"""
Milvus Retriever Client for NEXUS OS v2
Uses Free-01 and Serverless-01 clusters (aws-eu-central-1).

API key: loaded from env MILVUS_API_KEY or MILVUS_URI
"""
import os
from typing import List, Dict, Optional, Any
from dataclasses import dataclass

try:
    from pymilvus import MilvusClient, DataType
    MILVUS_AVAILABLE = True
except ImportError:
    MILVUS_AVAILABLE = False


@dataclass
class MilvusResult:
    text: str
    score: float
    metadata: Dict[str, Any]
    collection: str


class MilvusRetriever:
    """
    Milvus retriever using Zilliz Cloud clusters.
    Supports both Free-01 and Serverless-01 endpoints.
    """

    CLUSTERS = {
        "free-01": "https://in03-9e3e3e3e3e3e3e3e.api.aws-eu-central-1.zillizcloud.com",  # placeholder
        "serverless-01": "https://in03-serverless.api.aws-eu-central-1.zillizcloud.com",  # placeholder
    }

    def __init__(
        self,
        cluster: str = "serverless-01",
        api_key: Optional[str] = None,
        uri: Optional[str] = None,
        top_k: int = 10,
    ):
        if not MILVUS_AVAILABLE:
            raise ImportError("pymilvus not installed. Run: pip install pymilvus")
        self.api_key = api_key or os.environ.get("MILVUS_API_KEY")
        self.uri = uri or os.environ.get("MILVUS_URI") or self.CLUSTERS.get(cluster)
        if not self.uri:
            raise ValueError(f"MILVUS_URI or cluster name required. Known: {list(self.CLUSTERS.keys())}")
        self.client = MilvusClient(uri=self.uri, token=self.api_key)
        self.top_k = top_k

    def search(self, collection: str, query: str, top_k: Optional[int] = None) -> List[MilvusResult]:
        """Search a Milvus collection for relevant documents."""
        k = top_k or self.top_k
        results = self.client.search(
            collection_name=collection,
            data=[query],
            limit=k,
            output_fields=["text", "metadata"],
        )
        return [
            MilvusResult(
                text=r.get("entity", {}).get("text", ""),
                score=r.get("distance", 0.0),
                metadata=r.get("entity", {}).get("metadata", {}),
                collection=collection,
            )
            for r in results[0]  # Milvus returns list of lists
        ]

    def get_evidence(self, collection: str, query: str) -> List[Dict[str, Any]]:
        """Format Milvus results for CK-PLUG coupling."""
        results = self.search(collection, query)
        return [
            {"text": r.text, "relevance": r.score, "collection": r.collection}
            for r in results
        ]


class MockMilvusRetriever:
    """Offline mock of MilvusRetriever."""

    def __init__(self, top_k: int = 5):
        self.top_k = top_k
        self._collections = {
            "nexus_docs": [
                {"text": "NEXUS OS v2 uses BEC thermodynamic control for reasoning stability.", "score": 0.92},
                {"text": "Jarzynski equality filters non-equilibrium hallucination trajectories.", "score": 0.85},
                {"text": "ChimeraRouter selects between 35+ local models and 6 cloud APIs.", "score": 0.80},
            ],
            "research_papers": [
                {"text": "CK-PLUG modulates token-level knowledge reliance via Confidence Gain.", "score": 0.94},
                {"text": "Arnold et al. detect phase transitions in LLM output distributions.", "score": 0.87},
                {"text": "Kim derives intelligence Lagrangian on Fisher-metric manifold.", "score": 0.83},
            ],
        }

    def search(self, collection: str, query: str, top_k: Optional[int] = None) -> List[MilvusResult]:
        k = top_k or self.top_k
        docs = self._collections.get(collection, [])
        # Simple keyword scoring
        scored = []
        for doc in docs:
            overlap = len(set(query.lower().split()) & set(doc["text"].lower().split()))
            score = doc["score"] * (0.5 + 0.5 * (overlap / max(1, len(query.split()))))
            scored.append(MilvusResult(text=doc["text"], score=score, metadata={}, collection=collection))
        scored.sort(key=lambda x: x.score, reverse=True)
        return scored[:k]

    def get_evidence(self, collection: str, query: str) -> List[Dict[str, Any]]:
        results = self.search(collection, query)
        return [{"text": r.text, "relevance": r.score, "collection": r.collection} for r in results]