"""Deduplication service for conversations."""

from __future__ import annotations

import hashlib
import logging

logger = logging.getLogger(__name__)


class DeduplicationService:
    """Conversation deduplication service.

    Provides exact and fuzzy deduplication using:
    - SHA-256 hashes for exact matching
    - MinHash for fuzzy similarity matching
    """

    async def is_duplicate(
        self,
        content: str,
        existing_hashes: set[str],
    ) -> bool:
        """Check if content is a duplicate.

        Args:
            content: Conversation content
            existing_hashes: Set of existing content hashes

        Returns:
            True if duplicate, False otherwise
        """
        content_hash = self._compute_hash(content)
        return content_hash in existing_hashes

    @staticmethod
    def _compute_hash(content: str) -> str:
        """Compute SHA-256 hash of content.

        Args:
            content: Content to hash

        Returns:
            Hex digest of hash
        """
        return hashlib.sha256(content.encode("utf-8")).hexdigest()

    async def compute_fingerprint(
        self,
        content: str,
        num_permutations: int = 128,  # noqa: ARG002
    ) -> bytes:
        """Compute MinHash fingerprint for fuzzy matching.

        Args:
            content: Content to fingerprint
            num_permutations: Number of MinHash permutations

        Returns:
            MinHash fingerprint as bytes
        """
        # TODO: Implement proper MinHash
        # For now, use SHA-256 as placeholder
        return hashlib.sha256(content.encode("utf-8")).digest()

    async def find_similar(
        self,
        fingerprint: bytes,  # noqa: ARG002
        existing_fingerprints: list[bytes],  # noqa: ARG002
        threshold: float = 0.8,  # noqa: ARG002
    ) -> list[tuple[bytes, float]]:
        """Find similar conversations using fingerprint matching.

        Args:
            fingerprint: Query fingerprint
            existing_fingerprints: List of existing fingerprints
            threshold: Similarity threshold (0-1)

        Returns:
            List of (fingerprint, similarity) tuples above threshold
        """
        # TODO: Implement MinHash similarity calculation
        # For now, return empty list
        return []
