<?Php

/*
 * File: PromptPayQR.php
 * Created on: 31/08/2017
 * Last update: 31/08/2017
 * Name: Sonthaya Nongnuch <max30012540@hotmail.com> 
 * Copyright: CC-BY-4.0
 * 
 * -------------------------------------------------------
 *  Thank for think : https://www.blognone.com/node/95133
 * -------------------------------------------------------
 */
 
require_once('qrlib.php');

class PromptPayQR {
	public $size = 4;
	public $id = '';
	public $amount = 0;
	
	public function generate($file=false) {
	
		// format [Fee][Length][Data]
		$data =  '000201'; // Start
		$data .= '010212'; // accept recycle
		$data .= '3074'; //
		$data .= '0016A000000677010112';
		$data .= '0115010753700001716';
		$data .= '0217ABCD';
		$data .= '3640600111689';
		$data .= '03';
		$merchantInfo1 = '0001TP10SAT';
		$data .= strlen($merchantInfo1) . $merchantInfo1;
		
		// merchant account information
		$merchantInfo =  '0016A000000677010112'; // application ID  AID(fix)
		$merchantInfo .=  '0115010753700001716';
		
		// PromptPay ID
		$merchantInfo .= '01';
		if (strlen($this->id) == 13) { // ID card
			$merchantInfo .= '1500' . $this->id;
		} else if (strlen($this->id) == 10) {
			$merchantInfo .= '130066' . substr($this->id, -9);
		} else {
			return false;
		}
		
		$data .= '29' . strlen($merchantInfo) . $merchantInfo; // set merchant account information
		$data .= '5802TH'; // Thai baht
		
		// amount
		if ($this->amount > 0) {
			$amountText = number_format($this->amount, 2, '.', '');
			$amountLen = strlen($amountText);
			$data .= '54' . ($amountLen < 10 ? '0' . $amountLen : $amountLen) . $amountText;
		}
		
		$data .= '5303764'; // 764 is thai baht in ISO4217
		
		// check sum
		$data .= '6304';
		$sum = strtoupper(dechex($this->crc16($data)));
		$data .= $sum;
		
		$file = $file === false ? 'TMP_FILE_QRCODE_PROMPTPAY.png' : $file;
		
		QRcode::png($data, $file, QR_ECLEVEL_H, $this->size, 2);
		if ($file == 'TMP_FILE_QRCODE_PROMPTPAY.png') {
			return file_exists($file) ? 'data:image/png;base64,' . base64_encode(file_get_contents($file)) : false;
		}
		
		return $data;
	}
	
	/*
	 * crc16 function from https://stackoverflow.com/questions/14018508/how-to-calculate-crc16-in-php
	 * RomKazanova, thank for code.
	 */
	private function crc16($data) {
		$crc = 0xFFFF;
		for ($i = 0; $i < strlen($data); $i++) {
			$x = (($crc >> 8) ^ ord($data[$i])) & 0xFF;
			$x ^= $x >> 4;
			$crc = (($crc << 8) ^ ($x << 12) ^ ($x << 5) ^ $x) & 0xFFFF;
		}
		return $crc;
	}
}