import type {
Env,
X402Response,
X402PaymentPayload,
PaymentRequirement,
VerifyResponse,
} from "../types/index.js";
/**
* Build the 402 Payment Required response
*/
export function build402Response(env: Env): X402Response {
return {
x402Version: 1,
paymentRequirements: [
{
scheme: "exact-tezos",
network: env.NETWORK,
asset: "XTZ",
amount: env.PAYMENT_AMOUNT,
recipient: env.PAYMENT_RECIPIENT,
extra: {
name: "XTZ",
decimals: 6,
},
},
],
};
}
/**
* Get the payment requirement for verification
*/
export function getPaymentRequirement(env: Env): PaymentRequirement {
return {
scheme: "exact-tezos",
network: env.NETWORK,
asset: "XTZ",
amount: env.PAYMENT_AMOUNT,
recipient: env.PAYMENT_RECIPIENT,
};
}
/**
* Decode the X-PAYMENT header from base64
*/
export function decodePaymentHeader(header: string): X402PaymentPayload {
try {
const decoded = atob(header);
return JSON.parse(decoded) as X402PaymentPayload;
} catch {
throw new Error("Invalid X-PAYMENT header: failed to decode base64 or parse JSON");
}
}
/**
* Verify payment with the facilitator (via service binding)
*/
export async function verifyPayment(
payload: X402PaymentPayload,
env: Env
): Promise<VerifyResponse> {
const requirement = getPaymentRequirement(env);
// Check network matches
if (payload.network !== env.NETWORK) {
return {
valid: false,
reason: `Wrong network: expected ${env.NETWORK}, got ${payload.network}`,
};
}
console.log("[x402] Calling facilitator /verify via service binding");
// Use service binding to call facilitator directly (avoids public routing)
const response = await env.FACILITATOR.fetch("https://facilitator/verify", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({
payload,
requirements: requirement,
}),
});
console.log("[x402] Facilitator response status:", response.status);
if (!response.ok) {
const errorText = await response.text();
return {
valid: false,
reason: `Facilitator verification failed: ${response.status} - ${errorText}`,
};
}
const result = await response.json<VerifyResponse>();
// Add payer address from payload if verification succeeded
if (result.valid && payload.payload?.source) {
result.payer = payload.payload.source;
}
return result;
}
/**
* Settle the payment with the facilitator (via service binding, fire and forget)
*/
export async function settlePayment(
payload: X402PaymentPayload,
env: Env
): Promise<boolean> {
try {
console.log("[x402] Calling facilitator /settle via service binding");
const response = await env.FACILITATOR.fetch("https://facilitator/settle", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({ payload }),
});
console.log("[x402] Settle response status:", response.status);
return response.ok;
} catch (error) {
console.error("[x402] Settle failed:", error);
return false;
}
}
