Performance Impact Monitor - Hooks

#!/usr/bin/env bash

# Performance Impact Monitor Hook
# Monitors for performance-impacting changes in real-time

echo "⚡ Performance Impact Monitor" >&2

# Initialize performance monitoring
PERF_WARNINGS=0
PERF_ERRORS=0
PERF_INFO=0
FILE_SIZE=0
LINE_COUNT=0

# Performance thresholds (configurable)
LARGE_FILE_THRESHOLD=100000    # 100KB
MASSIVE_FILE_THRESHOLD=500000  # 500KB
LARGE_FUNCTION_LINES=50
COMPLEX_CYCLOMATIC=10
LONG_TIMER_MS=5000

# Function to report performance impacts
report_performance() {
  local level="$1"
  local message="$2"
  local suggestion="$3"
  
  case "$level" in
    "ERROR")
      echo "🚨 CRITICAL PERFORMANCE IMPACT: $message" >&2
      [ -n "$suggestion" ] && echo "   💡 Suggestion: $suggestion" >&2
      PERF_ERRORS=$((PERF_ERRORS + 1))
      ;;
    "WARNING")
      echo "⚠️ PERFORMANCE WARNING: $message" >&2
      [ -n "$suggestion" ] && echo "   💡 Suggestion: $suggestion" >&2
      PERF_WARNINGS=$((PERF_WARNINGS + 1))
      ;;
    "INFO")
      echo "ℹ️ PERFORMANCE INFO: $message" >&2
      [ -n "$suggestion" ] && echo "   💡 Tip: $suggestion" >&2
      PERF_INFO=$((PERF_INFO + 1))
      ;;
  esac
}

# Get environment variables (simulated Claude tool context)
TOOL_NAME="${CLAUDE_TOOL_NAME:-unknown}"
FILE_PATH="${CLAUDE_TOOL_FILE_PATH:-}"

# If no file path provided, try to get from stdin input
if [ -z "$FILE_PATH" ]; then
  # Try to read tool input from stdin (for newer hook format)
  INPUT=$(cat)
  TOOL_NAME=$(echo "$INPUT" | jq -r '.tool_name // "unknown"' 2>/dev/null || echo "unknown")
  FILE_PATH=$(echo "$INPUT" | jq -r '.tool_input.file_path // .tool_input.path // ""' 2>/dev/null || echo "")
fi

# Skip if no file path available
if [ -z "$FILE_PATH" ]; then
  exit 0
fi

# Skip if file doesn't exist or is not readable
if [ ! -f "$FILE_PATH" ] || [ ! -r "$FILE_PATH" ]; then
  exit 0
fi

# Only monitor for Edit/Write operations
if [[ "$TOOL_NAME" != "Edit" ]] && [[ "$TOOL_NAME" != "Write" ]] && [[ "$TOOL_NAME" != "MultiEdit" ]]; then
  exit 0
fi

FILE_NAME=$(basename "$FILE_PATH")
FILE_EXT="${FILE_NAME##*.}"

echo "   📊 Analyzing performance impact of: $FILE_NAME" >&2

# 1. File Size Impact Analysis
FILE_SIZE=$(stat -f%z "$FILE_PATH" 2>/dev/null || stat -c%s "$FILE_PATH" 2>/dev/null || echo "0")
LINE_COUNT=$(wc -l < "$FILE_PATH" 2>/dev/null || echo "0")

echo "   📏 File size: $(( FILE_SIZE / 1024 ))KB, Lines: $LINE_COUNT" >&2

# File size warnings
if [ "$FILE_SIZE" -gt "$MASSIVE_FILE_THRESHOLD" ]; then
  report_performance "ERROR" "Massive file detected ($(( FILE_SIZE / 1024 ))KB)" "Consider code splitting or modularization"
elif [ "$FILE_SIZE" -gt "$LARGE_FILE_THRESHOLD" ]; then
  report_performance "WARNING" "Large file detected ($(( FILE_SIZE / 1024 ))KB)" "Monitor bundle size impact and consider optimization"
fi

# 2. Language-Specific Performance Analysis
case "$FILE_EXT" in
  "js"|"jsx"|"ts"|"tsx")
    echo "   📦 JavaScript/TypeScript performance analysis..." >&2
    
