const besUrl = 'http://localhost:225/api/v2/check'

let besEditors = {} // Collection of all editors on page

window.onload = () => {
  // Search and prepare all our editors found in the document.
  document.querySelectorAll('.online-editor').forEach(edit => {
    let editor = {
      timer: null
    }
    besEditors[edit.id] = editor
    besCheckText(edit)

    edit.addEventListener('beforeinput', e => besBeforeInput(edit.id, e), false)

    edit.addEventListener('click', e => {
      besHandleClick(e)
    })
  })
}

function besIntervalsOverlap(start1, end1, start2, end2)
{
  return (
    start2 <= start1 && start1 < end2 ||
    start1 <= start2 && start2 < end1)
}

async function besCheckText(el)
{
  switch (el.nodeType) {
    case Node.TEXT_NODE:
      return [{ text: el.textContent, el: el, markup: false }]

    case Node.ELEMENT_NODE:
      if (el.getAttribute('besChecked') === 'true') {
        return [{ text: '<'+el.tagName+'/>', el: el, markup: true }]
      }
      for (const el2 of el.childNodes) {
        if (el2.tagName === 'SPAN' && el2.classList.contains('typo-mistake')) {
          el2.replaceWith(...el2.childNodes)
          el2.remove()
        }
      }
      let data = []
      for (const el2 of el.childNodes) {
        data = data.concat(await besCheckText(el2))
      }
      let defaultView = document.defaultView;
      switch (defaultView.getComputedStyle(el, null).getPropertyValue('display').toLowerCase())
      {
        case 'inline':
        case 'inline-block':
          data.splice(0, 0, { text: '<'+el.tagName+'>', el: el, markup: true })
          data.splice(data.length, 0, { text: '</'+el.tagName+'>', markup: true })
          return data;
        default:
          let regAllWhitespace = /^\s*$/
          if (data.some(x => !x.markup && !regAllWhitespace.test(x.text))) {
            const requestData = {
              format: 'plain',
              data: JSON.stringify({annotation: data.map(x => x.markup ? { markup: x.text } : { text: x.text })}),
              language: 'sl',
              level: 'picky'
            }
            const request = new Request(besUrl, {
              method: 'POST',
              headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
              body: new URLSearchParams(requestData)
            })
            fetch(request)
              .then(response => {
                if (!response.ok) {
                  // TODO: Make connectivity and BesStr issues non-fatal.
                  throw new Error('Backend server response was not OK')
                }
                return response.json()
              })
              .then(responseData => {
                if (!responseData.matches.length) return

                // Remove overlapping grammar mistakes for simplicity.
                for (let idx1 = 0; idx1 < responseData.matches.length - 1; ++idx1) {
                  for (let idx2 = idx1 + 1; idx2 < responseData.matches.length;) {
                    if (besIntervalsOverlap(
                      responseData.matches[idx1].offset, responseData.matches[idx1].offset + responseData.matches[idx1].length,
                      responseData.matches[idx2].offset, responseData.matches[idx2].offset + responseData.matches[idx2].length)) {
                      responseData.matches.splice(idx2, 1)
                    }
                    else idx2++
                  }
                }

                // Reverse sort grammar mistakes for easier markup insertion later.
                // When we start inserting grammar mistakes at the back, indexes before that remain valid.
                responseData.matches.sort((a, b) => a.offset < b.offset ? +1 : a.offset > b.offset ? -1 : 0);
                responseData.matches.forEach(match => {
                  let range = document.createRange()

                  // Locate start of the grammar mistake.
                  for (let idx = 0, startingOffset = 0; ; startingOffset += data[idx++].text.length) {
                    if (!data[idx].markup && /*startingOffset <= match.offset &&*/ match.offset < startingOffset + data[idx].text.length) {
                      range.setStart(data[idx].el, match.offset - startingOffset)
                      break
                    }
                  }

                  // Locate end of the grammar mistake.
                  let endOffset = match.offset + match.length
                  for (let idx = 0, startingOffset = 0; ; startingOffset += data[idx++].text.length) {
                    if (!data[idx].markup && /*startingOffset <= endOffset &&*/ endOffset <= startingOffset + data[idx].text.length) {
                      range.setEnd(data[idx].el, endOffset - startingOffset)
                      break
                    }
                  }

                  const span = document.createElement('span')
                  span.classList.add('typo-mistake')

                  // Dirty hack, copied from: https://stackoverflow.com/questions/67634286/invalidstateerror-failed-to-execute-surroundcontents-on-range-the-range-ha
                  span.appendChild(range.extractContents());
                  range.insertNode(span);

                  // This is a better way to apply span elements, 
                  // but it doesnt work when the range has partially selected a non-Text node.
                  // range.surroundContents(span)
                })

                el.setAttribute('besChecked', 'true')
              })
              .catch(error => {
                // TODO: Make parsing issues non-fatal.
                throw new Error('Parsing backend server response failed: ' + error)
              })
          }
          return [{ text: '<'+el.tagName+'/>', el: el, markup: true }]
      }

    default:
      return [{ text: '<?'+el.nodeType+'>', el: el, markup: true }]
  }
}

function besGetBlockParent(el, edit)
{
  const defaultView = document.defaultView
  while (el && el !== edit) {
    switch (el.nodeType) {
      case Node.TEXT_NODE:
        el = el.parentNode
        continue
  
      case Node.ELEMENT_NODE:
        switch (defaultView.getComputedStyle(el, null).getPropertyValue('display').toLowerCase())
        {
          case 'inline':
          case 'inline-block':
            el = el.parentNode
            continue
          default:
            return el
        }
    }
  }
  return el
}

function besBeforeInput(editorId, event)
{
  let editor = besEditors[editorId]
  if (editor.timer) clearTimeout(editor.timer)
  editor.timer = setTimeout(function(){ besCheckText(edit) }, 1000)

  // No need to invalidate elements after range.startContainer since they will
  // get either deleted or replaced.
  let edit = document.getElementById(editorId)
  event.getTargetRanges().forEach(range => besGetBlockParent(range.startContainer, edit)?.removeAttribute('besChecked'))
}

function besHandleClick(e) {
  switch (e.target) {
    case e.target.closest('span'):
      const clicked = e.target.closest('span')
      const infoText = clicked?.dataset.info
      const myComponent = document.querySelector('my-component')
      myComponent.setAttribute('my-attribute', infoText)
      console.log(clicked)
      break
  }
}