SillyCoinbaseClientExample.php

<?php

//
// NOTE: only one dependency is needed: `firebase/php-jwt`.
//       (install using: `composer require firebase/php-jwt`)
//
require(dirname(__FILE__) . "/vendor/autoload.php");

////////////////////////////////////////////////////////////////////////////////

interface CbKey {
  public function sign(string $requestLine, int $expiry): string;
}

class CbKeyEcDsa256 implements CbKey {
  protected string $id;
  protected OpenSSLAsymmetricKey $secretKey;

  public function __construct(string $id, OpenSSLAsymmetricKey $secretKey) {
    $this->secretKey = $secretKey;
    $this->id = $id;
  }

  public static function fromPem(string $id, string $pemEncodedPrivateKey): self {
    $secretKey = openssl_pkey_get_private($pemEncodedPrivateKey);
    if (!$secretKey) {
      throw new InvalidArgumentException("Failed to initialize a private key from decoded `pemEncodedPrivateKey`");
    }

    return new static($id, $secretKey);
  }

  public function sign(string $requestLine, int $expiry): string {
    $now = time();

    return \Firebase\JWT\JWT::encode([
      "sub" => $this->id,
      "iss" => "cdp",
      "nbf" => $now,
      "exp" => $now + max(1, intval($expiry)),
      "uri" => $requestLine,
    ], $this->secretKey, "ES256", $this->id, [
      "typ" => "JWT",
      "kid" => $this->id,
      "nonce" => bin2hex(random_bytes(16)),
    ]);
  }
}

class CbKeyEd25519 implements CbKey {
  protected string $id;
  protected string $base64EncodedPrivateKey;

  protected function __construct(string $id, string $base64EncodedPrivateKey) {
    $this->base64EncodedPrivateKey = $base64EncodedPrivateKey;
    $this->id = $id;
  }

  public static function fromBase64(string $id, string $base64EncodedPrivateKey): self {
    $secretKeyBytes = base64_decode($base64EncodedPrivateKey);
    if (strlen($secretKeyBytes) !== SODIUM_CRYPTO_SIGN_SECRETKEYBYTES) {
      throw new InvalidArgumentException(
        "Invalid length of decoded `base64EncodedPrivateKey`" .
          " (expected: " . SODIUM_CRYPTO_SIGN_SECRETKEYBYTES .
          ", got: " . strlen($secretKeyBytes) . ")",
      );
    }

    return new static($id, $base64EncodedPrivateKey);
  }

  public function sign(string $requestLine, int $expiry): string {
    $now = time();

    return \Firebase\JWT\JWT::encode([
      "sub" => $this->id,
      "iss" => "cdp",
      "nbf" => $now,
      "exp" => $now + max(1, intval($expiry)),
      "uri" => $requestLine,
    ], $this->base64EncodedPrivateKey, "EdDSA", $this->id, [
      "typ" => "JWT",
      "kid" => $this->id,
      "nonce" => bin2hex(random_bytes(16)),
    ]);
  }
}

class CbClient {
  public const DEFAULT_BASE_URL = "https://api.coinbase.com";

  public string $baseUrl = self::DEFAULT_BASE_URL;
  public int $defaultRequestTimeout = 60;
  public int $defaultSignatureExpiry = 120;
  protected ?CbKey $key = null;

  public function __construct(?CbKey $key = null) {
    if ($key) {
      $this->key = $key;
    }
  }

  public function request(
    string $method,
    string $uri,
    array $params = [],
    mixed $body = null,
    array $headers = [],
    bool $sign = true,
  ): array {
    $parsedUrl = parse_url(rtrim($this->baseUrl, "/") . "/" . ltrim($uri, "/"));
    $urlPort = $parsedUrl["port"] ?? 0;
    $urlAuthority = !isset($parsedUrl["host"]) ? ""
      : ($parsedUrl["host"] . ($urlPort ? ":" . $urlPort : ""));

    if (isset($parsedUrl["query"])) {
      $opaqueParams = [];
      parse_str($parsedUrl["query"], $opaqueParams);

      if (is_array($opaqueParams) && !empty($opaqueParams)) {
        foreach ($opaqueParams as $k => $v) {
          if (!isset($params[$k])) $params[$k] = $v;
        }
      }
    }
    $parsedUrl["query"] = !empty($params) ? http_build_query($params) : "";

    $method = is_string($method) ? strtoupper($method) : "GET";
    if ($sign) {
      if (!$this->key) {
        throw new Exception("Client request could not be signed due to missing `key`");
      }

