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

define('DATA_DIR', __DIR__ . '/data');
define('DATA_FILE', DATA_DIR . '/customers.json');
define('USERS_FILE', DATA_DIR . '/users.json');
define('CHANGELOG_FILE', DATA_DIR . '/changelog.json');
define('ARCHIVE_FILE', DATA_DIR . '/archive.json');

// Varmista data-kansio ja tiedostot
if (!file_exists(DATA_DIR)) mkdir(DATA_DIR, 0755, true);
foreach ([DATA_FILE, USERS_FILE, CHANGELOG_FILE, ARCHIVE_FILE] as $f) {
    if (!file_exists($f)) file_put_contents($f, '[]');
}

// Luo oletuskäyttäjä jos users.json on tyhjä
initUsers();

$method = $_SERVER['REQUEST_METHOD'];
$action = $_GET['action'] ?? '';

// ==================== HELPERS ====================

function requireAuth() {
    if (!isset($_SESSION['user_id'])) {
        http_response_code(401);
        echo json_encode(['error' => 'Kirjaudu sisään']);
        exit;
    }
}

function requireAdmin() {
    requireAuth();
    if (($_SESSION['role'] ?? '') !== 'admin') {
        http_response_code(403);
        echo json_encode(['error' => 'Vain ylläpitäjä voi tehdä tämän']);
        exit;
    }
}

function currentUser(): string {
    return $_SESSION['username'] ?? 'tuntematon';
}

function generateId(): string {
    return bin2hex(random_bytes(8));
}

// ==================== USERS ====================

function initUsers(): void {
    $users = json_decode(file_get_contents(USERS_FILE), true) ?: [];
    if (empty($users)) {
        $users[] = [
            'id' => generateId(),
            'username' => 'admin',
            'password_hash' => password_hash('cuitunet2024', PASSWORD_DEFAULT),
            'nimi' => 'Ylläpitäjä',
            'role' => 'admin',
            'luotu' => date('Y-m-d H:i:s'),
        ];
        file_put_contents(USERS_FILE, json_encode($users, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
    }
}

function loadUsers(): array {
    return json_decode(file_get_contents(USERS_FILE), true) ?: [];
}

function saveUsers(array $users): void {
    file_put_contents(USERS_FILE, json_encode($users, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}

// ==================== CHANGELOG ====================

function addLog(string $action, string $customerId = '', string $customerName = '', string $details = ''): void {
    $log = json_decode(file_get_contents(CHANGELOG_FILE), true) ?: [];
    array_unshift($log, [
        'id' => generateId(),
        'timestamp' => date('Y-m-d H:i:s'),
        'user' => currentUser(),
        'action' => $action,
        'customer_id' => $customerId,
        'customer_name' => $customerName,
        'details' => $details,
    ]);
    // Säilytä max 500 lokimerkintää
    if (count($log) > 500) $log = array_slice($log, 0, 500);
    file_put_contents(CHANGELOG_FILE, json_encode($log, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}

// ==================== CUSTOMERS ====================

function loadCustomers(): array {
    $data = file_get_contents(DATA_FILE);
    $customers = json_decode($data, true) ?: [];
    $migrated = false;
    foreach ($customers as &$c) {
        if (!isset($c['liittymat'])) {
            $c['liittymat'] = [[
                'asennusosoite' => $c['asennusosoite'] ?? '',
                'postinumero' => $c['postinumero'] ?? '',
                'kaupunki' => $c['kaupunki'] ?? '',
                'liittymanopeus' => $c['liittymanopeus'] ?? '',
                'hinta' => floatval($c['hinta'] ?? 0),
                'sopimuskausi' => '',
                'alkupvm' => '',
            ]];
            unset($c['asennusosoite'], $c['postinumero'], $c['kaupunki'], $c['liittymanopeus'], $c['hinta']);
            $migrated = true;
        }
    }
    unset($c);
    if ($migrated) {
        file_put_contents(DATA_FILE, json_encode($customers, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
    }
    return $customers;
}

function saveCustomers(array $customers): void {
    if (file_exists(DATA_FILE) && filesize(DATA_FILE) > 2) {
        $backupDir = DATA_DIR . '/backups';
        if (!file_exists($backupDir)) mkdir($backupDir, 0755, true);
        copy(DATA_FILE, $backupDir . '/customers_' . date('Y-m-d_His') . '.json');
        $backups = glob($backupDir . '/customers_*.json');
        if (count($backups) > 30) {
            sort($backups);
            array_map('unlink', array_slice($backups, 0, count($backups) - 30));
        }
    }
    file_put_contents(DATA_FILE, json_encode($customers, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}

