x402 Subscribe to a plan

import { createKeyPairSignerFromBytes } from '@solana/kit';
import { x402Client, x402HTTPClient } from '@x402/core/client';
import { registerExactSvmScheme } from '@x402/svm/exact/client';

const config = {
  apiUrl: process.env.API_URL ?? 'https://api.mobula.io',
  plan: process.env.PLAN ?? 'growth',
  paymentFrequency: process.env.PAYMENT_FREQUENCY ?? 'yearly',
};

const SUBSCRIPTION_ENDPOINT = `${config.apiUrl}/agent/x402/subscription`;

function base58ToBytes(b58: string): Uint8Array {
  const ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
  const map = new Uint8Array(256).fill(255);
  for (let i = 0; i < ALPHABET.length; i++) map[ALPHABET.charCodeAt(i)] = i;
  const bytes: number[] = [0];
  for (const char of b58) {
    const value = map[char.charCodeAt(0)];
    if (value === undefined || value === 255) throw new Error(`Invalid base58: ${char}`);
    let carry: number = value;
    for (let j = bytes.length - 1; j >= 0; j--) {
      carry += (bytes[j] as number) * 58;
      bytes[j] = carry & 0xff;
      carry >>= 8;
    }
    while (carry > 0) {
      bytes.unshift(carry & 0xff);
      carry >>= 8;
    }
  }
  for (const char of b58) {
    if (char !== '1') break;
    bytes.unshift(0);
  }
  return new Uint8Array(bytes);
}

function getSubscribeEndpoint(): string {
  const params = new URLSearchParams({
    plan: config.plan,
    payment_frequency: config.paymentFrequency,
  });
  return `${config.apiUrl}/agent/x402/subscribe?${params.toString()}`;
}

async function main() {
  const privateKeyB58 = process.env.SOLANA_PRIVATE_KEY;
  if (!privateKeyB58) {
    console.error('ERROR: SOLANA_PRIVATE_KEY is not set.');
    console.error('  Provide a base58-encoded private key for a wallet holding USDC and SOL.');
    console.error('  Devnet USDC faucet: https://faucet.circle.com');
    process.exit(1);
  }

  const signer = await createKeyPairSignerFromBytes(base58ToBytes(privateKeyB58));
  const walletAddress = typeof signer.address === 'string' ? signer.address : String(signer.address);

  const client = new x402Client();
  registerExactSvmScheme(client, { signer });
  const httpClient = new x402HTTPClient(client);

  // ── Step 1: Check plan status ─────────────────────────────────────────────
  console.log('Step 1 — Checking plan status...');
  console.log('  Wallet:', walletAddress);

  const statusProbeRes = await fetch(SUBSCRIPTION_ENDPOINT);
  if (statusProbeRes.status !== 402) {
    console.error('  Unexpected response (expected 402):', statusProbeRes.status, await statusProbeRes.text());
    process.exit(1);
  }

  const statusPaymentHeader = statusProbeRes.headers.get('payment-required');
  if (!statusPaymentHeader) {
    console.error('  Missing payment-required header on status check.');
    process.exit(1);
  }

  const statusDecoded = JSON.parse(Buffer.from(statusPaymentHeader, 'base64').toString('utf-8'));
  const statusPaymentRequired = httpClient.getPaymentRequiredResponse(
    (name) => statusProbeRes.headers.get(name),
    statusDecoded,
  );

  let statusPaymentHeaders: Record<string, string>;
  try {
    const payload = await httpClient.createPaymentPayload(statusPaymentRequired);
    statusPaymentHeaders = httpClient.encodePaymentSignatureHeader(payload);
  } catch (err) {
    console.error('  Failed to sign status-check payment:', err);
    process.exit(1);
  }

  const statusRes = await fetch(SUBSCRIPTION_ENDPOINT, { headers: statusPaymentHeaders });
  const statusBody = await statusRes.text();

  if (statusRes.status === 200) {
    const stats = JSON.parse(statusBody) as {
      plan_active?: boolean;
      left_days?: number;
      plan?: string;
    };
    const planName = (stats.plan ?? '').toString().toLowerCase().trim();
    const isActive =
      stats.plan_active === true ||
      (typeof stats.left_days === 'number' && stats.left_days > 0);

    if (isActive && planName !== 'free') {
      console.log('  Paid plan is already active — skipping subscribe.');
      console.log('  Current stats:', statusBody);
      process.exit(0);
    }
    if (isActive && planName === 'free') {
      console.log('  Wallet is on the Free plan. Proceeding to subscribe to a paid plan.');
    }
  }

  if (statusRes.status !== 200) {
    console.log('  No active plan found (404 or expired). Proceeding to subscribe.');
  }

