jjmontgo/GeneratePDF.php

## GeneratePDF.php
<?php
/**
 * Makes a POST request to a Lambda function through an API Gateway
 * which encapsulates a call to wkhtmltopdf, rendering an HTML
 * document as a PDF file and returning a signed URL to the
 * file in an S3 bucket.
 *
 * The POST can contain the following parameters:
 * body - A complete HTML5 document to be rendered in PDF (required)
 * header - A complete HTML5 document to be rendered in the header of every page (optional)
 * footer - A complete HTML5 document to be rendered in the footer of every page (optional)
 * filename - The preferred filename for the rendered PDF document (optional)
 * 						If not provided it will be 'generated.pdf'
 * margin_left, margin_right, margin_top, margin_bottom - optional integer values, in mm
 *
 * Make sure the following definitions are added to a file outside version control:
 * define("AWS_REGION", "");
 * define("PDF_API_GATEWAY_URL", "********.execute-api.us-east-1.amazonaws.com");
 * define("PDF_API_GATEWAY_STAGE", "***"); // usually "prod"
 * define("PDF_ACCESS_KEY", "");
 * define("PDF_SECRET_KEY", "");
 *
 * Then call the generator with:
 *
 * GeneratePDF::fromHTML("<!doctype html><html>...</html>")
 * 	->header("<!doctype html><html>...</html>")
 * 	->footer("<!doctype html><html>...</html>")
 * 	->leftMargin(0)
 * 	->rightMargin(0)
 * 	->andSendToBrowserAs("my-new-pdf-file.pdf"); // must be called, causes a redirect and exit
 */

class GeneratePDF {
	private static $instance;
	private $postParams = array();

	/**
	 * Instantiate the class and set the required body POST parameter
	 */
	public static function fromHTML($bodyHtml) {
		if (!isset(static::$instance)) {
			static::$instance = new GeneratePDF_V2();
		}
		static::$instance->setParam("body", $bodyHtml);
		return static::$instance;
	}

	/**
	 * Optionally put the PDF in a folder for the project
	 * @param  string $projectName This should follow appropriate standards for directory names
	 */
	public function projectName($projectName) {
		$this->setParam("project_name", $projectName);
		return $this;
	}

	public function header($headerHtml) {
		$this->setParam("header", $headerHtml);
		return $this;
	}

	public function footer($footerHtml) {
		$this->setParam("footer", $footerHtml);
		return $this;
	}

	public function topMargin($margin) {
		$this->setParam("margin_top", $margin);
		return $this;
	}

	public function leftMargin($margin) {
		$this->setParam("margin_left", $margin);
		return $this;
	}

	public function bottomMargin($margin) {
		$this->setParam("margin_bottom", $margin);
		return $this;
	}

	public function rightMargin($margin) {
		$this->setParam("margin_right", $margin);
		return $this;
	}

	public function andSendToBrowserAs($filename) {
		$this->setParam("filename", $filename);
		$signedPdfUrl = $this->getSignedPdfUrl();
		header("Location: {$signedPdfUrl}");
		exit();
	}

	public function setParam($key, $value) {
		$this->postParams[$key] = $value;
		return $this;
	}

	/**
	 * Delivers HTML to AWS and receives a URL to the rendered PDF
	 */
	private function getSignedPdfUrl() {
		$postBody = http_build_query($this->postParams);

		$date = new DateTime('UTC');
		$xAmzDate = $date->format('Ymd\THis\Z');
		$headers = array(
			'Content-Type: application/x-www-form-urlencoded; charset=utf-8',
			'Host: ' . PDF_API_GATEWAY_URL,
			'X-Amz-Date: ' . $xAmzDate,
		);
		$authorizationHeader = $this->getAuthorizationHeader($xAmzDate, $headers, $postBody);
		$headers[] = "Authorization: " . $authorizationHeader;
		$ch = curl_init();
		curl_setopt($ch, CURLOPT_URL, "https://" . PDF_API_GATEWAY_URL . "/" . PDF_API_GATEWAY_STAGE);
		curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
		curl_setopt($ch, CURLOPT_POST, count($this->postParams));
		curl_setopt($ch, CURLOPT_ENCODING, "gzip");
		curl_setopt($ch, CURLOPT_POSTFIELDS, $postBody); // the data to post
		curl_setopt($ch, CURLOPT_HEADER, 0); // dont include the header in the output
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // return the response as a string

		// curl_setopt($ch, CURLOPT_CAINFO, '/usr/share/ca-certificates/cacert.pem');
		if (defined('CURLOPT_IPRESOLVE') && defined('CURL_IPRESOLVE_V4')){
			curl_setopt(	$ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
		}

		$info = curl_getinfo($ch);

		$response = curl_exec($ch);

		$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		if ($httpCode !== 200) {
			throw new Exception('Failed to receive PDF file; remote server returned '.$httpCode.' status' . "\n\n" . $response);
		}
		return $response;
	}

