class Terrapin::CommandLine::MultiPipe

def close_read
  begin
    @stdout_in.close
  rescue IOError
    # do nothing
  end
  begin
  @stderr_in.close
  rescue IOError
    # do nothing
  end
end

def close_write
  @stdout_out.close
  @stderr_out.close
end

def initialize
  @stdout_in, @stdout_out = IO.pipe
  @stderr_in, @stderr_out = IO.pipe
end

def output
  Output.new(@stdout_output, @stderr_output)
end

def pipe_options
  { out: @stdout_out, err: @stderr_out }
end

def read
  read_streams(@stdout_in, @stderr_in)
end

def read_and_then(&block)
  close_write
  read
  block.call
  close_read
end

def read_stream(io)
  result = String.new
  begin
    while partial_result = io.read_nonblock(8192)
      result << partial_result
    end
  rescue EOFError, Errno::EPIPE
    io.close
  rescue Errno::EINTR, Errno::EWOULDBLOCK, Errno::EAGAIN
    # do nothing
  end
  result
end

def read_streams(output, error)
  @stdout_output = ""
  @stderr_output = ""
  read_fds = [output, error]
  while !read_fds.empty?
    to_read, = IO.select(read_fds)
    if to_read.include?(output)
      @stdout_output << read_stream(output)
      read_fds.delete(output) if output.closed?
    end
    if to_read.include?(error)
      @stderr_output << read_stream(error)
      read_fds.delete(error) if error.closed?
    end
  end
end