feat(example-images): add use case orchestration

py/services/use_cases/example_images/__init__.py

@@ -0,0 +1,19 @@
+"""Example image specific use case exports."""
+
+from .download_example_images_use_case import (
+    DownloadExampleImagesUseCase,
+    DownloadExampleImagesInProgressError,
+    DownloadExampleImagesConfigurationError,
+)
+from .import_example_images_use_case import (
+    ImportExampleImagesUseCase,
+    ImportExampleImagesValidationError,
+)
+
+__all__ = [
+    "DownloadExampleImagesUseCase",
+    "DownloadExampleImagesInProgressError",
+    "DownloadExampleImagesConfigurationError",
+    "ImportExampleImagesUseCase",
+    "ImportExampleImagesValidationError",
+]

py/services/use_cases/example_images/download_example_images_use_case.py

@@ -0,0 +1,42 @@
+"""Use case coordinating example image downloads."""
+
+from __future__ import annotations
+
+from typing import Any, Dict
+
+from ....utils.example_images_download_manager import (
+    DownloadConfigurationError,
+    DownloadInProgressError,
+    ExampleImagesDownloadError,
+)
+
+
+class DownloadExampleImagesInProgressError(RuntimeError):
+    """Raised when a download is already running."""
+
+    def __init__(self, progress: Dict[str, Any]) -> None:
+        super().__init__("Download already in progress")
+        self.progress = progress
+
+
+class DownloadExampleImagesConfigurationError(ValueError):
+    """Raised when settings prevent downloads from starting."""
+
+
+class DownloadExampleImagesUseCase:
+    """Validate payloads and trigger the download manager."""
+
+    def __init__(self, *, download_manager) -> None:
+        self._download_manager = download_manager
+
+    async def execute(self, payload: Dict[str, Any]) -> Dict[str, Any]:
+        """Start a download and translate manager errors."""
+
+        try:
+            return await self._download_manager.start_download(payload)
+        except DownloadInProgressError as exc:
+            raise DownloadExampleImagesInProgressError(exc.progress_snapshot) from exc
+        except DownloadConfigurationError as exc:
+            raise DownloadExampleImagesConfigurationError(str(exc)) from exc
+        except ExampleImagesDownloadError:
+            raise

py/services/use_cases/example_images/import_example_images_use_case.py

@@ -0,0 +1,86 @@
+"""Use case for importing example images."""
+
+from __future__ import annotations
+
+import os
+import tempfile
+from contextlib import suppress
+from typing import Any, Dict, List
+
+from aiohttp import web
+
+from ....utils.example_images_processor import (
+    ExampleImagesImportError,
+    ExampleImagesProcessor,
+    ExampleImagesValidationError,
+)
+
+
+class ImportExampleImagesValidationError(ValueError):
+    """Raised when request validation fails."""
+
+
+class ImportExampleImagesUseCase:
+    """Parse upload payloads and delegate to the processor service."""
+
+    def __init__(self, *, processor: ExampleImagesProcessor) -> None:
+        self._processor = processor
+
+    async def execute(self, request: web.Request) -> Dict[str, Any]:
+        model_hash: str | None = None
+        files_to_import: List[str] = []
+        temp_files: List[str] = []
+
+        try:
+            if request.content_type and "multipart/form-data" in request.content_type:
+                reader = await request.multipart()
+
+                first_field = await reader.next()
+                if first_field and first_field.name == "model_hash":
+                    model_hash = await first_field.text()
+                else:
+                    # Support clients that send files first and hash later
+                    if first_field is not None:
+                        await self._collect_upload_file(first_field, files_to_import, temp_files)
+
+                async for field in reader:
+                    if field.name == "model_hash" and not model_hash:
+                        model_hash = await field.text()
+                    elif field.name == "files":
+                        await self._collect_upload_file(field, files_to_import, temp_files)
+            else:
+                data = await request.json()
+                model_hash = data.get("model_hash")
+                files_to_import = list(data.get("file_paths", []))
+
+            result = await self._processor.import_images(model_hash, files_to_import)
+            return result
+        except ExampleImagesValidationError as exc:
+            raise ImportExampleImagesValidationError(str(exc)) from exc
+        except ExampleImagesImportError:
+            raise
+        finally:
+            for path in temp_files:
+                with suppress(Exception):
+                    os.remove(path)
+
+    async def _collect_upload_file(
+        self,
+        field: Any,
+        files_to_import: List[str],
+        temp_files: List[str],
+    ) -> None:
+        """Persist an uploaded file to disk and add it to the import list."""
+
+        filename = field.filename or "upload"
+        file_ext = os.path.splitext(filename)[1].lower()
+
+        with tempfile.NamedTemporaryFile(suffix=file_ext, delete=False) as tmp_file:
+            temp_files.append(tmp_file.name)
+            while True:
+                chunk = await field.read_chunk()
+                if not chunk:
+                    break
+                tmp_file.write(chunk)
+
+        files_to_import.append(tmp_file.name)