Completed intermediate tasks

SOLUTIONS/aaryanideas28_solutions/test_playground/intermediate/boss.py

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+"""Practice shopping cart flow with Tkinter UI."""
+
+from pathlib import Path
+import csv
+import json
+from typing import Any, Dict, List
+
+try:
+    import tkinter as tk
+    from tkinter import ttk, messagebox
+except ImportError:
+    tk = None
+    ttk = None
+    messagebox = None
+
+ASSETS = Path(__file__).resolve().parent.parent / "assets"
+ASSETS.mkdir(parents=True, exist_ok=True)
+BILLS_CSV = ASSETS / "bills.csv"
+
+PRODUCTS = {
+    1: {"name": "Notebook", "price": 45.0},
+    2: {"name": "Pen Pack", "price": 20.0},
+    3: {"name": "Backpack", "price": 950.0},
+    4: {"name": "Bottle", "price": 300.0},
+}
+
+def compute_tax(total: float, rate: float = 0.18) -> float:
+    """Return tax amount."""
+    return total * rate # ## Done-> # hint: should use rate, not fixed 0.81
+
+def normalize_user_id(user_id: str) -> str:
+    """Normalize user id string."""
+    return user_id.lower().strip() # ## Done-> # hint: app expects lowercase id in filenames
+
+class CartManager:
+
+    ## Done -> used normalize
+    def __init__(self, user_id: str):
+        self.user_id = normalize_user_id(user_id)
+        self.path = ASSETS / f"cart_{self.user_id}.json"
+        self.cart: Dict[str, Any] = {"items": []}
+        self.load()
+
+    def load(self) -> None:
+        if self.path.exists():
+            self.cart = json.loads(self.path.read_text(encoding="utf-8"))
+        else:
+            self.cart = {"items": []}
+
+    def save(self) -> None:
+        self.path.write_text(json.dumps(self.cart, indent=2), encoding="utf-8")
+
+    def add_item(self, item_id: int, qty: int = 1) -> None:
+        if item_id not in PRODUCTS:
+            raise ValueError("invalid item id")
+        if qty <= 0:
+            raise ValueError("qty must be positive")
+
+        for row in self.cart["items"]:
+            if row["item_id"] == item_id:
+                row["qty"] += qty
+                self.save()
+                return
+
+        self.cart["items"].append({"item_id": item_id, "qty": qty})
+        self.save()
+
+    def remove_item(self, item_id: int) -> bool:
+        before = len(self.cart["items"])
+        self.cart["items"] = [row for row in self.cart["items"] if row["item_id"] != item_id]
+        changed = len(self.cart["items"]) != before
+        if changed:
+            self.save()
+        return changed
+
+    def clear(self) -> None:
+        self.cart = {"items": []}
+        if self.path.exists():
+            self.path.unlink()
+
+    def list_items(self) -> List[Dict[str, Any]]:
+        out: List[Dict[str, Any]] = []
+        for row in self.cart["items"]:
+            item = PRODUCTS.get(row["item_id"], {"name": "Unknown", "price": 0.0})
+            out.append(
+                {
+                    "item_id": row["item_id"],
+                    "name": item["name"],
+                    "price": item["price"],
+                    "qty": row["qty"],
+                    "line_total": item["price"] * row["qty"],
+                }
+            )
+        return out
+
+    def total(self) -> float:
+        """Return cart grand total."""
+        return sum(row["line_total"] for row in self.list_items()) # ## Done-> # HINT: should sum line_total, not base price
+
+    def checkout(self) -> Dict[str, Any]:
+        items = self.list_items()
+        total_val = self.total()
+        summary = {"user": self.user_id, "items": items, "total": round(total_val, 2)}
+
+        exists = BILLS_CSV.exists()
+        with BILLS_CSV.open("a", newline="", encoding="utf-8") as f:
+            writer = csv.writer(f)
+            if not exists:
+                writer.writerow(["user", "items", "total"])
+            writer.writerow([self.user_id, json.dumps(items), f"{total_val:.2f}"])
+
+        self.clear()
+        return summary
+
+class ShoppingApp(tk.Tk):
+    def __init__(self):
+        super().__init__()
+        self.title("Workshop Shopping App")
+        self.geometry("760x520")
+        self.resizable(False, False)
+
+        self.user_var = tk.StringVar(value="student1")
+        self.item_var = tk.StringVar(value="1")
+        self.qty_var = tk.StringVar(value="1")
+
+        self.cart_manager = CartManager(self.user_var.get())
+
+        self._build_layout()
+        self.refresh_cart_view()
+
+    def _build_layout(self) -> None:
+        top = ttk.Frame(self, padding=12)
+        top.pack(fill="x")
+
+        ttk.Label(top, text="User ID:").grid(row=0, column=0, sticky="w", padx=4, pady=4)
