# app/services/memory/semantic/extraction.py
"""
Fact Extraction from Episodes.

Provides utilities for extracting semantic facts (subject-predicate-object triples)
from episodic memories and other text sources.
"""

import logging
import re
from dataclasses import dataclass, field
from typing import Any, ClassVar

from app.services.memory.types import Episode, FactCreate, Outcome

logger = logging.getLogger(__name__)


@dataclass
class ExtractionContext:
    """Context for fact extraction."""

    project_id: Any | None = None
    source_episode_id: Any | None = None
    min_confidence: float = 0.5
    max_facts_per_source: int = 10


@dataclass
class ExtractedFact:
    """A fact extracted from text before storage."""

    subject: str
    predicate: str
    object: str
    confidence: float
    source_text: str = ""
    metadata: dict[str, Any] = field(default_factory=dict)

    def to_fact_create(
        self,
        project_id: Any | None = None,
        source_episode_ids: list[Any] | None = None,
    ) -> FactCreate:
        """Convert to FactCreate for storage."""
        return FactCreate(
            subject=self.subject,
            predicate=self.predicate,
            object=self.object,
            confidence=self.confidence,
            project_id=project_id,
            source_episode_ids=source_episode_ids or [],
        )


class FactExtractor:
    """
    Extracts facts from episodes and text.

    This is a rule-based extractor. In production, this would be
    replaced or augmented with LLM-based extraction for better accuracy.
    """

    # Common predicates we can detect
    PREDICATE_PATTERNS: ClassVar[dict[str, str]] = {
        "uses": r"(?:uses?|using|utilizes?)",
        "requires": r"(?:requires?|needs?|depends?\s+on)",
        "is_a": r"(?:is\s+a|is\s+an|are\s+a|are)",
        "has": r"(?:has|have|contains?)",
        "part_of": r"(?:part\s+of|belongs?\s+to|member\s+of)",
        "causes": r"(?:causes?|leads?\s+to|results?\s+in)",
        "prevents": r"(?:prevents?|avoids?|stops?)",
        "solves": r"(?:solves?|fixes?|resolves?)",
    }

    def __init__(self) -> None:
        """Initialize extractor."""
        self._compiled_patterns = {
            pred: re.compile(pattern, re.IGNORECASE)
            for pred, pattern in self.PREDICATE_PATTERNS.items()
        }

    def extract_from_episode(
        self,
        episode: Episode,
        context: ExtractionContext | None = None,
    ) -> list[ExtractedFact]:
        """
        Extract facts from an episode.

        Args:
            episode: Episode to extract from
            context: Optional extraction context

        Returns:
            List of extracted facts
        """
        ctx = context or ExtractionContext()
        facts: list[ExtractedFact] = []

        # Extract from task description
        task_facts = self._extract_from_text(
            episode.task_description,
            source_prefix=episode.task_type,
        )
        facts.extend(task_facts)

        # Extract from lessons learned
        for lesson in episode.lessons_learned:
            lesson_facts = self._extract_from_lesson(lesson, episode)
            facts.extend(lesson_facts)

        # Extract outcome-based facts
        outcome_facts = self._extract_outcome_facts(episode)
        facts.extend(outcome_facts)

        # Limit and filter
        facts = [f for f in facts if f.confidence >= ctx.min_confidence]
        facts = facts[: ctx.max_facts_per_source]

        logger.debug(f"Extracted {len(facts)} facts from episode {episode.id}")

        return facts

    def _extract_from_text(
        self,
        text: str,
        source_prefix: str = "",
    ) -> list[ExtractedFact]:
        """Extract facts from free-form text using pattern matching."""
        facts: list[ExtractedFact] = []

        if not text or len(text) < 10:
            return facts

        # Split into sentences
        sentences = re.split(r"[.!?]+", text)

        for sentence in sentences:
            sentence = sentence.strip()
            if len(sentence) < 10:
                continue

