#
# = open3.rb: Popen, but with stderr, too
#
# Author:: Yukihiro Matsumoto
# Documentation:: Konrad Meyer
#
# Open3 gives you access to stdin, stdout, and stderr when running other
# programs.
#

#
# Open3 grants you access to stdin, stdout, stderr and a thread to wait the
# child process when running another program.
# You can specify various attributes, redirections, current directory, etc., of
# the program as Process.spawn.
#
# - Open3.popen3 : pipes for stdin, stdout, stderr
# - Open3.popen2 : pipes for stdin, stdout
# - Open3.popen2e : pipes for stdin, merged stdout and stderr
# - Open3.capture3 : give a string for stdin.  get strings for stdout, stderr
# - Open3.capture2 : give a string for stdin.  get a string for stdout
# - Open3.capture2e : give a string for stdin.  get a string for merged stdout and stderr
# - Open3.pipeline_rw : pipes for first stdin and last stdout of a pipeline
# - Open3.pipeline_r : pipe for last stdout of a pipeline
# - Open3.pipeline_w : pipe for first stdin of a pipeline
# - Open3.pipeline_start : a pipeline
# - Open3.pipeline : run a pipline and wait
#

module Open3

  # Open stdin, stdout, and stderr streams and start external executable.
  # In addition, a thread for waiting the started process is noticed.
  # The thread has a pid method and thread variable :pid which is the pid of
  # the started process.
  #
  # Block form:
  #
  #   Open3.popen3([env,] cmd... [, opts]) {|stdin, stdout, stderr, wait_thr|
  #     pid = wait_thr.pid # pid of the started process.
  #     ...
  #     exit_status = wait_thr.value # Process::Status object returned.
  #   }
  #
  # Non-block form:
  #
  #   stdin, stdout, stderr, wait_thr = Open3.popen3([env,] cmd... [, opts])
  #   pid = wait_thr[:pid]  # pid of the started process.
  #   ...
  #   stdin.close  # stdin, stdout and stderr should be closed explicitly in this form.
  #   stdout.close
  #   stderr.close
  #   exit_status = wait_thr.value  # Process::Status object returned.
  #
  # The parameters +cmd...+ is passed to Process.spawn.
  # So a commandline string and list of argument strings can be accepted as follows.
  #
  #   Open3.popen3("echo a") {|i, o, e, t| ... }
  #   Open3.popen3("echo", "a") {|i, o, e, t| ... }
  #   Open3.popen3(["echo", "argv0"], "a") {|i, o, e, t| ... }
  #
  # If the last parameter, opts, is a Hash, it is recognized as an option for Process.spawn.
  #
  #   Open3.popen3("pwd", :chdir=>"/") {|i,o,e,t|
  #     p o.read.chomp #=> "/"
  #   }
  #
  # wait_thr.value waits the termination of the process.
  # The block form also waits the process when it returns.
  #
  # Closing stdin, stdout and stderr does not wait the process.
  #
  def popen3(*cmd, &block)
    return IO::popen3(*cmd, &block) if RUBY_ENGINE == 'jruby'
    
    if Hash === cmd.last
      opts = cmd.pop.dup
    else
      opts = {}
    end

    in_r, in_w = IO.pipe
    opts[:in] = in_r
    in_w.sync = true

    out_r, out_w = IO.pipe
    opts[:out] = out_w

    err_r, err_w = IO.pipe
    opts[:err] = err_w

    popen_run(cmd, opts, [in_r, out_w, err_w], [in_w, out_r, err_r], &block)
  end
  module_function :popen3

  # Open3.popen2 is similer to Open3.popen3 except it doesn't make a pipe for
  # the standard error stream.
  #
  # Block form:
  #
  #   Open3.popen2([env,] cmd... [, opts]) {|stdin, stdout, wait_thr|
  #     pid = wait_thr.pid # pid of the started process.
  #     ...
  #     exit_status = wait_thr.value # Process::Status object returned.
  #   }
  #
  # Non-block form:
  #
  #   stdin, stdout, wait_thr = Open3.popen2([env,] cmd... [, opts])
  #   ...
  #   stdin.close  # stdin and stdout should be closed explicitly in this form.
  #   stdout.close
  #
  # See Process.spawn for the optional hash arguments _env_ and _opts_.
  #
  # Example:
  #
  #   Open3.popen2("wc -c") {|i,o,t|
  #     i.print "answer to life the universe and everything"
  #     i.close
  #     p o.gets #=> "42\n"
  #   }
  #
  #   Open3.popen2("bc -q") {|i,o,t|
  #     i.puts "obase=13"
  #     i.puts "6 * 9"
  #     p o.gets #=> "42\n"
  #   }
  #
  #   Open3.popen2("dc") {|i,o,t|
  #     i.print "42P"
  #     i.close
  #     p o.read #=> "*"
  #   }
  #
  def popen2(*cmd, &block)
    if Hash === cmd.last
      opts = cmd.pop.dup
    else
      opts = {}
    end

    in_r, in_w = IO.pipe
    opts[:in] = in_r
    in_w.sync = true

    out_r, out_w = IO.pipe
    opts[:out] = out_w

    popen_run(cmd, opts, [in_r, out_w], [in_w, out_r], &block)
  end
  module_function :popen2

