<?php
declare(strict_types=1);

if (session_status() !== PHP_SESSION_ACTIVE) {
    session_start();
}

require_once __DIR__ . '/../db/config.php';

date_default_timezone_set('UTC');

function app_env(string $key, string $default = ''): string
{
    $serverValue = $_SERVER[$key] ?? null;
    if (is_string($serverValue) && $serverValue !== '') {
        return $serverValue;
    }

    $envValue = getenv($key);
    return is_string($envValue) && $envValue !== '' ? $envValue : $default;
}

function app_base_path(): string
{
    static $basePath = null;
    if ($basePath !== null) {
        return $basePath;
    }

    $scriptName = str_replace('\\', '/', (string) ($_SERVER['SCRIPT_NAME'] ?? ''));
    $dir = str_replace('\\', '/', dirname($scriptName));
    if ($dir === '/' || $dir === '.' || $dir === '\\') {
        $basePath = '';
        return $basePath;
    }

    $basePath = rtrim($dir, '/');
    return $basePath;
}

function app_url(string $path = ''): string
{
    $path = trim($path);
    if ($path !== '' && (preg_match('#^[a-z][a-z0-9+.-]*://#i', $path) === 1 || str_starts_with($path, '//'))) {
        return $path;
    }

    $basePath = app_base_path();
    if ($path === '' || $path === '/') {
        return $basePath !== '' ? $basePath . '/' : '/';
    }

    return ($basePath !== '' ? $basePath : '') . '/' . ltrim($path, '/');
}

function asset_url(string $path): string
{
    return app_url($path);
}

function public_asset_url(string $path): string
{
    $path = trim($path);
    if ($path === '') {
        return '';
    }

    if (preg_match('#^[a-z][a-z0-9+.-]*://#i', $path) === 1 || str_starts_with($path, '//') || str_starts_with($path, 'data:')) {
        return $path;
    }

    return app_url(ltrim($path, '/'));
}

function e(?string $value): string
{
    return htmlspecialchars((string) $value, ENT_QUOTES, 'UTF-8');
}

function schema_column_exists(string $table, string $column): bool
{
    $stmt = db()->prepare(
        'SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = :schema AND TABLE_NAME = :table_name AND COLUMN_NAME = :column_name'
    );
    $stmt->execute([
        ':schema' => DB_NAME,
        ':table_name' => $table,
        ':column_name' => $column,
    ]);

    return (int) $stmt->fetchColumn() > 0;
}

function schema_index_exists(string $table, string $index): bool
{
    $stmt = db()->prepare(
        'SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS WHERE TABLE_SCHEMA = :schema AND TABLE_NAME = :table_name AND INDEX_NAME = :index_name'
    );
    $stmt->execute([
        ':schema' => DB_NAME,
        ':table_name' => $table,
        ':index_name' => $index,
    ]);

    return (int) $stmt->fetchColumn() > 0;
}

function ensure_column_exists(string $table, string $column, string $definition): void
{
    if (!schema_column_exists($table, $column)) {
        db()->exec(sprintf('ALTER TABLE %s ADD COLUMN %s %s', $table, $column, $definition));
    }
}

function ensure_index_exists(string $table, string $index, string $definition): void
{
    if (!schema_index_exists($table, $index)) {
        db()->exec(sprintf('ALTER TABLE %s ADD INDEX %s %s', $table, $index, $definition));
    }
}

function ensure_app_schema(): void
{
    static $done = false;
    if ($done) {
        return;
    }

    $usersSql = <<<'SQL'
CREATE TABLE IF NOT EXISTS app_users (
    id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(120) NOT NULL,
    email VARCHAR(190) NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    UNIQUE KEY uniq_user_email (email)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
SQL;

