Add helper functions for Book

helpers/book_helpers.py

@@ -0,0 +1,144 @@
+from typing import List, Dict, Optional, Union, Any
+from datetime import datetime
+from sqlalchemy.orm import Session
+from sqlalchemy import desc, asc
+from models.book import Book
+from schemas.book import BookCreate, BookResponse
+
+def get_books_with_filters(
+    db: Session,
+    skip: int = 0,
+    limit: int = 100,
+    sort_by: str = "title",
+    sort_order: str = "asc",
+    title_search: Optional[str] = None,
+    min_price: Optional[float] = None,
+    max_price: Optional[float] = None
+) -> List[Book]:
+    """
+    Get books with various filter options.
+    
+    Args:
+        db: Database session
+        skip: Number of records to skip
+        limit: Maximum number of records to return
+        sort_by: Field to sort by
+        sort_order: Sort direction (asc/desc)
+        title_search: Search string for title
+        min_price: Minimum price filter
+        max_price: Maximum price filter
+        
+    Returns:
+        List of Book objects matching the criteria
+    """
+    query = db.query(Book)
+    
+    if title_search:
+        query = query.filter(Book.title.ilike(f"%{title_search}%"))
+        
+    if min_price is not None:
+        query = query.filter(Book.price >= min_price)
+        
+    if max_price is not None:
+        query = query.filter(Book.price <= max_price)
+        
+    if sort_order == "desc":
+        query = query.order_by(desc(getattr(Book, sort_by)))
+    else:
+        query = query.order_by(asc(getattr(Book, sort_by)))
+        
+    return query.offset(skip).limit(limit).all()
+
+def get_book_by_id(db: Session, book_id: int) -> Optional[Book]:
+    """
+    Get a single book by ID.
+    
+    Args:
+        db: Database session
+        book_id: ID of the book to retrieve
+        
+    Returns:
+        Book object if found, None otherwise
+    """
+    return db.query(Book).filter(Book.id == book_id).first()
+
+def format_book_response(book: Book) -> BookResponse:
+    """
+    Format a book object into API response format.
+    
+    Args:
+        book: Book object to format
+        
+    Returns:
+        Formatted book response
+    """
+    return BookResponse(
+        id=book.id,
+        title=book.title,
+        author=book.author,
+        price=book.price,
+        isbn=book.isbn,
+        created_at=book.created_at,
+        updated_at=book.updated_at
+    )
+
+def validate_isbn(isbn: str) -> bool:
+    """
+    Validate ISBN format.
+    
+    Args:
+        isbn: ISBN string to validate
+        
+    Returns:
+        bool: True if valid ISBN format, False otherwise
+    """
+    # Remove hyphens and spaces
+    isbn = isbn.replace('-', '').replace(' ', '')
+    
+    if len(isbn) == 13:  # ISBN-13
+        try:
+            total = sum(
+                (3 if i % 2 else 1) * int(d)
+                for i, d in enumerate(isbn[:-1])
+            )
+            check_digit = (10 - (total % 10)) % 10
+            return check_digit == int(isbn[-1])
+        except ValueError:
+            return False
+    return False
+
+def check_book_availability(
+    db: Session,
+    book_id: int,
+    quantity_requested: int = 1
+) -> Dict[str, Any]:
+    """
+    Check if a book is available in requested quantity.
+    
+    Args:
+        db: Database session
+        book_id: ID of book to check
+        quantity_requested: Quantity being requested
+        
+    Returns:
+        Dict containing availability status and message
+    """
+    book = get_book_by_id(db, book_id)
+    if not book:
+        return {
+            "available": False,
+            "message": "Book not found"
+        }
+    
+    if book.stock_quantity >= quantity_requested:
+        return {
+            "available": True,
+            "message": "Book available",
+            "stock_quantity": book.stock_quantity
+        }
+    
+    return {
+        "available": False,
+        "message": f"Only {book.stock_quantity} copies available",
+        "stock_quantity": book.stock_quantity
+    }