complexity-reduction

Function Complexity Reduction Patterns

When to use: fdk validate shows "Function 'X' has a complexity of Y. Maximum allowed is 7."

Target: Keep complexity ≤ 7 (aim for ≤ 5 for maintainability)

Quick Fixes (Most Common)

1. Sets for Multiple OR Comparisons

Problem: Each || or === adds +1 complexity

// [INVALID] WRONG: Complexity 12
function matchesPriority(ticket, filter) {
  const p = (ticket.priority || ticket.urgency || 0).toString();
  if (filter.includes('high') && (p === '2' || p === '3' || p === 'high' || p === 'urgent')) {
    return true;
  }
  return false;
}

// [VALID] CORRECT: Complexity 3
const HIGH_PRIORITIES = new Set(['2', '3', 'high', 'urgent']);

function matchesPriority(ticket, filter) {
  const p = (ticket.priority || ticket.urgency || 0).toString();
  if (filter.includes('high') && HIGH_PRIORITIES.has(p)) {
    return true;
  }
  return false;
}

2. Lookup Objects (Replace if/else chains)

// [INVALID] WRONG: Complexity 6+
function getPriorityLabel(priority) {
  if (priority === 1) return 'Low';
  else if (priority === 2) return 'Medium';
  else if (priority === 3) return 'High';
  else if (priority === 4) return 'Urgent';
  else return 'Unknown';
}

// [VALID] CORRECT: Complexity 1
const PRIORITY_LABELS = { 1: 'Low', 2: 'Medium', 3: 'High', 4: 'Urgent' };

function getPriorityLabel(priority) {
  return PRIORITY_LABELS[priority] ?? 'Unknown';
}

3. Guard Clauses (Reduce nesting)

// [INVALID] WRONG: Complexity 5+ (nested conditions)
function processTicket(ticket) {
  if (ticket) {
    if (ticket.status === 'open') {
      if (ticket.priority >= 3) {
        if (ticket.assignee) {
          return handleUrgent(ticket);
        }
      }
    }
  }
  return null;
}

// [VALID] CORRECT: Complexity 4 (early returns)
function processTicket(ticket) {
  if (!ticket) return null;
  if (ticket.status !== 'open') return null;
  if (ticket.priority < 3) return null;
  if (!ticket.assignee) return null;
  return handleUrgent(ticket);
}