import os, json, glob, pickle, logging
from typing import List, Dict, Any
from underthesea import word_tokenize
from rank_bm25 import BM25Okapi
from pathlib import Path

# ---------------------------
# Config & Logging
# ---------------------------
logging.basicConfig(
    level=os.getenv("LOG_LEVEL", "INFO"),
    format="%(asctime)s | %(levelname)s | %(name)s | %(message)s"
)
logger = logging.getLogger("bm25_local_indexer")

BASE_DIR = Path(__file__).resolve().parent.parent
CHUNKS_DIR = BASE_DIR / "chunks"
INDEX_OUT = BASE_DIR / "bm25_index.pkl"
MAX_TOKENS = 512
# ---------------------------
# Tokenization (Tiếng Việt)
# ---------------------------
def tokenize_vi(text: str) -> List[str]:
    return word_tokenize(text, format="text").lower().split()

# ---------------------------
# Load Chunks
# ---------------------------
def load_chunks(chunks_dir: Path) -> List[Dict[str, Any]]:
    files = chunks_dir.glob("*.json")
    docs = []
    for fp in files:
        # Skip manifest files
        if "manifest" in fp.name.lower():
            logger.info("Skipping manifest file: %s", fp)
            continue
            
        try:
            with open(fp, "r", encoding="utf-8") as f:
                ch = json.load(f)
        except Exception as e:
            logger.warning("Failed to read %s: %s", fp, e)
            continue
        
        text = ch.get("chunk_text", "")
        docs.append({
            "id": ch["id"],
            "doc_id": ch.get("doc_id"),
            "path": ch.get("path"),
            "text": text,
            "chunk_for_embedding": ch.get("chunk_for_embedding"),
            "token_count": ch.get("token_count")
        })
    logger.info("Loaded %d chunks", len(docs))
    return docs

# ---------------------------
# Build BM25 Index
# ---------------------------
def build_bm25_index(chunks: List[Dict[str, Any]]) -> Dict[str, Any]:
    corpus = [tokenize_vi(c["text"]) for c in chunks]
    bm25 = BM25Okapi(corpus)
    index = {   
        "bm25": bm25,
        "chunks": chunks,
        "tokenized_corpus": corpus
    }
    return index

# ---------------------------
# Save & Load index
# ---------------------------
def save_index(index: Dict[str, Any], out_path: str):
    with open(out_path, "wb") as f:
        pickle.dump(index, f)
    logger.info("Saved BM25 index to %s", out_path)

def load_index(path: str) -> Dict[str, Any]:
    with open(path, "rb") as f:
        return pickle.load(f)

# ---------------------------
# CLI
# ---------------------------

def main(reindex: bool, check: bool):
    if reindex:
        chunks = load_chunks(CHUNKS_DIR)
        idx = build_bm25_index(chunks)
        save_index(idx, INDEX_OUT)
    
    if check:
        idx = load_index(INDEX_OUT)
        logger.info("Index contains %d chunks", len(idx["chunks"]))

if __name__ == "__main__":
    main(reindex=True, check=True)