# Complexity Metrics Guide

## Cyclomatic Complexity
Measures the number of linearly independent paths through code.

### Rankings
- **A (1-5)**: Simple, easy to maintain
- **B (6-10)**: Moderate complexity
- **C (11-20)**: High complexity, consider refactoring
- **D (21-30)**: Very high, definitely refactor
- **F (31+)**: Extremely complex, needs immediate attention

## Maintainability Index
Score from 0-100 indicating how maintainable code is.

### Thresholds
- **85-100**: Highly maintainable ✅
- **65-84**: Moderately maintainable  ⚠️
- **< 65**: Difficult to maintain ❌

## Reducing Complexity

### 1. Extract Methods
Break large functions into smaller, focused ones.

### 2. Eliminate Nested Logic
Replace nested if-else with early returns.

```python
# Bad: Nested
def process(data):
    if data:
        if data.valid:
            if data.ready:
                return data.process()
    return None

# Good: Early returns
def process(data):
    if not data:
        return None
    if not data.valid:
        return None
    if not data.ready:
        return None
    return data.process()
```

### 3. Use Design Patterns
Apply appropriate patterns to simplify logic.

### 4. Reduce Dependencies
Minimize coupling between modules.