Naive ERB to Slim Converter (because slimrb does a really terrible job converting)

Naive ERB to Slim Converter - convert_slim_to_erb

#!/usr/bin/env ruby

### USAGE: `./convert_slim_to_erb path/to/views/`

### LIMITATIONS:
### - Does not add closing tags such as `<% end %>` or `</div>`

SELF_CLOSING_TAGS = ["input","br","hr","img","meta","area","base","col","embed","link","source","track","wbr","param"].freeze

@line = nil
@indent = nil
@next_line = nil
@next_indent = nil

@ruby_block_indent = nil

Object.class_eval do
  def present?
    self && !self.strip.empty?
  end

  def blank?
    !present?
  end

  def presence
    self if present?
  end
end

def get_indent(str)
  str[/^\ */]
end

def prepend_attr(attr, value)
  return if value.to_s.blank?

  if value.is_a?(Array)
    value = value.join(" ")
  end

  if !@line.include?("#{attr}=")
    @line.sub!(">", " #{attr}=\"#{value}\">")
  else
    @line.sub!("#{attr}=\"", "#{attr}=\"#{value} ") # double quotes
    @line.sub!("#{attr}=\'", "#{attr}='#{value} ") # single quotes
  end

  return true
end

### SCRIPT START

files = ARGV[0].presence || "views/"

files = `find #{files} -name '*.slim'`.split("\n")

files.each do |file|
  @content = ""

  @lines = File.readlines(file)

  @total_num_lines = @lines.size

  @lines.each_with_index do |line, i|
    puts "Line: #{i+1} of #{@total_num_lines}, File: #{file}"

    @line = line
    @indent = get_indent(@line)

    if @line.strip.blank?
      @content << "\n"
      next
    else
      if @ruby_block_indent
        if @indent.size > @ruby_block_indent.size
          @content << @line
          next
        else
          if @ruby_block_indent
            @content << "#{@ruby_block_indent}%>\n\n"
          end
          @ruby_block_indent = nil
        end
      else
        ### TODO: Add close tag functionality
        # if @prev_indent && @indent.size <= @prev_indent.size
        #   if @prev_el_type.present?
        #     @content << "#{@prev_indent}</#{@prev_el_type}>\n\n"
        #   elsif ["else","elsif","when"].none?{|x| @line.strip.sub("-","").strip.start_with?(x) }
        #     @content.sub!(/\n\n\n$/, "\n")
        #     @content.sub!(/\n\n$/, "\n")
        #     @content << "#{@prev_indent[2..-1]}<% end %>\n\n"
        #   end
        # end
      end
    end

    if @line.strip.start_with?("ruby:")
      @line.sub!("ruby:", "<%")
      @ruby_block_indent = @indent
    elsif @line.strip.start_with?("-")
      @line.sub!("#{@indent}-", "#{@indent}<%")
      @line.sub!(/$/, " %>")
    elsif @line.strip.start_with?("=")
      @line.sub!("#{@indent}=", "#{@indent}<%=")
      @line.sub!(/$/, " %>")
    elsif @line.strip.start_with?("|")
      @line.sub!("#{@indent}|", "#{@indent}")
    else
      ### Normal element

      part1 = @line.split(" ").first

      element = part1.split(/\.|#/).first
      if element.blank?
        element = "div"
        el_match = /^/
      else
        el_match = element
      end

      classes = part1.sub(el_match, "").split(".").map{|y| y.split("#").first }.compact
      ids = part1.sub(el_match, "").split("#").map{|y| y.split(".").first }.compact

      prepend_attr("class", classes)
      prepend_attr("id", ids)

      @line.sub!(part1, element)

      parts = @line.split(" ")

      html_attrs = []

      element = @line.split(" ").first
      parts = @line.sub(element, "").strip.split('" ')

      inner_html = nil

      parts.map(&:strip).each_with_index do |part,i|
        if part.strip.start_with?("-")
          part.sub!("-", "<%")
          part.sub!(/$/, " %>")
          inner_html = part
        elsif part.strip.start_with?("=")
          part.sub!("=", "<%=")
          part.sub!(/$/, " %>")
          inner_html = part
        elsif part.strip.start_with?("|")
          part.sub!("|", "<%")
          part.sub!(/$/, " %>")
          inner_html = part
        elsif part.match?(/.+=[\"|\']/)
          html_attrs << part
        end

        if inner_html
          break
        end
      end

      @line = "#{@indent}<#{element}#{' ' if !html_attrs.empty?}#{html_attrs.join(" ")}#{'/' if SELF_CLOSING_TAGS.include?(element)}>#{inner_html}"

      if inner_html
        @line << "</#{element}>"
      end

      @line << "\n"
    end

    @content << @line
  end

  File.open(file.sub('slim', 'erb'), "wb") do |f|
    f.write @content
  end
end