From d0beabc78c9cb1f23b270e4d025190ea40b28df6 Mon Sep 17 00:00:00 2001
From: Backend IM Bot <bot@backend.im>
Date: Thu, 27 Mar 2025 10:30:03 +0000
Subject: [PATCH] Add helper functions for Book

---
 helpers/book_helpers.py | 156 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 helpers/book_helpers.py

diff --git a/helpers/book_helpers.py b/helpers/book_helpers.py
new file mode 100644
index 0000000..e985def
--- /dev/null
+++ b/helpers/book_helpers.py
@@ -0,0 +1,156 @@
+from typing import List, Dict, Optional, Union, Any
+from datetime import datetime
+import re
+from sqlalchemy.orm import Session
+from models.book import Book
+from schemas.book import BookCreate, BookUpdate
+
+def validate_isbn(isbn: str) -> bool:
+    """
+    Validate ISBN format (both ISBN-10 and ISBN-13).
+    
+    Args:
+        isbn: ISBN string to validate
+        
+    Returns:
+        bool: True if ISBN format is valid, False otherwise
+    """
+    # Remove hyphens and spaces
+    isbn = isbn.replace('-', '').replace(' ', '')
+    
+    if len(isbn) == 10:
+        # ISBN-10 validation
+        if not isbn[:-1].isdigit():
+            return False
+        check = sum((10 - i) * int(x) for i, x in enumerate(isbn[:9]))
+        check = (11 - (check % 11)) % 11
+        return str(check) == isbn[-1] or (check == 10 and isbn[-1].upper() == 'X')
+    
+    elif len(isbn) == 13:
+        # ISBN-13 validation
+        if not isbn.isdigit():
+            return False
+        check = sum((3 if i % 2 else 1) * int(x) for i, x in enumerate(isbn[:12]))
+        check = (10 - (check % 10)) % 10
+        return int(isbn[-1]) == check
+        
+    return False
+
+def get_book_by_isbn(db: Session, isbn: str) -> Optional[Book]:
+    """
+    Retrieve a book by its ISBN.
+    
+    Args:
+        db: Database session
+        isbn: ISBN to search for
+        
+    Returns:
+        Book object if found, None otherwise
+    """
+    return db.query(Book).filter(Book.isbn == isbn).first()
+
+def search_books(
+    db: Session,
+    title: Optional[str] = None,
+    author: Optional[str] = None,
+    publisher: Optional[str] = None,
+    year_from: Optional[int] = None,
+    year_to: Optional[int] = None,
+    available_only: bool = False
+) -> List[Book]:
+    """
+    Search books with multiple optional filters.
+    
+    Args:
+        db: Database session
+        title: Optional title search string
+        author: Optional author search string
+        publisher: Optional publisher search string
+        year_from: Optional start year for publication
+        year_to: Optional end year for publication
+        available_only: If True, return only available books
+        
+    Returns:
+        List of Book objects matching the search criteria
+    """
+    query = db.query(Book)
+    
+    if title:
+        query = query.filter(Book.title.ilike(f"%{title}%"))
+    if author:
+        query = query.filter(Book.author.ilike(f"%{author}%"))
+    if publisher:
+        query = query.filter(Book.publisher.ilike(f"%{publisher}%"))
+    if year_from:
+        query = query.filter(Book.publication_year >= year_from)
+    if year_to:
+        query = query.filter(Book.publication_year <= year_to)
+    if available_only:
+        query = query.filter(Book.is_available == True)
+        
+    return query.all()
+
+def create_book_safely(db: Session, book_data: BookCreate) -> Union[Book, Dict[str, str]]:
+    """
+    Create a new book with validation and error handling.
+    
+    Args:
+        db: Database session
+        book_data: Book data for creation
+        
+    Returns:
+        Book object if created successfully, error dict otherwise
+    """
+    # Validate ISBN
+    if not validate_isbn(book_data.isbn):
+        return {"error": "Invalid ISBN format"}
+    
+    # Check if book already exists
+    existing_book = get_book_by_isbn(db, book_data.isbn)
+    if existing_book:
+        return {"error": "ISBN already exists"}
+    
+    # Validate publication year
+    current_year = datetime.now().year
+    if book_data.publication_year > current_year:
+        return {"error": "Publication year cannot be in the future"}
+    
+    # Create the book
+    db_book = Book(
+        title=book_data.title,
+        author=book_data.author,
+        isbn=book_data.isbn,
+        description=book_data.description,
+        publication_year=book_data.publication_year,
+        pages=book_data.pages,
+        publisher=book_data.publisher,
+        is_available=book_data.is_available
+    )
+    
+    db.add(db_book)
+    db.commit()
+    db.refresh(db_book)
+    
+    return db_book
+
+def update_book_availability(db: Session, isbn: str, is_available: bool) -> Union[Book, Dict[str, str]]:
+    """
+    Update the availability status of a book.
+    
+    Args:
+        db: Database session
+        isbn: ISBN of the book to update
+        is_available: New availability status
+        
+    Returns:
+        Updated Book object if successful, error dict otherwise
+    """
+    book = get_book_by_isbn(db, isbn)
+    if not book:
+        return {"error": "Book not found"}
+        
+    book.is_available = is_available
+    db.commit()
+    db.refresh(book)
+    
+    return book
\ No newline at end of file