Vivoldi Webhook API & HMAC Signature Verification

<?php
// Environment Settings
$globalSecretKey = $_ENV['VIVOLDI_WEBHOOK_SECRET'] ?? 'your-global-secret-key';

/**
 * Main Webhook Handler Function
 */
function handleWebhook($payload) {
    // Header Information Extraction
    $headers = array_change_key_case(getallheaders(), CASE_LOWER);
    $requestId = $headers['x-vivoldi-request-id'] ?? '';
    $eventId = $headers['x-vivoldi-event-id'] ?? '';
    $webhookType = $headers['x-vivoldi-webhook-type'] ?? '';
    $resourceType = $headers['x-vivoldi-resource-type'] ?? '';
    $actionType = $headers['x-vivoldi-action-type'] ?? '';
    $signature = $headers['x-vivoldi-signature'] ?? '';

    // Signature Verification
    if (!verifySignature($payload, $signature, $webhookType, $resourceType, $eventId)) {
        http_response_code(401);
        echo json_encode(['error' => 'Invalid signature']);
        return;
    }

    // Processing by Resource Type
    switch ($resourceType) {
        case 'URL':
            handleLink($payload);
            break;
        case 'COUPON':
            handleCoupon($payload);
            break;
        case 'STAMP':
            handleStamp($payload, $actionType);
            break;
        default:
            error_log('Unknown resourceType: ' . $resourceType);
    }

    http_response_code(200);
    echo json_encode(['status' => 'success']);
}

function sha256($data) {
    return hash('sha256', $data);
}

/**
 * HMAC-SHA256 Signature Verification Function
 */
function verifySignature($payload, $signature, $webhookType, $resourceType, $eventId) {
    try {
        $timestamp = null;
        $sig = null;
        foreach (explode(',', $signature) as $part) {
            $part = trim($part);
            if (strpos($part, 't=') === 0) $timestamp = substr($part, 2);
            if (strpos($part, 'v1=') === 0) $sig = substr($part, 3);
        }
        if (!$timestamp || !$sig || !$eventId) return false;

        // Timestamp tolerance (±5 minutes)
        // X-Vivoldi-Timestamp is in MILLISECONDS, so compare against time() * 1000.
        if (abs(time() * 1000 - (int)$timestamp) > 300000) {
            return false;
        }

        // Payload SHA256
        $payloadSha256 = sha256($payload);
        $signedPayload = $timestamp . '.' . $eventId . '.' . $payloadSha256;
        $secretKey = getSecretKey($webhookType, $resourceType, $payload);
        if (empty($secretKey)) return false;

        $computedSig = hash_hmac('sha256', $signedPayload, $secretKey);

        // Safety Comparison (lowercase throughout)
        return hash_equals(strtolower($sig), strtolower($computedSig));
    } catch (Exception $e) {
        error_log('Signature verification failed: ' . $e->getMessage());
        return false;
    }
}

/**
 * Secret Key Return Based on Webhook Type and Group
 */
function getSecretKey($webhookType, $resourceType, $payload) {
    global $globalSecretKey;

    if ($webhookType === 'GLOBAL') {
        return $globalSecretKey;
    }

    // Group-Specific Secret Key Configuration
    $jsonData = json_decode($payload, true);

    if ($resourceType === 'STAMP') {
        if (!isset($jsonData['cardIdx'])) {
            return '';
        }

        // Stamp cardIdx
        $cardIdx = $jsonData['cardIdx'];
        switch ($cardIdx) {
            case 617:
                return 'your stamp card secret key for 617';
            case 3304:
                return 'your stamp card secret key for 3304';
            default:
                return '';
        }
    } else {
        if (!isset($jsonData['grpIdx'])) {
            return '';
        }

        $grpIdx = $jsonData['grpIdx'];
        if ($resourceType === 'LINK') {
            // Link grpIdx
            switch ($grpIdx) {
                case 17584:
                    return 'your group secret key for 17584';
                case 9158:
                    return 'your group secret key for 9158';
                default:
                    return '';
            }
        } else {
            // Coupon grpIdx
            switch ($grpIdx) {
                case 3570:
                    return 'your group secret key for 3570';
                case 4178:
                    return 'your group secret key for 4178';
                default:
                    return '';
            }
        }
    }
}

/**
 * Link Event Handler Function
 */
function handleLink($payload) {
    error_log('Link clicked: ' . $payload);

    // Processing link information by parsing JSON
    $linkData = json_decode($payload, true);

    if ($linkData) {
        // Link Click Statistics Update
        $linkId = $linkData['linkId'] ?? '';
        $clickTime = $linkData['timestamp'] ?? time();
        $userAgent = $linkData['userAgent'] ?? '';

        // Storing click information in the database
        saveClickEvent($linkId, $clickTime, $userAgent);

        error_log("Link {$linkId} clicked at {$clickTime}");
    }
}

/**
 * Coupon Event Handling Function
 */
function handleCoupon($payload) {
    error_log('Coupon redeemed: ' . $payload);

