From bae262abb7982651f72676ac4b0c254c05b0f27c Mon Sep 17 00:00:00 2001
From: Mika <kontakt@donau2space.de>
Date: Sat, 14 Feb 2026 15:32:01 +0000
Subject: [PATCH] Add drift_detector/src/drift_detector/core.py

---
 drift_detector/src/drift_detector/core.py | 76 +++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 drift_detector/src/drift_detector/core.py

diff --git a/drift_detector/src/drift_detector/core.py b/drift_detector/src/drift_detector/core.py
new file mode 100644
index 0000000..061ab70
--- /dev/null
+++ b/drift_detector/src/drift_detector/core.py
@@ -0,0 +1,76 @@
+import json
+import re
+from pathlib import Path
+from typing import Any, Dict, List
+
+
+class DriftSignature:
+    """Repräsentiert eine normalisierte Drift-Signatur."""
+
+    def __init__(self, normalized_path: str, original_path: str, is_drift: bool) -> None:
+        assert isinstance(normalized_path, str), "normalized_path muss ein String sein"
+        assert isinstance(original_path, str), "original_path muss ein String sein"
+        assert isinstance(is_drift, bool), "is_drift muss ein bool sein"
+        self.normalized_path = normalized_path
+        self.original_path = original_path
+        self.is_drift = is_drift
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Gibt die Signatur als Dictionary zurück."""
+        return {
+            "normalized_path": self.normalized_path,
+            "original_path": self.original_path,
+            "is_drift": self.is_drift,
+        }
+
+
+def _normalize_path(path_str: str) -> str:
+    """Normalisiert Pfade durch Entfernen/Ersetzen typischer Driftmuster."""
+    path_str = path_str.strip()
+    path_str = re.sub(r"/+", "/", path_str)  # Doppelslashes normalisieren
+    path_str = re.sub(r"(?i)(version_|v)[0-9]+", "version", path_str)  # Versionsnummern neutralisieren
+    path_str = re.sub(r"(?i)_?temp_?[0-9]*", "temp", path_str)  # temporäre Pattern
+    path_str = re.sub(r"(?i)date=[0-9]{8}", "date=YYYYMMDD", path_str)  # Datumsnormalisierung
+    return path_str
+
+
+def detect_drift(path: str) -> bool:
+    """Erkennt Pfad-Drift aus einer JSONL- oder CSV-Datei.
+
+    Args:
+        path (str): Pfad zur Logdatei mit Key-Einträgen.
+
+    Returns:
+        bool: True, falls Drift erkannt wurde, sonst False.
+    """
+    input_path = Path(path)
+    if not input_path.exists() or not input_path.is_file():
+        raise FileNotFoundError(f"Datei nicht gefunden: {path}")
+
+    signatures: List[DriftSignature] = []
+
+    with input_path.open("r", encoding="utf-8") as f:
+        for line in f:
+            if not line.strip():
+                continue
+            try:
+                entry = json.loads(line)
+            except json.JSONDecodeError as e:
+                raise ValueError(f"Ungültiger JSON-Eintrag: {e}") from e
+
+            if "original_path" not in entry:
+                raise KeyError("Fehlender Schlüssel 'original_path' im JSON-Eintrag")
+
+            original_path = str(entry["original_path"])
+            normalized_path = _normalize_path(original_path)
+            is_drift = normalized_path != original_path
+            signatures.append(DriftSignature(normalized_path, original_path, is_drift))
+
+    # Aggregation: wenn irgendein Eintrag Drift hat, gilt Gesamtfile als drifted
+    any_drift = any(sig.is_drift for sig in signatures)
+
+    report = [sig.to_dict() for sig in signatures]
+    with Path("output/drift_report.json").open("w", encoding="utf-8") as out_f:
+        json.dump(report, out_f, indent=2, ensure_ascii=False)
+
+    return any_drift