<?php
header('Content-Type: application/json');
require_once __DIR__ . '/../db/config.php';

$input = json_decode(file_get_contents('php://input'), true);
$message = $input['message'] ?? '';

if (empty($message)) {
    echo json_encode(['reply' => "I didn't catch that. Could you repeat?"]);
    exit;
}

$faqs = db()->query("SELECT keywords, answer FROM faqs")->fetchAll();

$bestMatch = null;
$maxOverlap = 0;

$userWords = preg_split('/\W+/', strtolower($message), -1, PREG_SPLIT_NO_EMPTY);

foreach ($faqs as $faq) {
    $keywords = preg_split('/[\s,]+/', strtolower($faq['keywords']), -1, PREG_SPLIT_NO_EMPTY);
    $overlap = count(array_intersect($userWords, $keywords));
    
    if ($overlap > $maxOverlap) {
        $maxOverlap = $overlap;
        $bestMatch = $faq['answer'];
    }
}

if ($bestMatch) {
    echo json_encode(['reply' => $bestMatch]);
} else {
    // Default fallback
    echo json_encode(['reply' => "I'm sorry, I don't have an answer for that yet. You can try asking about 'pricing' or 'support'."]);
}