"""
This file contains the core API for the LEANN project, now definitively updated
with the correct, original embedding logic from the user's reference code.
"""

import json
import logging
import os
import pickle
import re
import subprocess
import time
import warnings
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Literal, Optional, Union

import numpy as np
from leann_backend_hnsw.convert_to_csr import prune_hnsw_embeddings_inplace

from leann.interactive_utils import create_api_session
from leann.interface import LeannBackendSearcherInterface

from .chat import get_llm
from .embedding_server_manager import EmbeddingServerManager
from .interface import LeannBackendFactoryInterface
from .metadata_filter import MetadataFilterEngine
from .registry import BACKEND_REGISTRY

logger = logging.getLogger(__name__)


def get_registered_backends() -> list[str]:
    """Get list of registered backend names."""
    return list(BACKEND_REGISTRY.keys())


def compute_embeddings(
    chunks: list[str],
    model_name: str,
    mode: str = "sentence-transformers",
    use_server: bool = True,
    port: Optional[int] = None,
    is_build=False,
    provider_options: Optional[dict[str, Any]] = None,
) -> np.ndarray:
    """
    Computes embeddings using different backends.

    Args:
        chunks: List of text chunks to embed
        model_name: Name of the embedding model
        mode: Embedding backend mode. Options:
            - "sentence-transformers": Use sentence-transformers library (default)
            - "mlx": Use MLX backend for Apple Silicon
            - "openai": Use OpenAI embedding API
            - "gemini": Use Google Gemini embedding API
        use_server: Whether to use embedding server (True for search, False for build)

    Returns:
        numpy array of embeddings
    """
    if use_server:
        # Use embedding server (for search/query)
        if port is None:
            raise ValueError("port is required when use_server is True")
        return compute_embeddings_via_server(chunks, model_name, port=port)
    else:
        # Use direct computation (for build_index)
        from .embedding_compute import (
            compute_embeddings as compute_embeddings_direct,
        )

        return compute_embeddings_direct(
            chunks,
            model_name,
            mode=mode,
            is_build=is_build,
            provider_options=provider_options,
        )


def compute_embeddings_via_server(chunks: list[str], model_name: str, port: int) -> np.ndarray:
    """Computes embeddings using sentence-transformers.

    Args:
        chunks: List of text chunks to embed
        model_name: Name of the sentence transformer model
    """
    logger.info(
        f"Computing embeddings for {len(chunks)} chunks using SentenceTransformer model '{model_name}' (via embedding server)..."
    )
    import msgpack
    import numpy as np
    import zmq

    # Connect to embedding server
    context = zmq.Context()
    socket = context.socket(zmq.REQ)
    socket.connect(f"tcp://localhost:{port}")

    # Send chunks to server for embedding computation
    request = chunks
    socket.send(msgpack.packb(request))

    # Receive embeddings from server
    response = socket.recv()
    embeddings_list = msgpack.unpackb(response)

    # Convert back to numpy array
    embeddings = np.array(embeddings_list, dtype=np.float32)

    socket.close()
    context.term()

    return embeddings


@dataclass
class SearchResult:
    id: str
    score: float
    text: str
    metadata: dict[str, Any] = field(default_factory=dict)


class PassageManager:
    def __init__(
        self, passage_sources: list[dict[str, Any]], metadata_file_path: Optional[str] = None
    ):
        self.offset_maps: dict[str, dict[str, int]] = {}
        self.passage_files: dict[str, str] = {}
        # Avoid materializing a single gigantic global map to reduce memory
        # footprint on very large corpora (e.g., 60M+ passages). Instead, keep
        # per-shard maps and do a lightweight per-shard lookup on demand.
        self._total_count: int = 0
        self.filter_engine = MetadataFilterEngine()  # Initialize filter engine

        # Derive index base name for standard sibling fallbacks, e.g., <index_name>.passages.*
        index_name_base = None
        if metadata_file_path:
            meta_name = Path(metadata_file_path).name
            if meta_name.endswith(".meta.json"):
                index_name_base = meta_name[: -len(".meta.json")]

        for source in passage_sources:
            assert source["type"] == "jsonl", "only jsonl is supported"
            passage_file = source.get("path", "")
            index_file = source.get("index_path", "")  # .idx file

            # Fix path resolution - relative paths should be relative to metadata file directory
            def _resolve_candidates(
                primary: str,
                relative_key: str,
                default_name: Optional[str],
                source_dict: dict[str, Any],
            ) -> list[Path]:
                """
                Build an ordered list of candidate paths. For relative paths specified in
                metadata, prefer resolution relative to the metadata file directory first,
                then fall back to CWD-based resolution, and finally to conventional
                sibling defaults (e.g., <index_base>.passages.idx / .jsonl).
                """
                candidates: list[Path] = []
                # 1) Primary path
                if primary:
                    p = Path(primary)
                    if p.is_absolute():
                        candidates.append(p)
                    else:
                        # Prefer metadata-relative resolution for relative paths
                        if metadata_file_path:
                            candidates.append(Path(metadata_file_path).parent / p)
                        # Also consider CWD-relative as a fallback for legacy layouts
                        candidates.append(Path.cwd() / p)
                # 2) metadata-relative explicit relative key (if present)
                if metadata_file_path and source_dict.get(relative_key):
                    candidates.append(Path(metadata_file_path).parent / source_dict[relative_key])
                # 3) metadata-relative standard sibling filename
                if metadata_file_path and default_name:
                    candidates.append(Path(metadata_file_path).parent / default_name)
                return candidates

