Indie Dev SaaS Launch — Pricing Strategy, Stripe Integration, and Freemium-to-Paid Design

// supabase/functions/billing-hub/index.ts
import Stripe from 'https://esm.sh/stripe@12'
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2'

const stripe = new Stripe(Deno.env.get('STRIPE_SECRET_KEY')!, {
  apiVersion: '2023-10-16',
  httpClient: Stripe.createFetchHttpClient(),
})

export async function createCheckout(userId: string, priceId: string): Promise<string> {
  const supabase = createClient(
    Deno.env.get('SUPABASE_URL')!,
    Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!
  )

  // Get or create Stripe customer
  const { data: profile } = await supabase
    .from('profiles')
    .select('stripe_customer_id, email')
    .eq('id', userId)
    .single()

  let customerId = profile?.stripe_customer_id
  if (!customerId) {
    const customer = await stripe.customers.create({ email: profile?.email })
    customerId = customer.id
    await supabase
      .from('profiles')
      .update({ stripe_customer_id: customerId })
      .eq('id', userId)
  }

  const session = await stripe.checkout.sessions.create({
    customer: customerId,
    mode: 'subscription',
    payment_method_types: ['card'],
    line_items: [{ price: priceId, quantity: 1 }],
    subscription_data: { trial_period_days: 14 },
    success_url: `${Deno.env.get('APP_URL')}/billing/success?session={CHECKOUT_SESSION_ID}`,
    cancel_url: `${Deno.env.get('APP_URL')}/billing`,
  })

  return session.url!
}

export async function handleStripeWebhook(req: Request) {
  const body = await req.text()
  const sig = req.headers.get('stripe-signature')!
  const event = stripe.webhooks.constructEvent(
    body, sig, Deno.env.get('STRIPE_WEBHOOK_SECRET')!
  )

  const supabase = createClient(
    Deno.env.get('SUPABASE_URL')!,
    Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!
  )

  if (['customer.subscription.created', 'customer.subscription.updated']
       .includes(event.type)) {
    const sub = event.data.object as Stripe.Subscription
    await supabase.from('subscriptions').upsert({
      stripe_subscription_id: sub.id,
      stripe_customer_id: sub.customer as string,
      status: sub.status,
      plan_id: sub.items.data[0].price.id,
      current_period_end: new Date(sub.current_period_end * 1000).toISOString(),
      cancel_at_period_end: sub.cancel_at_period_end,
    }, { onConflict: 'stripe_subscription_id' })
  }

  if (event.type === 'customer.subscription.deleted') {
    const sub = event.data.object as Stripe.Subscription
    await supabase
      .from('subscriptions')
      .update({ status: 'canceled' })
      .eq('stripe_subscription_id', sub.id)
  }

  return new Response('ok')
}

// Domain model
enum UserPlan { free, pro, team }

extension UserPlanX on UserPlan {
  bool get isPro => this == UserPlan.pro || this == UserPlan.team;
  bool get isTeam => this == UserPlan.team;
  int get exportLimit => switch (this) {
    UserPlan.free => 100,
    UserPlan.pro => 10000,
    UserPlan.team => 0, // unlimited
  };
}

// Gate widget
class PlanGate extends StatelessWidget {
  final Widget child;
  final String featureName;
  final bool Function(UserPlan) allowed;

  const PlanGate({
    required this.child,
    required this.featureName,
    required this.allowed,
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    final plan = context.watch<UserPlanNotifier>().plan;
    if (allowed(plan)) return child;
    return _UpgradePrompt(featureName: featureName);
  }
}

// Usage
PlanGate(
  featureName: 'Team collaboration',
  allowed: (p) => p.isTeam,
  child: const TeamInviteButton(),
)

class UsageLimitBanner extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final usage = context.watch<UsageNotifier>();
    final plan = context.watch<UserPlanNotifier>().plan;
    final limit = plan.exportLimit;
    if (limit == 0) return const SizedBox.shrink();

    final pct = usage.exportsThisMonth / limit;
    if (pct < 0.8) return const SizedBox.shrink();

    return Container(
      color: pct >= 1.0 ? Colors.red.shade100 : Colors.orange.shade100,
      padding: const EdgeInsets.all(12),
      child: Row(children: [
        Icon(pct >= 1.0 ? Icons.lock : Icons.warning_amber),
        const SizedBox(width: 8),
        Expanded(child: Text(
          pct >= 1.0
            ? 'Monthly limit reached (${usage.exportsThisMonth}/$limit). Upgrade to continue.'
            : '${(pct * 100).round()}% of monthly limit used.',
        )),
        TextButton(onPressed: () => context.push('/billing'), child: const Text('Upgrade')),
      ]),
    );
  }
}