<?php
header('Content-Type: application/json');

$tokensFile = __DIR__ . '/door_tokens.json';
$tokens = [];

// Read existing tokens
if (file_exists($tokensFile)) {
    $content = file_get_contents($tokensFile);
    if ($content) {
        $tokens = json_decode($content, true) ?: [];
    }
}

// Cleanup expired tokens (> 5 minutes old)
$currentTime = time();
$activeTokens = [];
foreach ($tokens as $token => $data) {
    if (($currentTime - $data['created_at']) <= 300) { // 5 minutes
        if (!isset($data['used']) || !$data['used']) {
            $activeTokens[$token] = $data;
        }
    }
}

// Generate new random token
$newToken = bin2hex(random_bytes(16)); // 32 hex chars

$activeTokens[$newToken] = [
    'created_at' => $currentTime,
    'used' => false
];

// Save back
file_put_contents($tokensFile, json_decode('{}')); // clear out file first securely?
file_put_contents($tokensFile, json_encode($activeTokens, JSON_PRETTY_PRINT));

echo json_encode([
    'status' => 'success',
    'token'  => $newToken,
    'expires_in' => 300 
]);
?>