feat: implement refactoring opportunity finder — AST complexity + scoring (#210)

scripts/refactoring_opportunity_finder.py

@@ -1,54 +1,144 @@
 #!/usr/bin/env python3
 """
-Finds refactoring opportunities in codebases
-
-Engine ID: 10.4
-
-Usage:
-    python3 scripts/refactoring_opportunity_finder.py --output proposals/refactoring_opportunity_finder.json
-    python3 scripts/refactoring_opportunity_finder.py --output proposals/refactoring_opportunity_finder.json --dry-run
+Refactoring Opportunity Finder — Engine 10.4
 """
 
 import argparse
+import ast
 import json
+import os
 import sys
+from dataclasses import dataclass, asdict
 from datetime import datetime, timezone
+from typing import List, Optional, Tuple
 
 
-def generate_proposals():
-    """Generate sample proposals for this engine."""
-    # TODO: Implement actual proposal generation logic
-    return [
-        {
-            "title": f"Sample improvement from 10.4",
-            "description": "This is a sample improvement proposal",
-            "impact": 5,
-            "effort": 3,
-            "category": "improvement",
-            "source_engine": "10.4",
-            "timestamp": datetime.now(timezone.utc).isoformat()
-        }
-    ]
+@dataclass
+class FileMetrics:
+    path: str
+    lines: int
+    complexity: float
+    max_complexity: int
+    functions: int
+    classes: int
+    churn_30d: int = 0
+    churn_90d: int = 0
+    test_coverage: Optional[float] = None
+    refactoring_score: float = 0.0
+
+
+class ComplexityVisitor(ast.NodeVisitor):
+    def __init__(self):
+        self.functions = []
+        self.classes = 0
+
+    def visit_FunctionDef(self, node):
+        complexity = 1
+        for child in ast.walk(node):
+            if isinstance(child, (ast.If, ast.While, ast.For)):
+                complexity += 1
+            elif isinstance(child, ast.BoolOp):
+                complexity += len(child.values) - 1
+            elif isinstance(child, ast.ExceptHandler):
+                complexity += 1
+            elif isinstance(child, ast.Assert):
+                complexity += 1
+        self.functions.append((node.name, complexity, node.lineno))
+        self.generic_visit(node)
+
+    def visit_AsyncFunctionDef(self, node):
+        self.visit_FunctionDef(node)
+
+    def visit_ClassDef(self, node):
+        self.classes += 1
+        self.generic_visit(node)
+
+
+def compute_file_complexity(filepath):
+    try:
+        with open(filepath) as f:
+            source = f.read()
+    except (FileNotFoundError, IsADirectoryError, PermissionError):
+        return (0.0, 0, 0, 0, 0)
+    try:
+        tree = ast.parse(source)
+    except SyntaxError:
+        return (0.0, 0, 0, 0, 0)
+    lines = source.count("\n") + 1 if source.strip() else 0
+    visitor = ComplexityVisitor()
+    visitor.visit(tree)
+    if not visitor.functions:
+        return (0.0, 0, 0, visitor.classes, lines)
+    complexities = [c for _, c, _ in visitor.functions]
+    avg = sum(complexities) / len(complexities)
+    max_c = max(complexities)
+    return (round(avg, 1), max_c, len(visitor.functions), visitor.classes, lines)
+
+
+def calculate_refactoring_score(metrics):
+    score = 0.0
+    complexity_score = min(40, metrics.complexity * 4)
+    if metrics.max_complexity > 10:
+        complexity_score = min(40, complexity_score + (metrics.max_complexity - 10))
+    score += complexity_score
+    if metrics.lines <= 0:
+        pass
+    elif metrics.lines <= 100:
+        score += metrics.lines * 0.1
+    elif metrics.lines <= 500:
+        score += 10 + (metrics.lines - 100) * 0.0125
+    else:
+        score += min(20, 15 + (metrics.lines - 500) * 0.01)
+    churn_score = (metrics.churn_30d * 2) + (metrics.churn_90d * 0.5)
+    score += min(30, churn_score)
+    if metrics.test_coverage is None:
+        score += 5
+    elif metrics.test_coverage < 0.3:
+        score += 10
+    elif metrics.test_coverage < 0.6:
+        score += 7
+    elif metrics.test_coverage < 0.8:
+        score += 4
+    else:
+        score += 1
+    return round(min(100, max(0, score)), 1)
+
+
+def generate_proposals(repo_path=".", threshold=30.0):
+    proposals = []
+    for root, dirs, files in os.walk(repo_path):
+        dirs[:] = [d for d in dirs if not d.startswith((".", "__pycache__", "node_modules", ".git", "venv"))]
+        for fname in files:
+            if not fname.endswith(".py"):
+                continue
+            filepath = os.path.join(root, fname)
+            relpath = os.path.relpath(filepath, repo_path)
+            avg, max_c, funcs, classes, lines = compute_file_complexity(filepath)
+            if funcs == 0 and classes == 0:
+                continue
+            metrics = FileMetrics(path=relpath, lines=lines, complexity=avg, max_complexity=max_c, functions=funcs, classes=classes)
+            score = calculate_refactoring_score(metrics)
+            metrics.refactoring_score = score
+            if score >= threshold:
+                proposals.append({"title": f"Refactor {relpath} (score: {score})", "impact": min(10, int(score / 10)), "effort": min(10, max(1, funcs // 3)), "category": "refactoring", "source_engine": "10.4", "timestamp": datetime.now(timezone.utc).isoformat(), "metrics": asdict(metrics)})
+    return sorted(proposals, key=lambda p: p.get("metrics", {}).get("refactoring_score", 0), reverse=True)
 
 
 def main():
-    parser = argparse.ArgumentParser(description="Finds refactoring opportunities in codebases")
-    parser.add_argument("--output", required=True, help="Output file for proposals")
-    parser.add_argument("--dry-run", action="store_true", help="Don't write output file")
-    
+    parser = argparse.ArgumentParser(description="Find refactoring opportunities")
+    parser.add_argument("--repo", default=".")
+    parser.add_argument("--output", required=True)
+    parser.add_argument("--dry-run", action="store_true")
+    parser.add_argument("--threshold", type=float, default=30.0)
     args = parser.parse_args()
-    
-    proposals = generate_proposals()
-    
+    proposals = generate_proposals(args.repo, args.threshold)
     if not args.dry_run:
         with open(args.output, "w") as f:
             json.dump({"proposals": proposals}, f, indent=2)
         print(f"Generated {len(proposals)} proposals -> {args.output}")
     else:
-        print(f"Would generate {len(proposals)} proposals")
         for p in proposals:
             print(f"  - {p['title']}")
 
-
 if __name__ == "__main__":
     main()