    // Parsing JSON to process coupon information
    $couponData = json_decode($payload, true);

    if ($couponData) {
        // Coupon Usage Information Processing
        $couponCode = $couponData['couponCode'] ?? '';
        $redeemTime = $couponData['timestamp'] ?? time();
        $userId = $couponData['userId'] ?? '';

        // Storing coupon usage information in the database
        saveCouponRedemption($couponCode, $userId, $redeemTime);

        error_log("Coupon {$couponCode} redeemed by user {$userId}");
    }
}

/**
 * Stamp Event Handling Function
 */
function handleStamp($payload, $actionType) {
    error_log('Stamp payload: ' . $payload);

    // Parsing JSON to process coupon information
    $stampData = json_decode($payload, true);

    if ($stampData) {
        $stampIdx = $stampData['stampIdx'] ?? 0;
        switch ($actionType) {
            case "ADD":
                // Stamp added
                break;
            case "REMOVE":
                // Stamp removed
                break;
            case "USE":
                // Stamp benefit used
                break;
            default:
                return '';
        }
    }
}

/**
 * Store click events in the database
 */
function saveClickEvent($linkId, $clickTime, $userAgent) {
    // Implementation of actual database integration logic
    // Example: Stored in MySQL, PostgreSQL, etc.

    error_log("Saving click event - Link: {$linkId}, Time: {$clickTime}");
}

/**
 * Store coupon usage information in the database
 */
function saveCouponRedemption($couponCode, $userId, $redeemTime) {
    // Implementation of actual database integration logic
    // Example: Updating coupon status, storing usage history, etc.

    error_log("Saving coupon redemption - Code: {$couponCode}, User: {$userId}");
}

/**
 * Log recording function
 */
function logWebhookEvent($eventType, $data) {
    $timestamp = date('Y-m-d H:i:s');
    $logMessage = "[{$timestamp}] {$eventType}: " . json_encode($data);
    error_log($logMessage);
}

// ===========================================
// Webhook Endpoint Execution Unit
// ===========================================

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $payload = file_get_contents('php://input');
    handleWebhook($payload);
} else {
    http_response_code(405);
    echo json_encode(['error' => 'Method not allowed']);
}
?>

const express = require('express');
const crypto = require('crypto');
const app = express();

// Environment Settings
const globalSecretKey = process.env.VIVOLDI_WEBHOOK_SECRET || 'your-global-secret-key';

// Form data parser for webhook payloads
app.use(express.raw({ type: '*/*' }));

/**
 * Main Webhook Handler Function
 */
function handleWebhook(headers, res, payload) {
    const requestId = headers['x-vivoldi-request-id'] || '';
    const eventId = headers['x-vivoldi-event-id'] || '';
    const webhookType = headers['x-vivoldi-webhook-type'] || '';
    const resourceType = headers['x-vivoldi-resource-type'] || '';
    const actionType = headers['x-vivoldi-action-type'] || '';
    const signature = headers['x-vivoldi-signature'] || '';

    // Signature Verification
    if (!verifySignature(payload, signature, webhookType, resourceType, eventId)) {
        res.status(401).json({ error: 'Invalid signature' });
        return;
    }

    // Processing by Resource Type
    switch (resourceType) {
        case 'URL':
            handleLink(payload);
            break;
        case 'COUPON':
            handleCoupon(payload);
            break;
        case 'STAMP':
            handleStamp(payload);
            break;
        default:
            console.error('Unknown resourceType: ' + resourceType);
    }

    res.status(200).json({ status: 'success' });
}

/**
 * SHA256(hex)
 */
function sha256Hex(data) {
    return crypto.createHash('sha256').update(data, 'utf8').digest('hex');
}

/**
 * HMAC-SHA256 Signature Verification Function
 */
function verifySignature(payload, signature, webhookType, resourceType, eventId) {
    try {
        let timestamp, sig;
        for (const part of signature.split(',')) {
            const p = part.trim();
            if (p.startsWith('t=')) timestamp = p.slice(2);
            if (p.startsWith('v1=')) sig = p.slice(3);
        }
        if (!timestamp || !sig || !eventId) return false;

        // Timestamp tolerance (±5 minutes)
        // X-Vivoldi-Timestamp is in MILLISECONDS, so compare against Date.now() directly.
        if (Math.abs(Date.now() - Number(timestamp)) > 300000) return false;

        const signedPayload = `${timestamp}.${eventId}.${sha256Hex(payload)}`;

        // Secret Key Determination
        const secretKey = getSecretKey(webhookType, resourceType, payload);
        if (!secretKey) return false;

        // HMAC-SHA256 Signature Calculation
        const computedSig = crypto
            .createHmac('sha256', secretKey)
            .update(signedPayload)
            .digest('hex');