    # Large function detection
    LARGE_FUNCTIONS=$(grep -n 'function\\|=>' "$FILE_PATH" | while read line; do
      line_num=$(echo "$line" | cut -d: -f1)
      # Simple heuristic: look for next function or end of file
      next_func=$(tail -n +$((line_num + 1)) "$FILE_PATH" | grep -n 'function\\|=>' | head -1 | cut -d: -f1)
      if [ -n "$next_func" ]; then
        func_lines=$((next_func - 1))
      else
        func_lines=$(tail -n +$line_num "$FILE_PATH" | wc -l)
      fi
      
      if [ "$func_lines" -gt "$LARGE_FUNCTION_LINES" ]; then
        echo "$line_num:$func_lines"
      fi
    done)
    
    if [ -n "$LARGE_FUNCTIONS" ]; then
      func_count=$(echo "$LARGE_FUNCTIONS" | wc -l)
      report_performance "WARNING" "$func_count large function(s) detected (>$LARGE_FUNCTION_LINES lines)" "Consider breaking down into smaller functions"
    fi
    
    # Performance anti-patterns
    if grep -q '\\$(' "$FILE_PATH" 2>/dev/null; then
      jquery_count=$(grep -c '\\$(' "$FILE_PATH" 2>/dev/null || echo "0")
      if [ "$jquery_count" -gt 5 ]; then
        report_performance "INFO" "Heavy jQuery usage detected ($jquery_count instances)" "Consider modern alternatives like vanilla JS or React"
      fi
    fi
    
    # Long timers
    if grep -E '(setTimeout|setInterval).*[0-9]{4,}' "$FILE_PATH" 2>/dev/null; then
      report_performance "WARNING" "Long timer intervals detected (>=${LONG_TIMER_MS}ms)" "Verify if long delays are intentional"
    fi
    
    # Nested loops
    NESTED_LOOPS=$(grep -E 'for.*{[^}]*for.*{[^}]*for' "$FILE_PATH" 2>/dev/null || echo "")
    if [ -n "$NESTED_LOOPS" ]; then
      report_performance "ERROR" "Triple nested loops detected - O(n³) complexity" "Consider algorithm optimization or data structure changes"
    elif grep -E 'for.*{[^}]*for' "$FILE_PATH" 2>/dev/null; then
      nested_count=$(grep -c 'for.*{[^}]*for' "$FILE_PATH" 2>/dev/null || echo "0")
      if [ "$nested_count" -gt 3 ]; then
        report_performance "WARNING" "Multiple nested loops detected" "Review algorithmic complexity"
      fi
    fi
    
    # Memory leak patterns
    if grep -q 'addEventListener.*function' "$FILE_PATH" 2>/dev/null; then
      if ! grep -q 'removeEventListener' "$FILE_PATH" 2>/dev/null; then
        report_performance "WARNING" "Event listeners without cleanup detected" "Add removeEventListener calls to prevent memory leaks"
      fi
    fi
    
    # Global variable pollution
    GLOBAL_VARS=$(grep -c '^var\\|^let\\|^const' "$FILE_PATH" 2>/dev/null || echo "0")
    if [ "$GLOBAL_VARS" -gt 20 ]; then
      report_performance "INFO" "Many global variables detected ($GLOBAL_VARS)" "Consider using modules or namespacing"
    fi
    
    # Bundle size impact for dependencies
    if grep -q 'import.*from' "$FILE_PATH" 2>/dev/null; then
      LARGE_IMPORTS=$(grep -E 'import.*(lodash|moment|rxjs)' "$FILE_PATH" 2>/dev/null || echo "")
      if [ -n "$LARGE_IMPORTS" ]; then
        report_performance "INFO" "Large library imports detected" "Consider tree shaking or lighter alternatives"
      fi
    fi
    ;;
    
  "py")
    echo "   🐍 Python performance analysis..." >&2
    
    # List comprehensions vs loops
    if grep -q 'for.*in.*:' "$FILE_PATH" 2>/dev/null; then
      list_comp_count=$(grep -c '\\[.*for.*in.*\\]' "$FILE_PATH" 2>/dev/null || echo "0")
      loop_count=$(grep -c 'for.*in.*:' "$FILE_PATH" 2>/dev/null || echo "0")
      
      if [ "$loop_count" -gt 0 ] && [ "$list_comp_count" -eq 0 ]; then
        report_performance "INFO" "Consider using list comprehensions for better performance" "List comprehensions are often faster than explicit loops"
      fi
    fi
    
