from threading import Thread
import logging, os, pathlib, subprocess, json, tornado

# import logger
logger = logging.getLogger(__name__)


class IrisSystemError(Exception):
    pass


class IrisSystemPermissionError(IrisSystemError):
    reason = "Permission denied"

    def __init__(self, path):
        message = "Password-less access to %s was refused. Check your /etc/sudoers file." % path.as_uri()
        logger.error(message)
        super().__init__(message)


class IrisSystemThread(Thread):
    _USE_SUDO = True

    def __init__(self, action, callback):
        Thread.__init__(self)
        self.action = action
        self.callback = callback
        self.ioloop = tornado.ioloop.IOLoop.current()
        self.script_path = pathlib.Path(__file__).parent / "system.sh"

    def get_command(self, action=None, *, non_interactive=False):
        if self._USE_SUDO:
            if non_interactive:
                args = [b'sudo -n']
            else:
                args = [b'sudo']
        else:
            args = []
        
        if action is None:
            action = self.action

        args = args + [bytes(self.script_path), action.encode()]
        return args
    
    ##
    # Run the defined action
    ##
    def run(self):
        logger.info("Running system action '"+self.action+"'")

        try:
            self.can_run()
        except IrisSystemError as e:
            logger.error(e)

            error = {
                'message': e.reason,
                'description': e.message
            }
            
            return {
                'error': error
            }

        command = self.get_command()
        logger.debug("Running '%s'", os.fsdecode(b' '.join(command)))
        proc = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        
        stdout,stderr = proc.communicate()

        if stderr:
            error_string = os.fsdecode(stderr)
            logger.error(error_string)
            self.ioloop.add_callback(lambda: self.callback(None, {'error': error_string}))
        elif proc.returncode > 0:
            response_string = os.fsdecode(stdout)
            logger.info(response_string)
            self.ioloop.add_callback(lambda: self.callback(None, {'error': response_string}))
        else:
            response_string = os.fsdecode(stdout)
            logger.info(response_string)
            self.ioloop.add_callback(lambda: self.callback({'output': response_string}, None))

    ##
    # Check if we have access to the system script (system.sh)
    #
    # @return boolean or exception
    ##
    def can_run(self, *args, **kwargs):
        # Attempt an empty call to our system file
        command_bytes = b' '.join(self.get_command('check', non_interactive=True))
        process = subprocess.Popen(command_bytes, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
        result, error = process.communicate()
        exitCode = process.wait()

        # Some kind of failure, so we can't run any commands this way
        if exitCode > 0:
            raise IrisSystemPermissionError(self.script_path)
        else:
            return True