import Stripe from 'stripe';

import {
  BillingConfig,
  BillingWebhookHandlerService,
  getLineItemTypeById,
} from '@kit/billing';
import { getLogger } from '@kit/shared/logger';
import { Database } from '@kit/supabase/database';

import { StripeServerEnvSchema } from '../schema/stripe-server-env.schema';
import { createStripeClient } from './stripe-sdk';

type UpsertSubscriptionParams =
  Database['public']['Functions']['upsert_subscription']['Args'];

type UpsertOrderParams =
  Database['public']['Functions']['upsert_order']['Args'];

export class StripeWebhookHandlerService
  implements BillingWebhookHandlerService
{
  private stripe: Stripe | undefined;

  constructor(private readonly config: BillingConfig) {}

  private readonly provider: Database['public']['Enums']['billing_provider'] =
    'stripe';

  private readonly namespace = 'billing.stripe';

  /**
   * @description Verifies the webhook signature - should throw an error if the signature is invalid
   */
  async verifyWebhookSignature(request: Request) {
    const body = await request.clone().text();
    const signatureKey = `stripe-signature`;
    const signature = request.headers.get(signatureKey)!;

    const { webhooksSecret } = StripeServerEnvSchema.parse({
      secretKey: process.env.STRIPE_SECRET_KEY,
      webhooksSecret: process.env.STRIPE_WEBHOOK_SECRET,
    });

    const stripe = await this.loadStripe();

    const event = stripe.webhooks.constructEvent(
      body,
      signature,
      webhooksSecret,
    );

    if (!event) {
      throw new Error('Invalid signature');
    }

    return event;
  }

  private async loadStripe() {
    if (!this.stripe) {
      this.stripe = await createStripeClient();
    }

    return this.stripe;
  }

  async handleWebhookEvent(
    event: Stripe.Event,
    params: {
      onCheckoutSessionCompleted: (
        data: UpsertSubscriptionParams | UpsertOrderParams,
      ) => Promise<unknown>;
      onSubscriptionUpdated: (
        data: UpsertSubscriptionParams,
      ) => Promise<unknown>;
      onSubscriptionDeleted: (subscriptionId: string) => Promise<unknown>;
      onPaymentSucceeded: (sessionId: string) => Promise<unknown>;
      onPaymentFailed: (sessionId: string) => Promise<unknown>;
      onInvoicePaid: (data: UpsertSubscriptionParams) => Promise<unknown>;
      onEvent: (eventType: string) => Promise<unknown>;
    },
  ) {
    switch (event.type) {
      case 'checkout.session.completed': {
        return this.handleCheckoutSessionCompleted(
          event,
          params.onCheckoutSessionCompleted,
        );
      }

      case 'customer.subscription.updated': {
        return this.handleSubscriptionUpdatedEvent(
          event,
          params.onSubscriptionUpdated,
        );
      }

      case 'customer.subscription.deleted': {
        return this.handleSubscriptionDeletedEvent(
          event,
          params.onSubscriptionDeleted,
        );
      }

      case 'checkout.session.async_payment_failed': {
        return this.handleAsyncPaymentFailed(event, params.onPaymentFailed);
      }

      case 'invoice.paid': {
        return this.handleInvoicePaid(event, params.onInvoicePaid);
      }

      case 'checkout.session.async_payment_succeeded': {
        return this.handleAsyncPaymentSucceeded(
          event,
          params.onPaymentSucceeded,
        );
      }

      default: {
        if (params.onEvent) {
          return params.onEvent(event.type);
        }

        const Logger = await getLogger();

        Logger.info(
          {
            eventType: event.type,
            name: this.namespace,
          },
          `Unhandled Stripe event type: ${event.type}`,
        );

        return;
      }
    }
  }

  private async handleCheckoutSessionCompleted(
    event: Stripe.CheckoutSessionCompletedEvent,
    onCheckoutCompletedCallback: (
      data: UpsertSubscriptionParams | UpsertOrderParams,
    ) => Promise<unknown>,
  ) {
    const stripe = await this.loadStripe();

    const session = event.data.object;
    const isSubscription = session.mode === 'subscription';

    const accountId = session.client_reference_id!;
    const customerId = session.customer as string;

    // if it's a subscription, we need to retrieve the subscription
    // and build the payload for the subscription
    if (isSubscription) {
      const subscriptionId = session.subscription as string;
      const subscription = await stripe.subscriptions.retrieve(subscriptionId);

      const payload = this.buildSubscriptionPayload({
        accountId,
        customerId,
        id: subscription.id,
        lineItems: subscription.items.data,
        status: subscription.status,
        currency: subscription.currency,
        periodStartsAt: subscription.current_period_start,
        periodEndsAt: subscription.current_period_end,
        cancelAtPeriodEnd: subscription.cancel_at_period_end,
        trialStartsAt: subscription.trial_start,
        trialEndsAt: subscription.trial_end,
      });

      return onCheckoutCompletedCallback(payload);
    } else {
      // if it's a one-time payment, we need to retrieve the session
      const sessionId = event.data.object.id;