  # Open3.popen2e is similer to Open3.popen3 except it merges
  # the standard output stream and the standard error stream.
  #
  # Block form:
  #
  #   Open3.popen2e([env,] cmd... [, opts]) {|stdin, stdout_and_stderr, wait_thr|
  #     pid = wait_thr.pid # pid of the started process.
  #     ...
  #     exit_status = wait_thr.value # Process::Status object returned.
  #   }
  #
  # Non-block form:
  #
  #   stdin, stdout_and_stderr, wait_thr = Open3.popen2e([env,] cmd... [, opts])
  #   ...
  #   stdin.close  # stdin and stdout_and_stderr should be closed explicitly in this form.
  #   stdout_and_stderr.close
  #
  # See Process.spawn for the optional hash arguments _env_ and _opts_.
  #
  # Example:
  #   # check gcc warnings
  #   source = "foo.c"
  #   Open3.popen2e("gcc", "-Wall", source) {|i,oe,t|
  #     oe.each {|line|
  #       if /warning/ =~ line
  #         ...
  #       end
  #     }
  #   }
  #
  def popen2e(*cmd, &block)
    if Hash === cmd.last
      opts = cmd.pop.dup
    else
      opts = {}
    end

    in_r, in_w = IO.pipe
    opts[:in] = in_r
    in_w.sync = true

    out_r, out_w = IO.pipe
    opts[[:out, :err]] = out_w

    popen_run(cmd, opts, [in_r, out_w], [in_w, out_r], &block)
  end
  module_function :popen2e

  def popen_run(cmd, opts, child_io, parent_io) # :nodoc:
    pid = spawn(*cmd, opts)
    wait_thr = Process.detach(pid)
    child_io.each {|io| io.close }
    result = [*parent_io, wait_thr]
    if defined? yield
      begin
        return yield(*result)
      ensure
        parent_io.each{|io| io.close unless io.closed?}
        wait_thr.join
      end
    end
    result
  end
  module_function :popen_run
  class << self
    private :popen_run
  end

  # Open3.capture3 captures the standard output and the standard error of a command.
  #
  #   stdout_str, stderr_str, status = Open3.capture3([env,] cmd... [, opts])
  #
  # The arguments env, cmd and opts are passed to Open3.popen3 except
  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
  #
  # If opts[:stdin_data] is specified, it is sent to the command's standard input.
  #
  # If opts[:binmode] is true, internal pipes are set to binary mode.
  #
  # Example:
  #
  #   # dot is a command of graphviz.
  #   graph = <<'End'
  #     digraph g {
  #       a -> b
  #     }
  #   End
  #   layouted_graph, dot_log = Open3.capture3("dot -v", :stdin_data=>graph)
  #
  #   o, e, s = Open3.capture3("echo a; sort >&2", :stdin_data=>"foo\nbar\nbaz\n")
  #   p o #=> "a\n"
  #   p e #=> "bar\nbaz\nfoo\n"
  #   p s #=> #<Process::Status: pid 32682 exit 0>
  #
  #   # generate a thumnail image using the convert command of ImageMagick.
  #   # However, if the image stored really in a file,
  #   # system("convert", "-thumbnail", "80", "png:#{filename}", "png:-") is better
  #   # because memory consumption.
  #   # But if the image is stored in a DB or generated by gnuplot Open3.capture2 example,
  #   # Open3.capture3 is considerable.
  #   #
  #   image = File.read("/usr/share/openclipart/png/animals/mammals/sheep-md-v0.1.png", :binmode=>true)
  #   thumnail, err, s = Open3.capture3("convert -thumbnail 80 png:- png:-", :stdin_data=>image, :binmode=>true)
  #   if s.success?
  #     STDOUT.binmode; print thumnail
  #   end
  #
  def capture3(*cmd)
    if Hash === cmd.last
      opts = cmd.pop.dup
    else
      opts = {}
    end

    stdin_data = opts.delete(:stdin_data) || ''
    binmode = opts.delete(:binmode)

    popen3(*cmd, opts) {|i, o, e, t|
      if binmode
        i.binmode
        o.binmode
        e.binmode
      end
      out_reader = Thread.new { o.read }
      err_reader = Thread.new { e.read }
      i.write stdin_data
      i.close
      [out_reader.value, err_reader.value, t.value]
    }
  end
  module_function :capture3

  # Open3.capture2 captures the standard output of a command.
  #
  #   stdout_str, status = Open3.capture2([env,] cmd... [, opts])
  #
  # The arguments env, cmd and opts are passed to Open3.popen3 except
  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
  #
  # If opts[:stdin_data] is specified, it is sent to the command's standard input.
  #
  # If opts[:binmode] is true, internal pipes are set to binary mode.
  #
  # Example:
  #
  #   # factor is a command for integer factorization.
  #   o, s = Open3.capture2("factor", :stdin_data=>"42")
  #   p o #=> "42: 2 3 7\n"
  #
  #   # generate x**2 graph in png using gnuplot.
  #   gnuplot_commands = <<"End"
  #     set terminal png
  #     plot x**2, "-" with lines
  #     1 14
  #     2 1
  #     3 8
  #     4 5
  #     e
  #   End
  #   image, s = Open3.capture2("gnuplot", :stdin_data=>gnuplot_commands, :binmode=>true)
  #
  def capture2(*cmd)
    if Hash === cmd.last
      opts = cmd.pop.dup
    else
      opts = {}
    end

    stdin_data = opts.delete(:stdin_data) || ''
    binmode = opts.delete(:binmode)

    popen2(*cmd, opts) {|i, o, t|
      if binmode
        i.binmode
        o.binmode
      end
      out_reader = Thread.new { o.read }
      i.write stdin_data
      i.close
      [out_reader.value, t.value]
    }
  end
  module_function :capture2

  # Open3.capture2e captures the standard output and the standard error of a command.
  #
  #   stdout_and_stderr_str, status = Open3.capture2e([env,] cmd... [, opts])
  #
  # The arguments env, cmd and opts are passed to Open3.popen3 except
  # opts[:stdin_data] and opts[:binmode].  See Process.spawn.
  #