function insertAtLineStart(txtBefore) {
  let ret = saveSelection();
  let line = ret[0];
  let txt = line.innerText;
  if (txt == '\n') {
    txt = "";
  }
  line.innerHTML = txtBefore + txt;
  let span = document.createElement('span');
  span.innerHTML = txtBefore;
  ret[1] = ret[1] + span.innerText.length;;
  ret[3] = ret[3] + span.innerText.length;;
  loadSelection(ret);
}

function insertTextAtCaret(txtBefore, txtAfter = '') {
  let ret = saveSelection();
  let line = ret[0];
  let start = ret[1];
  let end = ret[3];
  let txt = line.innerText;
  let before = ''
  if (start == 0) {
  } else {
    before = txt.substring(0, start);
  }
  let after = txt.substring(end, txt.length);
  let selection = '';
  if (end > start) {
    selection = txt.substring(start, end);
  }
  line.innerHTML = before + txtBefore + selection + txtAfter + after;
  let span = document.createElement('span');
  if (start == end && ret[0] == ret[2]) {
    span.innerHTML = txtBefore;
    ret[1] = start + span.innerText.length;
    ret[3] = ret[1];
  } else {
    span.innerHTML = txtBefore + txtAfter;
    ret[3] = end + span.innerText.length;
  }
  loadSelection(ret);
}

function saveSelection() {
  let ret = getStartPositionInLine();
  let startLine = ret[0];
  let startPosition = ret[1];
  ret = getEndPositionInLine();
  let endLine = ret[0];
  let endPosition = ret[1];
  return [startLine, startPosition, endLine, endPosition];
}

function loadSelection(sel) {
  setStartPositionInLine(sel[0], sel[1]);
  setEndPositionInLine(sel[2], sel[3]);
}

function getStartPositionInLine() {
  let selection = window.getSelection();
  if (selection.rangeCount == 0) {
    return [null, 0];
  }
  let range = selection.getRangeAt(0).cloneRange();
  let obj = range.startContainer;

  let position = range.startOffset;

  if (obj.nodeName == 'DIV' && obj.classList.contains('cheezenotes_line')) {
    return [obj, position];
  }

  let line = null;

  while (obj != null) {
    if (obj.previousSibling != null) {
      obj = obj.previousSibling;
      if (obj.innerText != null) {
        position += obj.innerText.length;
      } else if (obj.length != null) {
        position += obj.length;
      }
    } else if (obj.parentNode != null && obj.parentNode.classList != null && !obj.parentNode.classList.contains('cheezenotes_line')) {
      obj = obj.parentNode;
    } else if (obj.parentNode != null && obj.parentNode.classList != null && obj.parentNode.classList.contains('cheezenotes_line')) {
      line = obj.parentNode;
      obj = null;
    } else {
      obj = null;
    }
  }
  return [line, position];
}

function setStartPositionInLine(line, position) {
  setStartPositionInDiv(line, position)
}

function setStartPositionInDiv(obj, position) {
  let temppos = position;
  if (temppos > obj.innerText.length) {
    return temppos - obj.innerText.length;
  }
  let children = obj.childNodes;
  for (let i = 0; i < children.length; i++) {
    let child = children[i];
    if (child.nodeType == 3) {
      temppos = setStartPositionInText(child, temppos);
    } else {
      temppos = setStartPositionInDiv(child, temppos);
    }
    if (temppos == 0) {
      return temppos;
    }
  }
  return temppos;
}

function setStartPositionInText(obj, position) {
  if (position > obj.length) {
    return position - obj.length;
  }

  let selection = window.getSelection();
  selection.removeAllRanges();
  let range = document.createRange();
  range.setStart(obj, position);
  selection.addRange(range);
  return 0;
}

function getEndPositionInLine() {
  let selection = window.getSelection();
  if (selection.rangeCount == 0) {
    return [null, 0];
  }
  let range = selection.getRangeAt(0).cloneRange();
  let obj = range.endContainer;

  let position = range.endOffset;

  if (obj.nodeName == 'DIV' && obj.classList.contains('cheezenotes_line')) {
    return [obj, position];
  }

  let line = null;

  while (obj != null) {
    if (obj.previousSibling != null) {
      obj = obj.previousSibling;
      if (obj.innerText != null) {
        position += obj.innerText.length;
      } else if (obj.length != null) {
        position += obj.length;
      }
    } else if (obj.parentNode != null && obj.parentNode.classList != null && !obj.parentNode.classList.contains('cheezenotes_line')) {
      obj = obj.parentNode;
    } else if (obj.parentNode != null && obj.parentNode.classList != null && obj.parentNode.classList.contains('cheezenotes_line')) {
      line = obj.parentNode;
      obj = null;
    } else {
      obj = null;
    }
  }
  return [line, position];
}

function setEndPositionInLine(line, position) {
  setEndPositionInDiv(line, position)
}

function setEndPositionInDiv(obj, position) {
  let temppos = position;
  if (temppos > obj.innerText.length) {
    return temppos - obj.innerText.length;
  }
  let children = obj.childNodes;
  for (let i = 0; i < children.length; i++) {
    let child = children[i];
    if (child.nodeType == 3) {
      temppos = setEndPositionInText(child, temppos);
    } else {
      temppos = setEndPositionInDiv(child, temppos);
    }
    if (temppos == 0) {
      return temppos;
    }
  }
  return temppos;
}

function setEndPositionInText(obj, position) {
  if (position > obj.length) {
    return position - obj.length;
  }

  let selection = window.getSelection();
  let oldRange = selection.getRangeAt(0);
  let range = document.createRange();
  range.setStart(oldRange.startContainer, oldRange.startOffset);
  range.setEnd(obj, position);
  selection.removeAllRanges();
  selection.addRange(range);
  return 0;
}

export { saveSelection, loadSelection, insertTextAtCaret, insertAtLineStart };