feat: Add announcements endpoints (#91)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Alexandre Teles (afterSt0rm) <alexandre.teles@ufba.br>

api/models/announcements.py

@@ -0,0 +1,37 @@
+from data.models import AnnouncementDbModel
+
+
+class ContentFields(dict):
+    message: str | None
+    attachment_urls: list[str] | None
+
+
+class AnnouncementResponseModel(dict):
+    id: int
+    author: str | None
+    title: str
+    content: ContentFields | None
+    channel: str
+    created_at: str
+    level: int | None
+
+    @staticmethod
+    def to_response(announcement: AnnouncementDbModel):
+        response = AnnouncementResponseModel(
+            id=announcement.id,
+            author=announcement.author,
+            title=announcement.title,
+            content=ContentFields(
+                message=announcement.message,
+                attachment_urls=[
+                    attachment.attachment_url for attachment in announcement.attachments
+                ],
+            )
+            if announcement.message or announcement.attachments
+            else None,
+            channel=announcement.channel,
+            created_at=str(announcement.created_at),
+            level=announcement.level,
+        )
+
+        return response