"""Document enrichment module for loading documents into vector storage."""

import hashlib
import os
from pathlib import Path
from typing import Iterator, List, Tuple

from dotenv import load_dotenv
from langchain_community.document_loaders import PyPDFLoader
from langchain_core.documents import Document
from langchain_text_splitters import RecursiveCharacterTextSplitter

# Dynamically import other loaders to handle optional dependencies
try:
    from langchain_community.document_loaders import UnstructuredWordDocumentLoader
except ImportError:
    UnstructuredWordDocumentLoader = None

try:
    from langchain_community.document_loaders import UnstructuredPowerPointLoader
except ImportError:
    UnstructuredPowerPointLoader = None

try:
    from langchain_community.document_loaders import UnstructuredExcelLoader
except ImportError:
    UnstructuredExcelLoader = None

try:
    from langchain_community.document_loaders import UnstructuredImageLoader
except ImportError:
    UnstructuredImageLoader = None

try:
    from langchain_community.document_loaders import UnstructuredODTLoader
except ImportError:
    UnstructuredODTLoader = None
from loguru import logger
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

from helpers import (
    LocalFilesystemAdaptiveCollection,
    YandexDiskAdaptiveCollection,
    _AdaptiveCollection,
    _AdaptiveFile,
    extract_russian_event_names,
    extract_years_from_text,
)

# Load environment variables
load_dotenv()


# Define the path to the data directory
DATA_DIR = Path("../../../data").resolve()
DB_PATH = Path("document_tracking.db").resolve()
ENRICHMENT_SOURCE = os.getenv("ENRICHMENT_SOURCE", "local").lower()
ENRICHMENT_LOCAL_PATH = os.getenv("ENRICHMENT_LOCAL_PATH")
ENRICHMENT_YADISK_PATH = os.getenv("ENRICHMENT_YADISK_PATH")
YADISK_TOKEN = os.getenv("YADISK_TOKEN")

SUPPORTED_EXTENSIONS = {
    ".pdf",
    ".docx",
    ".doc",
    ".pptx",
    ".xlsx",
    ".xls",
    ".jpg",
    ".jpeg",
    ".png",
    ".gif",
    ".bmp",
    ".tiff",
    ".webp",
    ".odt",
}


def try_guess_source(extension: str) -> str:
    if extension in [".xlsx", "xls"]:
        return "таблица"
    elif extension in [".jpg", ".jpeg", ".png", ".gif", ".bmp", ".tiff", ".webp"]:
        return "изображение"
    elif extension in [".pptx"]:
        return "презентация"
    else:
        return "документ"


Base = declarative_base()


class ProcessedDocument(Base):
    """Database model for tracking processed documents."""

    __tablename__ = "processed_documents"

    id = Column(Integer, primary_key=True)
    file_path = Column(String, unique=True, nullable=False)
    file_hash = Column(String, nullable=False)


class DocumentEnricher:
    """Class responsible for enriching documents and loading them to vector storage."""

    def __init__(self, vector_store):
        self.vector_store = vector_store
        self.text_splitter = RecursiveCharacterTextSplitter(
            chunk_size=1000,
            chunk_overlap=200,
            length_function=len,
        )

        # Initialize database for tracking processed documents
        self._init_db()

    def _init_db(self):
        """Initialize the SQLite database for tracking processed documents."""
        self.engine = create_engine(f"sqlite:///{DB_PATH}")
        Base.metadata.create_all(self.engine)
        Session = sessionmaker(bind=self.engine)
        self.session = Session()

    def _get_file_hash(self, file_path: str) -> str:
        """Calculate SHA256 hash of a file."""
        hash_sha256 = hashlib.sha256()
        with open(file_path, "rb") as f:
            # Read file in chunks to handle large files
            for chunk in iter(lambda: f.read(4096), b""):
                hash_sha256.update(chunk)
        return hash_sha256.hexdigest()

    def _is_document_hash_processed(self, file_hash: str) -> bool:
        """Check if a document hash has already been processed."""
        existing = (
            self.session.query(ProcessedDocument).filter_by(file_hash=file_hash).first()
        )
        return existing is not None

