claude-code-ultimate-guide/examples/commands/refactor.md

SOLID Refactoring Assistant

Analyze code for SOLID violations and suggest targeted improvements.

Purpose

Identify refactoring opportunities based on:

• SOLID principle violations
• Code smells and anti-patterns
• Complexity metrics
• Duplication detection

Instructions

Step 1: Scope Analysis

Determine the refactoring scope from user input:

• Single file: Deep analysis
• Directory: Pattern detection across files
• Function/class: Focused extraction suggestions

# Get file/directory stats
if [ -f "$TARGET" ]; then
  wc -l "$TARGET"
  echo "Single file analysis"
elif [ -d "$TARGET" ]; then
  find "$TARGET" -type f \( -name "*.ts" -o -name "*.js" -o -name "*.py" \) | wc -l
  echo "Directory analysis"
fi

Step 2: SOLID Violations Detection

S - Single Responsibility

Look for:

• Files > 300 lines
• Functions > 50 lines
• Classes with > 10 methods
• Mixed concerns (data + UI + business logic)

# Find large files
find . -name "*.{ts,js,py}" -exec wc -l {} + 2>/dev/null | sort -rn | head -10

# Functions with high line count (approximate)
grep -rn "function\|def \|fn " --include="*.{ts,js,py,rs}" . | head -20

O - Open/Closed Principle

Look for:

• Switch/case statements on types
• Repeated if/else type checking
• Direct modifications vs extensions

L - Liskov Substitution

Look for:

• Overridden methods that throw "not implemented"
• Type checks before method calls
• Empty method overrides

I - Interface Segregation

Look for:

• Large interfaces (> 10 methods)
• Classes implementing unused interface methods
• Fat service classes

D - Dependency Inversion

Look for:

• Direct instantiation of dependencies (new Service())
• Hardcoded class references
• Missing dependency injection

Step 3: Code Smells

# Duplication patterns
grep -rn --include="*.{ts,js,py}" . 2>/dev/null | \
  awk -F: '{print $3}' | sort | uniq -c | sort -rn | head -10

# Long parameter lists (> 4 params)
grep -rn "function.*,.*,.*,.*," --include="*.{ts,js}" . 2>/dev/null | head -10

# Deep nesting (4+ levels)
grep -rn "^\s\{16,\}" --include="*.{ts,js,py}" . 2>/dev/null | head -10

Step 4: Complexity Assessment

For each issue found, assess:

• Impact: How much code is affected?
• Risk: What could break?
• Effort: Lines to change, tests needed?

Output Format

---

🔧 Refactoring Analysis

Target: [file/directory] Lines Analyzed: [count]

📊 SOLID Scorecard

Principle	Status	Issues Found
Single Responsibility	🟡	3 large classes
Open/Closed	🟢	OK
Liskov Substitution	🟢	OK
Interface Segregation	🔴	2 fat interfaces
Dependency Inversion	🟡	5 direct instantiations

🎯 Priority Refactorings

1. [Highest Impact] - Extract class from UserService

Violation: Single Responsibility Current: 450 lines handling auth + profile + notifications Suggested:

UserService.ts (450 lines)
    ↓ Extract
AuthService.ts (~150 lines)
ProfileService.ts (~150 lines)
NotificationService.ts (~100 lines)

Risk: Medium (update imports) Tests Needed: Update dependency injection in tests

2. [Second Priority] - Replace switch with polymorphism

Location: src/handlers/payment.ts:45 Current:

switch (paymentType) {
  case 'card': // 50 lines
  case 'bank': // 50 lines
  case 'crypto': // 50 lines
}

Suggested: Strategy pattern with PaymentProcessor interface Risk: Low (isolated change)

📝 Code Smells

Smell	Location	Severity
Long Method	api.ts:calculateTotal (120 lines)	🟠 High
Duplicate Code	utils/*.ts (3 similar blocks)	🟡 Medium
Deep Nesting	parser.ts:parse (6 levels)	🟡 Medium

🚀 Quick Wins (Low Risk, High Value)

1. Extract validateEmail() to shared utils (used in 4 places)
2. Replace magic numbers with named constants
3. Add early returns to reduce nesting in processOrder()

⚠️ Technical Debt Notes

• [Item to track for future sprints]

---

Refactoring Safety Checklist

Before applying suggestions:

• Tests exist for affected code
• Create feature branch
• Commit current state
• Apply one refactoring at a time
• Run tests after each change
• Review diff before committing

Usage

Analyze specific file:

/refactor src/services/user.ts

Analyze directory:

/refactor src/api/

Focus on specific principle:

/refactor --focus=srp src/services/

With complexity threshold:

/refactor --threshold=high

References

• Martin Fowler's Refactoring Catalog
• Clean Code by Robert C. Martin
• SOLID principles by Robert C. Martin

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