Add helper functions for Book

helpers/book_helpers.py

@@ -0,0 +1,128 @@
+from typing import Optional, Dict, Union, List
+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 (ISBN-10 or ISBN-13).
+    
+    Args:
+        isbn: ISBN string to validate
+        
+    Returns:
+        bool: True if valid ISBN format, False otherwise
+    """
+    isbn = isbn.replace("-", "").replace(" ", "")
+    if len(isbn) == 10:
+        # ISBN-10 validation
+        if not isbn[:-1].isdigit() and isbn[-1].lower() != 'x':
+            return False
+        total = 0
+        for i in range(9):
+            total += int(isbn[i]) * (10 - i)
+        check = 11 - (total % 11)
+        return str(check) == isbn[-1] or (check == 10 and isbn[-1].lower() == 'x')
+    elif len(isbn) == 13:
+        # ISBN-13 validation
+        if not isbn.isdigit():
+            return False
+        total = 0
+        for i in range(12):
+            if i % 2 == 0:
+                total += int(isbn[i])
+            else:
+                total += int(isbn[i]) * 3
+        check = 10 - (total % 10)
+        if check == 10:
+            check = 0
+        return str(check) == isbn[-1]
+    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_by_title(db: Session, title: str, limit: int = 10) -> List[Book]:
+    """
+    Search for books by title using partial matching.
+    
+    Args:
+        db: Database session
+        title: Title to search for
+        limit: Maximum number of results to return
+        
+    Returns:
+        List of matching Book objects
+    """
+    return db.query(Book).filter(Book.title.ilike(f"%{title}%")).limit(limit).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 required fields
+    if not book_data.title or not book_data.title.strip():
+        return {"error": "Title is required"}
+        
+    if not book_data.author or not book_data.author.strip():
+        return {"error": "Author is required"}
+    
+    # Validate ISBN
+    if not validate_isbn(book_data.isbn):
+        return {"error": "Invalid ISBN format"}
+    
+    # Check for duplicate ISBN
+    existing_book = get_book_by_isbn(db, book_data.isbn)
+    if existing_book:
+        return {"error": "Book with this ISBN already exists"}
+    
+    # Create the book
+    db_book = Book(
+        title=book_data.title.strip(),
+        author=book_data.author.strip(),
+        description=book_data.description.strip() if book_data.description else None,
+        isbn=book_data.isbn.replace("-", "").replace(" ", "")
+    )
+    
+    db.add(db_book)
+    db.commit()
+    db.refresh(db_book)
+    
+    return db_book
+
+def format_book_response(book: Book) -> Dict[str, str]:
+    """
+    Format a book object into a standardized response format.
+    
+    Args:
+        book: Book object to format
+        
+    Returns:
+        Dictionary with formatted book data
+    """
+    return {
+        "title": book.title,
+        "author": book.author,
+        "description": book.description or "",
+        "isbn": f"{book.isbn[:3]}-{book.isbn[3:4]}-{book.isbn[4:6]}-{book.isbn[6:12]}-{book.isbn[12:]}" 
+        if len(book.isbn) == 13 
+        else f"{book.isbn[:1]}-{book.isbn[1:3]}-{book.isbn[3:9]}-{book.isbn[9:]}"
+    }