<?php

require_once __DIR__ . '/../includes/config.php';
require_once __DIR__ . '/../includes/functions.php';
require_once __DIR__ . '/../includes/jsondb.php';
require_once __DIR__ . '/../includes/srs.php';
require_once __DIR__ . '/../includes/auth.php';

requireLogin();

header('Content-Type: application/json; charset=utf-8');

$user = $_SESSION['user'];

$input = json_decode(file_get_contents('php://input'), true);

if (!is_array($input)) {
    echo json_encode(['error' => 'invalid_json']);
    exit;
}

$lang = $input['lang'] ?? '';
$list = $input['list'] ?? '';
$wordId = (int)($input['wordId'] ?? 0);
$userAnswer = trim($input['answer'] ?? '');

$file = listPath($user, $lang, $list);
$data = JsonDB::read($file);

if (!isset($data['words']) || !is_array($data['words'])) {
    echo json_encode(['error' => 'list_not_found']);
    exit;
}

$correct = false;
$updatedWord = null;

/**
 * SESSION STATS INIT
 */
if (!isset($_SESSION['session_stats'])) {
    $_SESSION['session_stats'] = [
        'correct' => 0,
        'wrong' => 0
    ];
}

foreach ($data['words'] as $i => $word) {

    if ((int)$word['id'] === $wordId) {

        // normalize
        $expected = strtolower(trim($data['words'][$i]['answer']));
        $given = strtolower(trim($userAnswer));

        $correct = ($expected === $given);

        /**
         * ❗ SESSIE STATS (DIT IS WAT JE WIL)
         */
        if ($correct) {
            $_SESSION['session_stats']['correct']++;
        } else {
            $_SESSION['session_stats']['wrong']++;
        }

        /**
         * SRS UPDATE (blijft op woordniveau)
         */
        updateWordStats($data['words'][$i], $correct);

        $updatedWord = $data['words'][$i];

        break;
    }
}

if ($updatedWord === null) {
    echo json_encode([
        'error' => 'word_not_found',
        'wordId' => $wordId
    ]);
    exit;
}

$ok = JsonDB::write($file, $data);

if (!$ok) {
    echo json_encode(['error' => 'write_failed']);
    exit;
}

echo json_encode([
    'correct' => $correct,

    /**
     * UI FEEDBACK (SESSIE)
     */
    'session' => $_SESSION['session_stats'],

    /**
     * DEBUG (optioneel)
     */
    'debug' => [
        'wordId' => $wordId
    ]
]);