How Much To Buy

{
  "basis": "cooked",
  "buyDisplay": {
    "best": "38.6 kg",
    "mid": "41.3 kg",
    "worst": "44.4 kg"
  },
  "cost": {
    "perPortion": {
      "best": 6.27,
      "mid": 6.71,
      "worst": 7.2
    }
  },
  "foodCostPct": {
    "best": 19.6,
    "mid": 21,
    "worst": 22.5
  },
  "ingredient": "whole brisket",
  "neededG": 21600,
  "provenance": {
    "label": "Chef-verified by Cristopher"
  },
  "status": "ok"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://kitchen-pass.netlify.app/v1/how-much-to-buy' \
  -H 'content-type: application/json' \
  --data-raw '{"currency":"AUD","ingredient":"brisket","portionSize":{"qty":180,"unit":"g"},"portions":120,"pricePerKg":19.5,"sellPrice":32}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://kitchen-pass.netlify.app/v1/how-much-to-buy' \
  -H 'content-type: application/json' \
  --data-raw '{"currency":"AUD","ingredient":"brisket","portionSize":{"qty":180,"unit":"g"},"portions":120,"pricePerKg":19.5,"sellPrice":32}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fkitchen-pass.netlify.app%2Fv1%2Fhow-much-to-buy&method=POST
const res = await pay("https://kitchen-pass.netlify.app/v1/how-much-to-buy", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "currency": "AUD",
    "ingredient": "brisket",
    "portionSize": {
      "qty": 180,
      "unit": "g"
    },
    "portions": 120,
    "pricePerKg": 19.5,
    "sellPrice": 32
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://kitchen-pass.netlify.app/v1/how-much-to-buy",
        json={
            "currency": "AUD",
            "ingredient": "brisket",
            "portionSize": {
                "qty": 180,
                "unit": "g",
            },
            "portions": 120,
            "pricePerKg": 19.5,
            "sellPrice": 32,
        },
    )
    print(res.status_code, res.text)