// ==================== ARCHIVE ====================

function loadArchive(): array {
    return json_decode(file_get_contents(ARCHIVE_FILE), true) ?: [];
}

function saveArchive(array $archive): void {
    file_put_contents(ARCHIVE_FILE, json_encode($archive, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
}

function parseLiittymat(array $input): array {
    $liittymat = [];
    foreach (($input['liittymat'] ?? []) as $l) {
        $liittymat[] = [
            'asennusosoite' => trim($l['asennusosoite'] ?? ''),
            'postinumero' => trim($l['postinumero'] ?? ''),
            'kaupunki' => trim($l['kaupunki'] ?? ''),
            'liittymanopeus' => trim($l['liittymanopeus'] ?? ''),
            'hinta' => floatval($l['hinta'] ?? 0),
            'sopimuskausi' => trim($l['sopimuskausi'] ?? ''),
            'alkupvm' => trim($l['alkupvm'] ?? ''),
        ];
    }
    if (empty($liittymat)) {
        $liittymat[] = ['asennusosoite' => '', 'postinumero' => '', 'kaupunki' => '', 'liittymanopeus' => '', 'hinta' => 0, 'sopimuskausi' => '', 'alkupvm' => ''];
    }
    return $liittymat;
}

// ==================== ROUTES ====================

switch ($action) {

    // ---------- AUTH ----------
    case 'login':
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $username = trim($input['username'] ?? '');
        $password = $input['password'] ?? '';
        $users = loadUsers();
        $found = false;
        foreach ($users as $u) {
            if ($u['username'] === $username && password_verify($password, $u['password_hash'])) {
                $_SESSION['user_id'] = $u['id'];
                $_SESSION['username'] = $u['username'];
                $_SESSION['nimi'] = $u['nimi'];
                $_SESSION['role'] = $u['role'];
                echo json_encode(['success' => true, 'username' => $u['username'], 'nimi' => $u['nimi'], 'role' => $u['role']]);
                $found = true;
                break;
            }
        }
        if (!$found) {
            http_response_code(401);
            echo json_encode(['error' => 'Väärä käyttäjätunnus tai salasana']);
        }
        break;

    case 'logout':
        session_destroy();
        echo json_encode(['success' => true]);
        break;

    case 'check_auth':
        if (isset($_SESSION['user_id'])) {
            echo json_encode([
                'authenticated' => true,
                'username' => $_SESSION['username'],
                'nimi' => $_SESSION['nimi'],
                'role' => $_SESSION['role'],
            ]);
        } else {
            echo json_encode(['authenticated' => false]);
        }
        break;

    // ---------- USERS ----------
    case 'users':
        requireAdmin();
        $users = loadUsers();
        // Älä palauta salasanoja
        $safe = array_map(function($u) {
            unset($u['password_hash']);
            return $u;
        }, $users);
        echo json_encode(array_values($safe));
        break;