    def _mark_document_processed(self, file_identifier: str, file_hash: str):
        """Mark a document as processed in the database."""
        doc_record = ProcessedDocument(file_path=file_identifier, file_hash=file_hash)
        self.session.add(doc_record)
        self.session.commit()

    def _get_loader_for_extension(self, file_path: str):
        """Get the appropriate loader for a given file extension."""
        ext = Path(file_path).suffix.lower()

        if ext == ".pdf":
            return PyPDFLoader(file_path)
        elif ext in [".docx", ".doc"]:
            if UnstructuredWordDocumentLoader is None:
                logger.warning(
                    f"UnstructuredWordDocumentLoader not available for {file_path}. Skipping."
                )
                return None
            return UnstructuredWordDocumentLoader(
                file_path, **{"strategy": "hi_res", "languages": ["rus"]}
            )
        elif ext == ".pptx":
            if UnstructuredPowerPointLoader is None:
                logger.warning(
                    f"UnstructuredPowerPointLoader not available for {file_path}. Skipping."
                )
                return None
            return UnstructuredPowerPointLoader(
                file_path, **{"strategy": "hi_res", "languages": ["rus"]}
            )
        elif ext in [".xlsx", ".xls"]:
            if UnstructuredExcelLoader is None:
                logger.warning(
                    f"UnstructuredExcelLoader not available for {file_path}. Skipping."
                )
                return None
            return UnstructuredExcelLoader(
                file_path, **{"strategy": "hi_res", "languages": ["rus"]}
            )
        elif ext in [".jpg", ".jpeg", ".png", ".gif", ".bmp", ".tiff", ".webp"]:
            if UnstructuredImageLoader is None:
                logger.warning(
                    f"UnstructuredImageLoader not available for {file_path}. Skipping."
                )
                return None
            # Use OCR strategy for images to extract text
            return UnstructuredImageLoader(
                file_path, **{"strategy": "ocr_only", "languages": ["rus"]}
            )
        elif ext == ".odt":
            if UnstructuredODTLoader is None:
                logger.warning(
                    f"UnstructuredODTLoader not available for {file_path}. Skipping."
                )
                return None
            return UnstructuredODTLoader(
                file_path, **{"strategy": "hi_res", "languages": ["rus"]}
            )
        else:
            return None

    def _load_one_adaptive_file(
        self, adaptive_file: _AdaptiveFile
    ) -> Tuple[List[Document], str | None]:
        """Load and split one adaptive file by using its local working callback."""
        loaded_docs: List[Document] = []
        file_hash: str | None = None
        source_identifier = try_guess_source(adaptive_file.extension)
        extension = adaptive_file.extension.lower()

        def process_local_file(local_file_path: str):
            nonlocal loaded_docs, file_hash

            file_hash = self._get_file_hash(local_file_path)
            if self._is_document_hash_processed(file_hash):
                logger.info(
                    f"Skipping already processed document hash for: {source_identifier}"
                )
                return

            loader = self._get_loader_for_extension(local_file_path)
            if loader is None:
                logger.warning(f"No loader available for file: {source_identifier}")
                return

            docs = loader.load()
            for doc in docs:
                doc.metadata["source"] = source_identifier
                doc.metadata["filename"] = adaptive_file.filename
                doc.metadata["file_path"] = source_identifier
                doc.metadata["file_size"] = os.path.getsize(local_file_path)
                doc.metadata["file_extension"] = extension

                if "page" in doc.metadata:
                    doc.metadata["page_number"] = doc.metadata["page"]

            split_docs = self.text_splitter.split_documents(docs)
            for chunk in split_docs:
                years = extract_years_from_text(chunk.page_content)
                events = extract_russian_event_names(chunk.page_content)
                chunk.metadata["years"] = years
                chunk.metadata["events"] = events

            loaded_docs = split_docs

        adaptive_file.work_with_file_locally(process_local_file)
        return loaded_docs, file_hash

