Add endpoint to fetch statistics for workflow

#24

app/api/endpoints/workflow.py

 from typing import Annotated, Any, Awaitable, Callable
 
 from clowmdb.models import Workflow, WorkflowVersion
-from fastapi import APIRouter, BackgroundTasks, Depends, File, HTTPException, Query, UploadFile, status
+from fastapi import APIRouter, BackgroundTasks, Depends, File, HTTPException, Query, Response, UploadFile, status
 
 from app.api.dependencies import AuthorizationDependency, CurrentUser, CurrentWorkflow, DBSession, HTTPClient, S3Service
 from app.api.utils import check_repo, upload_icon
 from app.core.config import settings
 from app.crud import CRUDWorkflow, CRUDWorkflowVersion
 from app.git_repository import build_repository
-from app.schemas.workflow import WorkflowIn, WorkflowOut
+from app.schemas.workflow import WorkflowIn, WorkflowOut, WorkflowStatistic
 from app.schemas.workflow_version import WorkflowVersionFull, WorkflowVersionUpdate
 
 router = APIRouter(prefix="/workflows", tags=["Workflow"])
@@ -72,7 +72,7 @@ async def list_workflows(
         rbac_operation = "list_filter"
 
     await authorization(rbac_operation)
-    workflows: list[Workflow] = await CRUDWorkflow.list(
+    workflows: list[Workflow] = await CRUDWorkflow.list_workflows(
         db,
         name_substring=name_substring,
         developer_id=developer_id,
@@ -205,6 +205,34 @@ async def get_workflow(
     return WorkflowOut.from_db_workflow(workflow, versions)
 
 
+@router.get("/{wid}/statistics", status_code=status.HTTP_200_OK, summary="Get statistics for a workflow")
+async def get_workflow_statistics(
+    workflow: CurrentWorkflow, db: DBSession, authorization: Authorization, response: Response
+) -> list[WorkflowStatistic]:
+    """
+    Get the number of started workflow per day.
+    \f
+    Parameters
+    ----------
+    workflow : clowmdb.models.Workflow
+        Workflow with given ID. Dependency Injection.
+    db : sqlalchemy.ext.asyncio.AsyncSession.
+        Async database session to perform query on. Dependency Injection.
+    authorization : Callable[[str], Awaitable[Any]]
+        Async function to ask the auth service for authorization. Dependency Injection.
+    response : fastapi.Response
+        Temporal Response object. Dependency Injection.
+
+    Returns
+    -------
+    statistics : list[app.schema.Workflow.WorkflowStatistic]
+    """
+    await authorization("read")
+    # Instruct client to cache response for 1 hour
+    response.headers["Cache-Control"] = "max-age=3600"
+    return await CRUDWorkflow.statistics(db, workflow.workflow_id)
+
+
 @router.delete("/{wid}", status_code=status.HTTP_204_NO_CONTENT, summary="Delete a workflow")
 async def delete_workflow(
     background_tasks: BackgroundTasks,

app/crud/crud_workflow.py

 from uuid import UUID
 
-from clowmdb.models import Workflow, WorkflowVersion
-from sqlalchemy import delete, or_, select
+from clowmdb.models import Workflow, WorkflowExecution, WorkflowVersion
+from sqlalchemy import Date, cast, delete, func, or_, select
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import joinedload
 
 from app.crud.crud_workflow_version import CRUDWorkflowVersion
-from app.schemas.workflow import WorkflowIn
+from app.schemas.workflow import WorkflowIn, WorkflowStatistic
 
 
 class CRUDWorkflow:
     @staticmethod
-    async def list(
+    async def list_workflows(
         db: AsyncSession,
         name_substring: str | None = None,
         developer_id: str | None = None,
@@ -66,6 +66,34 @@ class CRUDWorkflow:
         await db.execute(stmt)
         await db.commit()
 
