// Source: https://github.com/github/clipboard-copy-element
// License: MIT
export default class extends HTMLElement {
  constructor () {
    super()
    this.addEventListener('click', clicked)
    this.addEventListener('focus', focused)
    this.addEventListener('blur', blurred)
  }

  connectedCallback () {
    if (!this.hasAttribute('tabindex')) {
      this.setAttribute('tabindex', '0')
    }

    if (!this.hasAttribute('role')) {
      this.setAttribute('role', 'button')
    }
  }

  get value () {
    return this.getAttribute('value') || ''
  }

  set value (text) {
    this.setAttribute('value', text)
  }
}

function createNode (text) {
  const node = document.createElement('pre')
  node.style.width = '1px'
  node.style.height = '1px'
  node.style.position = 'fixed'
  node.style.top = '5px'
  node.textContent = text
  return node
}

function copyNode (node) {
  if ('clipboard' in navigator) {
    return navigator.clipboard.writeText(node.textContent || '')
  }

  const selection = getSelection()
  if (selection == null) {
    return Promise.reject(new Error())
  }

  selection.removeAllRanges()

  const range = document.createRange()
  range.selectNodeContents(node)
  selection.addRange(range)

  document.execCommand('copy')
  selection.removeAllRanges()
  return Promise.resolve()
}

function copyText (text) {
  if ('clipboard' in navigator) {
    return navigator.clipboard.writeText(text)
  }

  const body = document.body
  if (!body) {
    return Promise.reject(new Error())
  }

  const node = createNode(text)
  body.appendChild(node)
  copyNode(node)
  body.removeChild(node)
  return Promise.resolve()
}

function copyTarget (content) {
  if (
    content instanceof HTMLInputElement ||
    content instanceof HTMLTextAreaElement
  ) {
    return copyText(content.value)
  } else if (
    content instanceof HTMLAnchorElement &&
    content.hasAttribute('href')
  ) {
    return copyText(content.href)
  } else {
    return copyNode(content)
  }
}

async function copy (button) {
  const id = button.getAttribute('for')
  const text = button.getAttribute('value')

  function trigger () {
    button.dispatchEvent(new CustomEvent('clipboard-copy', { bubbles: true }))
  }

  function toggleActiveIcon () {
    if (button.classList.contains('swap')) {
      button.classList.toggle('swap-active')
    }
  }

  if (text) {
    await copyText(text)
    trigger()
    toggleActiveIcon()
  } else if (id) {
    const root = 'getRootNode' in Element.prototype ? button.getRootNode() : button.ownerDocument

    if (!(root instanceof Document || ('ShadowRoot' in window && root instanceof ShadowRoot))) return

    const node = root.getElementById(id)

    if (node) {
      await copyTarget(node)
      trigger()
      toggleActiveIcon()
    }
  }
}

function clicked (event) {
  const button = event.currentTarget

  if (button instanceof HTMLElement) {
    copy(button)
  }
}

function keydown (event) {
  if (event.key === ' ' || event.key === 'Enter') {
    const button = event.currentTarget

    if (button instanceof HTMLElement) {
      event.preventDefault()
      copy(button)
    }
  }
}

function focused (event) {
  event.currentTarget.addEventListener('keydown', keydown)
}

function blurred (event) {
  event.currentTarget.removeEventListener('keydown', keydown)
}