  // ── Step 2: Initiate subscribe ────────────────────────────────────────────
  const subscribePath = getSubscribeEndpoint();
  console.log(`\nStep 2 — Initiating subscribe (${subscribePath})...`);

  const subscribeProbeRes = await fetch(subscribePath);
  if (subscribeProbeRes.status !== 402) {
    console.error('  Unexpected response (expected 402):', await subscribeProbeRes.text());
    process.exit(1);
  }
  console.log('  402 received — payment details follow.');

  const subscribePaymentHeader = subscribeProbeRes.headers.get('payment-required');
  if (!subscribePaymentHeader) {
    console.error('  Missing payment-required header on subscribe probe.');
    process.exit(1);
  }

  const subscribeDecoded = JSON.parse(
    Buffer.from(subscribePaymentHeader, 'base64').toString('utf-8'),
  );
  const subscribeSolanaOption = subscribeDecoded.accepts?.find(
    (a: { network: string }) => a.network?.startsWith('solana:'),
  );
  if (!subscribeSolanaOption) {
    console.error('  No Solana payment option found in 402 response.');
    console.error('  Check that API_URL is set to https://api.mobula.io');
    process.exit(1);
  }

  // ── Step 3: Review payment details ───────────────────────────────────────
  const SOLANA_DEVNET_NETWORK_ID = 'solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1';
  const networkLabel = subscribeSolanaOption.network === SOLANA_DEVNET_NETWORK_ID ? 'devnet' : 'mainnet';
  const priceUsdc = Number(subscribeSolanaOption.amount) / 1_000_000;

  console.log(`\nStep 3 — Payment details (Solana ${networkLabel}):`);
  console.log('  network:', subscribeSolanaOption.network);
  console.log('  amount :', subscribeSolanaOption.amount, `($${priceUsdc.toFixed(2)} USDC)`);
  console.log('  payTo  :', subscribeSolanaOption.payTo);

  // ── Step 4: Sign payment ──────────────────────────────────────────────────
  console.log('\nStep 4 — Signing payment...');

  const subscribePaymentRequired = httpClient.getPaymentRequiredResponse(
    (name) => subscribeProbeRes.headers.get(name),
    subscribeDecoded,
  );

  let subscribePaymentHeaders: Record<string, string>;
  try {
    const payload = await httpClient.createPaymentPayload(subscribePaymentRequired);
    subscribePaymentHeaders = httpClient.encodePaymentSignatureHeader(payload);
  } catch (err) {
    console.error('  Failed to sign subscribe payment:', err);
    process.exit(1);
  }
  console.log('  Payment signed.');

  // ── Step 5: Submit and confirm ────────────────────────────────────────────
  console.log('\nStep 5 — Submitting payment...');

  const subscribeRes = await fetch(subscribePath, { headers: subscribePaymentHeaders });
  const subscribeBody = await subscribeRes.text();
  console.log('  Status:', subscribeRes.status);

  if (subscribeRes.status !== 200) {
    console.error(`\n❌ Subscribe failed (HTTP ${subscribeRes.status})`);
    if (subscribeBody) {
      try {
        const json = JSON.parse(subscribeBody) as Record<string, unknown>;
        const messages = [json.error, json.message, json.errorReason, json.errorMessage].filter(Boolean);
        if (messages.length > 0) {
          console.error('  Error:', messages.join(' — '));
        } else {
          console.error('  Response:', subscribeBody);
        }
      } catch {
        if (subscribeBody.trim()) console.error('  Response:', subscribeBody);
      }
    } else {
      console.error(
        '  No error details returned. Possible causes:\n' +
        '    - Invalid or already-used payment\n' +
        '    - Wrong network (devnet vs mainnet)\n' +
        '    - Payment not yet confirmed on-chain',
      );
    }
    process.exit(1);
  }

  // ── Step 6: Success ───────────────────────────────────────────────────────
  const result = JSON.parse(subscribeBody) as { api_key: string; user_id: string };

  console.log('\n✓ Subscribed successfully.');
  console.log('  api_key:', result.api_key);
  console.log('  user_id:', result.user_id);
  console.log('\n  Store both values:');
  console.log('    api_key → Authorization header for all Mobula API requests');
  console.log('    user_id → agent_id when calling the top-up endpoint');

  process.exit(0);
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});