Class: Collavre::MarkdownConverter

Inherits:
Object
  • Object
show all
Defined in:
app/services/collavre/markdown_converter.rb

Overview

Converts between Markdown and HTML for creative descriptions.

Extracted from CreativesHelper to keep conversion logic testable outside of view contexts and reusable from services (e.g. MarkdownImporter).

Class Method Summary collapse

Class Method Details

.data_image_to_attachment(data_url, alt) ⇒ Object

Convert a data-URI image to an Active Storage attachment <img> tag.



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# File 'app/services/collavre/markdown_converter.rb', line 184

def data_image_to_attachment(data_url, alt)
  if data_url =~ %r{\Adata:(image/[\w.+-]+);base64,(.+)\z}
    content_type = Regexp.last_match(1)
    data = Base64.decode64(Regexp.last_match(2))
    ext = Mime::Type.lookup(content_type).symbol.to_s
    filename = "import-#{SecureRandom.hex}.#{ext}"
    blob = ActiveStorage::Blob.create_and_upload!(io: StringIO.new(data), filename: filename, content_type: content_type)
    "<img src=\"#{Rails.application.routes.url_helpers.rails_blob_url(blob, only_path: true)}\" alt=\"#{alt}\" />"
  else
    "<img src=\"#{data_url}\" alt=\"#{alt}\" />"
  end
end

.html_to_markdown(text) ⇒ Object

Convert HTML (links, bold, images, tables) back to Markdown.



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# File 'app/services/collavre/markdown_converter.rb', line 50

def html_to_markdown(text)
  return "" if text.nil?
  markdown = text.dup
  placeholders = {}
  index = 0

  # Tables → Markdown tables
  markdown.gsub!(%r{<table\b[^>]*>.*?</table>}im) do |match|
    token = "__TABLE#{index}__"; index += 1
    placeholders[token] = table_to_markdown(match)
    token
  end

  # Action-text attachments → data-URI images
  markdown.gsub!(%r{<action-text-attachment ([^>]+)>(?:</action-text-attachment>)?}) do |_match|
    attrs = Hash[$1.scan(/(\S+?)="([^"]*)"/)]
    sgid = attrs["sgid"]
    caption = attrs["caption"] || ""
    if (blob = GlobalID::Locator.locate_signed(sgid, for: "attachable"))
      data = Base64.strict_encode64(blob.download)
      token = "__IMG#{index}__"; index += 1
      placeholders[token] = "![#{caption}](data:#{blob.content_type};base64,#{data})"
      token
    else
      ""
    end
  end

  # Active Storage blob images → data-URI
  markdown.gsub!(%r{<img [^>]*src=["'](/rails/active_storage/blobs/[^"']+)["'][^>]*alt=["']([^"']*)["'][^>]*>}) do |match|
    blob_path = $1
    alt_text = $2
    if blob_path =~ %r{/rails/active_storage/blobs/(?:redirect|proxy)/([^/]+)/}
      signed_id = $1
      begin
        blob = ActiveStorage::Blob.find_signed(signed_id)
        data = Base64.strict_encode64(blob.download)
        token = "__IMG#{index}__"; index += 1
        placeholders[token] = "![#{alt_text}](data:#{blob.content_type};base64,#{data})"
        token
      rescue StandardError
        match
      end
    else
      match
    end
  end

  # Inline data-URI images (src before alt)
  markdown.gsub!(/<img [^>]*src=['"](data:[^'"]+)['"][^>]*alt=['"]([^'"]*)['"][^>]*>/) do
    token = "__IMG#{index}__"; index += 1
    placeholders[token] = "![#{$2}](#{$1})"
    token
  end

  # Inline data-URI images (alt before src)
  markdown.gsub!(/<img [^>]*alt=['"]([^'"]*)['"][^>]*src=['"](data:[^'"]+)['"][^>]*>/) do
    token = "__IMG#{index}__"; index += 1
    placeholders[token] = "![#{$1}](#{$2})"
    token
  end

  # Links → [text](url)
  markdown.gsub!(/<a [^>]*href=['"]([^'"]+)['"][^>]*>(.*?)<\/a>/m) do
    inner = ActionView::Base.full_sanitizer.sanitize($2)
    token = "__LINK#{index}__"; index += 1
    placeholders[token] = "[#{inner}](#{$1})"
    token
  end

