platypush/platypush/message/request/__init__.py

import copy
import datetime
import json
import logging
import random
import re
import time

from threading import Thread

from platypush.config import Config
from platypush.context import get_plugin
from platypush.message import Message
from platypush.message.response import Response
from platypush.utils import get_hash, get_module_and_method_from_action, get_redis_queue_name_by_message, \
    is_functional_procedure

logger = logging.getLogger('platypush')


class Request(Message):
    """ Request message class """

    def __init__(self, target, action, origin=None, id=None, backend=None,
                 args=None, token=None, timestamp=None):
        """
        Params:
            target -- Target node [Str]
            action -- Action to be executed (e.g. music.mpd.play) [Str]
            origin -- Origin node [Str]
                id -- Message ID, or None to get it auto-generated
           backend -- Backend connected to the request, where the response will be delivered
              args -- Additional arguments for the action [Dict]
             token -- Authorization token, if required on the server [Str]
         timestamp -- Message creation timestamp [Float]
        """

        super().__init__(timestamp=timestamp)

        self.id = id if id else self._generate_id()
        self.target = target
        self.action = action
        self.origin = origin
        self.args = args if args else {}
        self.backend = backend
        self.token = token

    @classmethod
    def build(cls, msg):
        msg = super().parse(msg)
        args = {'target': msg.get('target', Config.get('device_id')), 'action': msg['action'],
                'args': msg.get('args', {}), 'id': msg['id'] if 'id' in msg else cls._generate_id(),
                'timestamp': msg['_timestamp'] if '_timestamp' in msg else time.time()}

        if 'origin' in msg:
            args['origin'] = msg['origin']
        if 'token' in msg:
            args['token'] = msg['token']
        return cls(**args)

    @staticmethod
    def _generate_id():
        _id = ''
        for i in range(0, 16):
            _id += '%.2x' % random.randint(0, 255)
        return _id

    def _execute_procedure(self, *args, **kwargs):
        from platypush.config import Config
        from platypush.procedure import Procedure

        logger.info('Executing procedure request: {}'.format(self.action))
        procedures = Config.get_procedures()
        proc_name = '.'.join(self.action.split('.')[1:])
        if proc_name not in procedures:
            proc_name = self.action.split('.')[-1]

        proc_config = procedures[proc_name]
        if is_functional_procedure(proc_config):
            self._expand_context(self.args, **kwargs)
            kwargs = {**self.args, **kwargs}
            if 'n_tries' in kwargs:
                del kwargs['n_tries']

            return proc_config(*args, **kwargs)

        proc = Procedure.build(name=proc_name, requests=proc_config['actions'],
                               _async=proc_config['_async'], args=self.args,
                               backend=self.backend, id=self.id)

        return proc.execute(*args, **kwargs)

    def _expand_context(self, event_args=None, **context):
        from platypush.config import Config

        if event_args is None:
            event_args = copy.deepcopy(self.args)

        constants = Config.get_constants()
        context['constants'] = {}
        for (name, value) in constants.items():
            context['constants'][name] = value

        keys = []
        if isinstance(event_args, dict):
            keys = event_args.keys()
        elif isinstance(event_args, list):
            keys = range(0, len(event_args))

        for key in keys:
            value = event_args[key]

            if isinstance(value, str):
                value = self.expand_value_from_context(value, **context)
            elif isinstance(value, dict) or isinstance(value, list):
                self._expand_context(event_args=value, **context)

            event_args[key] = value

        return event_args

    # noinspection PyBroadException
    @classmethod
    def expand_value_from_context(cls, _value, **context):
        for (k, v) in context.items():
            if isinstance(v, Message):
                v = json.loads(str(v))
            try:
                exec('{}={}'.format(k, v))
            except:
                if isinstance(v, str):
                    try:
                        exec('{}="{}"'.format(k, re.sub(r'(^|[^\\])"', '\1\\"', v)))
                    except Exception as e:
                        logger.warning('Could not set context variable {}={}'.format(k, v))
                        logger.warning('Context: {}'.format(json.dumps(context)))
                        logger.exception(e)

        parsed_value = ''
        if not isinstance(_value, str):
            parsed_value = _value

        while _value and isinstance(_value, str):
            m = re.match(r'([^$]*)(\${\s*(.+?)\s*})(.*)', _value)
            if m and not m.group(1).endswith('\\'):
                prefix = m.group(1)
                expr = m.group(2)
                inner_expr = m.group(3)
                _value = m.group(4)