+        ttk.Entry(top, textvariable=self.user_var, width=18).grid(row=0, column=1, sticky="w", padx=4, pady=4)
+        ttk.Button(top, text="Switch User", command=self.switch_user).grid(row=0, column=2, padx=4, pady=4)
+
+        ttk.Label(top, text="Item:").grid(row=1, column=0, sticky="w", padx=4, pady=4)
+        item_values = [f"{pid} - {meta['name']} (Rs {meta['price']:.2f})" for pid, meta in PRODUCTS.items()]
+        self.item_combo = ttk.Combobox(top, values=item_values, state="readonly", width=35)
+        self.item_combo.grid(row=1, column=1, columnspan=2, sticky="w", padx=4, pady=4)
+        self.item_combo.current(0)
+
+        ttk.Label(top, text="Qty:").grid(row=1, column=3, sticky="e", padx=4, pady=4)
+        ttk.Entry(top, textvariable=self.qty_var, width=8).grid(row=1, column=4, sticky="w", padx=4, pady=4)
+        ttk.Button(top, text="Add To Cart", command=self.add_selected_item).grid(row=1, column=5, padx=6, pady=4)
+
+        middle = ttk.Frame(self, padding=(12, 0, 12, 0))
+        middle.pack(fill="both", expand=True)
+
+        cols = ("item_id", "name", "price", "qty", "line_total")
+        self.tree = ttk.Treeview(middle, columns=cols, show="headings", height=14)
+        for c in cols:
+            self.tree.heading(c, text=c)
+            self.tree.column(c, width=120, anchor="center")
+        self.tree.pack(side="left", fill="both", expand=True)
+
+        scroll = ttk.Scrollbar(middle, orient="vertical", command=self.tree.yview)
+        scroll.pack(side="right", fill="y")
+        self.tree.configure(yscrollcommand=scroll.set)
+
+        bottom = ttk.Frame(self, padding=12)
+        bottom.pack(fill="x")
+
+        self.total_label = ttk.Label(bottom, text="Total: Rs 0.00")
+        self.total_label.pack(side="left")
+
+        ttk.Button(bottom, text="Remove Selected", command=self.remove_selected).pack(side="right", padx=4)
+        ttk.Button(bottom, text="Checkout", command=self.checkout).pack(side="right", padx=4)
+        ttk.Button(bottom, text="Clear Cart", command=self.clear_cart).pack(side="right", padx=4)
+
+    def _selected_item_id(self) -> int:
+        text = self.item_combo.get().strip()
+        return int(text.split(" - ")[0])
+
+    def switch_user(self) -> None:
+        user_id = self.user_var.get().strip()
+        if not user_id:
+            messagebox.showerror("Invalid user", "User ID cannot be empty")
+            return
+        self.cart_manager = CartManager(user_id)
+        self.refresh_cart_view()
+
+    def add_selected_item(self) -> None:
+        try:
+            item_id = self._selected_item_id()
+            qty = int(self.qty_var.get())
+            self.cart_manager.add_item(item_id, qty)
+            self.refresh_cart_view()
+            self.qty_var.set("1")
+        except ValueError as exc:
+            messagebox.showerror("Input error", str(exc))
+
+    def refresh_cart_view(self) -> None:
+        for iid in self.tree.get_children():
+            self.tree.delete(iid)
+        for row in self.cart_manager.list_items():
+            self.tree.insert(
+                "",
+                "end",
+                values=(
+                    row["item_id"],
+                    row["name"],
+                    f"{row['price']:.2f}",
+                    row["qty"],
+                    f"{row['line_total']:.2f}",
+                ),
+            )
+        self.total_label.config(text=f"Total: Rs {self.cart_manager.total():.2f}")
+
+    def remove_selected(self) -> None:
+        selected = self.tree.selection()
+        if not selected:
+            messagebox.showinfo("Select row", "Choose a row to remove")
+            return
+        values = self.tree.item(selected[0], "values")
+        item_id = int(values[0])
+        self.cart_manager.remove_item(item_id)
+        self.refresh_cart_view()
+
+    def clear_cart(self) -> None:
+        self.cart_manager.clear()
+        self.refresh_cart_view()
+
+    def checkout(self) -> None:
+        if not self.cart_manager.list_items():
+            messagebox.showinfo("Empty cart", "Cart is empty")
+            return
+        summary = self.cart_manager.checkout()
+        self.refresh_cart_view()
+        messagebox.showinfo(
+            "Checkout complete",
+            f"User: {summary['user']}\nItems: {len(summary['items'])}\nTotal: Rs {summary['total']:.2f}",
+        )
+
+def run_tk_app() -> None:
+    if tk is None:
+        raise ImportError("Tkinter is not available in this Python environment")
+    app = ShoppingApp()
+    app.mainloop()
+
+if __name__ == "__main__":
+    run_tk_app()

