import os

from subprocess import Popen, PIPE

from io import open

class Command:

    """Contains the needed data to run a command"""

    def __init__(self, args, stdin=None, stdout=None, shell=False):

        self.arguments = args

        self.stdin = stdin

        self.stdout = stdout

        self.shell = shell

class CommandRunner:

    """

    Execute the differents registered commands in the specified order,

    either independantly or as a pipe process chain if required

    """

    def __init__(self, module_name="", log=None):

        self.module_name = module_name

        self.commands = []

        self.processes = []

        self.log = log

    def info(self, text):

        if self.log: self.log.info(text)

    def set_name(self, module_name):

        self.module_name = module_name

    def add_command(self, args, stdin=None, stdout=None, shell=False):

        command = Command(args, stdin, stdout, shell)

        self.commands.append(command)

        return command

    def shcmd(self, args):

        nargs = []

        for arg in args:

            if len(arg.split()) > 1: arg = '"%s"' % arg

            nargs.append(arg)

        return " ".join(nargs)

    def run(self, kw=None):

        if not(self.commands):

            return

        if not(kw): kw = {}

        pipe_top = False

        rc = 0

        for cmd in self.commands:

            if rc != 0:

                break

            stdin, stdout = None, None

            prev_pipe = None

            if cmd.stdin == "PIPE":

                if self.processes:

                    prev_pipe = self.processes[-1]

                    stdin = prev_pipe.stdout

                else:

                    pipe_top = True

                    stdin = PIPE

            if cmd.stdout == "PIPE":

                stdout = PIPE

            elif cmd.stdout:

                stdout = open(cmd.stdout % kw, "wb")

            if kw: args = [a % kw for a in cmd.arguments]

            else: args = cmd.arguments

            self.info(" ".join(args))

            # Some commands work only in shell env (e.g. links), so take care

            if cmd.shell:

                p = Popen(self.shcmd(args), stdin=stdin, stdout=stdout,

                          shell=True)

            else:

                p = Popen(args, stdin=stdin, stdout=stdout)

            self.processes.append(p)

            if stdin and prev_pipe:

                # Close stdout to allow <prev_pipe> receiving SIGPIPE

                prev_pipe.stdout.close()

            if stdout != PIPE:

                # Wait until the process is finished if not in a pipe chain

                rc = p.wait()

                if stdout: stdout.close()

        return rc