      $requestLine = $method . " " . $urlAuthority . ($parsedUrl["path"] ?? "");

      $signature = "";
      try {
        $signature = $this->key->sign($requestLine, $this->defaultSignatureExpiry);
      } catch (\Exception $e) {
        throw new Exception("Client request could not be signed due to internal failure", 0, $e);
      }
      if (!is_string($signature) || empty($signature)) {
        throw new Exception("Client request could not be signed due to unexpected internal failure");
      }

      $headers["Authorization"] = "Bearer $signature";
    }

    $rawBody = $body === null ? "" : (is_string($body) ? $body : (json_encode($body) ?: ""));
    if (!empty($rawBody) && !isset($headers["Content-Type"])) {
      $headers["Content-Type"] = "application/json";
    }

    $url =
      (isset($parsedUrl["scheme"]) ? $parsedUrl["scheme"] . ":" : "") .
      (!empty($urlAuthority) ? "//" . $urlAuthority : "") .
      (isset($parsedUrl["path"]) ? $parsedUrl["path"] : "") .
      (!empty($parsedUrl["query"]) ? "?" . $parsedUrl["query"] : "");

    $rawResponse = $this->rawRequest($method, $url, $rawBody, $headers);
    $response = [];
    try {
      $response = json_decode($rawResponse, true);
    } catch (\Exception $e) {
      throw new Exception("Unexpected response format", 0, $e);
    }

    return is_array($response) ? $response : [];
  }

  protected function rawRequest(
    string $method,
    string $url,
    ?string $body,
    array $headers = [],
    array $options = [],
  ): string {
    $ch = curl_init();
    curl_setopt_array($ch, [
      CURLOPT_URL => $url,
      CURLOPT_RETURNTRANSFER => true,
      CURLOPT_FOLLOWLOCATION => true,
      CURLOPT_MAXREDIRS => 3,
      CURLOPT_TIMEOUT => (isset($options["timeout"]) ? max(0, intval($options["timeout"])) : $this->defaultRequestTimeout),
      CURLOPT_CUSTOMREQUEST => $method,
      CURLOPT_POSTFIELDS => $body,
      CURLOPT_HTTPHEADER => $headers ?
        array_map(fn($k, $v): string => "$k: $v", array_keys($headers), array_values($headers))
        : [],
    ]);

    $response = curl_exec($ch) ?: "";
    $status = intval(curl_getinfo($ch, CURLINFO_HTTP_CODE));
    if (!($status >= 200 && $status <= 299)) {
      throw new Exception("Erroneous response status code: " . $status);
    }
    curl_close($ch);

    return $response;
  }
}

////////////////////////////////////////////////////////////////////////////////

function main() {
  // // 🔑 Example: using an Ed25519-based API key.
  // $client = new CbClient(
  //   CbKeyEd25519::fromBase64(
  //     "00000000-0000-0000-0000-000000000000",
  //     "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==",
  //   ),
  // );
  //
  // // 🔑 Example: using an ECDSA-based API key.
  // $client = new CbClient(
  //   CbKeyEcDsa256::fromPem(
  //     "organizations/00000000-0000-0000-0000-000000000000/apiKeys/00000000-0000-0000-0000-000000000000",
  //     "-----BEGIN EC PRIVATE KEY-----\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==\n-----END EC PRIVATE KEY-----\n",
  //   ),
  // );

  // 🔓 Example: unauthenticated client.
  $client = new CbClient();

  //////////////////////////////////////////////////////////////////////////////

  // 🪪 Example: "List Accounts".
  try {
    $response = $client->request("GET", "/api/v3/brokerage/accounts");

    echo json_encode($response) . "\n\n";
  } catch (\Exception $e) {
    echo "[!] Request `···/accounts` has failed.\n ⇾ ERROR: " . $e->getMessage() . "\n\n";
  }

  // 📊 Example: "Get Public Product Candles".
  try {
    $now = time();
    $response = $client->request(
      "GET",
      "/api/v3/brokerage/market/products/BTC-USD/candles",
      [
        "start" => ($now - (60 * 60)),
        "end" => $now,
        "granularity" => "ONE_MINUTE",
        "limit" => 5,
      ],
      sign: false, // NOTE: explicitly setting `sign` to false (not strictly necessary).
    );

    echo json_encode($response) . "\n\n";
  } catch (\Exception $e) {
    echo "[!] Request `···/candles` has failed.\n ⇾ ERROR: " . $e->getMessage() . "\n\n";
  }
}

main();