Add service platform foundation

app/services/ocr_provider.py

@@ -0,0 +1,48 @@
+import re
+from dataclasses import dataclass
+
+from app.services.vehicle_identity import normalize_license_plate, validate_vin
+
+
+@dataclass
+class OcrCandidate:
+    type: str
+    value: str
+    confidence: float
+
+
+@dataclass
+class OcrResult:
+    recognized_text: str
+    candidates: list[OcrCandidate]
+
+
+class OCRProvider:
+    async def recognize(self, content: bytes, filename: str | None = None) -> OcrResult:
+        raise NotImplementedError
+
+
+class StubOCRProvider(OCRProvider):
+    async def recognize(self, content: bytes, filename: str | None = None) -> OcrResult:
+        text = " ".join(
+            [
+                filename or "",
+                content.decode("utf-8", errors="ignore"),
+            ]
+        )
+        compact = re.sub(r"\s+", " ", text).strip()
+        candidates: list[OcrCandidate] = []
+        for raw in re.findall(r"\b[A-HJ-NPR-Z0-9]{17}\b", compact.upper()):
+            try:
+                candidates.append(OcrCandidate(type="vin", value=validate_vin(raw) or raw, confidence=0.84))
+            except ValueError:
+                continue
+        for raw in re.findall(r"\b[0-9A-ZА-Я가-힣][0-9A-ZА-Я가-힣\-\s]{4,10}\b", compact.upper()):
+            normalized = normalize_license_plate(raw)
+            if normalized and 5 <= len(normalized) <= 10 and not any(item.value == normalized for item in candidates):
+                candidates.append(OcrCandidate(type="license_plate", value=normalized, confidence=0.62))
+        return OcrResult(recognized_text=compact, candidates=candidates[:8])
+
+
+def get_ocr_provider() -> OCRProvider:
+    return StubOCRProvider()