// ─────────────────────────────────────────────────────────────────────────────
// ADAPTER                                                           [Structural]
// ─────────────────────────────────────────────────────────────────────────────
// INTENT  : Convert the interface of a class into another interface clients expect, so classes with
//           incompatible interfaces can work together.
// PROBLEM : Your code speaks `gateway.charge({ amountCents, currency, token })`; the vendor SDK speaks
//           `sale(dollarsString, nonce, callback)`. You own neither side's shape.
// SAY     : Participants: Target (the interface you want), Adaptee (the thing you have), Adapter (implements
//           Target by wrapping the Adaptee — "object adapter" = composition), Client. Pitch: "a plug
//           converter — same electricity, new shape."
// SEEN IN : `util.promisify` / `util.callbackify` (callback API ↔ Promise API); axios adapters (one API over
//           XHR / Node http / fetch); `Readable.toWeb` / `Readable.fromWeb` (Node ↔ WHATWG streams); Knex
//           dialect drivers (pg/mysql2/sqlite behind one interface); your own wrappers around Stripe/Twilio/
//           S3 SDKs (`PaymentGateway`, `Mailer`, `BlobStore`); API response → domain model mappers.
// VS      : Decorator keeps the SAME interface and adds behavior; Adapter CHANGES the interface. Facade
//           simplifies a whole subsystem with a new API; Adapter makes one object fit an EXISTING API.
//           Proxy = same interface, controls access.
// ─────────────────────────────────────────────────────────────────────────────
'use strict';
const assert = require('node:assert/strict');
const { promisify } = require('node:util');

// ── Classic shape (classes, so the participant names are visible)
class LegacyBraintreeSdk {                                // Adaptee — vendor shape we can't change
  sale(amountDollars, nonce, cb) {
    if (!/^\d+\.\d{2}$/.test(amountDollars)) return cb(new Error(`bad amount ${amountDollars}`));
    cb(null, { success: true, transaction: { id: `bt_${nonce}`, amount: amountDollars } });
  }
}

// Target interface: charge({ amountCents, currency, token }) -> Promise<{ ok, id }>
class StripeGateway {                                     // a native Target implementation
  async charge({ amountCents, token }) { return { ok: true, id: `ch_${token}_${amountCents}` }; }
}

class BraintreeGatewayAdapter {                           // Adapter — implements Target, delegates to Adaptee
  #sdk;
  constructor(sdk) { this.#sdk = sdk; }
  charge({ amountCents, currency, token }) {
    if (currency !== 'USD') return Promise.reject(new Error('braintree adapter: USD only'));
    const dollars = (amountCents / 100).toFixed(2);       // cents → "12.34"
    return new Promise((resolve, reject) => {             // callback → promise
      this.#sdk.sale(dollars, token, (err, res) => {
        if (err) return reject(err);
        resolve({ ok: res.success, id: res.transaction.id });   // vendor result → our result
      });
    });
  }
}

async function checkout(gateway, cart) {                  // Client — only knows Target
  const amountCents = cart.items.reduce((s, i) => s + i.cents * i.qty, 0);
  return gateway.charge({ amountCents, currency: 'USD', token: cart.token });
}

// ── Idiomatic JS shape: a function that maps one shape onto another (+ promisify as a ready-made adapter)
const adaptBraintree = (sdk) => {
  const sale = promisify(sdk.sale.bind(sdk));
  return {
    charge: async ({ amountCents, token }) => {
      const res = await sale((amountCents / 100).toFixed(2), token);
      return { ok: res.success, id: res.transaction.id };
    },
  };
};

// Data-shape adapters are the most common kind: vendor payload → your domain model
const toCustomer = (vendor) => ({
  id: vendor.customer_id,
  name: `${vendor.first_name} ${vendor.last_name}`.trim(),
  email: vendor.contact?.email_address ?? null,
});

(async () => {
  const cart = { items: [{ cents: 1999, qty: 2 }], token: 'nonce42' };
  const viaStripe = await checkout(new StripeGateway(), cart);
  const viaBraintree = await checkout(new BraintreeGatewayAdapter(new LegacyBraintreeSdk()), cart);
  assert.deepEqual(viaStripe, { ok: true, id: 'ch_nonce42_3998' });
  assert.deepEqual(viaBraintree, { ok: true, id: 'bt_nonce42' });   // same client code, vendor swapped
  await assert.rejects(
    new BraintreeGatewayAdapter(new LegacyBraintreeSdk()).charge({ amountCents: 1, currency: 'EUR', token: 'x' }),
    /USD only/,
  );

  const sdk = new LegacyBraintreeSdk();
  const sale = promisify(sdk.sale.bind(sdk));
  assert.equal((await sale('10.00', 'n1')).transaction.id, 'bt_n1');  // promisify adapted the callback
  await assert.rejects(sale('10', 'n1'), /bad amount/);              // and errors became rejections
  assert.deepEqual(await adaptBraintree(sdk).charge({ amountCents: 250, token: 'n2' }), { ok: true, id: 'bt_n2' });

  assert.deepEqual(
    toCustomer({ customer_id: 'c1', first_name: 'Ada', last_name: 'L', contact: { email_address: 'a@x.io' } }),
    { id: 'c1', name: 'Ada L', email: 'a@x.io' },
  );
  assert.equal(toCustomer({ customer_id: 'c2', first_name: 'Bob', last_name: '' }).email, null);

  console.log('ok: design-patterns/structural/adapter.js');
})();