    $itemsSql = <<<'SQL'
CREATE TABLE IF NOT EXISTS service_tracker_items (
    id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    item_type ENUM('service','setting') NOT NULL DEFAULT 'service',
    user_id INT UNSIGNED DEFAULT NULL,
    slug_key VARCHAR(120) DEFAULT NULL,
    vehicle_name VARCHAR(120) DEFAULT NULL,
    vehicle_category VARCHAR(20) DEFAULT NULL,
    plate_number VARCHAR(40) DEFAULT NULL,
    service_name VARCHAR(80) DEFAULT NULL,
    last_service_date DATE DEFAULT NULL,
    reminder_interval_days INT DEFAULT NULL,
    next_due_date DATE DEFAULT NULL,
    odometer_km INT DEFAULT NULL,
    notes TEXT DEFAULT NULL,
    content_longtext LONGTEXT DEFAULT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    UNIQUE KEY uniq_item_slug (item_type, slug_key),
    KEY idx_service_due (item_type, next_due_date),
    KEY idx_vehicle_name (vehicle_name),
    KEY idx_user_service_due (user_id, item_type, next_due_date)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
SQL;

    db()->exec($usersSql);
    db()->exec($itemsSql);

    ensure_column_exists('service_tracker_items', 'user_id', 'INT UNSIGNED DEFAULT NULL AFTER item_type');
    ensure_index_exists('service_tracker_items', 'idx_user_service_due', '(user_id, item_type, next_due_date)');

    $done = true;
}

ensure_app_schema();

function service_catalog(): array
{
    return [
        'Ganti oli mesin' => 90,
        'Filter udara' => 120,
        'Bersihin CVT' => 90,
        'Vanbelt' => 180,
        'Ganti oli gardan' => 180,
        'Busi' => 180,
        'Tune up ringan' => 120,
        'Cek rem & kampas' => 90,
    ];
}

function normalize_email(string $email): string
{
    return strtolower(trim($email));
}

function current_user(): ?array
{
    $user = $_SESSION['user'] ?? null;
    return is_array($user) ? $user : null;
}

function current_user_id(): int
{
    return (int) ((current_user()['id'] ?? 0));
}

function current_user_name(): string
{
    $user = current_user();
    if (!$user) {
        return '';
    }

    $name = trim((string) ($user['name'] ?? ''));
    if ($name !== '') {
        return $name;
    }

    return (string) ($user['email'] ?? '');
}

function is_user_logged_in(): bool
{
    return current_user_id() > 0;
}

function login_user(array $user): void
{
    $_SESSION['user'] = [
        'id' => (int) ($user['id'] ?? 0),
        'name' => (string) ($user['name'] ?? ''),
        'email' => (string) ($user['email'] ?? ''),
    ];
    session_regenerate_id(true);
}

function logout_user(): void
{
    unset($_SESSION['user']);
    session_regenerate_id(true);
}

function auth_redirect_target(string $default = ''): string
{
    $fallback = $default !== '' ? $default : app_url('dashboard.php');
    if (!str_starts_with($fallback, '/') && preg_match('#^[a-z][a-z0-9+.-]*://#i', $fallback) !== 1) {
        $fallback = app_url($fallback);
    }

    $target = trim((string) ($_POST['redirect'] ?? $_GET['redirect'] ?? ''));
    if ($target === '') {
        return $fallback;
    }

    if (preg_match('#^[a-z][a-z0-9+.-]*://#i', $target) === 1 || str_starts_with($target, '//')) {
        return $fallback;
    }

    return str_starts_with($target, '/') ? $target : app_url($target);
}

function require_user_login(): void
{
    if (is_user_logged_in()) {
        return;
    }

    set_flash('warning', 'Silakan login dulu supaya catatan servis hanya terlihat oleh akun kamu sendiri.');
    $target = (string) ($_SERVER['REQUEST_URI'] ?? app_url('dashboard.php'));
    header('Location: ' . app_url('login.php') . '?redirect=' . urlencode($target));
    exit;
}

function find_user_by_email(string $email): ?array
{
    $stmt = db()->prepare('SELECT * FROM app_users WHERE email = :email LIMIT 1');
    $stmt->execute([
        ':email' => normalize_email($email),
    ]);

    $row = $stmt->fetch();
    return $row ?: null;
}

function create_user_account(string $name, string $email, string $password): int
{
    $stmt = db()->prepare(
        'INSERT INTO app_users (name, email, password_hash) VALUES (:name, :email, :password_hash)'
    );
    $stmt->execute([
        ':name' => trim($name),
        ':email' => normalize_email($email),
        ':password_hash' => password_hash($password, PASSWORD_DEFAULT),
    ]);

    return (int) db()->lastInsertId();
}

function verify_user_login(string $email, string $password): ?array
{
    $user = find_user_by_email($email);
    if (!$user) {
        return null;
    }

    return password_verify($password, (string) $user['password_hash']) ? $user : null;
}

