feat: update subscription when increasing/decreasing workspace members

packages/api/src/routers/member.ts

@@ -4,6 +4,7 @@ import { z } from "zod";
 import * as memberRepo from "@kan/db/repository/member.repo";
 import * as userRepo from "@kan/db/repository/user.repo";
 import * as workspaceRepo from "@kan/db/repository/workspace.repo";
+import { updateSubscriptionSeats } from "@kan/stripe";
 
 import { createTRPCRouter, protectedProcedure } from "../trpc";
 import { assertUserInWorkspace } from "../utils/auth";
@@ -60,6 +61,42 @@ export const memberRouter = createTRPCRouter({
         });
       }
 
+      if (process.env.NEXT_PUBLIC_KAN_ENV === "cloud") {
+        const subscriptions = await ctx.auth.api.listActiveSubscriptions({
+          workspacePublicId: workspace.publicId,
+        });
+
+        // get the active subscription
+        const activeSubscription = subscriptions.find(
+          (sub) =>
+            sub.status === "active" ||
+            (sub.status === "trialing" && sub.plan === "team"),
+        );
+
+        if (!activeSubscription) {
+          throw new TRPCError({
+            message: `Workspace with public ID ${workspace.publicId} does not have an active subscription`,
+            code: "NOT_FOUND",
+          });
+        }
+
+        // Update the Stripe subscription to add a seat with immediate proration
+        if (activeSubscription.stripeSubscriptionId) {
+          try {
+            await updateSubscriptionSeats(
+              activeSubscription.stripeSubscriptionId,
+              1,
+            );
+          } catch (error) {
+            console.error("Failed to update Stripe subscription seats:", error);
+            throw new TRPCError({
+              message: `Failed to update subscription for the new member.`,
+              code: "INTERNAL_SERVER_ERROR",
+            });
+          }
+        }
+      }
+
       const existingUser = await userRepo.getByEmail(ctx.db, input.email);
 
       const invite = await memberRepo.create(ctx.db, {
@@ -100,19 +137,6 @@ export const memberRouter = createTRPCRouter({
         });
       }
 
-      if (process.env.NEXT_PUBLIC_KAN_ENV === "cloud") {
-        const subscriptions = await ctx.auth.api.listActiveSubscriptions({
-          userId,
-        });
-
-        // get the active subscription
-        const activeSubscription = subscriptions.find(
-          (sub) => sub.status === "active" || sub.status === "trialing",
-        );
-
-        // @todo: update the subscription with the new seat
-      }
-
       return invite;
     }),
   delete: protectedProcedure
@@ -178,6 +202,35 @@ export const memberRouter = createTRPCRouter({
           code: "INTERNAL_SERVER_ERROR",
         });
 
+      // Handle subscription seat decrement for cloud environment
+      if (process.env.NEXT_PUBLIC_KAN_ENV === "cloud") {
+        const subscriptions = await ctx.auth.api.listActiveSubscriptions({
+          workspacePublicId: workspace.publicId,
+        });
+
+        // get the active subscription
+        const activeSubscription = subscriptions.find(
+          (sub) =>
+            sub.status === "active" ||
+            (sub.status === "trialing" && sub.plan === "team"),
+        );
+
+        // Only decrease seats if there's an active subscription and stripeSubscriptionId
+        if (activeSubscription?.stripeSubscriptionId) {
+          try {
+            await updateSubscriptionSeats(
+              activeSubscription.stripeSubscriptionId,
+              -1,
+            );
+          } catch (error) {
+            console.error(
+              "Failed to decrease Stripe subscription seats:",
+              error,
+            );
+          }
+        }
+      }
+
       return { success: true };
     }),
 });

packages/api/src/trpc.ts

@@ -28,16 +28,14 @@ const createAuthWithHeaders = (
     api: {
       getSession: () => auth.api.getSession({ headers }),
       signInMagicLink: (input: { email: string; callbackURL: string }) =>
-        // @ts-expect-error - types need fixing
         auth.api.signInMagicLink({
           headers,
           body: { email: input.email, callbackURL: input.callbackURL },
         }),
-      listActiveSubscriptions: (input: { userId: string }) =>
+      listActiveSubscriptions: (input: { workspacePublicId: string }) =>
-        // @ts-expect-error - types need fixing
         auth.api.listActiveSubscriptions({
           headers,
-          query: { referenceId: input.userId },
+          query: { referenceId: input.workspacePublicId },
         }),
     },
   };

packages/stripe/src/index.ts

@@ -16,4 +16,59 @@ const createStripeClient = () => {
   return stripe;
 };
 
+export const updateSubscriptionSeats = async (
+  stripeSubscriptionId: string,
+  seatIncrement = 1,
+): Promise<Stripe.Subscription> => {
+  const stripe = createStripeClient();
+
+  // First, retrieve the current subscription to get the subscription items
+  const subscription = await stripe.subscriptions.retrieve(
+    stripeSubscriptionId,
+    {
+      expand: ["items"],
+    },
+  );
+
+  if (!subscription.items.data.length) {
+    throw new Error(
+      `No subscription items found for subscription ${stripeSubscriptionId}`,
+    );
+  }
+
+  // Get the first subscription item
+  const subscriptionItem = subscription.items.data[0];
+  if (!subscriptionItem) {
+    throw new Error(
+      `No subscription item found for subscription ${stripeSubscriptionId}`,
+    );
+  }
+
+  const currentQuantity = subscriptionItem.quantity ?? 1;
+  const newQuantity = currentQuantity + seatIncrement;
+
+  // Ensure we don't go below 1 seat
+  if (newQuantity < 1) {
+    throw new Error(
+      `Cannot reduce seats below 1. Current: ${currentQuantity}, Requested change: ${seatIncrement}`,
+    );
+  }
+
+  // Update the subscription with the new quantity and immediate invoicing
+  const updatedSubscription = await stripe.subscriptions.update(
+    stripeSubscriptionId,
+    {
+      items: [
+        {
+          id: subscriptionItem.id,
+          quantity: newQuantity,
+        },
+      ],
+      proration_behavior: "always_invoice", // Accumulate charges for next billing cycle
+    },
+  );
+
+  return updatedSubscription;
+};
+
 export { createStripeClient };