add openai api

tests/test_openai_utils.py

@@ -0,0 +1,43 @@
+import base64
+
+import pytest
+from fastapi import HTTPException
+
+from openocr_markdown.openai_schemas import ChatMessage, ChatMessageContentImageUrl, ChatMessageContentPart
+from openocr_markdown.openai_utils import DATA_URL_PATTERN, extract_image_urls, materialize_image_url
+
+
+def test_extract_image_urls_from_multimodal_message() -> None:
+    messages = [
+        ChatMessage(
+            role="user",
+            content=[
+                ChatMessageContentPart(type="text", text="Convert to markdown"),
+                ChatMessageContentPart(
+                    type="image_url",
+                    image_url=ChatMessageContentImageUrl(url="https://example.com/page.png"),
+                ),
+            ],
+        )
+    ]
+    assert extract_image_urls(messages) == ["https://example.com/page.png"]
+
+
+def test_materialize_data_url(tmp_path) -> None:
+    png_bytes = base64.b64decode(
+        "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg=="
+    )
+    data_url = "data:image/png;base64," + base64.b64encode(png_bytes).decode()
+    path = materialize_image_url(data_url, tmp_path)
+    assert path.exists()
+    assert path.suffix == ".png"
+
+
+def test_data_url_pattern_rejects_invalid_input() -> None:
+    assert DATA_URL_PATTERN.match("not-a-data-url") is None
+
+
+def test_materialize_image_url_rejects_unsupported_scheme(tmp_path) -> None:
+    with pytest.raises(HTTPException) as exc:
+        materialize_image_url("ftp://example.com/a.png", tmp_path)
+    assert exc.value.status_code == 400