            # Build candidate lists and pick first existing; otherwise keep last candidate for error message
            idx_default = f"{index_name_base}.passages.idx" if index_name_base else None
            idx_candidates = _resolve_candidates(
                index_file, "index_path_relative", idx_default, source
            )
            pas_default = f"{index_name_base}.passages.jsonl" if index_name_base else None
            pas_candidates = _resolve_candidates(passage_file, "path_relative", pas_default, source)

            def _pick_existing(cands: list[Path]) -> str:
                for c in cands:
                    if c.exists():
                        return str(c.resolve())
                # Fallback to last candidate (best guess) even if not exists; will error below
                return str(cands[-1].resolve()) if cands else ""

            index_file = _pick_existing(idx_candidates)
            passage_file = _pick_existing(pas_candidates)

            if not Path(index_file).exists():
                raise FileNotFoundError(f"Passage index file not found: {index_file}")

            with open(index_file, "rb") as f:
                offset_map: dict[str, int] = pickle.load(f)
                self.offset_maps[passage_file] = offset_map
                self.passage_files[passage_file] = passage_file
                self._total_count += len(offset_map)

    def get_passage(self, passage_id: str) -> dict[str, Any]:
        # Fast path: check each shard map (there are typically few shards).
        # This avoids building a massive combined dict while keeping lookups
        # bounded by the number of shards.
        for passage_file, offset_map in self.offset_maps.items():
            try:
                offset = offset_map[passage_id]
                with open(passage_file, encoding="utf-8") as f:
                    f.seek(offset)
                    return json.loads(f.readline())
            except KeyError:
                continue
        raise KeyError(f"Passage ID not found: {passage_id}")

    def filter_search_results(
        self,
        search_results: list[SearchResult],
        metadata_filters: Optional[dict[str, dict[str, Union[str, int, float, bool, list]]]],
    ) -> list[SearchResult]:
        """
        Apply metadata filters to search results.

        Args:
            search_results: List of SearchResult objects
            metadata_filters: Filter specifications to apply

        Returns:
            Filtered list of SearchResult objects
        """
        if not metadata_filters:
            return search_results

        logger.debug(f"Applying metadata filters to {len(search_results)} results")

        # Convert SearchResult objects to dictionaries for the filter engine
        result_dicts = []
        for result in search_results:
            result_dicts.append(
                {
                    "id": result.id,
                    "score": result.score,
                    "text": result.text,
                    "metadata": result.metadata,
                }
            )

        # Apply filters using the filter engine
        filtered_dicts = self.filter_engine.apply_filters(result_dicts, metadata_filters)

        # Convert back to SearchResult objects
        filtered_results = []
        for result_dict in filtered_dicts:
            filtered_results.append(
                SearchResult(
                    id=result_dict["id"],
                    score=result_dict["score"],
                    text=result_dict["text"],
                    metadata=result_dict["metadata"],
                )
            )

        logger.debug(f"Filtered results: {len(filtered_results)} remaining")
        return filtered_results

    def __len__(self) -> int:
        return self._total_count


class LeannBuilder:
    def __init__(
        self,
        backend_name: str,
        embedding_model: str = "facebook/contriever",
        dimensions: Optional[int] = None,
        embedding_mode: str = "sentence-transformers",
        embedding_options: Optional[dict[str, Any]] = None,
        **backend_kwargs,
    ):
        self.backend_name = backend_name
        # Normalize incompatible combinations early (for consistent metadata)
        if backend_name == "hnsw":
            is_recompute = backend_kwargs.get("is_recompute", True)
            is_compact = backend_kwargs.get("is_compact", True)
            if is_recompute is False and is_compact is True:
                warnings.warn(
                    "HNSW with is_recompute=False requires non-compact storage. Forcing is_compact=False.",
                    UserWarning,
                    stacklevel=2,
                )
                backend_kwargs["is_compact"] = False

        backend_factory: Optional[LeannBackendFactoryInterface] = BACKEND_REGISTRY.get(backend_name)
        if backend_factory is None:
            raise ValueError(f"Backend '{backend_name}' not found or not registered.")
        self.backend_factory = backend_factory
        self.embedding_model = embedding_model
        self.dimensions = dimensions
        self.embedding_mode = embedding_mode
        self.embedding_options = embedding_options or {}

        # Check if we need to use cosine distance for normalized embeddings
        normalized_embeddings_models = {
            # OpenAI models
            ("openai", "text-embedding-ada-002"),
            ("openai", "text-embedding-3-small"),
            ("openai", "text-embedding-3-large"),
            # Voyage AI models
            ("voyage", "voyage-2"),
            ("voyage", "voyage-3"),
            ("voyage", "voyage-large-2"),
            ("voyage", "voyage-multilingual-2"),
            ("voyage", "voyage-code-2"),
            # Cohere models
            ("cohere", "embed-english-v3.0"),
            ("cohere", "embed-multilingual-v3.0"),
            ("cohere", "embed-english-light-v3.0"),
            ("cohere", "embed-multilingual-light-v3.0"),
        }

        # Also check for patterns in model names
        is_normalized = False
        current_model_lower = embedding_model.lower()
        current_mode_lower = embedding_mode.lower()

        # Check exact matches
        for mode, model in normalized_embeddings_models:
            if (current_mode_lower == mode and current_model_lower == model) or (
                mode in current_mode_lower and model in current_model_lower
            ):
                is_normalized = True
                break

