<?php
/**
 * Survey Proxy Handler
 * URL: https://relevantreflex.com/s/{encoded_string}
 * Decodes the string and redirects to client survey URL
 * Marks URL as "clicked" when first accessed
 * 
 * Status flow:
 *   available → clicked (on proxy click) → final status (from /r/ handler)
 *   'sent' is reserved for mailer automation dispatch only
 */

error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);

// Load client session for database connection
require_once __DIR__ . '/../clients/client-session.php';

// Get the encoded string from URL
$request_uri = $_SERVER['REQUEST_URI'];
$path = parse_url($request_uri, PHP_URL_PATH);
$parts = explode('/', trim($path, '/'));

// Expected: ['s', encoded_string]
if (count($parts) < 2 || $parts[0] !== 's') {
    header('HTTP/1.0 404 Not Found');
    echo "Invalid survey URL";
    exit;
}

$encoded = $parts[1];

try {
    // Make it base64-safe (reverse the URL-safe encoding)
    $encoded = strtr($encoded, '-_', '+/');
    $padding = strlen($encoded) % 4;
    if ($padding) {
        $encoded .= str_repeat('=', 4 - $padding);
    }
    
    // Decode
    $decoded = base64_decode($encoded, true);
    
    if ($decoded === false) {
        throw new Exception("Invalid encoded string");
    }
    
    // Extract project_id and unique_id
    if (strpos($decoded, '|') === false) {
        throw new Exception("Invalid URL format");
    }
    
    list($project_id, $unique_id) = explode('|', $decoded, 2);
    
    // Get database connection
    $pdo = getClientDBConnection();
    
    // Look up the client URL
    $stmt = $pdo->prepare("
        SELECT id, client_url, status
        FROM survey_urls 
        WHERE project_id = ? 
        AND unique_identifier = ?
        LIMIT 1
    ");
    $stmt->execute([$project_id, $unique_id]);
    $result = $stmt->fetch(PDO::FETCH_ASSOC);
    
    if (!$result) {
        header('HTTP/1.0 404 Not Found');
        echo "Survey URL not found or expired";
        exit;
    }
    
    // Mark as clicked if still available or sent (sent = dispatched by mailer but not yet clicked)
    if (in_array($result['status'], ['available', 'sent'])) {
        $stmt = $pdo->prepare("
            UPDATE survey_urls 
            SET status = 'clicked',
                clicked_at = NOW()
            WHERE id = ?
        ");
        $stmt->execute([$result['id']]);
    }
    
    // Log the click
    error_log("Survey URL clicked: Project=$project_id, UniqueID=$unique_id, PrevStatus={$result['status']}");
    
    // Redirect to client survey URL
    header('Location: ' . $result['client_url']);
    exit;
    
} catch (Exception $e) {
    error_log("Survey proxy error: " . $e->getMessage() . " | Encoded: " . $encoded);
    header('HTTP/1.0 500 Internal Server Error');
    echo "Error loading survey. Please contact support.";
    exit;
}
?>