    case 'user_create':
        requireAdmin();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $username = trim($input['username'] ?? '');
        $password = $input['password'] ?? '';
        $nimi = trim($input['nimi'] ?? '');
        $role = ($input['role'] ?? 'user') === 'admin' ? 'admin' : 'user';
        if (empty($username) || empty($password)) {
            http_response_code(400);
            echo json_encode(['error' => 'Käyttäjätunnus ja salasana vaaditaan']);
            break;
        }
        if (strlen($password) < 4) {
            http_response_code(400);
            echo json_encode(['error' => 'Salasanan pitää olla vähintään 4 merkkiä']);
            break;
        }
        $users = loadUsers();
        foreach ($users as $u) {
            if ($u['username'] === $username) {
                http_response_code(400);
                echo json_encode(['error' => 'Käyttäjätunnus on jo käytössä']);
                break 2;
            }
        }
        $newUser = [
            'id' => generateId(),
            'username' => $username,
            'password_hash' => password_hash($password, PASSWORD_DEFAULT),
            'nimi' => $nimi ?: $username,
            'role' => $role,
            'luotu' => date('Y-m-d H:i:s'),
        ];
        $users[] = $newUser;
        saveUsers($users);
        addLog('user_create', '', '', "Lisäsi käyttäjän: {$username} ({$role})");
        unset($newUser['password_hash']);
        echo json_encode($newUser);
        break;

    case 'user_update':
        requireAdmin();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        $users = loadUsers();
        $found = false;
        foreach ($users as &$u) {
            if ($u['id'] === $id) {
                if (isset($input['nimi'])) $u['nimi'] = trim($input['nimi']);
                if (isset($input['role'])) $u['role'] = $input['role'] === 'admin' ? 'admin' : 'user';
                if (!empty($input['password'])) {
                    $u['password_hash'] = password_hash($input['password'], PASSWORD_DEFAULT);
                }
                $found = true;
                addLog('user_update', '', '', "Muokkasi käyttäjää: {$u['username']}");
                $safe = $u;
                unset($safe['password_hash']);
                echo json_encode($safe);
                break;
            }
        }
        unset($u);
        if (!$found) {
            http_response_code(404);
            echo json_encode(['error' => 'Käyttäjää ei löydy']);
            break;
        }
        saveUsers($users);
        break;

    case 'user_delete':
        requireAdmin();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        if ($id === $_SESSION['user_id']) {
            http_response_code(400);
            echo json_encode(['error' => 'Et voi poistaa itseäsi']);
            break;
        }
        $users = loadUsers();
        $deleted = null;
        foreach ($users as $u) {
            if ($u['id'] === $id) { $deleted = $u; break; }
        }
        $users = array_values(array_filter($users, fn($u) => $u['id'] !== $id));
        saveUsers($users);
        if ($deleted) addLog('user_delete', '', '', "Poisti käyttäjän: {$deleted['username']}");
        echo json_encode(['success' => true]);
        break;

    // ---------- CHANGELOG ----------
    case 'changelog':
        requireAuth();
        $log = json_decode(file_get_contents(CHANGELOG_FILE), true) ?: [];
        $limit = intval($_GET['limit'] ?? 100);
        echo json_encode(array_slice($log, 0, $limit));
        break;

    // ---------- CUSTOMERS ----------
    case 'customers':
        requireAuth();
        if ($method === 'GET') {
            echo json_encode(loadCustomers());
        }
        break;

    case 'customer':
        requireAuth();
        if ($method === 'POST') {
            $input = json_decode(file_get_contents('php://input'), true);
            $customers = loadCustomers();
            $customer = [
                'id' => generateId(),
                'yritys' => trim($input['yritys'] ?? ''),
                'yhteyshenkilö' => trim($input['yhteyshenkilö'] ?? ''),
                'puhelin' => trim($input['puhelin'] ?? ''),
                'sahkoposti' => trim($input['sahkoposti'] ?? ''),
                'laskutusosoite' => trim($input['laskutusosoite'] ?? ''),
                'laskutuspostinumero' => trim($input['laskutuspostinumero'] ?? ''),
                'laskutuskaupunki' => trim($input['laskutuskaupunki'] ?? ''),
                'laskutussahkoposti' => trim($input['laskutussahkoposti'] ?? ''),
                'elaskuosoite' => trim($input['elaskuosoite'] ?? ''),
                'elaskuvalittaja' => trim($input['elaskuvalittaja'] ?? ''),
                'ytunnus' => trim($input['ytunnus'] ?? ''),
                'lisatiedot' => trim($input['lisatiedot'] ?? ''),
                'liittymat' => parseLiittymat($input),
                'luotu' => date('Y-m-d H:i:s'),
            ];
            if (empty($customer['yritys'])) {
                http_response_code(400);
                echo json_encode(['error' => 'Yrityksen nimi vaaditaan']);
                break;
            }
            $customers[] = $customer;
            saveCustomers($customers);
            addLog('customer_create', $customer['id'], $customer['yritys'], 'Lisäsi asiakkaan');
            echo json_encode($customer);
        }
        break;