        # Check patterns
        if not is_normalized:
            # OpenAI patterns
            if "openai" in current_mode_lower or "openai" in current_model_lower:
                if any(
                    pattern in current_model_lower
                    for pattern in ["text-embedding", "ada", "3-small", "3-large"]
                ):
                    is_normalized = True
            # Voyage patterns
            elif "voyage" in current_mode_lower or "voyage" in current_model_lower:
                is_normalized = True
            # Cohere patterns
            elif "cohere" in current_mode_lower or "cohere" in current_model_lower:
                if "embed" in current_model_lower:
                    is_normalized = True

        # Handle distance metric
        if is_normalized and "distance_metric" not in backend_kwargs:
            backend_kwargs["distance_metric"] = "cosine"
            warnings.warn(
                f"Detected normalized embeddings model '{embedding_model}' with mode '{embedding_mode}'. "
                f"Automatically setting distance_metric='cosine' for optimal performance. "
                f"Normalized embeddings (L2 norm = 1) should use cosine similarity instead of MIPS.",
                UserWarning,
                stacklevel=2,
            )
        elif is_normalized and backend_kwargs.get("distance_metric", "").lower() != "cosine":
            current_metric = backend_kwargs.get("distance_metric", "mips")
            warnings.warn(
                f"Warning: Using '{current_metric}' distance metric with normalized embeddings model "
                f"'{embedding_model}' may lead to suboptimal search results. "
                f"Consider using 'cosine' distance metric for better performance.",
                UserWarning,
                stacklevel=2,
            )

        self.backend_kwargs = backend_kwargs
        self.chunks: list[dict[str, Any]] = []

    def add_text(self, text: str, metadata: Optional[dict[str, Any]] = None):
        if metadata is None:
            metadata = {}
        passage_id = metadata.get("id", str(len(self.chunks)))
        chunk_data = {"id": passage_id, "text": text, "metadata": metadata}
        self.chunks.append(chunk_data)

    def build_index(self, index_path: str):
        if not self.chunks:
            raise ValueError("No chunks added.")

        # Filter out invalid/empty text chunks early to keep passage and embedding counts aligned
        valid_chunks: list[dict[str, Any]] = []
        skipped = 0
        for chunk in self.chunks:
            text = chunk.get("text", "")
            if isinstance(text, str) and text.strip():
                valid_chunks.append(chunk)
            else:
                skipped += 1
        if skipped > 0:
            print(
                f"Warning: Skipping {skipped} empty/invalid text chunk(s). Processing {len(valid_chunks)} valid chunks"
            )
            self.chunks = valid_chunks
            if not self.chunks:
                raise ValueError("All provided chunks are empty or invalid. Nothing to index.")
        if self.dimensions is None:
            self.dimensions = len(
                compute_embeddings(
                    ["dummy"],
                    self.embedding_model,
                    self.embedding_mode,
                    use_server=False,
                    provider_options=self.embedding_options,
                )[0]
            )
        path = Path(index_path)
        index_dir = path.parent
        index_name = path.name
        index_dir.mkdir(parents=True, exist_ok=True)
        passages_file = index_dir / f"{index_name}.passages.jsonl"
        offset_file = index_dir / f"{index_name}.passages.idx"
        offset_map = {}
        with open(passages_file, "w", encoding="utf-8") as f:
            try:
                from tqdm import tqdm

                chunk_iterator = tqdm(self.chunks, desc="Writing passages", unit="chunk")
            except ImportError:
                chunk_iterator = self.chunks

            for chunk in chunk_iterator:
                offset = f.tell()
                json.dump(
                    {
                        "id": chunk["id"],
                        "text": chunk["text"],
                        "metadata": chunk["metadata"],
                    },
                    f,
                    ensure_ascii=False,
                )
                f.write("\n")
                offset_map[chunk["id"]] = offset
        with open(offset_file, "wb") as f:
            pickle.dump(offset_map, f)
        texts_to_embed = [c["text"] for c in self.chunks]
        embeddings = compute_embeddings(
            texts_to_embed,
            self.embedding_model,
            self.embedding_mode,
            use_server=False,
            is_build=True,
            provider_options=self.embedding_options,
        )
        string_ids = [chunk["id"] for chunk in self.chunks]
        # Persist ID map alongside index so backends that return integer labels can remap to passage IDs
        try:
            idmap_file = (
                index_dir
                / f"{index_name[: -len('.leann')] if index_name.endswith('.leann') else index_name}.ids.txt"
            )
            with open(idmap_file, "w", encoding="utf-8") as f:
                for sid in string_ids:
                    f.write(str(sid) + "\n")
        except Exception:
            pass
        current_backend_kwargs = {**self.backend_kwargs, "dimensions": self.dimensions}
        builder_instance = self.backend_factory.builder(**current_backend_kwargs)
        builder_instance.build(embeddings, string_ids, index_path, **current_backend_kwargs)
        leann_meta_path = index_dir / f"{index_name}.meta.json"
        meta_data = {
            "version": "1.0",
            "backend_name": self.backend_name,
            "embedding_model": self.embedding_model,
            "dimensions": self.dimensions,
            "backend_kwargs": self.backend_kwargs,
            "embedding_mode": self.embedding_mode,
            "passage_sources": [
                {
                    "type": "jsonl",
                    # Preserve existing relative file names (backward-compatible)
                    "path": passages_file.name,
                    "index_path": offset_file.name,
                    # Add optional redundant relative keys for remote build portability (non-breaking)
                    "path_relative": passages_file.name,
                    "index_path_relative": offset_file.name,
                }
            ],
        }

        if self.embedding_options:
            meta_data["embedding_options"] = self.embedding_options

        # Add storage status flags for HNSW backend
        if self.backend_name == "hnsw":
            is_compact = self.backend_kwargs.get("is_compact", True)
            is_recompute = self.backend_kwargs.get("is_recompute", True)
            meta_data["is_compact"] = is_compact
            meta_data["is_pruned"] = bool(is_recompute)
        with open(leann_meta_path, "w", encoding="utf-8") as f:
            json.dump(meta_data, f, indent=2)

    def build_index_from_embeddings(self, index_path: str, embeddings_file: str):
        """
        Build an index from pre-computed embeddings stored in a pickle file.