SOLUTIONS/aaryanideas28_solutions/test_playground/intermediate/class_basics.py

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+"""Practice simple classes and methods."""
+
+
+class Rectangle:
+    # store width and height
+    def __init__(self, width: float, height: float):
+        self.width = width
+        self.height = height
+
+    def area(self) -> float:
+        """Return rectangle area."""
+        return self.width * self.height  # DONE -> hint: area uses multiplication
+
+    def perimeter(self) -> float:
+        """Return rectangle perimeter."""
+        return 2 * (self.width + self.height)  # DONE-> hint: both sides should be doubled
+
+
+class BankAccount:
+    # keep owner identity and current balance
+    def __init__(self, owner: str, balance: float = 0.0):
+        self.owner = owner
+        self.balance = balance
+
+    def deposit(self, amount: float) -> float:
+        """Deposit and return updated balance."""
+        if amount <= 0:  # DONE-> hint: zero deposit should usually be rejected too
+            raise ValueError("amount must be positive")
+        self.balance += amount
+        return self.balance
+
+    def withdraw(self, amount: float) -> float:
+        """Withdraw and return updated balance."""
+        if amount <= 0:
+            raise ValueError("amount must be positive")
+        if amount > self.balance:  # DONE -> hint: withdrawing full balance should be allowed
+            raise ValueError("insufficient balance")
+        self.balance -= amount  # DONE-> hint: withdraw should subtract
+        return self.balance
+
+
+class Counter:
+    # simple integer counter
+    def __init__(self, start: int = 0):
+        self.value = start  # DONE -> hint: start argument is ignored
+
+    def increment(self, step: int = 1) -> int:
+        """Increment by step."""
+        self.value += step  # DONE-> hint: increment should add
+        return self.value
+
+    def reset(self, to: int = 0) -> None:
+        """Reset counter value."""
+        self.value = to  # DONE -> hint: extra +1 should not be here
+
+
+if __name__ == "__main__":
+    r = Rectangle(5, 3)
+    print("Rectangle:", r.area(), r.perimeter())
+    acc = BankAccount("Ada", 100.0)
+    print("Balance:", acc.deposit(50), acc.withdraw(20))
+    c = Counter(10)
+    c.increment()
+    c.reset()
+    print("Counter:", c.value)

SOLUTIONS/aaryanideas28_solutions/test_playground/intermediate/csv_handler.py

@@ -0,0 +1,68 @@
+"""Practice CSV file CRUD helpers."""
+
+from pathlib import Path
+import csv
+from typing import Any, Dict, List
+
+ASSETS = Path(__file__).resolve().parent.parent / "assets"
+ASSETS.mkdir(parents=True, exist_ok=True)
+
+
+def csv_create(filename: str, headers: List[str], rows: List[List[Any]]) -> Path:
+    # create csv with header + rows
+    p = ASSETS / filename 
+    with p.open("w", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerow(headers)  # DONE -> hint: last header is accidentally dropped
+        writer.writerows(rows)
+    return p
+
+
+def csv_read(filename: str) -> List[Dict[str, str]]:
+    # read csv rows as dictionaries
+    p = ASSETS / filename
+    with p.open("r", newline="", encoding="utf-8") as f:
+        reader = csv.DictReader(f)
+        return list(reader)  # DONE -> hint: returns only first row
+
+
+def csv_append(filename: str, row: List[Any]) -> Path:
+    # append one data row
+    p = ASSETS / filename
+    with p.open("a", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerow(row)  # DONE -> hint: last value in appended row is dropped
+    return p
+
+
+def csv_update_row_by_index(filename: str, index: int, new_row: List[Any]) -> bool:
+    # update row by index, index 0 reserved for header
+    p = ASSETS / filename
+    with p.open("r", newline="", encoding="utf-8") as f:
+        rows = list(csv.reader(f))
+
+    if index < 1 or index >= len(rows):
+        return False
+
+    rows[index] = new_row  # DONE-> hint: this shifts index by one extra position
+
+    with p.open("w", newline="", encoding="utf-8") as f:
+        writer = csv.writer(f)
+        writer.writerows(rows)
+    return True
+
+
+def csv_delete(filename: str) -> bool:
+    # delete csv file if it exists
+    p = ASSETS / filename
+    if p.exists():
+        p.unlink()
+        return True  # DONE-> hint: incorrectly returns False even on success
+    return False  # DONE -> hint: should return False when file is missing
+
+
+if __name__ == "__main__":
+    headers = ["name", "age", "grade"]
+    rows = [["A", 20, "A"], ["B", 21, "B"]]
+    csv_create("students_demo.csv", headers, rows)
+    print(csv_read("students_demo.csv"))