    # Global imports inside functions
    if grep -A 5 'def ' "$FILE_PATH" | grep -q 'import' 2>/dev/null; then
      report_performance "WARNING" "Imports inside functions detected" "Move imports to module level for better performance"
    fi
    
    # String concatenation
    if grep -q '+.*+.*+' "$FILE_PATH" 2>/dev/null; then
      report_performance "INFO" "String concatenation chains detected" "Consider using f-strings or join() for better performance"
    fi
    ;;
    
  "sql")
    echo "   🗄️ SQL performance analysis..." >&2
    
    # Missing indexes (basic heuristics)
    if grep -qi 'where.*=' "$FILE_PATH" 2>/dev/null; then
      if ! grep -qi 'index' "$FILE_PATH" 2>/dev/null; then
        report_performance "WARNING" "WHERE clauses without visible indexes" "Ensure proper indexing for query performance"
      fi
    fi
    
    # SELECT * usage
    if grep -qi 'select \\*' "$FILE_PATH" 2>/dev/null; then
      select_star_count=$(grep -ci 'select \\*' "$FILE_PATH" 2>/dev/null || echo "0")
      report_performance "WARNING" "SELECT * queries detected ($select_star_count)" "Specify only needed columns for better performance"
    fi
    
    # Cartesian products
    if grep -qi 'from.*,.*where' "$FILE_PATH" 2>/dev/null; then
      if ! grep -qi 'join' "$FILE_PATH" 2>/dev/null; then
        report_performance "ERROR" "Potential cartesian product detected" "Use explicit JOINs instead of comma-separated tables"
      fi
    fi
    ;;
    
  "css"|"scss"|"sass")
    echo "   🎨 CSS performance analysis..." >&2
    
    # Complex selectors
    COMPLEX_SELECTORS=$(grep -c '[[:space:]].*[[:space:]].*[[:space:]].*[[:space:]]' "$FILE_PATH" 2>/dev/null || echo "0")
    if [ "$COMPLEX_SELECTORS" -gt 5 ]; then
      report_performance "WARNING" "Complex CSS selectors detected ($COMPLEX_SELECTORS)" "Simplify selectors for better rendering performance"
    fi
    
    # Expensive properties
    if grep -q 'box-shadow.*,.*,' "$FILE_PATH" 2>/dev/null; then
      report_performance "INFO" "Complex box-shadow detected" "Consider simpler shadow effects for better performance"
    fi
    
    if grep -q '@import' "$FILE_PATH" 2>/dev/null; then
      import_count=$(grep -c '@import' "$FILE_PATH" 2>/dev/null || echo "0")
      if [ "$import_count" -gt 3 ]; then
        report_performance "WARNING" "Multiple CSS @imports detected ($import_count)" "Consider bundling CSS files to reduce HTTP requests"
      fi
    fi
    ;;
    
  "html")
    echo "   🌐 HTML performance analysis..." >&2
    
    # Inline styles
    INLINE_STYLES=$(grep -c 'style=' "$FILE_PATH" 2>/dev/null || echo "0")
    if [ "$INLINE_STYLES" -gt 10 ]; then
      report_performance "WARNING" "Many inline styles detected ($INLINE_STYLES)" "Move styles to CSS files for better caching"
    fi
    
    # Large images without attributes
    if grep -q '<img' "$FILE_PATH" 2>/dev/null; then
      if ! grep -q 'width=\\|height=' "$FILE_PATH" 2>/dev/null; then
        img_count=$(grep -c '<img' "$FILE_PATH" 2>/dev/null || echo "0")
        report_performance "INFO" "Images without dimensions detected ($img_count)" "Add width/height attributes to prevent layout shifts"
      fi
    fi
    ;;
esac

# 3. Asset Performance Analysis
echo "   🖼️ Asset performance analysis..." >&2

# Check for asset imports/references
if [[ "$FILE_EXT" =~ ^(js|jsx|ts|tsx|css|scss|html)$ ]]; then
  # Image references
  IMAGE_REFS=$(grep -oE '\\.(jpg|jpeg|png|gif|svg|webp)' "$FILE_PATH" 2>/dev/null | wc -l || echo "0")
  if [ "$IMAGE_REFS" -gt 10 ]; then
    report_performance "INFO" "Many image references detected ($IMAGE_REFS)" "Consider image optimization and lazy loading"
  fi
  
