<?php
// /var/www/html/qdb/change_password.php
require_once __DIR__ . '/common.php';
header('Content-Type: application/json; charset=UTF-8');

// dieselben Defaults wie in login.php
$USERS_DEFAULT = [
    'user01' => 'pw1',
    'user02' => 'pw2',
    'Tmp_Daniel' => 'dummy4',
    'Tmp_Johanna' => 'dummy1',
    'Tmp_Anke' => 'dummy2',
    'Tmp_Liliana' => 'dummy3',
    'Amy_tmp' => 'dummy4',
    'Brigitte_tmp' => 'dummy5',
    'Extra1_tmp' => 'dummy6',
    'Extra2_tmp' => 'dummy7',
    'Danny' => 'pw1',
    'User1' => 'pw1',
    'User2' => 'pw2',
    'User3' => 'pw3',
    'User4' => 'pw4',
    'User5' => 'pw5',
    'User6' => 'pw6',
    'User7' => 'pw7',
    'User8' => 'pw8',
    'User9' => 'pw9',
    'User10' => 'pw10',
    'User11' => 'pw11'
];

$STORE_FILE = __DIR__ . '/users.json';

function load_store($path) {
    if (!file_exists($path)) return [];
    $txt = file_get_contents($path);
    $arr = json_decode($txt, true);
    return is_array($arr) ? $arr : [];
}
function save_store($path, $data) {
    file_put_contents($path, json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
}

$raw = file_get_contents("php://input");
$in = json_decode($raw, true) ?: [];

$username    = trim($in['username'] ?? '');
$oldPassword = (string)($in['old_password'] ?? '');
$newPassword = (string)($in['new_password'] ?? '');

if ($username === '' || $oldPassword === '' || $newPassword === '') {
    http_response_code(400);
    echo json_encode(["success" => false, "message" => "Felder fehlen"]);
    exit;
}
if (strlen($newPassword) < 6) {
    http_response_code(400);
    echo json_encode(["success" => false, "message" => "Neues Passwort zu kurz (min. 6 Zeichen)."]);
    exit;
}

$store = load_store($STORE_FILE);

// Fall A: User hat schon Hash -> altes Passwort gegen Hash prüfen
if (array_key_exists($username, $store) && isset($store[$username]['hash'])) {
    $hash = (string)$store[$username]['hash'];
    if (!password_verify($oldPassword, $hash)) {
        http_response_code(401);
        echo json_encode(["success" => false, "message" => "Altes Passwort falsch."]);
        exit;
    }
} else {
    // Fall B: User hat noch keinen Hash -> gegen Default prüfen
    if (!array_key_exists($username, $USERS_DEFAULT) || $USERS_DEFAULT[$username] !== $oldPassword) {
        http_response_code(401);
        echo json_encode(["success" => false, "message" => "Altes Passwort falsch."]);
        exit;
    }
}

// neuen Hash setzen (bcrypt)
$store[$username] = [
    "hash" => password_hash($newPassword, PASSWORD_DEFAULT),
    "changedAt" => time()
];
save_store($STORE_FILE, $store);

// Nach erfolgreichem Wechsel direkt einloggen (Token erstellen)
$token = bin2hex(random_bytes(32));
token_add($token, 30 * 24 * 60 * 60);

echo json_encode([
    "success" => true,
    "message" => "Passwort geändert.",
    "token"   => $token,
    "user"    => $username
]);