	/**
	 * @see https://docs.aws.amazon.com/apigateway/api-reference/signing-requests/
	 */
	private function getAuthorizationHeader($xAmzDate, $headers, $postBody) {
		// Task 1: Create a Canonical Request for Signature Version 4
		$canonicalHeaders = "";
		foreach ($headers as $header) {
			$headerParts = explode(":", $header);
			$canonicalHeaders .= trim(strtolower($headerParts[0])) . ":" . trim($headerParts[1]) . "\n";
		}

		$signedHeaders = "content-type;host;x-amz-date";
		$canonicalRequest =
			"POST\n" .
			"/" . PDF_API_GATEWAY_STAGE . "\n" .
			"\n" .
			$canonicalHeaders . "\n" .
			$signedHeaders . "\n" .
			hash("sha256", $postBody);

		$hashedCanonicalRequest = hash("sha256", $canonicalRequest);

		// Task 2: Create a String to Sign for Signature Version 4
		$dateObj = new DateTime('UTC');
		$date = $dateObj->format('Ymd');

		$region = AWS_REGION;
		$service = "execute-api";
		$alg = "sha256";
		$credentialScope = "{$date}/{$region}/{$service}/aws4_request";

		$stringToSign =
			"AWS4-HMAC-SHA256\n" .
			$xAmzDate . "\n" .
			"{$credentialScope}\n" .
			$hashedCanonicalRequest;

		// Task 3: Calculate the Signature for AWS Signature Version 4
		$secretKey = PDF_SECRET_KEY;
		$kSecret = "AWS4" . $secretKey; // @todo update this with secret key
		$kDate = hash_hmac($alg, $date, $kSecret, true);
		$kRegion = hash_hmac($alg, $region, $kDate, true);
		$kService = hash_hmac($alg, $service, $kRegion, true );
		$kSigning = hash_hmac($alg, 'aws4_request', $kService, true);

		$signature = hash_hmac($alg, $stringToSign, $kSigning);

		// Task 4: Add the Signature to the HTTP Request
		// Using authorization header method
		$accessKey = PDF_ACCESS_KEY; // to update
		$authorizationHeader =
			'AWS4-HMAC-SHA256 ' .
			'Credential=' . $accessKey . '/' . $credentialScope . ', ' .
			'SignedHeaders=' . $signedHeaders . ', ' . 'Signature=' . $signature;

		return $authorizationHeader;
	}

	/**
	 * Private constructor called internally
	 */
	private function __construct() {}
}
	<?php
	/**
	* Makes a POST request to a Lambda function through an API Gateway
	* which encapsulates a call to wkhtmltopdf, rendering an HTML
	* document as a PDF file and returning a signed URL to the
	* file in an S3 bucket.
	*
	* The POST can contain the following parameters:
	* body - A complete HTML5 document to be rendered in PDF (required)
	* header - A complete HTML5 document to be rendered in the header of every page (optional)
	* footer - A complete HTML5 document to be rendered in the footer of every page (optional)
	* filename - The preferred filename for the rendered PDF document (optional)
	* If not provided it will be 'generated.pdf'
	* margin_left, margin_right, margin_top, margin_bottom - optional integer values, in mm
	*
	* Make sure the following definitions are added to a file outside version control:
	* define("AWS_REGION", "");
	* define("PDF_API_GATEWAY_URL", "********.execute-api.us-east-1.amazonaws.com");
	* define("PDF_API_GATEWAY_STAGE", "***"); // usually "prod"
	* define("PDF_ACCESS_KEY", "");
	* define("PDF_SECRET_KEY", "");
	*
	* Then call the generator with:
	*
	* GeneratePDF::fromHTML("<!doctype html><html>...</html>")
	* ->header("<!doctype html><html>...</html>")
	* ->footer("<!doctype html><html>...</html>")
	* ->leftMargin(0)
	* ->rightMargin(0)
	* ->andSendToBrowserAs("my-new-pdf-file.pdf"); // must be called, causes a redirect and exit
	*/

	class GeneratePDF {
	private static $instance;
	private $postParams = array();

	/**
	* Instantiate the class and set the required body POST parameter
	*/
	public static function fromHTML($bodyHtml) {
	if (!isset(static::$instance)) {
	static::$instance = new GeneratePDF_V2();
	}
	static::$instance->setParam("body", $bodyHtml);
	return static::$instance;
	}

