balanceboard/filter_lib.py

"""
Filter Library
Bare bones utilities for filtering posts and comments based on rules.
"""

import json
from pathlib import Path
from typing import Dict, List, Any, Optional
from abc import ABC, abstractmethod


class filter_lib:
    """Atomic filter utility functions"""

    @staticmethod
    def load_filterset(path: str) -> Dict:
        """Load filterset JSON from file"""
        with open(path, 'r') as f:
            return json.load(f)

    @staticmethod
    def load_data_by_uuid(uuid: str, data_dir: str) -> Optional[Dict]:
        """Load single JSON file by UUID"""
        file_path = Path(data_dir) / f"{uuid}.json"
        if not file_path.exists():
            return None

        with open(file_path, 'r') as f:
            return json.load(f)

    @staticmethod
    def merge_moderation(item: Dict, moderation_data: Dict) -> Dict:
        """Merge item with its moderation data by UUID"""
        mod_uuid = item.get('moderation_uuid')
        if mod_uuid and mod_uuid in moderation_data:
            item['moderation'] = moderation_data[mod_uuid]
        else:
            item['moderation'] = {}
        return item

    @staticmethod
    def get_nested_value(obj: Dict, path: str) -> Any:
        """Get value from nested dict using dot notation (e.g., 'moderation.flags.is_safe')"""
        keys = path.split('.')
        value = obj
        for key in keys:
            if isinstance(value, dict) and key in value:
                value = value[key]
            else:
                return None
        return value

    @staticmethod
    def evaluate_rule(value: Any, operator: str, target: Any) -> bool:
        """Evaluate single rule: value operator target"""
        if value is None:
            return False

        if operator == 'equals':
            return value == target
        elif operator == 'not_equals':
            return value != target
        elif operator == 'in':
            return value in target
        elif operator == 'not_in':
            return value not in target
        elif operator == 'min':
            return value >= target
        elif operator == 'max':
            return value <= target
        elif operator == 'after':
            return value > target
        elif operator == 'before':
            return value < target
        elif operator == 'contains':
            return target in value
        elif operator == 'excludes':
            if isinstance(value, list):
                return not any(item in target for item in value)
            return target not in value
        elif operator == 'includes':
            if isinstance(value, list):
                return target in value
            return False
        elif operator == 'includes_any':
            # Special case for topic matching
            if isinstance(value, list) and isinstance(target, list):
                for topic_item in value:
                    for rule in target:
                        if (topic_item.get('topic') == rule.get('topic') and
                            topic_item.get('confidence', 0) >= rule.get('confidence_min', 0)):
                            return True
            return False
        elif operator == 'min_length':
            return len(str(value)) >= target
        elif operator == 'max_length':
            return len(str(value)) <= target
        else:
            return False

    @staticmethod
    def apply_rules(item: Dict, rules: Dict) -> bool:
        """
        Apply multiple rules to item, return True if all pass (AND logic).
        Rules format: {"field.path": {"operator": value}}
        """
        if not rules:
            return True  # Empty rules = pass all

        for field_path, rule_def in rules.items():
            value = filter_lib.get_nested_value(item, field_path)

            # Support multiple operators per field
            for operator, target in rule_def.items():
                if not filter_lib.evaluate_rule(value, operator, target):
                    return False

        return True


class CommentFilterMode(ABC):
    """Abstract base class for comment filtering modes"""

    @staticmethod
    @abstractmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """Filter comments based on rules and moderation data. Override in subclasses."""
        pass


class TreePruningMode(CommentFilterMode):
    """
    Tree Pruning Filter Mode (Default)
    Fruit of the poisonous tree: if parent fails moderation, remove all children.
    """

    @staticmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """
        Filter comments using tree pruning.
        Build tree structure, evaluate from root down, prune toxic branches.
        """
        if not comments:
            return []

        # Merge moderation data into comments
        for comment in comments:
            filter_lib.merge_moderation(comment, moderation_data)

        # Build tree structure
        tree = TreePruningMode._build_tree(comments)

        # Prune tree based on rules
        pruned = TreePruningMode._prune_tree(tree, rules)

        # Flatten back to list
        return TreePruningMode._flatten_tree(pruned)

    @staticmethod
    def _build_tree(comments: List[Dict]) -> List[Dict]:
        """Build nested tree from flat comment list"""
        # Create lookup dict
        comment_map = {c['uuid']: {**c, 'children': []} for c in comments}

