"""Celery tasks for PDF parsing."""
import logging
import hashlib
from app.core.celery_app import celery_app
from app.services.pdf_text import extract_text_from_pdf, PDFExtractionError
from app.services.parser import parse_incrementables, ParsingError

logger = logging.getLogger(__name__)


@celery_app.task(bind=True, name="parse_pdf_task")
def parse_pdf_task(self, pdf_bytes_hex: str, filename: str, document_ref: str = None):
    """
    Celery task to parse PDF incrementables asynchronously.
    
    Args:
        self: Celery task instance
        pdf_bytes_hex: PDF content as hex string (to serialize)
        filename: Original filename
        document_ref: Optional document reference
        
    Returns:
        Dictionary with parsed data or error information
    """
    task_id = self.request.id
    logger.info(f"Starting PDF parse task {task_id} for {filename}")
    
    try:
        # Convert hex back to bytes
        pdf_bytes = bytes.fromhex(pdf_bytes_hex)
        
        # Calculate SHA256
        file_hash = hashlib.sha256(pdf_bytes).hexdigest()
        
        # Extract text
        try:
            text, page_count, extraction_method = extract_text_from_pdf(pdf_bytes)
            logger.info(f"Task {task_id}: Extracted {len(text)} chars from {page_count} pages")
        except PDFExtractionError as e:
            logger.error(f"Task {task_id}: Extraction failed - {str(e)}")
            return {
                "status": "failed",
                "error": "extraction_failed",
                "message": str(e),
                "task_id": task_id
            }
        
        # Parse incrementables
        try:
            parsed_data = parse_incrementables(text)
            logger.info(f"Task {task_id}: Successfully parsed incrementables")
        except ParsingError as e:
            logger.error(f"Task {task_id}: Parsing failed - {str(e)}")
            return {
                "status": "failed",
                "error": "parsing_failed",
                "message": str(e),
                "task_id": task_id
            }
        
        # Build successful response
        result = {
            "status": "completed",
            "task_id": task_id,
            "document": {
                "filename": filename,
                "pages": page_count,
                "sha256": file_hash,
                "document_ref": document_ref
            },
            "incrementables": {
                "currency": parsed_data["currency"],
                "fletes": parsed_data["fletes"],
                "seguros": parsed_data["seguros"],
                "almacenaje_consolidacion": parsed_data["almacenaje_consolidacion"],
                "regalias": parsed_data["regalias"]
            },
            "extraction": {
                "method": extraction_method,
                "anchors_found": parsed_data["anchors_found"],
                "warnings": parsed_data["warnings"]
            }
        }
        
        logger.info(f"Task {task_id}: Completed successfully")
        return result
        
    except Exception as e:
        logger.error(f"Task {task_id}: Unexpected error - {str(e)}", exc_info=True)
        return {
            "status": "failed",
            "error": "unexpected_error",
            "message": str(e),
            "task_id": task_id
        }