Add grouped missing reference report

serato_doctor/report.py

@@ -0,0 +1,42 @@
+from collections import Counter, defaultdict
+from pathlib import Path
+import csv
+
+
+def write_missing_report(rows: list[dict], out: Path) -> None:
+    missing = [r for r in rows if not r["exists_by_filename"]]
+
+    crate_counts = Counter(r["crate"] for r in missing)
+    filename_counts = Counter(r["filename"] for r in missing)
+
+    with out.open("w", encoding="utf-8") as f:
+        f.write("# Serato Doctor Missing Report\n\n")
+        f.write(f"Total missing references: {len(missing)}\n\n")
+
+        f.write("## Missing by crate\n\n")
+        for crate, count in crate_counts.most_common():
+            f.write(f"{count:5}  {crate}\n")
+
+        f.write("\n## Most common missing filenames\n\n")
+        for filename, count in filename_counts.most_common(100):
+            f.write(f"{count:5}  {filename}\n")
+
+        f.write("\n## Detail\n\n")
+        by_crate = defaultdict(list)
+        for r in missing:
+            by_crate[r["crate"]].append(r["filename"])
+
+        for crate, names in sorted(by_crate.items()):
+            f.write(f"\n### {crate}\n")
+            for name in sorted(set(names)):
+                f.write(f"- {name}\n")
+
+
+def write_csv(rows: list[dict], out: Path) -> None:
+    with out.open("w", newline="", encoding="utf-8") as f:
+        writer = csv.DictWriter(
+            f,
+            fieldnames=["crate", "serato_path", "filename", "exists_by_filename"],
+        )
+        writer.writeheader()
+        writer.writerows(rows)