195 lines
4.7 KiB
Ruby
195 lines
4.7 KiB
Ruby
# frozen_string_literal: true
|
||
|
||
class PlainTextToMarkdown
|
||
SIGNATURE_SEPARATOR ||= "-- "
|
||
|
||
def initialize(plaintext, opts = {})
|
||
@plaintext = plaintext
|
||
@lines = []
|
||
|
||
@format_flowed = opts[:format_flowed] || false
|
||
@delete_flowed_space = opts[:delete_flowed_space] || false
|
||
end
|
||
|
||
def to_markdown
|
||
prepare_lines
|
||
classify_lines
|
||
|
||
markdown = +""
|
||
last_quote_level = 0
|
||
last_line_blank = false
|
||
|
||
@lines.each do |line|
|
||
current_line_blank = line.text.blank?
|
||
|
||
unless last_line_blank && current_line_blank
|
||
if line.quote_level > 0
|
||
quote_identifiers = ">" * line.quote_level
|
||
markdown << quote_identifiers << "\n" unless line.quote_level >= last_quote_level || current_line_blank
|
||
markdown << quote_identifiers
|
||
markdown << " " unless current_line_blank
|
||
else
|
||
markdown << "\n" unless last_quote_level == 0 || current_line_blank
|
||
end
|
||
|
||
markdown << convert_text(line)
|
||
markdown << "\n"
|
||
end
|
||
|
||
last_line_blank = current_line_blank
|
||
last_quote_level = line.quote_level
|
||
end
|
||
|
||
markdown.rstrip!
|
||
markdown
|
||
end
|
||
|
||
private
|
||
|
||
class CodeBlock < Struct.new(:start_line, :end_line)
|
||
def initialize(start_line, end_line = nil)
|
||
super
|
||
end
|
||
|
||
def valid?
|
||
start_line.present? && end_line.present?
|
||
end
|
||
end
|
||
|
||
class Line < Struct.new(:text, :quote_level, :code_block)
|
||
def initialize(text, quote_level = 0, code_block = nil)
|
||
super
|
||
end
|
||
|
||
def valid_code_block?
|
||
code_block&.valid?
|
||
end
|
||
end
|
||
|
||
def prepare_lines
|
||
previous_line = nil
|
||
|
||
@plaintext.each_line do |text|
|
||
text.chomp!
|
||
line = Line.new(text)
|
||
|
||
remove_quote_level_indicators!(line)
|
||
|
||
if @format_flowed
|
||
line = merge_lines(line, previous_line)
|
||
@lines << line unless line == previous_line
|
||
else
|
||
@lines << line
|
||
end
|
||
|
||
previous_line = line
|
||
end
|
||
end
|
||
|
||
def classify_lines
|
||
previous_line = nil
|
||
|
||
@lines.each do |line|
|
||
classify_line_as_code!(line, previous_line)
|
||
|
||
previous_line = line
|
||
end
|
||
end
|
||
|
||
# @param line [Line]
|
||
def remove_quote_level_indicators!(line)
|
||
match_data = line.text.match(/^(?<indicators>>+)\s?(?<text>.*)/)
|
||
|
||
if match_data
|
||
line.text = match_data[:text]
|
||
line.quote_level = match_data[:indicators].length
|
||
end
|
||
end
|
||
|
||
# @param line [Line]
|
||
# @param previous_line [Line]
|
||
# @return [Line]
|
||
def merge_lines(line, previous_line)
|
||
return line if previous_line.nil? || line.text.blank?
|
||
return line if line.text == SIGNATURE_SEPARATOR || previous_line.text == SIGNATURE_SEPARATOR
|
||
return line unless line.quote_level == previous_line.quote_level && previous_line.text.end_with?(" ")
|
||
|
||
previous_line.text = previous_line.text[0...-1] if @delete_flowed_space
|
||
previous_line.text += line.text
|
||
previous_line
|
||
end
|
||
|
||
# @param line [Line]
|
||
# @param previous_line [Line]
|
||
def classify_line_as_code!(line, previous_line)
|
||
line.code_block = previous_line.code_block unless previous_line.nil? || previous_line.valid_code_block?
|
||
return unless line.text =~ /^\s{0,3}```/
|
||
|
||
if line.code_block.present?
|
||
line.code_block.end_line = line
|
||
else
|
||
line.code_block = CodeBlock.new(line)
|
||
end
|
||
end
|
||
|
||
# @param line [Line]
|
||
# @return [string]
|
||
def convert_text(line)
|
||
text = line.text
|
||
|
||
if line.valid_code_block?
|
||
code_block = line.code_block
|
||
return code_block.start_line == line || code_block.end_line == line ? text.lstrip : text
|
||
end
|
||
|
||
converted_text = replace_duplicate_links(text)
|
||
converted_text = escape_special_characters(converted_text)
|
||
converted_text = indent_with_non_breaking_spaces(converted_text)
|
||
converted_text
|
||
end
|
||
|
||
URL_REGEX ||= URI.regexp(%w{http https ftp mailto})
|
||
BEFORE ||= Regexp.escape(%Q|([<«"“'‘|)
|
||
AFTER ||= Regexp.escape(%Q|)]>»"”'’|)
|
||
|
||
def replace_duplicate_links(text)
|
||
urls = Set.new
|
||
text.scan(URL_REGEX) { urls << $& }
|
||
|
||
urls.each do |url|
|
||
escaped = Regexp.escape(url)
|
||
text.gsub!(Regexp.new(%Q|#{escaped}\s*[#{BEFORE}]?#{escaped}[#{AFTER}]?|, Regexp::IGNORECASE), url)
|
||
end
|
||
|
||
text
|
||
end
|
||
|
||
def indent_with_non_breaking_spaces(text)
|
||
text.sub(/^\s+/) do |s|
|
||
# replace tabs with 2 spaces
|
||
s.gsub!("\t", " ")
|
||
|
||
# replace indentation with non-breaking spaces
|
||
s.length > 1 ? " " * s.length : s
|
||
end
|
||
end
|
||
|
||
def escape_special_characters(text)
|
||
urls = Set.new
|
||
text.scan(URL_REGEX) { urls << $& }
|
||
|
||
hoisted = urls
|
||
.map { |url| [SecureRandom.hex, url] }
|
||
.to_h
|
||
|
||
hoisted.each { |h, url| text.gsub!(url, h) }
|
||
|
||
text.gsub!(/[\\`*_{}\[\]()#+\-.!~]/) { |c| "\\#{c}" }
|
||
text = CGI.escapeHTML(text)
|
||
|
||
hoisted.each { |h, url| text.gsub!(h, url) }
|
||
|
||
text
|
||
end
|
||
end
|