Learning Python Through
Copra & Rubber —
A Complete Walkthrough

from abc import ABC, abstractmethod
from datetime import datetime


class TradableProduct(ABC):
    """Abstract base -- enforces buy_price, sell_price, and display()."""

    def __init__(self, code, name, unit, origin, grade):
        self.code   = code
        self.name   = name
        self.unit   = unit
        self.origin = origin
        self.grade  = grade

    @property
    @abstractmethod
    def buy_price(self): ...

    @property
    @abstractmethod
    def sell_price(self): ...

    @abstractmethod
    def display(self): ...

    def margin(self):
        return self.sell_price - self.buy_price


class CopraProduct(TradableProduct):
    def __init__(self, code, name, origin, grade, buy, sell):
        super().__init__(code, name, "kg", origin, grade)
        self._buy, self._sell = buy, sell

    @property
    def buy_price(self):  return self._buy

    @property
    def sell_price(self): return self._sell

    def display(self):
        print(f"  [{self.code}] {self.name:<28} | Grade: {self.grade:<8} | "
              f"Buy: ₱{self._buy:>7.2f}/kg  Sell: ₱{self._sell:>7.2f}/kg")


class RubberProduct(TradableProduct):
    def __init__(self, code, name, origin, grade, buy, sell, rubber_type):
        super().__init__(code, name, "kg", origin, grade)
        self._buy, self._sell = buy, sell
        self.rubber_type = rubber_type

    @property
    def buy_price(self):  return self._buy

    @property
    def sell_price(self): return self._sell

    def display(self):
        print(f"  [{self.code}] {self.name:<28} | Type: {self.rubber_type:<10} | "
              f"Buy: ₱{self._buy:>7.2f}/kg  Sell: ₱{self._sell:>7.2f}/kg")


class CopraRubberTradingPost:
    def __init__(self):
        self.catalog = {
            "C1": CopraProduct("C1", "Sun-Dried Copra",  "Quezon",    "Grade A", 28.00, 32.00),
            "C2": CopraProduct("C2", "Kiln-Dried Copra", "Davao",     "Grade A", 30.00, 35.00),
            "C3": CopraProduct("C3", "Ball Copra",       "Laguna",    "Grade B", 24.00, 28.00),
            "R1": RubberProduct("R1", "Cup Lump Standard", "Cotabato", "Grade 1", 52.00, 58.00, "Cup Lump"),
            "R2": RubberProduct("R2", "RSS-1 Smoked Sheet", "Zamboanga", "RSS-1", 68.00, 75.00, "RSS"),
        }
        self.transaction_log = []

    def show_catalog(self):
        print("\n  📦  CURRENT PRICE LIST:")
        for code, p in self.catalog.items():
            p.display()

    def _encode_items(self, mode):
        # mode = 'buy' (we pay a seller) or 'sell' (we charge a customer)
        items = []
        while True:
            code = input("Enter code (DONE to finish): ").strip().upper()
            if code == "DONE": break
            if code not in self.catalog:
                print("❌ Invalid code."); continue
            try:
                qty = float(input(f"Quantity in kg for {self.catalog[code].name}? "))
                price = self.catalog[code].buy_price if mode == "buy" else self.catalog[code].sell_price
                items.append((code, qty, price, price * qty))
                print(f"✅ {qty}kg × ₱{price:.2f} = ₱{price*qty:.2f}")
            except ValueError:
                print("❌ Invalid quantity.")
        return items

    def print_transaction(self, party, mode, items):
        if not items: print("🛒 No items encoded."); return
        total = sum(s for _, _, _, s in items)
        label = "BUYING RECEIPT" if mode == "buy" else "SELLING RECEIPT"
        print(f"\n{label} — {party} — {datetime.now():%b %d, %Y}")
        for code, qty, price, sub in items:
            p = self.catalog[code]
            print(f"  {p.name:<28} {qty:>6.1f}kg  ₱{sub:>9.2f}")
        print(f"  {'TOTAL':<28} {'':>6}    ₱{total:>9.2f}")
        self.transaction_log.append({"party": party, "mode": mode, "total": total})

    def run(self):
        self.show_catalog()
        choice = input("\n[1] BUY from seller  [2] SELL to customer: ").strip()
        mode   = "buy" if choice == "1" else "sell"
        party  = input("Name: ").strip().title()
        items  = self._encode_items(mode)
        self.print_transaction(party, mode, items)


if __name__ == "__main__":
    post = CopraRubberTradingPost()
    post.run()