[#253] Added support for relational filters on event hooks.

platypush/message/event/__init__.py

@@ -2,9 +2,12 @@ import copy
 import json
 import logging
 import random
+import re
 import time
 
+from dataclasses import dataclass, field
 from datetime import date
+from typing import Any
 
 from platypush.config import Config
 from platypush.message import Message
@@ -90,6 +93,70 @@ class Event(Message):
         """Generate a unique event ID"""
         return ''.join([f'{random.randint(0, 255):02x}' for _ in range(16)])
 
+    @staticmethod
+    def _is_relational_filter(filter: dict) -> bool:
+        """
+        Check if a condition is a relational filter.
+
+        For a condition to be a relational filter, it must have at least one
+        key starting with `$`.
+        """
+        if not isinstance(filter, dict):
+            return False
+        return any(key.startswith('$') for key in filter)
+
+    @staticmethod
+    def __relational_filter_matches(filter: dict, value: Any) -> bool:
+        """
+        Return True if the conditions in the filter match the given event
+        arguments.
+        """
+        for op, filter_val in filter.items():
+            comparator = _event_filter_operators.get(op)
+            assert comparator, f'Invalid operator: {op}'
+
+            # If this is a numeric or string filter, and one of the two values
+            # is null, return False - it doesn't make sense to run numeric or
+            # string comparison with null values.
+            if (op in _numeric_filter_operators or op in _string_filter_operators) and (
+                filter_val is None or value is None
+            ):
+                return False
+
+            # If this is a numeric-only or string-only filter, then the
+            # operands' types should be consistent with the operator.
+            if op in _numeric_filter_operators:
+                try:
+                    value = float(value)
+                    filter_val = float(filter_val)
+                except (ValueError, TypeError) as e:
+                    raise AssertionError(
+                        f'Could not convert either "{value}" nor "{filter_val} to a number'
+                    ) from e
+            elif op in _string_filter_operators:
+                assert isinstance(filter_val, str) and isinstance(value, str), (
+                    f'Expected two strings, got "{filter_val}" '
+                    f'({type(filter_val)}) and "{value}" ({type(value)})'
+                )
+
+            if not comparator(value, filter_val):
+                return False
+
+        return True
+
+    @classmethod
+    def _relational_filter_matches(cls, filter: dict, value: Any) -> bool:
+        is_match = False
+        try:
+            is_match = cls.__relational_filter_matches(filter, value)
+        except AssertionError as e:
+            logger.error('Invalid filter: %s', e)
+
+        if not is_match:
+            return False
+
+        return True
+
     def _matches_condition(
         self,
         condition: dict,
@@ -102,24 +169,33 @@ class Event(Message):
                 return False
 
             if isinstance(args[attr], str):
-                self._matches_argument(
-                    argname=attr, condition_value=value, args=args, result=result
-                )
-
-                if result.is_match:
-                    match_scores.append(result.score)
+                if self._is_relational_filter(value):
+                    if not self._relational_filter_matches(value, args[attr]):
+                        return False
                 else:
-                    return False
-            elif isinstance(value, dict):
-                if not isinstance(args[attr], dict):
-                    return False
+                    self._matches_argument(
+                        argname=attr, condition_value=value, args=args, result=result
+                    )
 
-                return self._matches_condition(
-                    condition=value,
-                    args=args[attr],
-                    result=result,
-                    match_scores=match_scores,
-                )
+                    if result.is_match:
+                        match_scores.append(result.score)
+                    else:
+                        return False
+            elif isinstance(value, dict):
+                if self._is_relational_filter(value):
+                    if not self._relational_filter_matches(value, args[attr]):
+                        return False
+                else:
+                    if not isinstance(args[attr], dict):
+                        return False
+
+                    if not self._matches_condition(
+                        condition=value,
+                        args=args[attr],
+                        result=result,
+                        match_scores=match_scores,
+                    ):
+                        return False
             elif args[attr] != value:
                 return False
 
@@ -188,6 +264,7 @@ class Event(Message):
         )
 
 
+@dataclass
 class EventMatchResult:
     """
     When comparing an event against an event condition, you want to
@@ -197,10 +274,9 @@ class EventMatchResult:
     highest score will win.
     """
 
-    def __init__(self, is_match, score=0.0, parsed_args=None):
-        self.is_match = is_match
-        self.score = score
-        self.parsed_args = parsed_args or {}
+    is_match: bool
+    score: float = 0.0
+    parsed_args: dict = field(default_factory=dict)
 
 
 def flatten(args):
@@ -221,4 +297,19 @@ def flatten(args):
                 flatten(args[i])
 
 
+_event_filter_operators = {
+    '$gt': lambda a, b: a > b,
+    '$gte': lambda a, b: a >= b,
+    '$lt': lambda a, b: a < b,
+    '$lte': lambda a, b: a <= b,
+    '$eq': lambda a, b: a == b,
+    '$ne': lambda a, b: a != b,
+    '$regex': lambda a, b: re.search(b, a),
+}
+
+_numeric_filter_operators = {'$gt', '$gte', '$lt', '$lte'}
+
+_string_filter_operators = {'$regex'}
+
+
 # vim:sw=4:ts=4:et:

tests/test_event_parse.py

@@ -87,6 +87,56 @@ def test_speech_recognized_event_parse():
     assert not result.is_match
 
 
+def test_condition_with_relational_operators():
+    """
+    Test relational operators used in event conditions.
+    """
+    # Given: A condition with a relational operator.
+    condition = EventCondition.build(
+        {
+            'type': 'platypush.message.event.ping.PingEvent',
+            'message': {'foo': {'$gt': 25}},
+        }
+    )
+
+    # When: An event with a value greater than 25 is received.
+    event = PingEvent(message={'foo': 26})
+
+    # Then: The condition is matched.
+    assert event.matches_condition(condition).is_match
+
+    # When: An event with a value lower than 25 is received.
+    event = PingEvent(message={'foo': 24})
+
+    # Then: The condition is not matched.
+    assert not event.matches_condition(condition).is_match
+
+
+def test_filter_with_regex_condition():
+    """
+    Test an event matcher with a regex filter on an attribute.
+    """
+    # Given: A condition with a regex filter.
+    condition = EventCondition.build(
+        {
+            'type': 'platypush.message.event.ping.PingEvent',
+            'message': {'foo': {'$regex': '^ba[rz]'}},
+        }
+    )
+
+    # When: An event with a matching string is received.
+    event = PingEvent(message={'foo': 'bart'})
+
+    # Then: The condition is matched.
+    assert event.matches_condition(condition).is_match
+
+    # When: An event with a non-matching string is received.
+    event = PingEvent(message={'foo': 'back'})
+
+    # Then: The condition is not matched.
+    assert not event.matches_condition(condition).is_match
+
+
 if __name__ == '__main__':
     pytest.main()