"""
Knowledge Universe — Embedding Adapter
Produces vector embeddings for RAG pipeline consumption.
Uses local sentence-transformers (all-MiniLM-L6-v2) — no OpenAI API needed.

Output is a KnowledgeObject with embedding field populated,
ready to be inserted into any vector store (Qdrant, Weaviate, Chroma, Pinecone).
"""

import logging
from typing import Any, Dict, List, Optional
from datetime import datetime

from src.api.models import Source, KnowledgeObject
from src.format_adapters.base_adapter import BaseFormatAdapter

logger = logging.getLogger(__name__)

# Lazy-loaded model (first call loads it, subsequent calls reuse)
_model = None


def _get_model():
    global _model
    if _model is None:
        try:
            from sentence_transformers import SentenceTransformer
            _model = SentenceTransformer("all-MiniLM-L6-v2")
            logger.info("SentenceTransformer loaded: all-MiniLM-L6-v2")
        except Exception as e:
            logger.error(f"Failed to load embedding model: {e}")
            raise
    return _model


class EmbeddingAdapter(BaseFormatAdapter):
    """
    Converts sources to KnowledgeObjects with vector embeddings.

    The embedding encodes: title + summary + tags + platform
    Dimensionality: 384 (all-MiniLM-L6-v2)

    Ready for: Qdrant, Weaviate, ChromaDB, Pinecone, pgvector
    """

    def transform(self, source: Source) -> KnowledgeObject:
        embedding = self._embed(source)

        return KnowledgeObject(
            source_id=source.id,
            title=source.title,
            url=source.url,
            platform=source.source_platform,
            format=source.formats[0] if source.formats else None,

            quality_score=source.quality_score,
            pedagogical_fit=source.pedagogical_fit,
            freshness_score=self._freshness_score(source),

            authors=source.authors,
            publication_date=source.publication_date,
            license=source.license,
            open_access=source.open_access,

            embedding=embedding,

            summary=source.summary,
            tags=source.tags,
        )

    def transform_many(self, sources: list) -> list:
        """Batch embed — more efficient than one-by-one."""
        if not sources:
            return []

        texts = [self._source_to_text(s) for s in sources]

        try:
            model = _get_model()
            embeddings = model.encode(texts, convert_to_numpy=True)
            embeddings_list = embeddings.tolist()
        except Exception as e:
            logger.error(f"Batch embedding failed: {e}")
            embeddings_list = [None] * len(sources)

        results = []
        for source, embedding in zip(sources, embeddings_list):
            obj = KnowledgeObject(
                source_id=source.id,
                title=source.title,
                url=source.url,
                platform=source.source_platform,
                format=source.formats[0] if source.formats else None,

                quality_score=source.quality_score,
                pedagogical_fit=source.pedagogical_fit,
                freshness_score=self._freshness_score(source),

                authors=source.authors,
                publication_date=source.publication_date,
                license=source.license,
                open_access=source.open_access,

                embedding=embedding,
                summary=source.summary,
                tags=source.tags,
            )
            results.append(obj)

        return results

    def _embed(self, source: Source) -> Optional[List[float]]:
        try:
            model = _get_model()
            text = self._source_to_text(source)
            vector = model.encode(text, convert_to_numpy=True)
            return vector.tolist()
        except Exception as e:
            logger.error(f"Embedding failed for {source.id}: {e}")
            return None

    def _source_to_text(self, source: Source) -> str:
        """Concatenate fields that describe the source's semantic content."""
        parts = [
            source.title,
            source.summary[:300] if source.summary else "",
            " ".join(source.tags[:10]),
            source.source_platform,
            " ".join(f.value for f in source.formats),
            " ".join(source.authors[:2]),
        ]
        return " | ".join(p for p in parts if p)

    def _freshness_score(self, source: Source) -> float:
        """Compute 0-1 freshness score from publication date."""
        if not source.publication_date:
            return 0.5
        try:
            days = (datetime.now(source.publication_date.tzinfo) - source.publication_date).days
            if days < 180:   return 1.0
            if days < 720:   return 0.8
            if days < 1800:  return 0.6
            return 0.4
        except Exception:
            return 0.5


# ── Qdrant upload helper (optional, call from scripts) ─────────────────────

def upload_to_qdrant(
    knowledge_objects: List[KnowledgeObject],
    collection: str = "knowledge_universe",
    qdrant_url: str = "http://localhost:6333",
):
    """
    Upload KnowledgeObjects to a local Qdrant instance.
    Run Qdrant with: docker run -p 6333:6333 qdrant/qdrant

    This is completely free — no cloud dependency.
    """
    try:
        from qdrant_client import QdrantClient
        from qdrant_client.models import PointStruct, Distance, VectorParams

        client = QdrantClient(url=qdrant_url)

        # Create collection if needed
        try:
            client.create_collection(
                collection_name=collection,
                vectors_config=VectorParams(size=384, distance=Distance.COSINE),
            )
        except Exception:
            pass   # already exists

        points = [
            PointStruct(
                id=abs(hash(obj.source_id)) % (2**32),
                vector=obj.embedding,
                payload={
                    "source_id": obj.source_id,
                    "title": obj.title,
                    "url": obj.url,
                    "platform": obj.platform,
                    "quality_score": obj.quality_score,
                    "summary": obj.summary,
                    "tags": obj.tags,
                },
            )
            for obj in knowledge_objects
            if obj.embedding
        ]

        client.upsert(collection_name=collection, points=points)
        logger.info(f"Uploaded {len(points)} vectors to Qdrant collection '{collection}'")
        return len(points)

    except ImportError:
        logger.error("qdrant-client not installed. Run: pip install qdrant-client")
        return 0
    except Exception as e:
        logger.error(f"Qdrant upload failed: {e}")
        return 0