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import os
import json
import time
import logging
from pathlib import Path
from typing import List, Dict, Optional
from dataclasses import dataclass
from fastapi.encoders import jsonable_encoder
import fitz  # PyMuPDF
from sentence_transformers import SentenceTransformer
from llama_cpp import Llama

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)


@dataclass
class ProductSpec:
    name: str
    description: Optional[str] = None
    price: Optional[float] = None
    attributes: Dict[str, str] = None
    tables: List[Dict] = None

    def to_dict(self):
        return jsonable_encoder(self)


class PDFProcessor:
    def __init__(self):
        self.emb_model = self._initialize_emb_model("all-MiniLM-L6-v2")
        # Choose the appropriate model filename below; adjust if needed.
        # self.llm = self._initialize_llm("deepseek-llm-7b-base.Q2_K.gguf")
        self.llm = self._initialize_llm("llama-2-7b.Q2_K.gguf")
        self.output_dir = Path("./output")
        self.output_dir.mkdir(exist_ok=True)

    def _initialize_emb_model(self, model_name):
        try:
            # Use SentenceTransformer if available
            return SentenceTransformer('sentence-transformers/all-MiniLM-L6-v2')
        except Exception as e:
            logger.warning(f"SentenceTransformer failed: {e}. Falling back to transformers model.")
            from transformers import AutoTokenizer, AutoModel
            tokenizer = AutoTokenizer.from_pretrained("sentence-transformers/" + model_name)
            model = AutoModel.from_pretrained("sentence-transformers/" + model_name)
            return model

    def _initialize_llm(self, model_name):
        """Initialize LLM with automatic download if needed"""
        # Here we use from_pretrained so that if the model is missing locally it downloads it.
        model_path = os.path.join("models/", model_name)
        if os.path.exists(model_path):
            return Llama(
                model_path=model_path,
                n_ctx=1024,
                n_gpu_layers=-1,
                n_threads=os.cpu_count() - 1,
                verbose=False
            )
        else:
            return Llama.from_pretrained(
                repo_id="Tien203/llama.cpp",
                filename="Llama-2-7b-hf-q4_0.gguf",
            )

    def process_pdf(self, pdf_path: str) -> Dict:
        """Process PDF using PyMuPDF"""
        start_time = time.time()

        # Open PDF
        try:
            doc = fitz.open(pdf_path)
        except Exception as e:
            logger.error(f"Failed to open PDF: {e}")
            raise RuntimeError("Cannot open PDF file.") from e

        text_blocks = []
        tables = []

        # Extract text and tables from each page
        for page_num, page in enumerate(doc):
            # Extract text blocks from page and filter out very short blocks (noise)
            blocks = self._extract_text_blocks(page)
            filtered = [block for block in blocks if len(block.strip()) >= 10]
            logger.debug(f"Page {page_num + 1}: Extracted {len(blocks)} blocks, {len(filtered)} kept after filtering.")
            text_blocks.extend(filtered)

            # Extract tables (if any)
            tables.extend(self._extract_tables(page, page_num))

        # Process text blocks with LLM to extract product information
        products = []
        for idx, block in enumerate(text_blocks):
            # Log the text block for debugging
            logger.debug(f"Processing text block {idx}: {block[:100]}...")
            product = self._process_text_block(block)
            if product:
                product.tables = tables
                # Only add if at least one key (like name) is non-empty
                if product.name or product.description or product.price or (
                        product.attributes and len(product.attributes) > 0):
                    products.append(product.to_dict())
                else:
                    logger.debug(f"LLM returned empty product for block {idx}.")
            else:
                logger.debug(f"No product extracted from block {idx}.")

        logger.info(f"Processed {len(products)} products in {time.time() - start_time:.2f}s")
        return {"products": products, "tables": tables}

    def _extract_text_blocks(self, page) -> List[str]:
        """Extract text blocks from a PDF page using PyMuPDF's blocks method."""
        blocks = []
        for block in page.get_text("blocks"):
            # block[4] contains the text content
            text = block[4].strip()
            if text:
                blocks.append(text)
        return blocks

    def _extract_tables(self, page, page_num: int) -> List[Dict]:
        """Extract tables from a PDF page using PyMuPDF's table extraction (if available)."""
        tables = []
        try:
            tab = page.find_tables()
            if tab and hasattr(tab, 'tables') and tab.tables:
                for table in tab.tables:
                    table_data = table.extract()
                    if table_data:
                        tables.append({
                            "page": page_num + 1,
                            "cells": table_data,
                            "header": table.header.names if table.header else [],
                            "content": table_data
                        })
        except Exception as e:
            logger.warning(f"Error extracting tables from page {page_num + 1}: {e}")
        return tables

    def _process_text_block(self, text: str) -> Optional[ProductSpec]:
        """Process a text block with LLM to extract product specifications."""
        prompt = self._generate_query_prompt(text)
        logger.debug(f"Generated prompt: {prompt[:200]}...")
        try:
            response = self.llm.create_chat_completion(
                messages=[{"role": "user", "content": prompt}],
                temperature=0.1,
                max_tokens=512
            )
            # Debug: log raw response
            logger.debug(f"LLM raw response: {response}")
            return self._parse_response(response['choices'][0]['message']['content'])
        except Exception as e:
            logger.warning(f"Error processing text block: {e}")
            return None

    def _generate_query_prompt(self, text: str) -> str:
        """Generate a prompt instructing the LLM to extract product information."""
        return f"""Extract product specifications from the following text. If no product is found, return an empty JSON object with keys.\n\nText:\n{text}\n\nReturn JSON format exactly as:\n{{\n    \"name\": \"product name\",\n    \"description\": \"product description\",\n    \"price\": numeric_price,\n    \"attributes\": {{ \"key\": \"value\" }}\n}}"""

    def _parse_response(self, response: str) -> Optional[ProductSpec]:
        """Parse the LLM's response to extract a product specification."""
        try:
            json_start = response.find('{')
            json_end = response.rfind('}') + 1
            json_str = response[json_start:json_end].strip()
            if not json_str:
                raise ValueError("No JSON content found in response.")
            data = json.loads(json_str)
            # If the returned JSON is essentially empty, return None
            if all(not data.get(key) for key in ['name', 'description', 'price', 'attributes']):
                return None
            return ProductSpec(
                name=data.get('name', ''),
                description=data.get('description'),
                price=data.get('price'),
                attributes=data.get('attributes', {})
            )
        except (json.JSONDecodeError, KeyError, ValueError) as e:
            logger.warning(f"Parse error: {e} in response: {response}")
            return None


def process_pdf_catalog(pdf_path: str):
    processor = PDFProcessor()
    try:
        result = processor.process_pdf(pdf_path)
        return result, "Processing completed successfully!"
    except Exception as e:
        logger.error(f"Processing failed: {e}")
        return {}, "Error processing PDF"


if __name__ == "__main__":
    # Example usage: change this if you call process_pdf_catalog elsewhere
    pdf_path = "path/to/your/pdf_file.pdf"
    result, message = process_pdf_catalog(pdf_path)
    print(result, message)