function app_setting(string $key, string $default = ''): string
{
    $stmt = db()->prepare('SELECT content_longtext FROM service_tracker_items WHERE item_type = :type AND slug_key = :slug LIMIT 1');
    $stmt->execute([
        ':type' => 'setting',
        ':slug' => $key,
    ]);
    $value = $stmt->fetchColumn();

    return is_string($value) ? $value : $default;
}

function save_setting(string $key, string $value): void
{
    $stmt = db()->prepare(
        'INSERT INTO service_tracker_items (item_type, slug_key, content_longtext) VALUES (:type, :slug, :content)
         ON DUPLICATE KEY UPDATE content_longtext = VALUES(content_longtext), updated_at = CURRENT_TIMESTAMP'
    );
    $stmt->execute([
        ':type' => 'setting',
        ':slug' => $key,
        ':content' => $value,
    ]);
}

function head_ad_code(): string
{
    return app_setting('ads_head');
}

function body_ad_code(): string
{
    return app_setting('ads_body');
}

function app_project_name(): string
{
    return app_env('PROJECT_NAME', 'ServisIngat');
}

function app_brand_initial(): string
{
    $projectName = trim(app_project_name());
    if ($projectName === '') {
        return 'S';
    }

    if (function_exists('mb_substr')) {
        return mb_strtoupper((string) mb_substr($projectName, 0, 1, 'UTF-8'), 'UTF-8');
    }

    return strtoupper(substr($projectName, 0, 1));
}

function app_logo_url(): string
{
    return app_setting('brand_logo_url');
}

function app_favicon_url(): string
{
    return app_setting('brand_favicon_url');
}

function set_flash(string $type, string $message): void
{
    $_SESSION['flash'] = [
        'type' => $type,
        'message' => $message,
    ];
}

function consume_flash(): ?array
{
    if (empty($_SESSION['flash']) || !is_array($_SESSION['flash'])) {
        return null;
    }

    $flash = $_SESSION['flash'];
    unset($_SESSION['flash']);
    return $flash;
}

function empty_dashboard_summary(): array
{
    return [
        'total_services' => 0,
        'overdue_count' => 0,
        'due_soon_count' => 0,
        'last_update' => null,
    ];
}

function dashboard_summary(): array
{
    $stmt = db()->query(
        "SELECT
            SUM(CASE WHEN item_type = 'service' THEN 1 ELSE 0 END) AS total_services,
            SUM(CASE WHEN item_type = 'service' AND next_due_date < CURDATE() THEN 1 ELSE 0 END) AS overdue_count,
            SUM(CASE WHEN item_type = 'service' AND next_due_date BETWEEN CURDATE() AND DATE_ADD(CURDATE(), INTERVAL 14 DAY) THEN 1 ELSE 0 END) AS due_soon_count,
            MAX(CASE WHEN item_type = 'service' THEN updated_at ELSE NULL END) AS last_update
         FROM service_tracker_items"
    );

    $row = $stmt->fetch() ?: [];
    return [
        'total_services' => (int) ($row['total_services'] ?? 0),
        'overdue_count' => (int) ($row['overdue_count'] ?? 0),
        'due_soon_count' => (int) ($row['due_soon_count'] ?? 0),
        'last_update' => $row['last_update'] ?? null,
    ];
}

function dashboard_summary_for_user(int $userId): array
{
    if ($userId <= 0) {
        return empty_dashboard_summary();
    }

    $stmt = db()->prepare(
        "SELECT
            COUNT(*) AS total_services,
            SUM(CASE WHEN next_due_date < CURDATE() THEN 1 ELSE 0 END) AS overdue_count,
            SUM(CASE WHEN next_due_date BETWEEN CURDATE() AND DATE_ADD(CURDATE(), INTERVAL 14 DAY) THEN 1 ELSE 0 END) AS due_soon_count,
            MAX(updated_at) AS last_update
         FROM service_tracker_items
         WHERE item_type = 'service' AND user_id = :user_id"
    );
    $stmt->execute([
        ':user_id' => $userId,
    ]);

