class Pronto::Rustcov

def parse_lcov(path)
  uncovered = Hash.new { |h, k| h[k] = [] }
  file = nil
  File.foreach(path) do |line|
    case line
    when /^SF:(.+)/
      file = File.expand_path($1.strip)
    when /^DA:(\d+),0$/
      uncovered[file] << $1.to_i if file
    when /^end_of_record/
      file = nil
    end
  end
  uncovered
end

def run
  return [] unless @patches
  lcov = parse_lcov('target/lcov.info')
  grouped = Hash.new { |h, k| h[k] = [] }
  @patches.each do |patch|
    next unless patch.added_lines.any?
    file_path = patch.new_file_full_path.to_s
    uncovered = lcov[file_path]
    next unless uncovered
    patch.added_lines.each do |line|
      if uncovered.include?(line.new_lineno)
        grouped[patch].push(line)
      end
    end
  end
  grouped.map do |patch, lines|
    linenos = lines.map(&:new_lineno).sort
    ranges = linenos.chunk_while { |i, j| j == i + 1 }
                    .map { |group| group.size > 1 ? "#{group.first}–#{group.last}" : group.first.to_s }
    message_text = "⚠️ Test coverage is missing for lines: #{ranges.join(', ')}"
    # Attach the message to the first uncovered line
    Pronto::Message.new(
      patch.new_file_path,
      lines.first,
      :warning,
      message_text,
      nil,
      self.class
    )
  end
end