+    @staticmethod
+    async def statistics(db: AsyncSession, workflow_id: bytes | UUID) -> list[WorkflowStatistic]:
+        """
+        Calculate the number of workflows started per day for a specific workflow
+
+        Parameters
+        ----------
+        db : sqlalchemy.ext.asyncio.AsyncSession.
+            Async database session to perform query on.
+        workflow_id : bytes | uuid.UUID
+            UID of a workflow.
+
+        Returns
+        -------
+        stat : list[app.schemas.Workflow.WorkflowStatistic]
+            List of datapoints
+        """
+        wid = workflow_id.bytes if isinstance(workflow_id, UUID) else workflow_id
+        stmt = (
+            select(cast(WorkflowExecution.start_time, Date).label("day"), func.count())
+            .select_from(WorkflowExecution)
+            .join(WorkflowVersion)
+            .where(WorkflowVersion._workflow_id == wid)
+            .group_by("day")
+            .order_by("day")
+        )
+        return [WorkflowStatistic(day=row.day, count=row.count) for row in await db.execute(stmt)]
+
     @staticmethod
     async def get(db: AsyncSession, workflow_id: UUID | bytes) -> Workflow | None:
         """

app/schemas/workflow.py

+from datetime import date
 from uuid import UUID
 
 from clowmdb.models import Workflow as WorkflowDB
@@ -67,3 +68,8 @@ class WorkflowOut(_BaseWorkflow):
             versions=temp_versions,
             developer_id=db_workflow.developer_id,
         )
+
+
+class WorkflowStatistic(BaseModel):
+    day: date = Field(..., description="Day of the datapoint", example=date(day=1, month=1, year=2023))
+    count: int = Field(..., description="Number of started workflows on that day", example=1)

app/tests/crud/test_workflow.py

@@ -24,7 +24,7 @@ class TestWorkflowCRUDList:
         random_workflow : app.schemas.workflow.WorkflowOut
             Random bucket for testing. pytest fixture.
         """
-        workflows = await CRUDWorkflow.list(db)
+        workflows = await CRUDWorkflow.list_workflows(db)
         assert len(workflows) == 1
         assert workflows[0].workflow_id == random_workflow.workflow_id
 
@@ -44,7 +44,7 @@ class TestWorkflowCRUDList:
         random_user : app.tests.utils.user.UserWithAuthHeader
             Random user for testing. pytest fixture.
         """
-        workflows = await CRUDWorkflow.list(db, developer_id=random_user.user.uid)
+        workflows = await CRUDWorkflow.list_workflows(db, developer_id=random_user.user.uid)
         assert len(workflows) == 1
         assert workflows[0].workflow_id == random_workflow.workflow_id
 
@@ -60,7 +60,7 @@ class TestWorkflowCRUDList:
         random_workflow : app.schemas.workflow.WorkflowOut
             Random bucket for testing. pytest fixture.
         """
-        workflows = await CRUDWorkflow.list(db, version_status=[WorkflowVersion.Status.CREATED])
+        workflows = await CRUDWorkflow.list_workflows(db, version_status=[WorkflowVersion.Status.CREATED])
         assert len(workflows) == 1
         assert workflows[0].workflow_id == random_workflow.workflow_id
 
@@ -81,7 +81,7 @@ class TestWorkflowCRUDList:
             substring_indices = sorted(random.choices(range(len(random_workflow.name)), k=2))
 
         random_substring = random_workflow.name[substring_indices[0] : substring_indices[1]]
-        workflows = await CRUDWorkflow.list(db, name_substring=random_substring)
+        workflows = await CRUDWorkflow.list_workflows(db, name_substring=random_substring)
         assert len(workflows) > 0
         assert random_workflow.workflow_id in map(lambda w: w.workflow_id, workflows)
 
@@ -97,7 +97,7 @@ class TestWorkflowCRUDList:
         random_workflow : app.schemas.workflow.WorkflowOut
             Random bucket for testing. pytest fixture.
         """
-        workflows = await CRUDWorkflow.list(db, name_substring=2 * random_workflow.name)
+        workflows = await CRUDWorkflow.list_workflows(db, name_substring=2 * random_workflow.name)
         assert sum(1 for w in workflows if w.workflow_id == random_workflow.workflow_id) == 0