The ledger and settlement

cURL

# paydirect.sh - source this, then call `paydirect POST /transactions/collect "$BODY"`
# Works for GET, POST, PATCH and DELETE; a body is optional.
paydirect() {
  local method="$1" path="$2" body="${3:-}"
  local ts sig
  ts=$(date +%s000)                                   # milliseconds, not seconds
  sig=$(printf '%s:%s' "$PAYDIRECT_RAW_KEY" "$ts" \
    | openssl dgst -sha256 -hmac "$PAYDIRECT_SECRET_KEY" -hex \
    | awk '{print $2}')

  curl -sS -X "$method" "$PAYDIRECT_HOST$path" \
    -H "Content-Type: application/json" \
    -H "x-api-key-id: $PAYDIRECT_PUBLIC_KEY" \
    -H "x-api-timestamp: $ts" \
    -H "x-api-signature: $sig" \
    ${body:+-H "Idempotency-Key: $(uuidgen)"} \
    ${body:+-d "$body"}
}

Node.js

// paydirect.js - Node 18+, no dependencies
const crypto = require('crypto');

function signedHeaders() {
  const timestamp = Date.now().toString(); // milliseconds
  const signature = crypto
    .createHmac('sha256', process.env.PAYDIRECT_SECRET_KEY)
    .update(`${process.env.PAYDIRECT_RAW_KEY}:${timestamp}`)
    .digest('hex');

  return {
    'Content-Type': 'application/json',
    'x-api-key-id': process.env.PAYDIRECT_PUBLIC_KEY,
    'x-api-timestamp': timestamp,
    'x-api-signature': signature,
  };
}

async function request(method, path, body, idempotencyKey) {
  const headers = signedHeaders();
  if (idempotencyKey) headers['Idempotency-Key'] = idempotencyKey;

  const response = await fetch(`${process.env.PAYDIRECT_HOST}${path}`, {
    method,
    headers,
    body: body ? JSON.stringify(body) : undefined,
  });
  return { status: response.status, body: await response.json() };
}

const payDirect = {
  get: path => request('GET', path),
  post: (path, body, idempotencyKey) => request('POST', path, body, idempotencyKey),
  patch: (path, body) => request('PATCH', path, body),
  del: path => request('DELETE', path),
};

module.exports = { payDirect };

Python

# paydirect.py - requires `requests`
import hashlib, hmac, os, time, uuid
import requests

HOST = os.environ["PAYDIRECT_HOST"]

def _signed_headers() -> dict:
    timestamp = str(int(time.time() * 1000))  # milliseconds, not seconds
    signature = hmac.new(
        os.environ["PAYDIRECT_SECRET_KEY"].encode(),
        f'{os.environ["PAYDIRECT_RAW_KEY"]}:{timestamp}'.encode(),
        hashlib.sha256,
    ).hexdigest()

    return {
        "Content-Type": "application/json",
        "x-api-key-id": os.environ["PAYDIRECT_PUBLIC_KEY"],
        "x-api-timestamp": timestamp,
        "x-api-signature": signature,
    }

def request(method: str, path: str, body: dict | None = None, idempotency_key: str | None = None):
    headers = _signed_headers()
    if idempotency_key:
        headers["Idempotency-Key"] = idempotency_key

    response = requests.request(method, f"{HOST}{path}", json=body, headers=headers, timeout=30)
    return response.status_code, response.json()

def get(path: str):
    return request("GET", path)

def post(path: str, body: dict, idempotency_key: str | None = None):
    return request("POST", path, body, idempotency_key or str(uuid.uuid4()))

def patch(path: str, body: dict):
    return request("PATCH", path, body)

def delete(path: str):
    return request("DELETE", path)

PHP

<?php
// PayDirect.php - requires ext-curl, no packages

final class PayDirect
{
    public function get(string $path): array
    {
        return $this->request('GET', $path);
    }

    public function post(string $path, array $body, ?string $idempotencyKey = null): array
    {
        return $this->request('POST', $path, $body, $idempotencyKey ?? bin2hex(random_bytes(16)));
    }

    public function patch(string $path, array $body): array
    {
        return $this->request('PATCH', $path, $body);
    }

    public function delete(string $path): array
    {
        return $this->request('DELETE', $path);
    }

    private function signedHeaders(): array
    {
        $timestamp = (string) round(microtime(true) * 1000); // milliseconds
        $signature = hash_hmac(
            'sha256',
            getenv('PAYDIRECT_RAW_KEY') . ':' . $timestamp,
            getenv('PAYDIRECT_SECRET_KEY')
        );

        return [
            'Content-Type: application/json',
            'x-api-key-id: ' . getenv('PAYDIRECT_PUBLIC_KEY'),
            'x-api-timestamp: ' . $timestamp,
            'x-api-signature: ' . $signature,
        ];
    }

    private function request(string $method, string $path, ?array $body = null, ?string $key = null): array
    {
        $headers = $this->signedHeaders();
        if ($key !== null) {
            $headers[] = 'Idempotency-Key: ' . $key;
        }