                try:
                    context_value = eval(inner_expr)

                    if callable(context_value):
                        context_value = context_value()
                    if isinstance(context_value, range) or isinstance(context_value, tuple):
                        context_value = [*context_value]
                    if isinstance(context_value, datetime.date):
                        context_value = context_value.isoformat()
                except Exception as e:
                    logger.exception(e)
                    context_value = expr

                parsed_value += prefix + (
                    json.dumps(context_value)
                    if isinstance(context_value, list) or isinstance(context_value, dict)
                    else str(context_value)
                )
            else:
                parsed_value += _value
                _value = ''

        try:
            return json.loads(parsed_value)
        except:
            return parsed_value

    def _send_response(self, response):
        response = Response.build(response)
        response.id = self.id
        response.target = self.origin
        response.origin = Config.get('device_id')

        if self.backend and self.origin:
            self.backend.send_response(response=response, request=self)
        else:
            redis = get_plugin('redis')
            if redis:
                queue_name = get_redis_queue_name_by_message(self)
                redis.send_message(queue_name, response)
                redis.expire(queue_name, 60)

    def execute(self, n_tries=1, _async=True, **context):
        """
        Execute this request and returns a Response object
        Params:
            n_tries -- Number of tries in case of failure before raising a RuntimeError
            _async   -- If True, the request will be run asynchronously and the
                       response posted on the bus when available (default),
                       otherwise the current thread will wait for the response
                       to be returned synchronously.
            context -- Key-valued context. Example:
                context = (group_name='Kitchen lights')
                request.args:
                    - group: ${group_name}  # will be expanded as "Kitchen lights")
        """

        def _thread_func(_n_tries, errors=None):
            response = None

            if self.action.startswith('procedure.'):
                context['n_tries'] = _n_tries
                response = self._execute_procedure(**context)
                if response is not None:
                    self._send_response(response)
                return response
            # utils.get_context is a special action that simply returns the current context
            elif self.action == 'utils.get_context':
                response = Response(output=context)
                self._send_response(response)
                return response
            else:
                action = self.expand_value_from_context(self.action, **context)
                (module_name, method_name) = get_module_and_method_from_action(action)
                plugin = get_plugin(module_name)

            try:
                # Run the action
                args = self._expand_context(**context)
                args = self.expand_value_from_context(args, **context)
                if isinstance(args, dict):
                    response = plugin.run(method_name, **args)
                elif isinstance(args, list):
                    response = plugin.run(method_name, *args)
                else:
                    response = plugin.run(method_name, args)

                if not response:
                    logger.warning('Received null response from action {}'.format(action))
                else:
                    if response.is_error():
                        logger.warning(('Response processed with errors from ' +
                                        'action {}: {}').format(
                            action, str(response)))
                    elif not response.disable_logging:
                        logger.info('Processed response from action {}: {}'.
                                    format(action, str(response)))
            except (AssertionError, TimeoutError) as e:
                plugin.logger.exception(e)
                logger.warning('{} from action [{}]: {}'.format(type(e), action, str(e)))
                response = Response(output=None, errors=[str(e)])
            except Exception as e:
                # Retry mechanism
                plugin.logger.exception(e)
                logger.warning(('Uncaught exception while processing response ' +
                                'from action [{}]: {}').format(action, str(e)))

                errors = errors or []
                if str(e) not in errors:
                    errors.append(str(e))

                response = Response(output=None, errors=errors)
                if _n_tries - 1 > 0:
                    logger.info('Reloading plugin {} and retrying'.format(module_name))
                    get_plugin(module_name, reload=True)
                    response = _thread_func(_n_tries=_n_tries-1, errors=errors)
            finally:
                self._send_response(response)
                return response

        token_hash = Config.get('token_hash')

        if token_hash:
            if self.token is None or get_hash(self.token) != token_hash:
                raise PermissionError()

        if _async:
            Thread(target=_thread_func, args=(n_tries,)).start()
        else:
            return _thread_func(n_tries)

    def __str__(self):
        """
        Overrides the str() operator and converts
        the message into a UTF-8 JSON string
        """

        return json.dumps({
            'type': 'request',
            'target': self.target,
            'action': self.action,
            'args': self.args,
            'origin': self.origin if hasattr(self, 'origin') else None,
            'id': self.id if hasattr(self, 'id') else None,
            'token': self.token if hasattr(self, 'token') else None,
            '_timestamp': self.timestamp,
        })

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