<?php
function encrypt_e_openssl($input, $ky){
    $iv = "@@@@&&&&####$$$$";
    $data = openssl_encrypt ( $input , "AES-128-CBC" , $ky, 0, $iv );
    return $data;
}

function decrypt_e_openssl($crypt, $ky){
    $iv = "@@@@&&&&####$$$$";
    $data = openssl_decrypt ( $crypt , "AES-128-CBC" , $ky, 0, $iv );
    return $data;
}

function generateSalt_e($length) {
    $random = "";
    srand((double) microtime() * 1000000);

    $data = "AbcDE123IJKLMN67QRSTUVWXYZ";
    $data .= "aBCdefghijklmn123opq45rs67tuv89wxyz";
    $data .= "0FGH45OP89";

    for ($i = 0; $i < $length; $i++) {
        $random .= substr($data, (rand() % (strlen($data))), 1);
    }

    return $random;
}

function checkString_e($value) {
    $myvalue = ltrim($value);
    $myvalue = rtrim($myvalue);
    if (in_array($myvalue, ['null', 'NULL'])) {
        $myvalue = '';
    }
    return $myvalue;
}

function getChecksumFromArray($arrayList, $key, $sort=1) {
    if ($sort != 0) {
        ksort($arrayList);
    }
    $str = getArray2Str($arrayList);
    $salt = generateSalt_e(4);
    $finalString = $str . "|" . $salt;
    $hash = hash("sha256", $finalString);
    $hashString = $hash . $salt;
    $checksum = encrypt_e_openssl($hashString, $key);

    return $checksum;
}
function getChecksumFromString($str, $key) {

    $salt = generateSalt_e(4);
    $finalString = $str . "|" . $salt;
    $hash = hash("sha256", $finalString);
    $hashString = $hash . $salt;
    $checksum = encrypt_e_openssl($hashString, $key);
    return $checksum;
}

function verifychecksum_e($arrayList, $key, $checksumvalue) {
    $arrayList = removeCheckSumParam($arrayList);
    ksort($arrayList);
    $str = getArray2Str($arrayList);
    $paytm_hash = decrypt_e_openssl($checksumvalue, $key);
    $salt = substr($paytm_hash, -4);

    $finalString = $str . "|" . $salt;

    $website_hash = hash("sha256", $finalString);
    $website_hash .= $salt;

    $validFlag = "FALSE";
    if ($website_hash == $paytm_hash) {
        $validFlag = "TRUE";
    } else {
        $validFlag = "FALSE";
    }
    return $validFlag;
}

function verifychecksum_eFromStr($str, $key, $checksumvalue) {
    $paytm_hash = decrypt_e_openssl($checksumvalue, $key);
    $salt = substr($paytm_hash, -4);

    $finalString = $str . "|" . $salt;

    $website_hash = hash("sha256", $finalString);
    $website_hash .= $salt;

    $validFlag = "FALSE";
    if ($website_hash == $paytm_hash) {
        $validFlag = "TRUE";
    } else {
        $validFlag = "FALSE";
    }
    return $validFlag;
}

function getArray2Str($arrayList) {
    $paramStr = "";
    $flag = 1;
    foreach ($arrayList as $key => $value) {
        if ($flag) {
            $paramStr .= checkString_e($value);
            $flag = 0;
        } else {
            $paramStr .= "|" . checkString_e($value);
        }
    }
    return $paramStr;
}

function redirect2PG($paramList, $key) {
    $hashString = getchecksumFromArray($paramList);
    $checksum = encrypt_e_openssl($hashString, $key);
}

function removeCheckSumParam($arrayList) {
    if (isset($arrayList["CHECKSUMHASH"])) {
        unset($arrayList["CHECKSUMHASH"]);
    }
    return $arrayList;
}

function getTxnStatus($requestParamList) {
    return callAPI(PAYTM_STATUS_QUERY_URL, $requestParamList);
}

function initiateTxnRefund($requestParamList) {
    $CHECKSUM = getChecksumFromArray($requestParamList,PAYTM_MERCHANT_KEY,0);
    $requestParamList["CHECKSUM"] = $CHECKSUM;
    return callAPI(PAYTM_REFUND_URL, $requestParamList);
}

function callAPI($apiURL, $requestParamList) {
    $jsonResponse = "";
    $responseParamList = array();
    $JsonData =json_encode($requestParamList);
    $postData = 'JsonData='.urlencode($JsonData);
    $ch = curl_init($apiURL);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0);
    curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'Content-Type: application/json',
            'Content-Length: ' . strlen($postData))
    );
    $jsonResponse = curl_exec($ch);
    $responseParamList = json_decode($jsonResponse,true);
    return $responseParamList;
}