    case 'customer_update':
        requireAuth();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        $customers = loadCustomers();
        $found = false;
        foreach ($customers as &$c) {
            if ($c['id'] === $id) {
                $changes = [];
                $fields = ['yritys','yhteyshenkilö','puhelin','sahkoposti','laskutusosoite','laskutuspostinumero','laskutuskaupunki','laskutussahkoposti','elaskuosoite','elaskuvalittaja','ytunnus','lisatiedot'];
                foreach ($fields as $f) {
                    if (isset($input[$f])) {
                        $old = $c[$f] ?? '';
                        $new = trim($input[$f]);
                        if ($old !== $new) $changes[] = $f;
                        $c[$f] = $new;
                    }
                }
                if (isset($input['liittymat'])) {
                    $c['liittymat'] = parseLiittymat($input);
                    $changes[] = 'liittymat';
                }
                $c['muokattu'] = date('Y-m-d H:i:s');
                $found = true;
                addLog('customer_update', $c['id'], $c['yritys'], 'Muokkasi: ' . implode(', ', $changes));
                echo json_encode($c);
                break;
            }
        }
        unset($c);
        if (!$found) {
            http_response_code(404);
            echo json_encode(['error' => 'Asiakasta ei löydy']);
            break;
        }
        saveCustomers($customers);
        break;

    case 'customer_delete':
        requireAuth();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        $customers = loadCustomers();
        $archived = null;
        $remaining = [];
        foreach ($customers as $c) {
            if ($c['id'] === $id) {
                $c['arkistoitu'] = date('Y-m-d H:i:s');
                $c['arkistoija'] = currentUser();
                $archived = $c;
            } else {
                $remaining[] = $c;
            }
        }
        if ($archived) {
            $archive = loadArchive();
            $archive[] = $archived;
            saveArchive($archive);
            saveCustomers($remaining);
            addLog('customer_archive', $archived['id'], $archived['yritys'], 'Arkistoi asiakkaan');
        }
        echo json_encode(['success' => true]);
        break;

    // ---------- ARCHIVE ----------
    case 'archived_customers':
        requireAuth();
        echo json_encode(loadArchive());
        break;

    case 'customer_restore':
        requireAuth();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        $archive = loadArchive();
        $restored = null;
        $remaining = [];
        foreach ($archive as $c) {
            if ($c['id'] === $id) {
                unset($c['arkistoitu'], $c['arkistoija']);
                $restored = $c;
            } else {
                $remaining[] = $c;
            }
        }
        if ($restored) {
            $customers = loadCustomers();
            $customers[] = $restored;
            saveCustomers($customers);
            saveArchive($remaining);
            addLog('customer_restore', $restored['id'], $restored['yritys'], 'Palautti asiakkaan arkistosta');
        }
        echo json_encode(['success' => true]);
        break;

    case 'customer_permanent_delete':
        requireAdmin();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $id = $input['id'] ?? '';
        $archive = loadArchive();
        $deleted = null;
        foreach ($archive as $c) {
            if ($c['id'] === $id) { $deleted = $c; break; }
        }
        $archive = array_values(array_filter($archive, fn($c) => $c['id'] !== $id));
        saveArchive($archive);
        // Poista tiedostot
        $filesDir = DATA_DIR . '/files/' . $id;
        if (is_dir($filesDir)) {
            array_map('unlink', glob($filesDir . '/*'));
            rmdir($filesDir);
        }
        if ($deleted) addLog('customer_permanent_delete', $id, $deleted['yritys'] ?? '', 'Poisti pysyvästi');
        echo json_encode(['success' => true]);
        break;

