0])
  })

  describe('sample', () => {
    it('returns element at index from rand() * length', () => {
      const arr = ['a', 'b', 'c']
      expect(sample(arr, () => 0)).toBe('a')
      expect(sample(arr, () => 0.33)).toBe('a')
      expect(sample(arr, () => 0.334)).toBe('b')
      expect(sample(arr, () => 0.666)).toBe('b')
      expect(sample(arr, () => 0.999)).toBe('c')
    })

    it('single-element array always returns that element', () => {
      const arr = [42]
      expect(sample(arr, () => 0)).toBe(42)
      expect(sample(arr, () => 0.5)).toBe(42)
      expect(sample(arr, () => 0.999)).toBe(42)
    })

    it('result is always an element of the array', () => {
      const arr = [1, 2, 3]
      for (let i = 0; i < 100; i++) {
        const r = sample(arr, () => i / 100)
        expect(arr).toContain(r)
      }
    })
  })

  it('times', () => {
    const arr = times(3, 'a')

    expect(arr).toEqual(['a', 'a', 'a'])
  })

  it('without', () => {
    const arr = [1, 2, 3, 4, 5]
    const result = without(arr, 3, 5)

    expect(result).toEqual([1, 2, 4])
  })
})