import os
import faiss
import numpy as np
from src.customlogger import log_time, logger

# Type alias to decouple from FAISS
Index = faiss.IndexFlat

INDEX_FILE = "proverbs.index"

# This were the index types tested
INDEX_TYPES = [faiss.IndexFlatL2, faiss.IndexFlatIP]
# This is the pooling method used in the final iteration
DEFAULT_INDEX_TYPE = faiss.IndexFlatL2


def index_exists(index_file: str = INDEX_FILE) -> bool:
    """Check if the index file exists."""
    return os.path.exists(index_file)


@log_time
def create_index(embeddings: np.ndarray, index_type: type = None, index_file: str = INDEX_FILE) -> Index:
    """Create a FAISS index and store the given embeddings."""
    if not index_type:
        index_type = DEFAULT_INDEX_TYPE

    dimension = embeddings.shape[1]
    logger.debug(
        f"Creating FAISS index with {len(embeddings)} {embeddings.shape[1]}-dimensional embeddings...")
    index = index_type(dimension)
    index.add(embeddings)
    logger.debug(f"Saving FAISS index to '{index_file}'...")
    faiss.write_index(index, index_file)
    return index


@log_time
def load_index(index_file: str = INDEX_FILE) -> Index:
    """Load the FAISS index from the specified file."""
    logger.debug(f"Loading FAISS index from '{index_file}'...")
    index = faiss.read_index(index_file)
    return index


@log_time
def find_closest(embeddings, index: Index, k=5) -> tuple[np.ndarray, np.ndarray]:
    """Find the closest k vectors in the index for the given embeddings."""
    logger.debug(
        f"Performing search for the top {k} matches of {len(embeddings)} embedding...")
    distances, indices = index.search(embeddings, k)
    return distances, indices