	/**
	* Optionally put the PDF in a folder for the project
	* @param string $projectName This should follow appropriate standards for directory names
	*/
	public function projectName($projectName) {
	$this->setParam("project_name", $projectName);
	return $this;
	}

	public function header($headerHtml) {
	$this->setParam("header", $headerHtml);
	return $this;
	}

	public function footer($footerHtml) {
	$this->setParam("footer", $footerHtml);
	return $this;
	}

	public function topMargin($margin) {
	$this->setParam("margin_top", $margin);
	return $this;
	}

	public function leftMargin($margin) {
	$this->setParam("margin_left", $margin);
	return $this;
	}

	public function bottomMargin($margin) {
	$this->setParam("margin_bottom", $margin);
	return $this;
	}

	public function rightMargin($margin) {
	$this->setParam("margin_right", $margin);
	return $this;
	}

	public function andSendToBrowserAs($filename) {
	$this->setParam("filename", $filename);
	$signedPdfUrl = $this->getSignedPdfUrl();
	header("Location: {$signedPdfUrl}");
	exit();
	}

	public function setParam($key, $value) {
	$this->postParams[$key] = $value;
	return $this;
	}

	/**
	* Delivers HTML to AWS and receives a URL to the rendered PDF
	*/
	private function getSignedPdfUrl() {
	$postBody = http_build_query($this->postParams);

	$date = new DateTime('UTC');
	$xAmzDate = $date->format('Ymd\THis\Z');
	$headers = array(
	'Content-Type: application/x-www-form-urlencoded; charset=utf-8',
	'Host: ' . PDF_API_GATEWAY_URL,
	'X-Amz-Date: ' . $xAmzDate,
	);
	$authorizationHeader = $this->getAuthorizationHeader($xAmzDate, $headers, $postBody);
	$headers[] = "Authorization: " . $authorizationHeader;
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, "https://" . PDF_API_GATEWAY_URL . "/" . PDF_API_GATEWAY_STAGE);
	curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
	curl_setopt($ch, CURLOPT_POST, count($this->postParams));
	curl_setopt($ch, CURLOPT_ENCODING, "gzip");
	curl_setopt($ch, CURLOPT_POSTFIELDS, $postBody); // the data to post
	curl_setopt($ch, CURLOPT_HEADER, 0); // dont include the header in the output
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // return the response as a string

	// curl_setopt($ch, CURLOPT_CAINFO, '/usr/share/ca-certificates/cacert.pem');
	if (defined('CURLOPT_IPRESOLVE') && defined('CURL_IPRESOLVE_V4')){
	curl_setopt( $ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
	}

	$info = curl_getinfo($ch);

	$response = curl_exec($ch);

	$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
	if ($httpCode !== 200) {
	throw new Exception('Failed to receive PDF file; remote server returned '.$httpCode.' status' . "\n\n" . $response);
	}
	return $response;
	}

	/**
	* @see https://docs.aws.amazon.com/apigateway/api-reference/signing-requests/
	*/
	private function getAuthorizationHeader($xAmzDate, $headers, $postBody) {
	// Task 1: Create a Canonical Request for Signature Version 4
	$canonicalHeaders = "";
	foreach ($headers as $header) {
	$headerParts = explode(":", $header);
	$canonicalHeaders .= trim(strtolower($headerParts[0])) . ":" . trim($headerParts[1]) . "\n";
	}

	$signedHeaders = "content-type;host;x-amz-date";
	$canonicalRequest =
	"POST\n" .
	"/" . PDF_API_GATEWAY_STAGE . "\n" .
	"\n" .
	$canonicalHeaders . "\n" .
	$signedHeaders . "\n" .
	hash("sha256", $postBody);

	$hashedCanonicalRequest = hash("sha256", $canonicalRequest);

	// Task 2: Create a String to Sign for Signature Version 4
	$dateObj = new DateTime('UTC');
	$date = $dateObj->format('Ymd');

	$region = AWS_REGION;
	$service = "execute-api";
	$alg = "sha256";
	$credentialScope = "{$date}/{$region}/{$service}/aws4_request";

	$stringToSign =
	"AWS4-HMAC-SHA256\n" .
	$xAmzDate . "\n" .
	"{$credentialScope}\n" .
	$hashedCanonicalRequest;

	// Task 3: Calculate the Signature for AWS Signature Version 4
	$secretKey = PDF_SECRET_KEY;
	$kSecret = "AWS4" . $secretKey; // @todo update this with secret key
	$kDate = hash_hmac($alg, $date, $kSecret, true);
	$kRegion = hash_hmac($alg, $region, $kDate, true);
	$kService = hash_hmac($alg, $service, $kRegion, true );
	$kSigning = hash_hmac($alg, 'aws4_request', $kService, true);

	$signature = hash_hmac($alg, $stringToSign, $kSigning);

	// Task 4: Add the Signature to the HTTP Request
	// Using authorization header method
	$accessKey = PDF_ACCESS_KEY; // to update
	$authorizationHeader =
	'AWS4-HMAC-SHA256 ' .
	'Credential=' . $accessKey . '/' . $credentialScope . ', ' .
	'SignedHeaders=' . $signedHeaders . ', ' . 'Signature=' . $signature;

	return $authorizationHeader;
	}

	/**
	* Private constructor called internally
	*/
	private function __construct() {}
	}