        # Build tree
        roots = []
        for comment in comments:
            parent_uuid = comment.get('parent_comment_uuid')
            if parent_uuid and parent_uuid in comment_map:
                comment_map[parent_uuid]['children'].append(comment_map[comment['uuid']])
            else:
                roots.append(comment_map[comment['uuid']])

        return roots

    @staticmethod
    def _prune_tree(tree: List[Dict], rules: Dict) -> List[Dict]:
        """
        Recursively prune tree.
        If node fails rules, remove it and all children.
        """
        pruned = []

        for node in tree:
            # Check if this node passes rules
            if filter_lib.apply_rules(node, rules):
                # Node passes, recursively check children
                if node.get('children'):
                    node['children'] = TreePruningMode._prune_tree(node['children'], rules)
                pruned.append(node)
            # If node fails, it and all children are discarded (tree pruning)

        return pruned

    @staticmethod
    def _flatten_tree(tree: List[Dict]) -> List[Dict]:
        """Flatten tree back to list"""
        flat = []

        def traverse(nodes):
            for node in nodes:
                children = node.pop('children', [])
                flat.append(node)
                if children:
                    traverse(children)

        traverse(tree)
        return flat


class IndividualFilterMode(CommentFilterMode):
    """
    Individual Filter Mode
    Each comment evaluated independently, no tree pruning.
    """

    @staticmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """Filter comments individually"""
        filtered = []

        for comment in comments:
            # Merge moderation
            filter_lib.merge_moderation(comment, moderation_data)

            # Apply rules
            if filter_lib.apply_rules(comment, rules):
                filtered.append(comment)

        return filtered


class ScoreBasedFilterMode(CommentFilterMode):
    """
    Score-Based Filter Mode
    Filter comments based on score thresholds, keeping high-quality content.
    """

    @staticmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """Filter comments based on score and rules"""
        filtered = []

        for comment in comments:
            # Merge moderation
            filter_lib.merge_moderation(comment, moderation_data)

            # Apply basic rules first
            if not filter_lib.apply_rules(comment, rules):
                continue

            # Additional score-based filtering
            score = comment.get('score', 0)
            min_score = rules.get('score', {}).get('min', -1000)  # Default very low threshold
            
            if score >= min_score:
                filtered.append(comment)

        return filtered


class TimeBoundFilterMode(CommentFilterMode):
    """
    Time-Bound Filter Mode
    Filter comments within specific time ranges.
    """

    @staticmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """Filter comments within time bounds"""
        from datetime import datetime
        
        filtered = []

        for comment in comments:
            # Merge moderation
            filter_lib.merge_moderation(comment, moderation_data)

            # Apply basic rules first
            if not filter_lib.apply_rules(comment, rules):
                continue

            # Time-based filtering
            timestamp = comment.get('timestamp')
            if timestamp:
                try:
                    comment_time = datetime.fromisoformat(timestamp.replace('Z', '+00:00'))
                    time_rules = rules.get('timestamp', {})
                    
                    after = time_rules.get('after')
                    before = time_rules.get('before')
                    
                    if after:
                        after_time = datetime.fromisoformat(after.replace('Z', '+00:00'))
                        if comment_time <= after_time:
                            continue
                    
                    if before:
                        before_time = datetime.fromisoformat(before.replace('Z', '+00:00'))
                        if comment_time >= before_time:
                            continue
                            
                    filtered.append(comment)
                except (ValueError, TypeError):
                    # Skip malformed timestamps
                    continue
            else:
                # No timestamp, include if no time rules
                if 'timestamp' not in rules:
                    filtered.append(comment)

        return filtered


class ContentLengthFilterMode(CommentFilterMode):
    """
    Content Length Filter Mode
    Filter comments based on content length criteria.
    """

    @staticmethod
    def filter(comments: List[Dict], rules: Dict, moderation_data: Dict) -> List[Dict]:
        """Filter comments based on content length"""
        filtered = []

        for comment in comments:
            # Merge moderation
            filter_lib.merge_moderation(comment, moderation_data)

            # Apply basic rules first
            if not filter_lib.apply_rules(comment, rules):
                continue

            # Content length filtering
            content = comment.get('content', '')
            content_length = len(content)
            
            length_rules = rules.get('content_length', {})
            min_length = length_rules.get('min', 0)
            max_length = length_rules.get('max', float('inf'))
            
            if min_length <= content_length <= max_length:
                filtered.append(comment)

        return filtered