        Args:
            index_path: Path where the index will be saved
            embeddings_file: Path to pickle file containing (ids, embeddings) tuple
        """
        # Load pre-computed embeddings
        with open(embeddings_file, "rb") as f:
            data = pickle.load(f)

        if not isinstance(data, tuple) or len(data) != 2:
            raise ValueError(
                f"Invalid embeddings file format. Expected tuple with 2 elements, got {type(data)}"
            )

        ids, embeddings = data

        if not isinstance(embeddings, np.ndarray):
            raise ValueError(f"Expected embeddings to be numpy array, got {type(embeddings)}")

        if len(ids) != embeddings.shape[0]:
            raise ValueError(
                f"Mismatch between number of IDs ({len(ids)}) and embeddings ({embeddings.shape[0]})"
            )

        # Validate/set dimensions
        embedding_dim = embeddings.shape[1]
        if self.dimensions is None:
            self.dimensions = embedding_dim
        elif self.dimensions != embedding_dim:
            raise ValueError(f"Dimension mismatch: expected {self.dimensions}, got {embedding_dim}")

        logger.info(
            f"Building index from precomputed embeddings: {len(ids)} items, {embedding_dim} dimensions"
        )

        # Ensure we have text data for each embedding
        if len(self.chunks) != len(ids):
            # If no text chunks provided, create placeholder text entries
            if not self.chunks:
                logger.info("No text chunks provided, creating placeholder entries...")
                for id_val in ids:
                    self.add_text(
                        f"Document {id_val}",
                        metadata={"id": str(id_val), "from_embeddings": True},
                    )
            else:
                raise ValueError(
                    f"Number of text chunks ({len(self.chunks)}) doesn't match number of embeddings ({len(ids)})"
                )

        # Build file structure
        path = Path(index_path)
        index_dir = path.parent
        index_name = path.name
        index_dir.mkdir(parents=True, exist_ok=True)
        passages_file = index_dir / f"{index_name}.passages.jsonl"
        offset_file = index_dir / f"{index_name}.passages.idx"

        # Write passages and create offset map
        offset_map = {}
        with open(passages_file, "w", encoding="utf-8") as f:
            for chunk in self.chunks:
                offset = f.tell()
                json.dump(
                    {
                        "id": chunk["id"],
                        "text": chunk["text"],
                        "metadata": chunk["metadata"],
                    },
                    f,
                    ensure_ascii=False,
                )
                f.write("\n")
                offset_map[chunk["id"]] = offset

        with open(offset_file, "wb") as f:
            pickle.dump(offset_map, f)

        # Build the vector index using precomputed embeddings
        string_ids = [str(id_val) for id_val in ids]
        # Persist ID map (order == embeddings order)
        try:
            idmap_file = (
                index_dir
                / f"{index_name[: -len('.leann')] if index_name.endswith('.leann') else index_name}.ids.txt"
            )
            with open(idmap_file, "w", encoding="utf-8") as f:
                for sid in string_ids:
                    f.write(str(sid) + "\n")
        except Exception:
            pass
        current_backend_kwargs = {**self.backend_kwargs, "dimensions": self.dimensions}
        builder_instance = self.backend_factory.builder(**current_backend_kwargs)
        builder_instance.build(embeddings, string_ids, index_path)

        # Create metadata file
        leann_meta_path = index_dir / f"{index_name}.meta.json"
        meta_data = {
            "version": "1.0",
            "backend_name": self.backend_name,
            "embedding_model": self.embedding_model,
            "dimensions": self.dimensions,
            "backend_kwargs": self.backend_kwargs,
            "embedding_mode": self.embedding_mode,
            "passage_sources": [
                {
                    "type": "jsonl",
                    # Preserve existing relative file names (backward-compatible)
                    "path": passages_file.name,
                    "index_path": offset_file.name,
                    # Add optional redundant relative keys for remote build portability (non-breaking)
                    "path_relative": passages_file.name,
                    "index_path_relative": offset_file.name,
                }
            ],
            "built_from_precomputed_embeddings": True,
            "embeddings_source": str(embeddings_file),
        }

        if self.embedding_options:
            meta_data["embedding_options"] = self.embedding_options

        # Add storage status flags for HNSW backend
        if self.backend_name == "hnsw":
            is_compact = self.backend_kwargs.get("is_compact", True)
            is_recompute = self.backend_kwargs.get("is_recompute", True)
            meta_data["is_compact"] = is_compact
            meta_data["is_pruned"] = bool(is_recompute)

        with open(leann_meta_path, "w", encoding="utf-8") as f:
            json.dump(meta_data, f, indent=2)

        logger.info(f"Index built successfully from precomputed embeddings: {index_path}")

    def update_index(self, index_path: str):
        """Append new passages and vectors to an existing HNSW index."""
        if not self.chunks:
            raise ValueError("No new chunks provided for update.")