    $row = $stmt->fetch() ?: [];
    return [
        'total_services' => (int) ($row['total_services'] ?? 0),
        'overdue_count' => (int) ($row['overdue_count'] ?? 0),
        'due_soon_count' => (int) ($row['due_soon_count'] ?? 0),
        'last_update' => $row['last_update'] ?? null,
    ];
}

function fetch_services(int $limit = 100): array
{
    $stmt = db()->prepare(
        'SELECT * FROM service_tracker_items WHERE item_type = :type ORDER BY next_due_date IS NULL, next_due_date ASC, updated_at DESC LIMIT :limit'
    );
    $stmt->bindValue(':type', 'service');
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();
    return $stmt->fetchAll();
}

function fetch_services_for_user(int $userId, int $limit = 100): array
{
    if ($userId <= 0) {
        return [];
    }

    $stmt = db()->prepare(
        'SELECT * FROM service_tracker_items WHERE item_type = :type AND user_id = :user_id ORDER BY next_due_date IS NULL, next_due_date ASC, updated_at DESC LIMIT :limit'
    );
    $stmt->bindValue(':type', 'service');
    $stmt->bindValue(':user_id', $userId, PDO::PARAM_INT);
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();
    return $stmt->fetchAll();
}

function fetch_recent_services(int $limit = 5): array
{
    $stmt = db()->prepare(
        'SELECT * FROM service_tracker_items WHERE item_type = :type ORDER BY created_at DESC LIMIT :limit'
    );
    $stmt->bindValue(':type', 'service');
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();
    return $stmt->fetchAll();
}

function fetch_recent_services_for_user(int $userId, int $limit = 5): array
{
    if ($userId <= 0) {
        return [];
    }

    $stmt = db()->prepare(
        'SELECT * FROM service_tracker_items WHERE item_type = :type AND user_id = :user_id ORDER BY created_at DESC LIMIT :limit'
    );
    $stmt->bindValue(':type', 'service');
    $stmt->bindValue(':user_id', $userId, PDO::PARAM_INT);
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->execute();
    return $stmt->fetchAll();
}

function fetch_service_by_id(int $id): ?array
{
    $stmt = db()->prepare('SELECT * FROM service_tracker_items WHERE item_type = :type AND id = :id LIMIT 1');
    $stmt->execute([
        ':type' => 'service',
        ':id' => $id,
    ]);
    $row = $stmt->fetch();
    return $row ?: null;
}

function fetch_service_by_id_for_user(int $userId, int $id): ?array
{
    if ($userId <= 0 || $id <= 0) {
        return null;
    }

    $stmt = db()->prepare('SELECT * FROM service_tracker_items WHERE item_type = :type AND user_id = :user_id AND id = :id LIMIT 1');
    $stmt->execute([
        ':type' => 'service',
        ':user_id' => $userId,
        ':id' => $id,
    ]);
    $row = $stmt->fetch();
    return $row ?: null;
}

function due_state(?string $dateValue): array
{
    if (!$dateValue) {
        return [
            'label' => 'Belum dijadwalkan',
            'class' => 'status-neutral',
            'tone' => 'secondary',
            'description' => 'Atur tanggal servis berikutnya untuk mulai dipantau.',
        ];
    }

    $today = new DateTimeImmutable('today');
    $dueDate = new DateTimeImmutable($dateValue);
    $diff = (int) $today->diff($dueDate)->format('%r%a');

    if ($diff < 0) {
        $days = abs($diff);
        return [
            'label' => 'Terlambat ' . $days . ' hari',
            'class' => 'status-overdue',
            'tone' => 'danger',
            'description' => 'Sudah melewati jadwal, sebaiknya segera ditindaklanjuti.',
        ];
    }

    if ($diff <= 14) {
        return [
            'label' => 'Jatuh tempo ' . $diff . ' hari lagi',
            'class' => 'status-soon',
            'tone' => 'warning',
            'description' => 'Sudah dekat dengan jadwal berikutnya, cocok masuk prioritas.',
        ];
    }

    return [
        'label' => 'Aman ' . $diff . ' hari lagi',
        'class' => 'status-ok',
        'tone' => 'success',
        'description' => 'Masih aman, tapi sudah tercatat untuk pengingat berikutnya.',
    ];
}

function validate_service_payload(array $data): array
{
    $catalog = service_catalog();
    $vehicleName = trim((string) ($data['vehicle_name'] ?? ''));
    $vehicleCategory = trim((string) ($data['vehicle_category'] ?? ''));
    $plateNumber = strtoupper(trim((string) ($data['plate_number'] ?? '')));
    $serviceName = trim((string) ($data['service_name'] ?? ''));
    $lastServiceDate = trim((string) ($data['last_service_date'] ?? ''));
    $intervalDays = (int) ($data['reminder_interval_days'] ?? 0);
    $odometerKm = trim((string) ($data['odometer_km'] ?? ''));
    $notes = trim((string) ($data['notes'] ?? ''));

