from formatters import Printer
from io import StringIO


class BaseCommand(object):

    def __call__(self, *args, **kwargs):
        raise NotImplementedError(
            "BaseCommands must be callable and return a generator")


class NoneCommand(BaseCommand):

    def __call__(self, *args, **kwargs):
        return []



class RawCommand(BaseCommand):
    """Fallback raw command that just invokes an existing Unix utility program
    with the builtin subprocess module. Each output object is just a tree node
    whose data is a simple string."""

    def __init__(self, cmd, input_generator=[], args=tuple()):
        self.input_generator = input_generator
        self.cmd = cmd
        self.args = args

    def __call__(self, input_generator=[], *args, **kwargs):
        import subprocess
        try:
            p = subprocess.Popen((self.cmd,) + self.args, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
            def output_generator():
                input_str = b""
                for line in input_generator:
                    input_str += line
                outs, errs = p.communicate(input_str)
                if outs:
                    yield outs

            return output_generator()
        except:
            import traceback
            traceback.print_exc()
        return []


registered_cmds = []

def register_cmd(cls):
    registered_cmds.append(cls.__name__)
    return cls