        path = Path(index_path)
        index_dir = path.parent
        index_name = path.name
        index_prefix = path.stem

        meta_path = index_dir / f"{index_name}.meta.json"
        passages_file = index_dir / f"{index_name}.passages.jsonl"
        offset_file = index_dir / f"{index_name}.passages.idx"
        index_file = index_dir / f"{index_prefix}.index"

        if not meta_path.exists() or not passages_file.exists() or not offset_file.exists():
            raise FileNotFoundError("Index metadata or passage files are missing; cannot update.")
        if not index_file.exists():
            raise FileNotFoundError(f"HNSW index file not found: {index_file}")

        with open(meta_path, encoding="utf-8") as f:
            meta = json.load(f)
        backend_name = meta.get("backend_name")
        if backend_name != self.backend_name:
            raise ValueError(
                f"Index was built with backend '{backend_name}', cannot update with '{self.backend_name}'."
            )

        meta_backend_kwargs = meta.get("backend_kwargs", {})
        index_is_compact = meta.get("is_compact", meta_backend_kwargs.get("is_compact", True))
        if index_is_compact:
            raise ValueError(
                "Compact HNSW indices do not support in-place updates. Rebuild required."
            )

        distance_metric = meta_backend_kwargs.get(
            "distance_metric", self.backend_kwargs.get("distance_metric", "mips")
        ).lower()
        needs_recompute = bool(
            meta.get("is_pruned")
            or meta_backend_kwargs.get("is_recompute")
            or self.backend_kwargs.get("is_recompute")
        )

        with open(offset_file, "rb") as f:
            offset_map: dict[str, int] = pickle.load(f)
        existing_ids = set(offset_map.keys())

        valid_chunks: list[dict[str, Any]] = []
        for chunk in self.chunks:
            text = chunk.get("text", "")
            if not isinstance(text, str) or not text.strip():
                continue
            metadata = chunk.setdefault("metadata", {})
            passage_id = chunk.get("id") or metadata.get("id")
            if passage_id and passage_id in existing_ids:
                raise ValueError(f"Passage ID '{passage_id}' already exists in the index.")
            valid_chunks.append(chunk)

        if not valid_chunks:
            raise ValueError("No valid chunks to append.")

        texts_to_embed = [chunk["text"] for chunk in valid_chunks]
        embeddings = compute_embeddings(
            texts_to_embed,
            self.embedding_model,
            self.embedding_mode,
            use_server=False,
            is_build=True,
            provider_options=self.embedding_options,
        )

        embedding_dim = embeddings.shape[1]
        expected_dim = meta.get("dimensions")
        if expected_dim is not None and expected_dim != embedding_dim:
            raise ValueError(
                f"Dimension mismatch during update: existing index uses {expected_dim}, got {embedding_dim}."
            )

        from leann_backend_hnsw import faiss  # type: ignore

        embeddings = np.ascontiguousarray(embeddings, dtype=np.float32)
        if distance_metric == "cosine":
            norms = np.linalg.norm(embeddings, axis=1, keepdims=True)
            norms[norms == 0] = 1
            embeddings = embeddings / norms

        index = faiss.read_index(str(index_file))
        if hasattr(index, "is_recompute"):
            index.is_recompute = needs_recompute
            print(f"index.is_recompute: {index.is_recompute}")
        if getattr(index, "storage", None) is None:
            if index.metric_type == faiss.METRIC_INNER_PRODUCT:
                storage_index = faiss.IndexFlatIP(index.d)
            else:
                storage_index = faiss.IndexFlatL2(index.d)
            index.storage = storage_index
            index.own_fields = True
            # Faiss expects storage.ntotal to reflect the existing graph's
            # population (even if the vectors themselves were pruned from disk
            # for recompute mode).  When we attach a fresh IndexFlat here its
            # ntotal starts at zero, which later causes IndexHNSW::add to
            # believe new "preset" levels were provided and trips the
            # `n0 + n == levels.size()` assertion.  Seed the temporary storage
            # with the current ntotal so Faiss maintains the proper offset for
            # incoming vectors.
            try:
                storage_index.ntotal = index.ntotal
            except AttributeError:
                # Older Faiss builds may not expose ntotal as a writable
                # attribute; in that case we fall back to the default behaviour.
                pass
        if index.d != embedding_dim:
            raise ValueError(
                f"Existing index dimension ({index.d}) does not match new embeddings ({embedding_dim})."
            )

        passage_meta_mode = meta.get("embedding_mode", self.embedding_mode)
        passage_provider_options = meta.get("embedding_options", self.embedding_options)

        base_id = index.ntotal
        for offset, chunk in enumerate(valid_chunks):
            new_id = str(base_id + offset)
            chunk.setdefault("metadata", {})["id"] = new_id
            chunk["id"] = new_id

