Initial commit

backend/app/services/attachments.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+import hashlib
+from pathlib import Path
+
+
+IMAGE_SUFFIXES = {".png", ".jpg", ".jpeg", ".webp"}
+DOCUMENT_SUFFIXES = {".txt", ".md", ".csv", ".json"}
+MAX_IMAGE_BYTES = 10 * 1024 * 1024
+MAX_DOCUMENT_BYTES = 2 * 1024 * 1024
+MAX_EXTRACTED_CHARS = 30_000
+
+
+def classify_upload(filename: str, mime: str, size: int) -> str:
+    suffix = Path(filename).suffix.lower()
+    if suffix in {".step", ".stp"}:
+        raise ValueError("STEP/STP upload is not supported in this version")
+    if suffix in IMAGE_SUFFIXES or mime.startswith("image/"):
+        if size > MAX_IMAGE_BYTES:
+            raise ValueError("Image upload exceeds the 10 MB limit")
+        return "image"
+    if suffix in DOCUMENT_SUFFIXES:
+        if size > MAX_DOCUMENT_BYTES:
+            raise ValueError("Document upload exceeds the 2 MB limit")
+        return "document"
+    raise ValueError("Only PNG, JPG, WEBP, TXT, MD, CSV, and JSON uploads are supported")
+
+
+def extract_document_text(data: bytes) -> str:
+    try:
+        text = data.decode("utf-8")
+    except UnicodeDecodeError as error:
+        raise ValueError("Documents must be UTF-8 text") from error
+    return text[:MAX_EXTRACTED_CHARS]
+
+
+def attachment_record(task_id: str, filename: str, mime: str, relative_path: str, data: bytes, kind: str, extracted_path: str = "") -> dict[str, object]:
+    return {
+        "id": Path(relative_path).stem,
+        "task_id": task_id,
+        "name": filename,
+        "kind": kind,
+        "path": relative_path,
+        "mime": mime or "application/octet-stream",
+        "size": len(data),
+        "sha256": hashlib.sha256(data).hexdigest(),
+        "extracted_path": extracted_path,
+    }