  # Bold → **text**
  markdown.gsub!(/<(strong|b)(?:\s+[^>]*)?>(.*?)<\/\1>/im) do
    token = "__BOLD#{index}__"; index += 1
    placeholders[token] = "**#{$2.strip}**"
    token
  end

  # Escape markdown special chars in remaining text
  markdown.gsub!(/([\\*\[\]()!#~+\-])/) { "\\#{$1}" }

  # Restore placeholders
  placeholders.each { |k, v| markdown.gsub!(k, v) }

  # Strip remaining HTML tags
  markdown.gsub!(/<[^>]+>/, "")
  markdown
end

.markdown_to_html(text, image_refs = {}) ⇒ Object

Convert Markdown to HTML using commonmarker (GFM full support). Falls back to lightweight regex conversion for short inline fragments.



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# File 'app/services/collavre/markdown_converter.rb', line 15

def markdown_to_html(text, image_refs = {})
  return "" if text.nil?
  input = text.dup

  # Collect reference-style data-URI images: [alt]: <data:...>
  input.gsub!(/^\s*\[([^\]]+)\]:\s*<\s*(data:image\/[^>]+)\s*>\s*$/) do
    image_refs[$1] = $2.strip
    ""
  end

  # Convert data-URI images to Active Storage before rendering
  input.gsub!(/(?<!\\)!\[([^\]]*)\]\[([^\]]+)\]/) do
    if (data_url = image_refs[$2])
      data_image_to_attachment(data_url, $1)
    else
      "![#{$1}][#{$2}]"
    end
  end

  input.gsub!(/(?<!\\)!\[([^\]]*)\]\((data:image\/[^)]+)\)/) do
    data_image_to_attachment($2, $1)
  end

  # Render with commonmarker (GFM extensions: table, strikethrough, autolink, tasklist, tagfilter)
  html = Commonmarker.to_html(input, options: {
    parse: { smart: true },
    render: { unsafe: true },
    extension: { table: true, strikethrough: true, autolink: true, tasklist: true, tagfilter: true }
  })

  html.strip!
  html
end

.table_block?(text) ⇒ Boolean

Check whether text looks like a Markdown table block.

Returns:

  • (Boolean) 


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# File 'app/services/collavre/markdown_converter.rb', line 139

def table_block?(text)
  lines = text.to_s.strip.split("\n")
  return false if lines.length < 2

  header_line = lines[0]
  alignment_line = lines[1]
  return false unless header_line.match?(/\A\|.*\|\z/)
  return false unless alignment_line.match?(/\A\|[ \-:\|]+\|\z/)

  true
end

.table_to_markdown(table_html) ⇒ Object

Convert an HTML <table> fragment to a Markdown table string.



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# File 'app/services/collavre/markdown_converter.rb', line 152

def table_to_markdown(table_html)
  fragment = Nokogiri::HTML::DocumentFragment.parse(table_html)
  table = fragment.at_css("table")
  return "" unless table

  header_row = table.at_css("thead tr") || table.css("tr").first
  return "" unless header_row

  header_cells = header_row.css("th,td")
  headers = header_cells.map { |cell| escape_table_cell(html_to_markdown(cell.inner_html).strip) }
  alignments = header_cells.map { |cell| alignment_from_cell(cell) }

  body_rows = table.css("tbody tr")
  if body_rows.empty?
    all_rows = table.css("tr")
    body_rows = all_rows.drop(1)
  end

  body_lines = body_rows.map do |row|
    cells = row.css("th,td").map { |cell| escape_table_cell(html_to_markdown(cell.inner_html).strip) }
    normalized = pad_cells(cells, headers.length)
    "| #{normalized.join(' | ')} |"
  end

  alignment_cells = pad_cells(alignments, headers.length).map { |align| alignment_marker(align) }
  header_line = "| #{headers.map(&:strip).join(' | ')} |"
  alignment_line = "| #{alignment_cells.join(' | ')} |"

  ([ header_line, alignment_line ] + body_lines).join("\n")
end