        # Append passages/offsets before we attempt index.add so the ZMQ server
        # can resolve newly assigned IDs during recompute. Keep rollback hooks
        # so we can restore files if the update fails mid-way.
        rollback_passages_size = passages_file.stat().st_size if passages_file.exists() else 0
        offset_map_backup = offset_map.copy()

        try:
            with open(passages_file, "a", encoding="utf-8") as f:
                for chunk in valid_chunks:
                    offset = f.tell()
                    json.dump(
                        {
                            "id": chunk["id"],
                            "text": chunk["text"],
                            "metadata": chunk.get("metadata", {}),
                        },
                        f,
                        ensure_ascii=False,
                    )
                    f.write("\n")
                    offset_map[chunk["id"]] = offset

            with open(offset_file, "wb") as f:
                pickle.dump(offset_map, f)

            server_manager: Optional[EmbeddingServerManager] = None
            server_started = False
            requested_zmq_port = int(os.getenv("LEANN_UPDATE_ZMQ_PORT", "5557"))

            try:
                if needs_recompute:
                    server_manager = EmbeddingServerManager(
                        backend_module_name="leann_backend_hnsw.hnsw_embedding_server"
                    )
                    server_started, actual_port = server_manager.start_server(
                        port=requested_zmq_port,
                        model_name=self.embedding_model,
                        embedding_mode=passage_meta_mode,
                        passages_file=str(meta_path),
                        distance_metric=distance_metric,
                        provider_options=passage_provider_options,
                    )
                    if not server_started:
                        raise RuntimeError(
                            "Failed to start HNSW embedding server for recompute update."
                        )
                    if actual_port != requested_zmq_port:
                        logger.warning(
                            "Embedding server started on port %s instead of requested %s. "
                            "Using reassigned port.",
                            actual_port,
                            requested_zmq_port,
                        )
                    try:
                        index.hnsw.zmq_port = actual_port
                    except AttributeError:
                        pass

                if needs_recompute:
                    for i in range(embeddings.shape[0]):
                        print(f"add {i} embeddings")
                        index.add(1, faiss.swig_ptr(embeddings[i : i + 1]))
                else:
                    index.add(embeddings.shape[0], faiss.swig_ptr(embeddings))
                faiss.write_index(index, str(index_file))
            finally:
                if server_started and server_manager is not None:
                    server_manager.stop_server()

        except Exception:
            # Roll back appended passages/offset map to keep files consistent.
            if passages_file.exists():
                with open(passages_file, "rb+") as f:
                    f.truncate(rollback_passages_size)
            offset_map = offset_map_backup
            with open(offset_file, "wb") as f:
                pickle.dump(offset_map, f)
            raise

        meta["total_passages"] = len(offset_map)
        with open(meta_path, "w", encoding="utf-8") as f:
            json.dump(meta, f, indent=2)

        logger.info(
            "Appended %d passages to index '%s'. New total: %d",
            len(valid_chunks),
            index_path,
            len(offset_map),
        )

        self.chunks.clear()

        if needs_recompute:
            prune_hnsw_embeddings_inplace(str(index_file))


class LeannSearcher:
    def __init__(self, index_path: str, enable_warmup: bool = False, **backend_kwargs):
        # Fix path resolution for Colab and other environments
        if not Path(index_path).is_absolute():
            index_path = str(Path(index_path).resolve())

        self.meta_path_str = f"{index_path}.meta.json"
        if not Path(self.meta_path_str).exists():
            parent_dir = Path(index_path).parent
            print(
                f"Leann metadata file not found at {self.meta_path_str}, and you may need to rm -rf {parent_dir}"
            )
            # highlight in red the filenotfound error
            raise FileNotFoundError(
                f"Leann metadata file not found at {self.meta_path_str}, \033[91m you may need to rm -rf {parent_dir}\033[0m"
            )
        with open(self.meta_path_str, encoding="utf-8") as f:
            self.meta_data = json.load(f)
        backend_name = self.meta_data["backend_name"]
        self.embedding_model = self.meta_data["embedding_model"]
        # Support both old and new format
        self.embedding_mode = self.meta_data.get("embedding_mode", "sentence-transformers")
        self.embedding_options = self.meta_data.get("embedding_options", {})
        # Delegate portability handling to PassageManager
        self.passage_manager = PassageManager(
            self.meta_data.get("passage_sources", []), metadata_file_path=self.meta_path_str
        )
        # Preserve backend name for conditional parameter forwarding
        self.backend_name = backend_name
        backend_factory = BACKEND_REGISTRY.get(backend_name)
        if backend_factory is None:
            raise ValueError(f"Backend '{backend_name}' not found.")
        final_kwargs = {**self.meta_data.get("backend_kwargs", {}), **backend_kwargs}
        final_kwargs["enable_warmup"] = enable_warmup
        if self.embedding_options:
            final_kwargs.setdefault("embedding_options", self.embedding_options)
        self.backend_impl: LeannBackendSearcherInterface = backend_factory.searcher(
            index_path, **final_kwargs
        )

    def search(
        self,
        query: str,
        top_k: int = 5,
        complexity: int = 64,
        beam_width: int = 1,
        prune_ratio: float = 0.0,
        recompute_embeddings: bool = True,
        pruning_strategy: Literal["global", "local", "proportional"] = "global",
        expected_zmq_port: int = 5557,
        metadata_filters: Optional[dict[str, dict[str, Union[str, int, float, bool, list]]]] = None,
        batch_size: int = 0,
        use_grep: bool = False,
        **kwargs,
    ) -> list[SearchResult]:
        """
        Search for nearest neighbors with optional metadata filtering.

