function solve () {
  let buttons = Array.from(
    document.querySelectorAll('fieldset button')
  ).forEach(x => x.addEventListener('click', getResult))

  function getResult () {
    let text = document.querySelector('#input').value
    if (this.parentNode.id === 'filter') {
      let filter = document.getElementById('filterSecondaryCmd').value
      let filterPosition = +document.querySelector('#filterPosition').value
      switch (filter) {
        case 'uppercase':
          text = text.split('').filter(x => x.match(/[A-Z]/))[
            filterPosition - 1
          ]
          break
        case 'lowercase':
          text = text.split('').filter(x => x.match(/[a-z]/))[
            filterPosition - 1
          ]
          break
        case 'nums':
          text = text.split('').filter(x => x.match(/[0-9]/))[
            filterPosition - 1
          ]
          break
      }
      document.querySelector('#output p').textContent += text
    } else if (this.parentNode.id === 'sort') {
      let sort = document.getElementById('sortSecondaryCmd').value
      let sortPosition = +document.querySelector('#sortPosition').value
      switch (sort) {
        case 'A':
          text = text.split('').sort()[sortPosition - 1]
          break
        case 'Z':
          text = text
            .split('')
            .sort()
            .reverse()[sortPosition - 1]
          break
      }
      document.querySelector('#output p').textContent += text
    } else if (this.parentNode.id === 'rotate') {
      let rotate = document.querySelector('#rotateSecondaryCmd').value
      let rotatePosition = +document.querySelector('#rotatePosition').value
      text = text.split('')
      for (let i = 1; i <= rotate; i++) {
        let temp = text.pop()
        text.unshift(temp)
      }
      text = text[rotatePosition - 1]
      document.querySelector('#output p').textContent += text
    } else if (this.parentNode.id === 'get') {
      let getPosition = +document.querySelector('#getPosition').value
      text = text.split('')[getPosition - 1]
      document.querySelector('#output p').textContent += text
    }
  }
}