"""KB 隔离的 ChromaDB 语义搜索适配器。

每个知识库拥有独立的 ChromaDB collection。
调用者: backend/rag_adapter.py, agent/nodes.py, api_server.py
"""

import os
import logging
from pathlib import Path
from typing import Optional

from dotenv import load_dotenv

load_dotenv()

logger = logging.getLogger(__name__)

_PROJECT_ROOT = Path(__file__).resolve().parent.parent


def _resolve(path: str) -> Path:
    p = Path(path)
    return p if p.is_absolute() else _PROJECT_ROOT / p


class KBChromaSearcher:
    """连接指定 KB 的 ChromaDB，提供语义搜索。"""

    def __init__(self, chroma_path: str, collection_name: str = "kb_chunks",
                 model_name: Optional[str] = None, use_gpu: Optional[bool] = None,
                 use_fp16: Optional[bool] = None):
        self.chroma_path = str(_resolve(chroma_path))
        self.collection_name = collection_name
        model_path = model_name or os.getenv(
            "RAG_EMBED_MODEL", "./rag/models/paraphrase-multilingual-MiniLM-L12-v2")
        resolved = _resolve(model_path)
        self.model_name = str(resolved) if resolved.exists() else model_path
        self.use_gpu = (use_gpu if use_gpu is not None
                        else os.getenv("RAG_USE_GPU", "true").lower() in ("true", "1"))
        self.use_fp16 = (use_fp16 if use_fp16 is not None
                         else os.getenv("RAG_USE_FP16", "true").lower() in ("true", "1"))
        self._model = None
        self._client = None
        self._collection = None

    @property
    def model(self):
        if self._model is None:
            import torch
            from sentence_transformers import SentenceTransformer
            device = "cuda" if (self.use_gpu and torch.cuda.is_available()) else "cpu"
            logger.info("加载嵌入模型: %s (device=%s)", self.model_name, device)
            model = SentenceTransformer(self.model_name, device=device)
            if device == "cuda" and self.use_fp16:
                model = model.half()
            self._model = model
        return self._model

    @property
    def client(self):
        if self._client is None:
            import chromadb
            self._client = chromadb.PersistentClient(path=self.chroma_path)
        return self._client

    @property
    def collection(self):
        if self._collection is None:
            try:
                self._collection = self.client.get_collection(self.collection_name)
            except Exception:
                self._collection = self.client.create_collection(
                    self.collection_name, metadata={"hnsw:space": "cosine"})
        return self._collection

    def is_ready(self) -> bool:
        try:
            self.client.get_collection(self.collection_name)
            return True
        except Exception:
            return False

    def search(self, query: str, k: int = 5, threshold: Optional[float] = None) -> list[dict]:
        if not self.is_ready():
            return []
        query_embedding = self.model.encode(
            query, normalize_embeddings=True, show_progress_bar=False)
        results = self.collection.query(
            query_embeddings=[query_embedding.tolist()],
            n_results=k, include=["documents", "metadatas", "distances"])
        output = []
        if not results["ids"] or not results["ids"][0]:
            return output
        for i, doc_id in enumerate(results["ids"][0]):
            dist = results["distances"][0][i]
            if threshold is not None and dist > threshold:
                continue
            output.append({
                "id": doc_id,
                "content": results["documents"][0][i],
                "metadata": results["metadatas"][0][i] or {},
                "distance": dist,
            })
        return output

    def search_templates(self, query: str, k: int = 3) -> list[dict]:
        results = self.search(query, k=k * 2)
        templates = []
        for r in results:
            meta = r.get("metadata", {})
            chunk_type = meta.get("chunk_type", "")
            if "jrxml" in chunk_type.lower() or meta.get("report_name"):
                templates.append(r)
                if len(templates) >= k:
                    break
        return templates

    def search_as_context(self, query: str, k: int = 5) -> str:
        results = self.search(query, k=k)
        if not results:
            return ""
        parts = []
        for r in results:
            meta = r.get("metadata", {})
            header = f"[类型:{meta.get('chunk_type', 'N/A')}]"
            if meta.get("report_name"):
                header += f" [报表:{meta['report_name']}]"
            parts.append(f"{header}\n{r['content']}")
        return "\n\n---\n\n".join(parts)

    def add_chunks(self, chunks: list[dict]) -> None:
        if not chunks:
            return
        ids = [c["id"] for c in chunks]
        docs = [c["content"] for c in chunks]
        metas = [c.get("metadata", {}) for c in chunks]
        embeddings = self.model.encode(
            docs, normalize_embeddings=True, show_progress_bar=True)
        self.collection.upsert(
            ids=ids, documents=docs, metadatas=metas,
            embeddings=embeddings.tolist())


_searchers: dict = {}


def get_kb_searcher(kb_id: str) -> Optional[KBChromaSearcher]:
    from backend.kb_manager import get_kb_chroma_path
    if kb_id in _searchers:
        return _searchers[kb_id]
    chroma_path = get_kb_chroma_path(kb_id)
    if chroma_path is None:
        return None
    searcher = KBChromaSearcher(str(chroma_path))
    _searchers[kb_id] = searcher
    return searcher


def search_kb(kb_id: str, query: str, k: int = 5) -> str:
    searcher = get_kb_searcher(kb_id)
    if searcher is None:
        return ""
    return searcher.search_as_context(query, k=k)


def search_templates_in_kb(kb_id: str, query: str, k: int = 3) -> list[dict]:
    searcher = get_kb_searcher(kb_id)
    if searcher is None:
        return []
    return searcher.search_templates(query, k=k)