        Args:
            query: Text query to search for
            top_k: Number of nearest neighbors to return
            complexity: Search complexity/candidate list size, higher = more accurate but slower
            beam_width: Number of parallel search paths/IO requests per iteration
            prune_ratio: Ratio of neighbors to prune via approximate distance (0.0-1.0)
            recompute_embeddings: Whether to fetch fresh embeddings from server vs use stored codes
            pruning_strategy: Candidate selection strategy - "global" (default), "local", or "proportional"
            expected_zmq_port: ZMQ port for embedding server communication
            metadata_filters: Optional filters to apply to search results based on metadata.
                Format: {"field_name": {"operator": value}}
                Supported operators:
                - Comparison: "==", "!=", "<", "<=", ">", ">="
                - Membership: "in", "not_in"
                - String: "contains", "starts_with", "ends_with"
                Example: {"chapter": {"<=": 5}, "tags": {"in": ["fiction", "drama"]}}
            **kwargs: Backend-specific parameters

        Returns:
            List of SearchResult objects with text, metadata, and similarity scores
        """
        # Handle grep search
        if use_grep:
            return self._grep_search(query, top_k)

        logger.info("🔍 LeannSearcher.search() called:")
        logger.info(f"  Query: '{query}'")
        logger.info(f"  Top_k: {top_k}")
        logger.info(f"  Metadata filters: {metadata_filters}")
        logger.info(f"  Additional kwargs: {kwargs}")

        # Smart top_k detection and adjustment
        # Use PassageManager length (sum of shard sizes) to avoid
        # depending on a massive combined map
        total_docs = len(self.passage_manager)
        original_top_k = top_k
        if top_k > total_docs:
            top_k = total_docs
            logger.warning(
                f"  ⚠️  Requested top_k ({original_top_k}) exceeds total documents ({total_docs})"
            )
            logger.warning(f"  ✅ Auto-adjusted top_k to {top_k} to match available documents")

        zmq_port = None

        start_time = time.time()
        if recompute_embeddings:
            zmq_port = self.backend_impl._ensure_server_running(
                self.meta_path_str,
                port=expected_zmq_port,
                **kwargs,
            )
            del expected_zmq_port
        zmq_time = time.time() - start_time
        logger.info(f"  Launching server time: {zmq_time} seconds")

        start_time = time.time()

        query_embedding = self.backend_impl.compute_query_embedding(
            query,
            use_server_if_available=recompute_embeddings,
            zmq_port=zmq_port,
        )
        logger.info(f"  Generated embedding shape: {query_embedding.shape}")
        embedding_time = time.time() - start_time
        logger.info(f"  Embedding time: {embedding_time} seconds")

        start_time = time.time()
        backend_search_kwargs: dict[str, Any] = {
            "complexity": complexity,
            "beam_width": beam_width,
            "prune_ratio": prune_ratio,
            "recompute_embeddings": recompute_embeddings,
            "pruning_strategy": pruning_strategy,
            "zmq_port": zmq_port,
        }
        # Only HNSW supports batching; forward conditionally
        if self.backend_name == "hnsw":
            backend_search_kwargs["batch_size"] = batch_size

        # Merge any extra kwargs last
        backend_search_kwargs.update(kwargs)

        results = self.backend_impl.search(
            query_embedding,
            top_k,
            **backend_search_kwargs,
        )
        search_time = time.time() - start_time
        logger.info(f"  Search time in search() LEANN searcher: {search_time} seconds")
        logger.info(f"  Backend returned: labels={len(results.get('labels', [[]])[0])} results")

        enriched_results = []
        if "labels" in results and "distances" in results:
            logger.info(f"  Processing {len(results['labels'][0])} passage IDs:")
            # Python 3.9 does not support zip(strict=...); lengths are expected to match
            for i, (string_id, dist) in enumerate(
                zip(results["labels"][0], results["distances"][0])
            ):
                try:
                    passage_data = self.passage_manager.get_passage(string_id)
                    enriched_results.append(
                        SearchResult(
                            id=string_id,
                            score=dist,
                            text=passage_data["text"],
                            metadata=passage_data.get("metadata", {}),
                        )
                    )

                    # Color codes for better logging
                    GREEN = "\033[92m"
                    BLUE = "\033[94m"
                    YELLOW = "\033[93m"
                    RESET = "\033[0m"

                    # Truncate text for display (first 100 chars)
                    display_text = passage_data["text"]
                    logger.info(
                        f"   {GREEN}✓{RESET} {BLUE}[{i + 1:2d}]{RESET} {YELLOW}ID:{RESET} '{string_id}' {YELLOW}Score:{RESET} {dist:.4f} {YELLOW}Text:{RESET} {display_text}"
                    )
                except KeyError:
                    RED = "\033[91m"
                    RESET = "\033[0m"
                    logger.error(
                        f"   {RED}✗{RESET} [{i + 1:2d}] ID: '{string_id}' -> {RED}ERROR: Passage not found!{RESET}"
                    )

        # Apply metadata filters if specified
        if metadata_filters:
            logger.info(f"  🔍 Applying metadata filters: {metadata_filters}")
            enriched_results = self.passage_manager.filter_search_results(
                enriched_results, metadata_filters
            )

        # Define color codes outside the loop for final message
        GREEN = "\033[92m"
        RESET = "\033[0m"
        logger.info(f"  {GREEN}✓ Final enriched results: {len(enriched_results)} passages{RESET}")
        return enriched_results

    def _find_jsonl_file(self) -> Optional[str]:
        """Find the .jsonl file containing raw passages for grep search"""
        index_path = Path(self.meta_path_str).parent
        potential_files = [
            index_path / "documents.leann.passages.jsonl",
            index_path.parent / "documents.leann.passages.jsonl",
        ]

        for file_path in potential_files:
            if file_path.exists():
                return str(file_path)
        return None

    def _grep_search(self, query: str, top_k: int = 5) -> list[SearchResult]:
        """Perform grep-based search on raw passages"""
        jsonl_file = self._find_jsonl_file()
        if not jsonl_file:
            raise FileNotFoundError("No .jsonl passages file found for grep search")