  # Large base64 data
  if grep -q 'data:image' "$FILE_PATH" 2>/dev/null; then
    BASE64_COUNT=$(grep -c 'data:image' "$FILE_PATH" 2>/dev/null || echo "0")
    report_performance "WARNING" "Base64 encoded images detected ($BASE64_COUNT)" "Consider using separate image files for better caching"
  fi
fi

# 4. Database Query Analysis
if grep -qi 'select\\|insert\\|update\\|delete' "$FILE_PATH" 2>/dev/null; then
  echo "   🗄️ Database query analysis..." >&2
  
  # N+1 query patterns
  if grep -q 'for.*in' "$FILE_PATH" 2>/dev/null && grep -q 'select\\|query' "$FILE_PATH" 2>/dev/null; then
    report_performance "WARNING" "Potential N+1 query pattern detected" "Consider using joins or batch queries"
  fi
  
  # Missing LIMIT clauses
  if grep -qi 'select.*from' "$FILE_PATH" 2>/dev/null; then
    if ! grep -qi 'limit\\|top\\|rownum' "$FILE_PATH" 2>/dev/null; then
      unlimited_queries=$(grep -ci 'select.*from' "$FILE_PATH" 2>/dev/null || echo "0")
      if [ "$unlimited_queries" -gt 2 ]; then
        report_performance "WARNING" "Queries without LIMIT detected ($unlimited_queries)" "Add LIMIT clauses to prevent large result sets"
      fi
    fi
  fi
fi

# 5. Framework-Specific Analysis
if [[ "$FILE_EXT" =~ ^(jsx|tsx)$ ]]; then
  echo "   ⚛️ React performance analysis..." >&2
  
  # Component re-render patterns
  if grep -q 'useState\\|useEffect' "$FILE_PATH" 2>/dev/null; then
    if ! grep -q 'useMemo\\|useCallback\\|React.memo' "$FILE_PATH" 2>/dev/null; then
      hooks_count=$(grep -c 'useState\\|useEffect' "$FILE_PATH" 2>/dev/null || echo "0")
      if [ "$hooks_count" -gt 5 ]; then
        report_performance "INFO" "Many React hooks without memoization" "Consider useMemo/useCallback for expensive operations"
      fi
    fi
  fi
  
  # Inline object/function creation in props
  if grep -q '={{' "$FILE_PATH" 2>/dev/null; then
    inline_objects=$(grep -c '={{' "$FILE_PATH" 2>/dev/null || echo "0")
    if [ "$inline_objects" -gt 5 ]; then
      report_performance "WARNING" "Many inline objects in JSX props ($inline_objects)" "Extract to variables to prevent unnecessary re-renders"
    fi
  fi
fi

# 6. Generate Performance Impact Summary
echo "" >&2
echo "⚡ Performance Impact Summary" >&2
echo "============================" >&2
echo "   📄 File: $FILE_NAME ($(( FILE_SIZE / 1024 ))KB)" >&2
echo "   🚨 Critical Issues: $PERF_ERRORS" >&2
echo "   ⚠️ Warnings: $PERF_WARNINGS" >&2
echo "   ℹ️ Optimization Tips: $PERF_INFO" >&2

# Performance impact assessment
TOTAL_ISSUES=$((PERF_ERRORS + PERF_WARNINGS))

if [ "$PERF_ERRORS" -gt 0 ]; then
  echo "   🚨 Impact Level: HIGH - Critical performance issues detected" >&2
elif [ "$PERF_WARNINGS" -gt 3 ]; then
  echo "   ⚠️ Impact Level: MODERATE - Multiple performance concerns" >&2
elif [ "$PERF_WARNINGS" -gt 0 ]; then
  echo "   ⚠️ Impact Level: LOW - Minor performance considerations" >&2
elif [ "$PERF_INFO" -gt 0 ]; then
  echo "   ✅ Impact Level: MINIMAL - Good practices recommended" >&2
else
  echo "   🎉 Impact Level: OPTIMAL - No performance issues detected" >&2
fi

if [ "$TOTAL_ISSUES" -gt 0 ]; then
  echo "" >&2
  echo "💡 Performance Optimization Resources:" >&2
  echo "   • Web: Core Web Vitals and Lighthouse audits" >&2
  echo "   • JavaScript: Profiler tools and performance monitoring" >&2
  echo "   • Database: Query optimization and indexing strategies" >&2
  echo "   • Bundle: Code splitting and tree shaking" >&2
fi

echo "⚡ Performance impact monitoring complete" >&2
exit 0