    def load_and_split_documents(
        self, adaptive_collection: _AdaptiveCollection, recursive: bool = True
    ) -> Iterator[Tuple[List[Document], List[Tuple[str, str]]]]:
        """Load documents from adaptive collection and split them appropriately."""
        docs_chunk: List[Document] = []
        processed_file_records: dict[str, str] = {}

        for adaptive_file in adaptive_collection.iterate(recursive=recursive):
            if len(processed_file_records) >= 2:
                yield docs_chunk, list(processed_file_records.items())
                docs_chunk = []
                processed_file_records = {}

            if adaptive_file.extension.lower() not in SUPPORTED_EXTENSIONS:
                logger.debug(
                    f"Skipping unsupported file extension for {adaptive_file.filename}: {adaptive_file.extension}"
                )
                continue

            logger.info(f"Processing document: {adaptive_file.filename}")
            try:
                split_docs, file_hash = self._load_one_adaptive_file(adaptive_file)
                if split_docs:
                    docs_chunk.extend(split_docs)
                if file_hash:
                    processed_file_records[adaptive_file.filename] = file_hash
            except Exception as e:
                logger.error(f"Error processing {adaptive_file.filename}: {str(e)}")
                continue

    def enrich_and_store(self, adaptive_collection: _AdaptiveCollection):
        """Load, enrich, and store documents in the vector store."""
        logger.info("Starting enrichment process...")

        # Load and split documents
        for documents, processed_file_records in self.load_and_split_documents(
            adaptive_collection
        ):
            if not documents:
                logger.info("No new documents to process.")
                return

            logger.info(
                f"Loaded and split {len(documents)} document chunks, adding to vector store..."
            )
            logger.debug(
                f"Documents len: {len(documents)}, processed_file_records len: {len(processed_file_records)}"
            )

            # Add documents to vector store
            try:
                self.vector_store.add_documents(documents)

                # Only mark documents as processed after successful insertion to vector store
                for file_identifier, file_hash in processed_file_records:
                    self._mark_document_processed(file_identifier, file_hash)

                logger.info(
                    f"Successfully added {len(documents)} document chunks to vector store and marked {len(processed_file_records)} files as processed."
                )
            except Exception as e:
                logger.error(f"Error adding documents to vector store: {str(e)}")
                raise


def get_enrichment_adaptive_collection() -> _AdaptiveCollection:
    """Create adaptive collection based on environment source configuration."""
    source = ENRICHMENT_SOURCE
    if source == "local":
        local_path = ENRICHMENT_LOCAL_PATH
        if local_path is None:
            raise RuntimeError(
                "Enrichment strategy is local, but no ENRICHMENT_LOCAL_PATH is defined!"
            )

        logger.info(f"Using local adaptive collection from path: {local_path}")
        return LocalFilesystemAdaptiveCollection(local_path)

    if source == "yadisk":
        if not YADISK_TOKEN:
            raise ValueError("YADISK_TOKEN must be set when ENRICHMENT_SOURCE=yadisk")
        if not ENRICHMENT_YADISK_PATH:
            raise ValueError(
                "ENRICHMENT_YADISK_PATH must be set when ENRICHMENT_SOURCE=yadisk"
            )
        logger.info(
            f"Using Yandex Disk adaptive collection from path: {ENRICHMENT_YADISK_PATH}"
        )
        return YandexDiskAdaptiveCollection(
            token=YADISK_TOKEN,
            base_dir=ENRICHMENT_YADISK_PATH,
        )

    raise ValueError(
        f"Unsupported ENRICHMENT_SOURCE='{source}'. Allowed values: local, yadisk"
    )


def run_enrichment_process(vector_store):
    """Run the full enrichment process."""
    logger.info("Starting document enrichment process")

    adaptive_collection = get_enrichment_adaptive_collection()

    # Initialize the document enricher
    enricher = DocumentEnricher(vector_store)

    # Run the enrichment process
    enricher.enrich_and_store(adaptive_collection)

    logger.info("Document enrichment process completed!")


if __name__ == "__main__":
    # Example usage
    from vector_storage import initialize_vector_store

    # Initialize vector store
    vector_store = initialize_vector_store()

    # Run enrichment process
    run_enrichment_process(vector_store)