module Mdopen

# File lib/mdopen.rb, line 17
def erb_render(content, tmp_file)
  template_path = File.join(__dir__, 'templates/github.html.erb')
  template = Tilt::ERBTemplate.new(template_path)
  output = template.render(self, content: content)
  tmp_file.write(output)
  tmp_file.close
end

# File lib/mdopen.rb, line 25
def md2html(md_file)
  parser = Redcarpet::Markdown.new(
    Redcarpet::Render::HTML.new,
    fenced_code_blocks: true,
    tables: true,
    autolink: true,
    space_after_headers: true,
    highlight: true,
    quote: true,
    strikethrough: true,
    superscript: true,
    no_intra_emphasis: true)
  parser.render(md_file)
end

# File lib/mdopen.rb, line 50
def new_tmpfile
  filename = tmp_filename
  tmp_file = Tempfile.new([filename, '.html'])
  # prevent tempfile from deleting by GC
  ObjectSpace.undefine_finalizer(tmp_file)
  tmp_file
end

# File lib/mdopen.rb, line 40
def open_cmd
  if OS.mac?
    "open"
  elsif OS.windows?
    "cmd /c start"
  else
    "xdg-open"
  end
end

# File lib/mdopen.rb, line 9
def preview(md_file)
  content = md2html(md_file)
  tmp_file = new_tmpfile
  html_file_path = tmp_file.path
  erb_render(content, tmp_file)
  system "#{open_cmd} file://#{html_file_path}"
end

# File lib/mdopen.rb, line 58
def tmp_filename
  [('a'..'z'), ('A'..'Z'), (0..9)].map(&:to_a).flatten.sample(12).join
end