        try:
            cmd = ["grep", "-i", "-n", query, jsonl_file]
            result = subprocess.run(cmd, capture_output=True, text=True, check=False)

            if result.returncode == 1:
                return []
            elif result.returncode != 0:
                raise RuntimeError(f"Grep failed: {result.stderr}")

            matches = []
            for line in result.stdout.strip().split("\n"):
                if not line:
                    continue
                parts = line.split(":", 1)
                if len(parts) != 2:
                    continue

                try:
                    data = json.loads(parts[1])
                    text = data.get("text", "")
                    score = text.lower().count(query.lower())

                    matches.append(
                        SearchResult(
                            id=data.get("id", parts[0]),
                            text=text,
                            metadata=data.get("metadata", {}),
                            score=float(score),
                        )
                    )
                except json.JSONDecodeError:
                    continue

            matches.sort(key=lambda x: x.score, reverse=True)
            return matches[:top_k]

        except FileNotFoundError:
            raise RuntimeError(
                "grep command not found. Please install grep or use semantic search."
            )

    def _python_regex_search(self, query: str, top_k: int = 5) -> list[SearchResult]:
        """Fallback regex search"""
        jsonl_file = self._find_jsonl_file()
        if not jsonl_file:
            raise FileNotFoundError("No .jsonl file found")

        pattern = re.compile(re.escape(query), re.IGNORECASE)
        matches = []

        with open(jsonl_file, encoding="utf-8") as f:
            for line_num, line in enumerate(f, 1):
                if pattern.search(line):
                    try:
                        data = json.loads(line.strip())
                        matches.append(
                            SearchResult(
                                id=data.get("id", str(line_num)),
                                text=data.get("text", ""),
                                metadata=data.get("metadata", {}),
                                score=float(len(pattern.findall(data.get("text", "")))),
                            )
                        )
                    except json.JSONDecodeError:
                        continue

        matches.sort(key=lambda x: x.score, reverse=True)
        return matches[:top_k]

    def cleanup(self):
        """Explicitly cleanup embedding server resources.
        This method should be called after you're done using the searcher,
        especially in test environments or batch processing scenarios.
        """
        backend = getattr(self.backend_impl, "embedding_server_manager", None)
        if backend is not None:
            backend.stop_server()

    # Enable automatic cleanup patterns
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc, tb):
        try:
            self.cleanup()
        except Exception:
            pass

    def __del__(self):
        try:
            self.cleanup()
        except Exception:
            # Avoid noisy errors during interpreter shutdown
            pass


class LeannChat:
    def __init__(
        self,
        index_path: str,
        llm_config: Optional[dict[str, Any]] = None,
        enable_warmup: bool = False,
        searcher: Optional[LeannSearcher] = None,
        **kwargs,
    ):
        if searcher is None:
            self.searcher = LeannSearcher(index_path, enable_warmup=enable_warmup, **kwargs)
            self._owns_searcher = True
        else:
            self.searcher = searcher
            self._owns_searcher = False
        self.llm = get_llm(llm_config)

    def ask(
        self,
        question: str,
        top_k: int = 5,
        complexity: int = 64,
        beam_width: int = 1,
        prune_ratio: float = 0.0,
        recompute_embeddings: bool = True,
        pruning_strategy: Literal["global", "local", "proportional"] = "global",
        llm_kwargs: Optional[dict[str, Any]] = None,
        expected_zmq_port: int = 5557,
        metadata_filters: Optional[dict[str, dict[str, Union[str, int, float, bool, list]]]] = None,
        batch_size: int = 0,
        use_grep: bool = False,
        **search_kwargs,
    ):
        if llm_kwargs is None:
            llm_kwargs = {}
        search_time = time.time()
        results = self.searcher.search(
            question,
            top_k=top_k,
            complexity=complexity,
            beam_width=beam_width,
            prune_ratio=prune_ratio,
            recompute_embeddings=recompute_embeddings,
            pruning_strategy=pruning_strategy,
            expected_zmq_port=expected_zmq_port,
            metadata_filters=metadata_filters,
            batch_size=batch_size,
            **search_kwargs,
        )
        search_time = time.time() - search_time
        logger.info(f"  Search time: {search_time} seconds")
        context = "\n\n".join([r.text for r in results])
        prompt = (
            "Here is some retrieved context that might help answer your question:\n\n"
            f"{context}\n\n"
            f"Question: {question}\n\n"
            "Please provide the best answer you can based on this context and your knowledge."
        )

        ask_time = time.time()
        ans = self.llm.ask(prompt, **llm_kwargs)
        ask_time = time.time() - ask_time
        logger.info(f"  Ask time: {ask_time} seconds")
        return ans

    def start_interactive(self):
        """Start interactive chat session."""
        session = create_api_session()

        def handle_query(user_input: str):
            response = self.ask(user_input)
            print(f"Leann: {response}")

        session.run_interactive_loop(handle_query)

    def cleanup(self):
        """Explicitly cleanup embedding server resources.

        This method should be called after you're done using the chat interface,
        especially in test environments or batch processing scenarios.
        """
        # Only stop the embedding server if this LeannChat instance created the searcher.
        # When a shared searcher is passed in, avoid shutting down the server to enable reuse.
        if getattr(self, "_owns_searcher", False) and hasattr(self.searcher, "cleanup"):
            self.searcher.cleanup()

    # Enable automatic cleanup patterns
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc, tb):
        try:
            self.cleanup()
        except Exception:
            pass

    def __del__(self):
        try:
            self.cleanup()
        except Exception:
            pass
