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diff --git a/src/services/html_converter/html_line_converter.service.js b/src/services/html_converter/html_line_converter.service.js
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+import { getTagName } from './utility.service.js'
+
+/**
+ * This is a tiny purpose-built HTML parser/processor. This basically detects
+ * any type of visual newline and converts entire HTML into a array structure.
+ *
+ * Text nodes are represented as object with single property - text - containing
+ * the visual line. Intended usage is to process the array with .map() in which
+ * map function returns a string and resulting array can be converted back to html
+ * with a .join('').
+ *
+ * Generally this isn't very useful except for when you really need to either
+ * modify visual lines (greentext i.e. simple quoting) or do something with
+ * first/last line.
+ *
+ * known issue: doesn't handle CDATA so nested CDATA might not work well
+ *
+ * @param {Object} input - input data
+ * @return {(string|{ text: string })[]} processed html in form of a list.
+ */
+export const convertHtmlToLines = (html = '') => {
+  // Elements that are implicitly self-closing
+  // https://developer.mozilla.org/en-US/docs/Glossary/empty_element
+  const emptyElements = new Set([
+    'area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input',
+    'keygen', 'link', 'meta', 'param', 'source', 'track', 'wbr'
+  ])
+  // Block-level element (they make a visual line)
+  // https://developer.mozilla.org/en-US/docs/Web/HTML/Block-level_elements
+  const blockElements = new Set([
+    'address', 'article', 'aside', 'blockquote', 'details', 'dialog', 'dd',
+    'div', 'dl', 'dt', 'fieldset', 'figcaption', 'figure', 'footer', 'form',
+    'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'header', 'hgroup', 'hr', 'li', 'main',
+    'nav', 'ol', 'p', 'pre', 'section', 'table', 'ul'
+  ])
+  // br is very weird in a way that it's technically not block-level, it's
+  // essentially converted to a \n (or \r\n). There's also wbr but it doesn't
+  // guarantee linebreak, only suggest it.
+  const linebreakElements = new Set(['br'])
+
+  const visualLineElements = new Set([
+    ...blockElements.values(),
+    ...linebreakElements.values()
+  ])
+
+  // All block-level elements that aren't empty elements, i.e. not <hr>
+  const nonEmptyElements = new Set(visualLineElements)
+  // Difference
+  for (let elem of emptyElements) {
+    nonEmptyElements.delete(elem)
+  }
+
+  // All elements that we are recognizing
+  const allElements = new Set([
+    ...nonEmptyElements.values(),
+    ...emptyElements.values()
+  ])
+
+  let buffer = [] // Current output buffer
+  const level = [] // How deep we are in tags and which tags were there
+  let textBuffer = '' // Current line content
+  let tagBuffer = null // Current tag buffer, if null = we are not currently reading a tag
+
+  const flush = () => { // Processes current line buffer, adds it to output buffer and clears line buffer
+    if (textBuffer.trim().length > 0) {
+      buffer.push({ level: [...level], text: textBuffer })
+    } else {
+      buffer.push(textBuffer)
+    }
+    textBuffer = ''
+  }
+
+  const handleBr = (tag) => { // handles single newlines/linebreaks/selfclosing
+    flush()
+    buffer.push(tag)
+  }
+
+  const handleOpen = (tag) => { // handles opening tags
+    flush()
+    buffer.push(tag)
+    level.unshift(getTagName(tag))
+  }
+
+  const handleClose = (tag) => { // handles closing tags
+    if (level[0] === getTagName(tag)) {
+      flush()
+      buffer.push(tag)
+      level.shift()
+    } else { // Broken case
+      textBuffer += tag
+    }
+  }
+
+  for (let i = 0; i < html.length; i++) {
+    const char = html[i]
+    if (char === '<' && tagBuffer === null) {
+      tagBuffer = char
+    } else if (char !== '>' && tagBuffer !== null) {
+      tagBuffer += char
+    } else if (char === '>' && tagBuffer !== null) {
+      tagBuffer += char
+      const tagFull = tagBuffer
+      tagBuffer = null
+      const tagName = getTagName(tagFull)
+      if (allElements.has(tagName)) {
+        if (linebreakElements.has(tagName)) {
+          handleBr(tagFull)
+        } else if (nonEmptyElements.has(tagName)) {
+          if (tagFull[1] === '/') {
+            handleClose(tagFull)
+          } else if (tagFull[tagFull.length - 2] === '/') {
+            // self-closing
+            handleBr(tagFull)
+          } else {
+            handleOpen(tagFull)
+          }
+        } else {
+          textBuffer += tagFull
+        }
+      } else {
+        textBuffer += tagFull
+      }
+    } else if (char === '\n') {
+      handleBr(char)
+    } else {
+      textBuffer += char
+    }
+  }
+  if (tagBuffer) {
+    textBuffer += tagBuffer
+  }
+
+  flush()
+
+  return buffer
+}