            # Try to match predicate patterns
            for predicate, pattern in self._compiled_patterns.items():
                match = pattern.search(sentence)
                if match:
                    # Extract subject (text before predicate)
                    subject = sentence[: match.start()].strip()
                    # Extract object (text after predicate)
                    obj = sentence[match.end() :].strip()

                    if len(subject) > 2 and len(obj) > 2:
                        facts.append(
                            ExtractedFact(
                                subject=subject[:200],  # Limit length
                                predicate=predicate,
                                object=obj[:500],
                                confidence=0.6,  # Medium confidence for pattern matching
                                source_text=sentence,
                            )
                        )
                        break  # One fact per sentence

        return facts

    def _extract_from_lesson(
        self,
        lesson: str,
        episode: Episode,
    ) -> list[ExtractedFact]:
        """Extract facts from a lesson learned."""
        facts: list[ExtractedFact] = []

        if not lesson or len(lesson) < 10:
            return facts

        # Lessons are typically in the form "Always do X" or "Never do Y"
        # or "When X, do Y"

        # Direct lesson fact
        facts.append(
            ExtractedFact(
                subject=episode.task_type,
                predicate="lesson_learned",
                object=lesson,
                confidence=0.8,  # High confidence for explicit lessons
                source_text=lesson,
                metadata={"outcome": episode.outcome.value},
            )
        )

        # Extract conditional patterns
        conditional_match = re.match(
            r"(?:when|if)\s+(.+?),\s*(.+)",
            lesson,
            re.IGNORECASE,
        )
        if conditional_match:
            condition, action = conditional_match.groups()
            facts.append(
                ExtractedFact(
                    subject=condition.strip(),
                    predicate="requires_action",
                    object=action.strip(),
                    confidence=0.7,
                    source_text=lesson,
                )
            )

        # Extract "always/never" patterns
        always_match = re.match(
            r"(?:always)\s+(.+)",
            lesson,
            re.IGNORECASE,
        )
        if always_match:
            facts.append(
                ExtractedFact(
                    subject=episode.task_type,
                    predicate="best_practice",
                    object=always_match.group(1).strip(),
                    confidence=0.85,
                    source_text=lesson,
                )
            )

        never_match = re.match(
            r"(?:never|avoid)\s+(.+)",
            lesson,
            re.IGNORECASE,
        )
        if never_match:
            facts.append(
                ExtractedFact(
                    subject=episode.task_type,
                    predicate="anti_pattern",
                    object=never_match.group(1).strip(),
                    confidence=0.85,
                    source_text=lesson,
                )
            )

        return facts

    def _extract_outcome_facts(
        self,
        episode: Episode,
    ) -> list[ExtractedFact]:
        """Extract facts based on episode outcome."""
        facts: list[ExtractedFact] = []

        # Create fact based on outcome
        if episode.outcome == Outcome.SUCCESS:
            if episode.outcome_details:
                facts.append(
                    ExtractedFact(
                        subject=episode.task_type,
                        predicate="successful_approach",
                        object=episode.outcome_details[:500],
                        confidence=0.75,
                        source_text=episode.outcome_details,
                    )
                )
        elif episode.outcome == Outcome.FAILURE:
            if episode.outcome_details:
                facts.append(
                    ExtractedFact(
                        subject=episode.task_type,
                        predicate="known_failure_mode",
                        object=episode.outcome_details[:500],
                        confidence=0.8,  # High confidence for failures
                        source_text=episode.outcome_details,
                    )
                )

        return facts

    def extract_from_text(
        self,
        text: str,
        context: ExtractionContext | None = None,
    ) -> list[ExtractedFact]:
        """
        Extract facts from arbitrary text.

        Args:
            text: Text to extract from
            context: Optional extraction context

        Returns:
            List of extracted facts
        """
        ctx = context or ExtractionContext()

        facts = self._extract_from_text(text)

        # Filter by confidence
        facts = [f for f in facts if f.confidence >= ctx.min_confidence]

        return facts[: ctx.max_facts_per_source]


# Singleton extractor instance
_extractor: FactExtractor | None = None


def get_fact_extractor() -> FactExtractor:
    """Get the singleton fact extractor instance."""
    global _extractor
    if _extractor is None:
        _extractor = FactExtractor()
    return _extractor