      // from the session, we need to retrieve the line items
      const sessionWithLineItems = await stripe.checkout.sessions.retrieve(
        event.data.object.id,
        {
          expand: ['line_items'],
        },
      );

      const lineItems = sessionWithLineItems.line_items?.data ?? [];
      const paymentStatus = sessionWithLineItems.payment_status;
      const status = paymentStatus === 'unpaid' ? 'pending' : 'succeeded';
      const currency = event.data.object.currency as string;

      const payload: UpsertOrderParams = {
        target_account_id: accountId,
        target_customer_id: customerId,
        target_order_id: sessionId,
        billing_provider: this.provider,
        status: status,
        currency: currency,
        total_amount: sessionWithLineItems.amount_total ?? 0,
        line_items: lineItems.map((item) => {
          const price = item.price as Stripe.Price;

          return {
            id: item.id,
            product_id: price.product as string,
            variant_id: price.id,
            price_amount: price.unit_amount,
            quantity: item.quantity,
          };
        }),
      };

      return onCheckoutCompletedCallback(payload);
    }
  }

  private handleAsyncPaymentFailed(
    event: Stripe.CheckoutSessionAsyncPaymentFailedEvent,
    onPaymentFailed: (sessionId: string) => Promise<unknown>,
  ) {
    const sessionId = event.data.object.id;

    return onPaymentFailed(sessionId);
  }

  private handleAsyncPaymentSucceeded(
    event: Stripe.CheckoutSessionAsyncPaymentSucceededEvent,
    onPaymentSucceeded: (sessionId: string) => Promise<unknown>,
  ) {
    const sessionId = event.data.object.id;

    return onPaymentSucceeded(sessionId);
  }

  private handleSubscriptionUpdatedEvent(
    event: Stripe.CustomerSubscriptionUpdatedEvent,
    onSubscriptionUpdatedCallback: (
      subscription: UpsertSubscriptionParams,
    ) => Promise<unknown>,
  ) {
    const subscription = event.data.object;
    const subscriptionId = subscription.id;
    const accountId = subscription.metadata.accountId as string;

    const payload = this.buildSubscriptionPayload({
      customerId: subscription.customer as string,
      id: subscriptionId,
      accountId,
      lineItems: subscription.items.data,
      status: subscription.status,
      currency: subscription.currency,
      periodStartsAt: subscription.current_period_start,
      periodEndsAt: subscription.current_period_end,
      cancelAtPeriodEnd: subscription.cancel_at_period_end,
      trialStartsAt: subscription.trial_start,
      trialEndsAt: subscription.trial_end,
    });

    return onSubscriptionUpdatedCallback(payload);
  }

  private handleSubscriptionDeletedEvent(
    subscription: Stripe.CustomerSubscriptionDeletedEvent,
    onSubscriptionDeletedCallback: (subscriptionId: string) => Promise<unknown>,
  ) {
    // Here we don't need to do anything, so we just return the callback

    return onSubscriptionDeletedCallback(subscription.id);
  }

  private buildSubscriptionPayload<
    LineItem extends {
      id: string;
      quantity?: number;
      price?: Stripe.Price;
    },
  >(params: {
    id: string;
    accountId: string;
    customerId: string;
    lineItems: LineItem[];
    status: Stripe.Subscription.Status;
    currency: string;
    cancelAtPeriodEnd: boolean;
    periodStartsAt: number;
    periodEndsAt: number;
    trialStartsAt: number | null;
    trialEndsAt: number | null;
  }): UpsertSubscriptionParams {
    const active = params.status === 'active' || params.status === 'trialing';

    const lineItems = params.lineItems.map((item) => {
      const quantity = item.quantity ?? 1;
      const variantId = item.price?.id as string;

      return {
        id: item.id,
        quantity,
        subscription_id: params.id,
        product_id: item.price?.product as string,
        variant_id: variantId,
        price_amount: item.price?.unit_amount,
        interval: item.price?.recurring?.interval as string,
        interval_count: item.price?.recurring?.interval_count as number,
        type: getLineItemTypeById(this.config, variantId),
      };
    });

    // otherwise we are updating a subscription
    // and we only need to return the update payload
    return {
      target_subscription_id: params.id,
      target_account_id: params.accountId,
      target_customer_id: params.customerId,
      billing_provider: this.provider,
      status: params.status,
      line_items: lineItems,
      active,
      currency: params.currency,
      cancel_at_period_end: params.cancelAtPeriodEnd ?? false,
      period_starts_at: getISOString(params.periodStartsAt) as string,
      period_ends_at: getISOString(params.periodEndsAt) as string,
      trial_starts_at: getISOString(params.trialStartsAt),
      trial_ends_at: getISOString(params.trialEndsAt),
    };
  }

  private async handleInvoicePaid(
    event: Stripe.InvoicePaidEvent,
    onInvoicePaid: (params: UpsertSubscriptionParams) => Promise<unknown>,
  ) {
    const stripe = await this.loadStripe();

    const subscriptionId = event.data.object.subscription as string;
    const subscription = await stripe.subscriptions.retrieve(subscriptionId);

    const accountId = subscription.metadata.accountId as string;

    const payload = this.buildSubscriptionPayload({
      customerId: subscription.customer as string,
      id: subscriptionId,
      accountId,
      lineItems: subscription.items.data,
      status: subscription.status,
      currency: subscription.currency,
      periodStartsAt: subscription.current_period_start,
      periodEndsAt: subscription.current_period_end,
      cancelAtPeriodEnd: subscription.cancel_at_period_end,
      trialStartsAt: subscription.trial_start,
      trialEndsAt: subscription.trial_end,
    });

    return onInvoicePaid(payload);
  }
}

function getISOString(date: number | null) {
  return date ? new Date(date * 1000).toISOString() : undefined;
}