import asyncio
import os
import re
import tempfile
from pathlib import Path
from typing import List

import aiofiles
import fitz
import torch
from fastapi import HTTPException, UploadFile
from loguru import logger

from src.utils import TextExtractor, model_manager


class PDFProcessorService:
    def __init__(self):
        logger.info("Initializing PDFProcessorService")
        self._ensure_models_loaded()

    def _ensure_models_loaded(self):
        if not model_manager.models_loaded:
            logger.info("Models not loaded, initializing model manager...")
            _ = model_manager.doctr_model
            logger.debug("Model manager initialization completed")

    @property
    def doctr_model(self):
        return model_manager.doctr_model

    @property
    def device(self):
        return model_manager.device

    async def __aenter__(self):
        return self

    async def __aexit__(self, exc_type, exc_value, traceback):
        pass

    async def is_pdf_scanned(self, pdf_path: str) -> bool:
        logger.debug(f"Checking if PDF is scanned: {pdf_path}")

        def _check_scanned():
            try:
                doc = fitz.open(pdf_path)
                for page in doc:
                    text = page.get_text()
                    if text.strip():
                        return False
                return True
            except Exception as e:
                logger.error(f"Error checking if PDF is scanned: {e}")
                raise

        return await asyncio.get_event_loop().run_in_executor(None, _check_scanned)

    async def save_uploaded_file(self, uploaded_file: UploadFile) -> str:
        logger.info(f"Saving uploaded file: {uploaded_file.filename}")
        try:
            file_name = uploaded_file.filename
            suffix = Path(file_name).suffix
            with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as tmp:
                temp_path = tmp.name
            async with aiofiles.open(temp_path, "wb") as f:
                await f.write(await uploaded_file.read())
            logger.debug(f"File saved to temporary path: {temp_path}")
            return temp_path
        except Exception as e:
            logger.error(f"Error saving uploaded file: {e}")
            raise

    async def extract_text_from_digital_pdf(self, pdf_path: str) -> List[List[str]]:
        logger.debug(f"Extracting text from digital PDF: {pdf_path}")

        async def _extract_text():
            try:
                doc = fitz.open(pdf_path)
                extracted_data = []

                for page in doc:
                    ptext = page.get_text()
                    if ptext:
                        data = []
                        for line in ptext.splitlines():
                            cleaned_line = await self._split_on_repeated_pattern(
                                line.strip()
                            )
                            if cleaned_line:
                                data.append(cleaned_line[0])
                            extracted_data.append(data)

                logger.info(
                    f"Successfully extracted text from {len(extracted_data)} pages"
                )
                return extracted_data
            except Exception as e:
                logger.error(f"Error extracting text from digital PDF: {e}")
                raise

        return await asyncio.get_event_loop().run_in_executor(None, _extract_text)

    async def _split_on_repeated_pattern(
        self, line: str, min_space: int = 10
    ) -> List[str]:
        logger.debug(f"Processing line for repeated patterns: {line[:50]}...")
        import re
        from difflib import SequenceMatcher

        original_line = line.strip()

        space_spans = [
            (m.start(), len(m.group()))
            for m in re.finditer(r" {%d,}" % min_space, original_line)
        ]

        if not space_spans:
            return [original_line]

        gaps = [span[1] for span in space_spans]
        gap_counts = {}
        for g in gaps:
            gap_counts[g] = gap_counts.get(g, 0) + 1

        sorted_gaps = sorted(
            gap_counts.items(), key=lambda x: x[1] * x[0], reverse=True
        )

        if not sorted_gaps:
            return [original_line]

        dominant_gap = sorted_gaps[0][0]

        chunks = re.split(rf" {{%d,}}" % dominant_gap, original_line)

        base = chunks[0].strip()
        repeated = False
        for chunk in chunks[1:]:
            chunk = chunk.strip()
            if chunk and SequenceMatcher(None, base, chunk).ratio() > 0.8:
                repeated = True
                break

        return [base] if repeated else [original_line]

    async def process_pdf(self, file):
        logger.info(f"Processing PDF file: {file.filename}")
        try:
            pdf_path = await self.save_uploaded_file(file)
            is_scanned = await self.is_pdf_scanned(pdf_path)
            text_extractor = TextExtractor(self.doctr_model)

            if is_scanned:
                if not torch.cuda.is_available():
                    raise HTTPException(
                        status_code=400, detail="Scanned PDFs are not supported."
                    )
                logger.info(f"PDF {pdf_path} is scanned, using OCR extraction")
                extracted_text_list = (
                    await text_extractor.extract_lines_with_bbox_from_scanned_pdf(
                        pdf_path
                    )
                )
            else:
                logger.info(f"PDF {pdf_path} is digital, extracting text directly")
                extracted_text_list = await text_extractor.extract_lines_with_bbox(
                    pdf_path
                )
                pdf_text = ""
                for block in extracted_text_list:
                    for line in block:
                        pdf_text += " " + line["line"]
                text_noisy = text_extractor.is_text_noisy(pdf_text)
                if text_noisy:
                    if not torch.cuda.is_available():
                        raise HTTPException(
                            status_code=400, detail="Scanned PDFs are not supported."
                        )
                    logger.warning("Text is noisy, falling back to OCR extraction")
                    extracted_text_list = (
                        await text_extractor.extract_lines_with_bbox_from_scanned_pdf(
                            pdf_path
                        )
                    )

            logger.info(
                f"Successfully processed PDF with {len(extracted_text_list)} text blocks"
            )
            return extracted_text_list
        except Exception as e:
            logger.error(f"Error processing PDF: {e}")
            raise
        finally:
            if os.path.exists(pdf_path):
                os.remove(pdf_path)

    async def extract_entity(self, text: str):
        logger.debug(f"Extracting entities from text: {text[:100]}...")
        try:
            text = re.sub(r"[^\w\s]", " ", text)
            doc = model_manager.spacy_model(text)
            entities = {ent.text: ent.label_ for ent in doc.ents}

            for key, value in entities.items():
                if value == "ORG":
                    logger.info(f"Found organization entity: {key}")
                    return key

            if entities:
                entity = list(entities.keys())[0]
                logger.info(f"Found entity: {entity}")
                return entity

            logger.debug("No entities found, returning original text")
            return text
        except Exception as e:
            logger.error(f"Error extracting entities: {e}")
            return text