feat(coderd): add tasks delete endpoint (#19638)

This change adds a DELETE endpoint for tasks (for now, alias of
workspace build delete transition).

Fixes coder/internal#903

coderd/aitasks.go

@@ -472,3 +472,78 @@ func (api *API) taskGet(rw http.ResponseWriter, r *http.Request) {
 
 	httpapi.Write(ctx, rw, http.StatusOK, tasks[0])
 }
+
+// taskDelete is an experimental endpoint to delete a task by ID (workspace ID).
+// It creates a delete workspace build and returns 202 Accepted if the build was
+// created.
+func (api *API) taskDelete(rw http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	apiKey := httpmw.APIKey(r)
+
+	idStr := chi.URLParam(r, "id")
+	taskID, err := uuid.Parse(idStr)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusBadRequest, codersdk.Response{
+			Message: fmt.Sprintf("Invalid UUID %q for task ID.", idStr),
+		})
+		return
+	}
+
+	// For now, taskID = workspaceID, once we have a task data model in
+	// the DB, we can change this lookup.
+	workspaceID := taskID
+	workspace, err := api.Database.GetWorkspaceByID(ctx, workspaceID)
+	if httpapi.Is404Error(err) {
+		httpapi.ResourceNotFound(rw)
+		return
+	}
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching workspace.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	data, err := api.workspaceData(ctx, []database.Workspace{workspace})
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching workspace resources.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+	if len(data.builds) == 0 || len(data.templates) == 0 {
+		httpapi.ResourceNotFound(rw)
+		return
+	}
+	if data.builds[0].HasAITask == nil || !*data.builds[0].HasAITask {
+		httpapi.ResourceNotFound(rw)
+		return
+	}
+
+	// Construct a request to the workspace build creation handler to
+	// initiate deletion.
+	buildReq := codersdk.CreateWorkspaceBuildRequest{
+		Transition: codersdk.WorkspaceTransitionDelete,
+		Reason:     "Deleted via tasks API",
+	}
+
+	_, err = api.postWorkspaceBuildsInternal(
+		ctx,
+		apiKey,
+		workspace,
+		buildReq,
+		func(action policy.Action, object rbac.Objecter) bool {
+			return api.Authorize(r, action, object)
+		},
+		audit.WorkspaceBuildBaggageFromRequest(r),
+	)
+	if err != nil {
+		httperror.WriteWorkspaceBuildError(ctx, rw, err)
+		return
+	}
+
+	// Delete build created successfully.
+	rw.WriteHeader(http.StatusAccepted)
+}