        // Timing-Safe Comparison
        return crypto.timingSafeEqual(
            Buffer.from(sig.toLowerCase(), 'hex'),
            Buffer.from(computedSig.toLowerCase(), 'hex')
        );
    } catch (e) {
        console.error('Signature verification failed: ' + e.message);
        return false;
    }
}

/**
 * Secret Key Return Based on Webhook Type and Group
 */
function getSecretKey(webhookType, resourceType, payload) {
    if (webhookType === 'GLOBAL') {
        return globalSecretKey;
    }

    // Group-Specific Secret Key Configuration
    let jsonData;
    try {
        jsonData = JSON.parse(payload);
    } catch (error) {
        return '';
    }

    if (resourceType === 'STAMP') {
        if (!jsonData.cardIdx) {
            return '';
        }

        const cardIdx = jsonData.cardIdx;
        switch (cardIdx) {
            case 3570:
                return 'your stamp card secret key for 3570';
            case 4178:
                return 'your stamp card secret key for 4178';
            default:
                return '';
        }
    } else {
        if (!jsonData.grpIdx) {
            return '';
        }

        const grpIdx = jsonData.grpIdx;
        if (resourceType === 'LINK') {
            // Link grpIdx
            switch (grpIdx) {
                case 17584:
                    return 'your group secret key for 17584';
                case 9158:
                    return 'your group secret key for 9158';
                default:
                    return '';
            }
        } else {
            // Coupon grpIdx
            switch (grpIdx) {
                case 6350:
                    return 'your group secret key for 6350';
                case 17884:
                    return 'your group secret key for 17884';
                default:
                    return '';
            }
        }
    }
}

/**
 * Link Event Handler Function
 */
function handleLink(payload) {
    console.error('Link clicked: ' + payload);

    // Processing link information by parsing JSON
    let linkData;
    try {
        linkData = JSON.parse(payload);
    } catch (error) {
        return;
    }

    if (linkData) {
        // Link Click Statistics Update
        const linkId = linkData.linkId || '';
        const clickTime = linkData.timestamp || Math.floor(Date.now() / 1000);
        const userAgent = linkData.userAgent || '';

        // Storing click information in the database
        saveClickEvent(linkId, clickTime, userAgent);

        console.error(`Link ${linkId} clicked at ${clickTime}`);
    }
}

/**
 * Coupon Event Handling Function
 */
function handleCoupon(payload) {
    console.error('Coupon redeemed: ' + payload);

    // Parsing JSON to process coupon information
    let couponData;
    try {
        couponData = JSON.parse(payload);
    } catch (error) {
        return;
    }

    if (couponData) {
        // Coupon Usage Information Processing
        const couponCode = couponData.couponCode || '';
        const redeemTime = couponData.timestamp || Math.floor(Date.now() / 1000);
        const userId = couponData.userId || '';

        // Storing coupon usage information in the database
        saveCouponRedemption(couponCode, userId, redeemTime);

        console.error(`Coupon ${couponCode} redeemed by user ${userId}`);
    }
}

/**
 * Stamp Event Handling Function
 */
function handleStamp(payload, actionType) {
    console.error('Stamp payload: ' + payload);

    // Parsing JSON to process coupon information
    let stampData;
    try {
        stampData = JSON.parse(payload);
    } catch (error) {
        return;
    }

    if (stampData) {
        const stampIdx = stampData.stampIdx || 0;
        switch (actionType) {
            case "ADD":
                // Stamp added
                break;
            case "REMOVE":
                // Stamp removed
                break;
            case "USE":
                // Stamp benefit used
                break;
        }
    }
}

/**
 * Store click events in the database
 */
function saveClickEvent(linkId, clickTime, userAgent) {
    // Implementation of actual database integration logic
    // Example: Stored in MongoDB, MySQL, PostgreSQL, etc.

    console.error(`Saving click event - Link: ${linkId}, Time: ${clickTime}`);
}

/**
 * Store coupon usage information in the database
 */
function saveCouponRedemption(couponCode, userId, redeemTime) {
    // Implementation of actual database integration logic
    // Example: Updating coupon status, storing usage history, etc.

    console.error(`Saving coupon redemption - Code: ${couponCode}, User: ${userId}`);
}

/**
 * Log recording function
 */
function logWebhookEvent(eventType, data) {
    const timestamp = new Date().toISOString().replace('T', ' ').substring(0, 19);
    const logMessage = `[${timestamp}] ${eventType}: ${JSON.stringify(data)}`;
    console.error(logMessage);
}

// ===========================================
// Webhook Endpoint Execution Unit
// ===========================================

app.post('/webhook/vivoldi', (req, res) => {
    const payload = req.body.toString('utf8');
    const headers = req.headers;

    if (!verifySignature(payload, headers['x-vivoldi-signature'], headers['x-vivoldi-webhook-type'], headers['x-vivoldi-event-id'])) {
        return res.status(401).json({ error: 'Invalid signature' });
    }

    handleWebhook(req.headers, res, payload);
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
    console.log(`Webhook server running on port ${PORT}`);
});