class TerraformLandscape::Printer

def initialize(output)
  @output = output
end

def process_stream(io)
  buffer = StringIO.new
  begin
    block_size = 1024
    done = false
    until done
      readable_fds, = IO.select([io])
      next unless readable_fds
      readable_fds.each do |f|
        begin
          buffer << f.read_nonblock(block_size)
        rescue IO::WaitReadable # rubocop:disable Lint/HandleExceptions
          # Ignore; we'll call IO.select again
        rescue EOFError
          done = true
        end
      end
    end
  ensure
    io.close
  end
  process_string(buffer.string)
end

def process_string(plan_output)
  scrubbed_output = plan_output.gsub(/\e\[\d+m/, '')
  # Remove preface
  if (match = scrubbed_output.match(/^Path:[^\n]+/))
    scrubbed_output = scrubbed_output[match.end(0)..-1]
  elsif (match = scrubbed_output.match(/^Terraform.+following\sactions:/))
    scrubbed_output = scrubbed_output[match.end(0)..-1]
  elsif (match = scrubbed_output.match(/^\s*(~|\+|\-)/))
    scrubbed_output = scrubbed_output[match.begin(0)..-1]
  elsif scrubbed_output =~ /^No changes/
    @output.puts 'No changes'
    return
  else
    raise ParseError, 'Output does not contain proper preface'
  end
  # Remove postface
  if (match = scrubbed_output.match(/^Plan:[^\n]+/))
    plan_summary = scrubbed_output[match.begin(0)..match.end(0)]
    scrubbed_output = scrubbed_output[0...match.begin(0)]
  end
  plan = TerraformPlan.from_output(scrubbed_output)
  plan.display(@output)
  @output.puts plan_summary
end