class CssSplitter::Splitter

# File lib/css_splitter/splitter.rb, line 92
def self.count_selectors(css_file)
  raise "file could not be found" unless File.exists? css_file

  # get all the rules of the stylesheet using the closing '}'
  rules = IO.readlines(css_file, '}')
  return if rules.first.nil?

  rules.sum{ |rule| count_selectors_of_rule(rule) }.tap do |result|
    puts File.basename(css_file) + " contains #{result} selectors."
  end
end

# File lib/css_splitter/splitter.rb, line 44
def self.count_selectors_of_rule(rule)
  strip_comments(rule).partition(/\{/).first.scan(/,/).count.to_i + 1
end

# File lib/css_splitter/splitter.rb, line 19
def self.extract_part(rules, part = 1, max_selectors = MAX_SELECTORS_DEFAULT)
  return if rules.first.nil?

  charset_statement, rules[0] = extract_charset(rules.first)
  return if rules.nil?

  output = charset_statement || ""
  selectors_count = 0
  selector_range = max_selectors * (part - 1) + 1 .. max_selectors * part # e.g (4096..8190)

  rules.each do |rule|
    rule_selectors_count = count_selectors_of_rule rule
    selectors_count += rule_selectors_count

    if selector_range.cover? selectors_count # add rule to current output if within selector_range
      output << rule
    elsif selectors_count > selector_range.end # stop writing to output
      break
    end
  end

  output
end

# File lib/css_splitter/splitter.rb, line 54
def self.split(infile, outdir = File.dirname(infile), max_selectors = MAX_SELECTORS_DEFAULT)

  raise "infile could not be found" unless File.exists? infile

  rules = IO.readlines(infile, "}")
  return if rules.first.nil?

  charset_statement, rules[0] = extract_charset(rules.first)
  return if rules.nil?

  file_id = 1 # The infile remains the first file
  selectors_count = 0
  output = nil

  rules.each do |rule|
    rule_selectors_count = count_selectors_of_rule rule
    selectors_count += rule_selectors_count

    # Nothing happens until the selectors limit is reached for the first time
    if selectors_count > max_selectors
      # Close current file if there is already one
      output.close if output

      # Prepare next file
      file_id += 1
      filename = File.join(outdir, File.basename(infile, File.extname(infile)) + "_#{file_id.to_s}" + File.extname(infile))
      output = File.new(filename, "w")
      output.write charset_statement

      # Reset count with current rule count
      selectors_count = rule_selectors_count
    end

    output.write rule if output
  end
end

# File lib/css_splitter/splitter.rb, line 8
def self.split_string(css_string, split = 1, max_selectors = MAX_SELECTORS_DEFAULT)
  rules = split_string_into_rules(css_string)
  extract_part rules, split, max_selectors
end

# File lib/css_splitter/splitter.rb, line 14
def self.split_string_into_rules(css_string)
  strip_comments(css_string).chomp.scan /[^}]*}/
end