        $ch = curl_init(getenv('PAYDIRECT_HOST') . $path);
        curl_setopt_array($ch, [
            CURLOPT_CUSTOMREQUEST  => $method,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HTTPHEADER     => $headers,
            CURLOPT_TIMEOUT        => 30,
        ]);
        if ($body !== null) {
            curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($body));
        }

        $raw    = curl_exec($ch);
        $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        curl_close($ch);

        return ['status' => $status, 'body' => json_decode($raw, true)];
    }
}

Java

// PayDirect.java - JDK 11+, no dependencies
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.net.URI;
import java.net.http.*;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.UUID;

public final class PayDirect {
    private static final String HOST = System.getenv("PAYDIRECT_HOST");
    private final HttpClient http = HttpClient.newHttpClient();

    public HttpResponse<String> get(String path) throws Exception {
        return request("GET", path, null, null);
    }

    public HttpResponse<String> post(String path, String jsonBody) throws Exception {
        return request("POST", path, jsonBody, UUID.randomUUID().toString());
    }

    public HttpResponse<String> patch(String path, String jsonBody) throws Exception {
        return request("PATCH", path, jsonBody, null);
    }

    public HttpResponse<String> delete(String path) throws Exception {
        return request("DELETE", path, null, null);
    }

    private static String hmacHex(String message, String secret) throws Exception {
        Mac mac = Mac.getInstance("HmacSHA256");
        mac.init(new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256"));
        StringBuilder hex = new StringBuilder();
        for (byte b : mac.doFinal(message.getBytes(StandardCharsets.UTF_8))) {
            hex.append(String.format("%02x", b)); // lowercase hex
        }
        return hex.toString();
    }

    private HttpResponse<String> request(String method, String path, String body, String key)
            throws Exception {
        String timestamp = String.valueOf(System.currentTimeMillis()); // milliseconds
        String signature = hmacHex(System.getenv("PAYDIRECT_RAW_KEY") + ":" + timestamp,
                                   System.getenv("PAYDIRECT_SECRET_KEY"));

        HttpRequest.Builder builder = HttpRequest.newBuilder(URI.create(HOST + path))
                .timeout(Duration.ofSeconds(30))
                .header("Content-Type", "application/json")
                .header("x-api-key-id", System.getenv("PAYDIRECT_PUBLIC_KEY"))
                .header("x-api-timestamp", timestamp)
                .header("x-api-signature", signature)
                .method(method, body == null
                        ? HttpRequest.BodyPublishers.noBody()
                        : HttpRequest.BodyPublishers.ofString(body));

        if (key != null) {
            builder.header("Idempotency-Key", key);
        }
        return http.send(builder.build(), HttpResponse.BodyHandlers.ofString());
    }
}

C#

// PayDirect.cs - .NET 6+, no packages
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;

public sealed class PayDirect
{
    private static readonly HttpClient Http = new();
    private static readonly string Host = Environment.GetEnvironmentVariable("PAYDIRECT_HOST")!;

    public Task<HttpResponseMessage> GetAsync(string path) =>
        SendAsync(HttpMethod.Get, path, null, null);

    public Task<HttpResponseMessage> PostAsync(string path, object body, string? idempotencyKey = null) =>
        SendAsync(HttpMethod.Post, path, body, idempotencyKey ?? Guid.NewGuid().ToString());

    public Task<HttpResponseMessage> PatchAsync(string path, object body) =>
        SendAsync(HttpMethod.Patch, path, body, null);

    public Task<HttpResponseMessage> DeleteAsync(string path) =>
        SendAsync(HttpMethod.Delete, path, null, null);

    private static string HmacHex(string message, string secret)
    {
        using var mac = new HMACSHA256(Encoding.UTF8.GetBytes(secret));
        var hash = mac.ComputeHash(Encoding.UTF8.GetBytes(message));
        return Convert.ToHexString(hash).ToLowerInvariant(); // lowercase hex
    }

    private static async Task<HttpResponseMessage> SendAsync(
        HttpMethod method, string path, object? body, string? idempotencyKey)
    {
        // Milliseconds since the epoch, not seconds.
        var timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds().ToString();
        var signature = HmacHex(
            $"{Environment.GetEnvironmentVariable("PAYDIRECT_RAW_KEY")}:{timestamp}",
            Environment.GetEnvironmentVariable("PAYDIRECT_SECRET_KEY")!);

        using var request = new HttpRequestMessage(method, Host + path);
        request.Headers.Add("x-api-key-id", Environment.GetEnvironmentVariable("PAYDIRECT_PUBLIC_KEY"));
        request.Headers.Add("x-api-timestamp", timestamp);
        request.Headers.Add("x-api-signature", signature);
        if (idempotencyKey is not null)
        {
            request.Headers.Add("Idempotency-Key", idempotencyKey);
        }
        if (body is not null)
        {
            request.Content = JsonContent.Create(body);
        }

        return await Http.SendAsync(request);
    }
}