Codex

# Code Review and Optimization for E-Commerce Platform

## Current Code Analysis
```python
def calculate_discount(price, discount_code):
    if discount_code == 'SUMMER20':
        return price * 0.8
    elif discount_code == 'BLACKFRIDAY':
        return price * 0.7
    else:
        return price
```

## Issues Identified
- **Hardcoded Discounts**: Discount codes and percentages are hardcoded, making updates cumbersome.
- **Limited Flexibility**: The function doesn't account for invalid discount codes or expired promotions.
- **No Logging**: There's no tracking of applied discounts for analytics.

## Optimized Solution
```python
class DiscountManager:
    def __init__(self):
        self.discounts = {
            'SUMMER20': 0.2,
            'BLACKFRIDAY': 0.3,
            'NEWYEAR': 0.15
        }
        self.active_discounts = self.discounts

    def apply_discount(self, price, discount_code):
        if discount_code in self.active_discounts:
            discount_percentage = self.active_discounts[discount_code]
            discounted_price = price * (1 - discount_percentage)
            return discounted_price
        return price
```

## Implementation Recommendations
- **Database Integration**: Store discount codes and percentages in a database for easy management.
- **Validation**: Add input validation for discount codes and price values.
- **Logging**: Implement logging to track discount usage patterns.
- **Unit Tests**: Create comprehensive unit tests to ensure discount logic works as expected.