feat(csv): read/write inventory from/to csv file

main.py

@@ -1,3 +1,6 @@
+#!/usr/bin/env python3
+
+
 def main() -> None:
     pass
 

src/bookstore/book.py

@@ -13,10 +13,14 @@ def _check_stock_value(instance, attribute, value):
         raise ValueError("Stock must be larger or equal to 0!")
 
 
+def _to_isbn(number: str):
+    return ISBN(number)
+
+
 @define
 class Book:
     title: str = field()
     author: str = field()  # TODO: add default author as "Unknown"
-    isbn: ISBN = field(on_setattr=setters.frozen, repr=lambda value: f"'{value}'")
+    isbn: ISBN = field(converter=_to_isbn, validator=validators.instance_of(ISBN), on_setattr=setters.frozen, repr=lambda value: f"'{value}'")
     price: float = field(converter=float, validator=[validators.instance_of(float), _check_price_value])
     stock: int = field(converter=int, validator=[validators.instance_of(int), _check_stock_value])

src/bookstore/inventory.py

@@ -1,3 +1,4 @@
+import csv
 from pathlib import Path
 
 from .book import Book
@@ -5,14 +6,29 @@ from .isbn import ISBN
 
 
 class Inventory:
-    def __init__(self, books: list[Book]) -> None:
+    def __init__(self, books: list[Book] | None) -> None:
-        self.books: dict[ISBN, Book] = {book.isbn: book for book in books}
+        self.books: dict[ISBN, Book] = {book.isbn: book for book in books} if books else {}
 
     def read_from_file(self, path: Path) -> None:
         """Read `Inventory` from `path` csv file."""
+        with open(path, mode="r") as file:
+            reader = csv.reader(file)
+
+            next(reader, None)  # Skip header
+
+            for title, author, isbn, price, stock in reader:
+                book = Book(title, author, isbn, price, stock)
+                self.add(book)
 
     def save_to_file(self, path: Path) -> None:
         """Save `Inventory` to `path` csv file."""
+        with open(path, mode="w") as file:
+            writer = csv.writer(file)
+
+            writer.writerow(["Title", "Auther", "ISBN", "Price", "Stock"])
+
+            for book in self.books.values():
+                writer.writerow([book.title, book.author, book.isbn, book.price, book.stock])
 
     def add(self, book: Book) -> None:
         """Add `Book` to the `Inventory`. `Book`s ISBN must be unique."""