    // ---------- FILES ----------
    case 'file_upload':
        requireAuth();
        if ($method !== 'POST') break;
        $customerId = $_POST['customer_id'] ?? '';
        if (!$customerId || !preg_match('/^[a-f0-9]+$/', $customerId)) {
            http_response_code(400);
            echo json_encode(['error' => 'Virheellinen asiakas-ID']);
            break;
        }
        if (empty($_FILES['file'])) {
            http_response_code(400);
            echo json_encode(['error' => 'Tiedosto puuttuu']);
            break;
        }
        $file = $_FILES['file'];
        if ($file['error'] !== UPLOAD_ERR_OK) {
            http_response_code(400);
            echo json_encode(['error' => 'Tiedoston lähetys epäonnistui']);
            break;
        }
        if ($file['size'] > 20 * 1024 * 1024) {
            http_response_code(400);
            echo json_encode(['error' => 'Tiedosto on liian suuri (max 20 MB)']);
            break;
        }
        $uploadDir = DATA_DIR . '/files/' . $customerId;
        if (!file_exists($uploadDir)) mkdir($uploadDir, 0755, true);
        $safeName = preg_replace('/[^a-zA-Z0-9._-]/', '_', basename($file['name']));
        $dest = $uploadDir . '/' . $safeName;
        if (file_exists($dest)) {
            $ext = pathinfo($safeName, PATHINFO_EXTENSION);
            $base = pathinfo($safeName, PATHINFO_FILENAME);
            $safeName = $base . '_' . date('His') . ($ext ? '.' . $ext : '');
            $dest = $uploadDir . '/' . $safeName;
        }
        if (move_uploaded_file($file['tmp_name'], $dest)) {
            echo json_encode(['success' => true, 'filename' => $safeName, 'size' => $file['size']]);
        } else {
            http_response_code(500);
            echo json_encode(['error' => 'Tallennusvirhe']);
        }
        break;

    case 'file_list':
        requireAuth();
        $customerId = $_GET['customer_id'] ?? '';
        if (!$customerId || !preg_match('/^[a-f0-9]+$/', $customerId)) {
            echo json_encode([]);
            break;
        }
        $dir = DATA_DIR . '/files/' . $customerId;
        $files = [];
        if (is_dir($dir)) {
            foreach (scandir($dir) as $f) {
                if ($f === '.' || $f === '..') continue;
                $path = $dir . '/' . $f;
                $files[] = ['filename' => $f, 'size' => filesize($path), 'modified' => date('Y-m-d H:i', filemtime($path))];
            }
        }
        usort($files, fn($a, $b) => strcmp($b['modified'], $a['modified']));
        echo json_encode($files);
        break;

    case 'file_download':
        requireAuth();
        $customerId = $_GET['customer_id'] ?? '';
        $filename = $_GET['filename'] ?? '';
        if (!$customerId || !preg_match('/^[a-f0-9]+$/', $customerId) || !$filename) {
            http_response_code(400);
            echo json_encode(['error' => 'Virheelliset parametrit']);
            break;
        }
        $safeName = basename($filename);
        $path = DATA_DIR . '/files/' . $customerId . '/' . $safeName;
        if (!file_exists($path)) {
            http_response_code(404);
            echo json_encode(['error' => 'Tiedostoa ei löydy']);
            break;
        }
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename="' . $safeName . '"');
        header('Content-Length: ' . filesize($path));
        readfile($path);
        exit;

    case 'file_delete':
        requireAuth();
        if ($method !== 'POST') break;
        $input = json_decode(file_get_contents('php://input'), true);
        $customerId = $input['customer_id'] ?? '';
        $filename = $input['filename'] ?? '';
        if (!$customerId || !preg_match('/^[a-f0-9]+$/', $customerId) || !$filename) {
            http_response_code(400);
            echo json_encode(['error' => 'Virheelliset parametrit']);
            break;
        }
        $safeName = basename($filename);
        $path = DATA_DIR . '/files/' . $customerId . '/' . $safeName;
        if (file_exists($path)) unlink($path);
        echo json_encode(['success' => true]);
        break;

    default:
        http_response_code(404);
        echo json_encode(['error' => 'Tuntematon toiminto']);
        break;
}