<?php

namespace WPFitter\Aws\CloudFront;

/**
 * @internal
 */
class Signer
{
    private $keyPairId;
    private $pkHandle;
    /**
     * A signer for creating the signature values used in CloudFront signed URLs
     * and signed cookies.
     *
     * @param $keyPairId  string ID of the key pair
     * @param $privateKey string Path to the private key used for signing
     * @param $passphrase string Passphrase to private key file, if one exists
     *
     * @throws \RuntimeException if the openssl extension is missing
     * @throws \InvalidArgumentException if the private key cannot be found.
     */
    public function __construct($keyPairId, $privateKey, $passphrase = "")
    {
        if (!\extension_loaded('openssl')) {
            //@codeCoverageIgnoreStart
            throw new \RuntimeException('The openssl extension is required to ' . 'sign CloudFront urls.');
            //@codeCoverageIgnoreEnd
        }
        $this->keyPairId = $keyPairId;
        if (!($this->pkHandle = \openssl_pkey_get_private($privateKey, $passphrase))) {
            if (!\file_exists($privateKey)) {
                throw new \InvalidArgumentException("PK file not found: {$privateKey}");
            }
            $this->pkHandle = \openssl_pkey_get_private("file://{$privateKey}", $passphrase);
            if (!$this->pkHandle) {
                $errorMessages = [];
                while (($newMessage = \openssl_error_string()) !== \false) {
                    $errorMessages[] = $newMessage;
                }
                throw new \InvalidArgumentException(\implode("\n", $errorMessages));
            }
        }
    }
    public function __destruct()
    {
        if (\PHP_MAJOR_VERSION < 8) {
            $this->pkHandle && \openssl_pkey_free($this->pkHandle);
        }
    }
    /**
     * Create the values used to construct signed URLs and cookies.
     *
     * @param string              $resource     The CloudFront resource to which
     *                                          this signature will grant access.
     *                                          Not used when a custom policy is
     *                                          provided.
     * @param string|integer|null $expires      UTC Unix timestamp used when
     *                                          signing with a canned policy.
     *                                          Not required when passing a
     *                                          custom $policy.
     * @param string              $policy       JSON policy. Use this option when
     *                                          creating a signature for a custom
     *                                          policy.
     *
     * @return array The values needed to construct a signed URL or cookie
     * @throws \InvalidArgumentException  when not provided either a policy or a
     *                                    resource and a expires
     * @throws \RuntimeException when generated signature is empty
     *
     * @link http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-signed-cookies.html
     */
    public function getSignature($resource = null, $expires = null, $policy = null)
    {
        $signatureHash = [];
        if ($policy) {
            $policy = \preg_replace('/\\s/s', '', $policy);
            $signatureHash['Policy'] = $this->encode($policy);
        } elseif ($resource && $expires) {
            $expires = (int) $expires;
            // Handle epoch passed as string
            $policy = $this->createCannedPolicy($resource, $expires);
            $signatureHash['Expires'] = $expires;
        } else {
            throw new \InvalidArgumentException('Either a policy or a resource' . ' and an expiration time must be provided.');
        }
        $signatureHash['Signature'] = $this->encode($this->sign($policy));
        $signatureHash['Key-Pair-Id'] = $this->keyPairId;
        return $signatureHash;
    }
    private function createCannedPolicy($resource, $expiration)
    {
        return \json_encode(['Statement' => [['Resource' => $resource, 'Condition' => ['DateLessThan' => ['AWS:EpochTime' => $expiration]]]]], \JSON_UNESCAPED_SLASHES);
    }
    private function sign($policy)
    {
        $signature = '';
        if (!\openssl_sign($policy, $signature, $this->pkHandle)) {
            $errorMessages = [];
            while (($newMessage = \openssl_error_string()) !== \false) {
                $errorMessages[] = $newMessage;
            }
            $exceptionMessage = "An error has occurred when signing the policy";
            if (\count($errorMessages) > 0) {
                $exceptionMessage = \implode("\n", $errorMessages);
            }
            throw new \RuntimeException($exceptionMessage);
        }
        return $signature;
    }
    private function encode($policy)
    {
        return \strtr(\base64_encode($policy), '+=/', '-_~');
    }
}
