"""
embed_chromadb.py
-----------------
Generates BioLORD-2023 embeddings for each Orphanet disease and stores
them in ChromaDB.

Primary:  ChromaDB HTTP client (Docker service at localhost:8000)
Fallback: ChromaDB PersistentClient (embedded, no server required)

Embedding text strategy:
  "<name>. <definition>. Also known as: <syn1>, <syn2>, ..."
"""

import os
import sys
from pathlib import Path
from lxml import etree
import chromadb
from chromadb.config import Settings
from sentence_transformers import SentenceTransformer
from dotenv import load_dotenv

load_dotenv(Path(__file__).parents[2] / ".env")

CHROMA_HOST = os.getenv("CHROMA_HOST", "localhost")
CHROMA_PORT = int(os.getenv("CHROMA_PORT", "8000"))
COLLECTION_NAME = os.getenv("CHROMA_COLLECTION", "rare_diseases")
EMBED_MODEL = os.getenv("EMBED_MODEL", "FremyCompany/BioLORD-2023")
XML_PATH = Path(os.getenv("ORPHANET_XML", "./data/orphanet/en_product1.xml"))

CHROMA_PERSIST_DIR = Path(__file__).parents[2] / "data" / "chromadb"
BATCH_SIZE = 32


# ---------------------------------------------------------------------------
# XML parsing
# ---------------------------------------------------------------------------

def _text(element, xpath: str) -> str:
    nodes = element.xpath(xpath)
    if nodes:
        val = nodes[0]
        return (val.text or "").strip() if hasattr(val, "text") else str(val).strip()
    return ""


def parse_disorders(xml_path: Path) -> list[dict]:
    print(f"Parsing {xml_path} ...")
    tree = etree.parse(str(xml_path))
    root = tree.getroot()
    disorders = []
    for disorder in root.xpath("//Disorder"):
        orpha_code = _text(disorder, "OrphaCode")
        name = _text(disorder, "Name[@lang='en']")
        definition = _text(disorder, "TextAuto[@lang='en']")
        synonyms = [
            s.text.strip()
            for s in disorder.xpath("SynonymList/Synonym[@lang='en']")
            if s.text and s.text.strip()
        ]
        if not orpha_code or not name:
            continue

        parts = [name]
        if definition:
            parts.append(definition)
        if synonyms:
            parts.append(f"Also known as: {', '.join(synonyms)}.")
        embed_text = " ".join(parts)

        disorders.append({
            "id": f"ORPHA:{orpha_code}",
            "orpha_code": orpha_code,
            "name": name,
            "definition": definition,
            "synonyms": synonyms,
            "embed_text": embed_text,
        })

    print(f"  Parsed {len(disorders)} disorders.")
    return disorders


# ---------------------------------------------------------------------------
# ChromaDB client — HTTP first, persistent fallback
# ---------------------------------------------------------------------------

def get_chroma_client() -> tuple[chromadb.ClientAPI, str]:
    """
    Try HTTP client (Docker). On failure, fall back to embedded PersistentClient.
    Returns (client, backend_label).
    """
    try:
        client = chromadb.HttpClient(
            host=CHROMA_HOST,
            port=CHROMA_PORT,
            settings=Settings(anonymized_telemetry=False),
        )
        client.heartbeat()
        print("  ChromaDB HTTP server connected.")
        return client, "ChromaDB HTTP (Docker)"
    except Exception as exc:
        print(f"  ChromaDB HTTP not reachable ({exc}).")
        print(f"  Using embedded PersistentClient at {CHROMA_PERSIST_DIR}")
        CHROMA_PERSIST_DIR.mkdir(parents=True, exist_ok=True)
        client = chromadb.PersistentClient(
            path=str(CHROMA_PERSIST_DIR),
            settings=Settings(anonymized_telemetry=False),
        )
        return client, "ChromaDB Embedded (local)"


def get_or_create_collection(client: chromadb.ClientAPI, name: str) -> chromadb.Collection:
    try:
        client.delete_collection(name)
        print(f"  Deleted existing collection '{name}'.")
    except Exception:
        pass
    collection = client.create_collection(
        name=name,
        metadata={"hnsw:space": "cosine"},
    )
    print(f"  Created collection '{name}'.")
    return collection


def upsert_in_batches(
    collection: chromadb.Collection,
    disorders: list[dict],
    embeddings: list[list[float]],
) -> None:
    for i in range(0, len(disorders), BATCH_SIZE):
        bd = disorders[i : i + BATCH_SIZE]
        be = embeddings[i : i + BATCH_SIZE]
        collection.upsert(
            ids=[d["id"] for d in bd],
            embeddings=be,
            documents=[d["embed_text"] for d in bd],
            metadatas=[
                {
                    "orpha_code": d["orpha_code"],
                    "name": d["name"],
                    "definition": d["definition"][:500] if d["definition"] else "",
                    "synonyms": ", ".join(d["synonyms"]),
                }
                for d in bd
            ],
        )
        print(f"  Upserted {min(i + BATCH_SIZE, len(disorders))} / {len(disorders)} ...", end="\r")
    print()


# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------

def main() -> None:
    print("=" * 60)
    print("RareDx — Step 3: Embed Diseases into ChromaDB (BioLORD-2023)")
    print("=" * 60)

    if not XML_PATH.exists():
        print(f"ERROR: XML not found at {XML_PATH}. Run download_orphanet.py first.")
        sys.exit(1)

    disorders = parse_disorders(XML_PATH)

    # Load BioLORD-2023
    print(f"\nLoading embedding model: {EMBED_MODEL}")
    print("  (First run will download ~440 MB from HuggingFace — please wait.)")
    model = SentenceTransformer(EMBED_MODEL)
    dim = model.get_sentence_embedding_dimension()
    print(f"  Model loaded. Embedding dim: {dim}")

    # Generate embeddings
    print(f"\nGenerating embeddings for {len(disorders)} diseases...")
    texts = [d["embed_text"] for d in disorders]
    embeddings = model.encode(
        texts,
        batch_size=BATCH_SIZE,
        show_progress_bar=True,
        normalize_embeddings=True,
    )
    print(f"  Embeddings shape: {embeddings.shape}")

    # Connect to ChromaDB
    print("\nConnecting to ChromaDB...")
    chroma, backend_label = get_chroma_client()
    collection = get_or_create_collection(chroma, COLLECTION_NAME)

    print(f"\nUpserting {len(disorders)} documents...")
    upsert_in_batches(collection, disorders, embeddings.tolist())

    final_count = collection.count()
    print(f"  Collection '{COLLECTION_NAME}' has {final_count} documents.")

    # Sanity check
    print("\nSanity check: semantic search for 'connective tissue disorder'")
    probe = model.encode(["connective tissue disorder"], normalize_embeddings=True)
    results = collection.query(query_embeddings=probe.tolist(), n_results=3)
    for meta in results["metadatas"][0]:
        print(f"  -> [{meta['orpha_code']}] {meta['name']}")

    print(f"\nStep 3 complete — backend: {backend_label}")


if __name__ == "__main__":
    main()