    $errors = [];

    if ($vehicleName === '' || strlen($vehicleName) < 3) {
        $errors['vehicle_name'] = 'Nama kendaraan minimal 3 karakter.';
    }

    if (!in_array($vehicleCategory, ['Motor', 'Mobil'], true)) {
        $errors['vehicle_category'] = 'Pilih jenis kendaraan.';
    }

    if ($serviceName === '') {
        $errors['service_name'] = 'Pilih item servis utama.';
    }

    if ($lastServiceDate === '' || !preg_match('/^\d{4}-\d{2}-\d{2}$/', $lastServiceDate)) {
        $errors['last_service_date'] = 'Tanggal servis terakhir wajib diisi.';
    }

    if ($intervalDays < 14 || $intervalDays > 365) {
        $errors['reminder_interval_days'] = 'Interval pengingat harus 14–365 hari.';
    }

    if ($odometerKm !== '' && (!ctype_digit($odometerKm) || (int) $odometerKm < 0)) {
        $errors['odometer_km'] = 'Kilometer harus berupa angka positif.';
    }

    $nextDueDate = null;
    if (!isset($errors['last_service_date']) && !isset($errors['reminder_interval_days'])) {
        try {
            $nextDueDate = (new DateTimeImmutable($lastServiceDate))
                ->modify('+' . $intervalDays . ' days')
                ->format('Y-m-d');
        } catch (Throwable $exception) {
            $errors['last_service_date'] = 'Tanggal servis terakhir tidak valid.';
        }
    }

    return [
        'errors' => $errors,
        'clean' => [
            'vehicle_name' => $vehicleName,
            'vehicle_category' => $vehicleCategory,
            'plate_number' => $plateNumber,
            'service_name' => $serviceName,
            'last_service_date' => $lastServiceDate,
            'reminder_interval_days' => $intervalDays,
            'next_due_date' => $nextDueDate,
            'odometer_km' => $odometerKm === '' ? null : (int) $odometerKm,
            'notes' => $notes,
            'suggested_days' => $catalog[$serviceName] ?? null,
        ],
    ];
}

function create_service(array $payload): int
{
    $userId = current_user_id();
    if ($userId <= 0) {
        throw new RuntimeException('User must be logged in before creating a service record.');
    }

    $stmt = db()->prepare(
        'INSERT INTO service_tracker_items (
            item_type, user_id, vehicle_name, vehicle_category, plate_number, service_name,
            last_service_date, reminder_interval_days, next_due_date, odometer_km, notes
        ) VALUES (
            :item_type, :user_id, :vehicle_name, :vehicle_category, :plate_number, :service_name,
            :last_service_date, :reminder_interval_days, :next_due_date, :odometer_km, :notes
        )'
    );

    $stmt->execute([
        ':item_type' => 'service',
        ':user_id' => $userId,
        ':vehicle_name' => $payload['vehicle_name'],
        ':vehicle_category' => $payload['vehicle_category'],
        ':plate_number' => $payload['plate_number'],
        ':service_name' => $payload['service_name'],
        ':last_service_date' => $payload['last_service_date'],
        ':reminder_interval_days' => $payload['reminder_interval_days'],
        ':next_due_date' => $payload['next_due_date'],
        ':odometer_km' => $payload['odometer_km'],
        ':notes' => $payload['notes'],
    ]);

    return (int) db()->lastInsertId();
}

function is_admin_logged_in(): bool
{
    return !empty($_SESSION['is_admin_logged_in']);
}

function admin_username(): string
{
    return app_env('ADMIN_PORTAL_USER', 'admin');
}

function admin_default_password_hint(): string
{
    return app_env('ADMIN_PORTAL_PASSWORD_HINT', 'servis123!');
}

function admin_password_hash(): string
{
    $storedHash = app_setting('admin_password_hash');
    if ($storedHash !== '') {
        return $storedHash;
    }

    return app_env('ADMIN_PORTAL_PASSWORD_HASH', '$2y$10$riyTXC1R9fEPRr2T18rxUuycZVTjpQVvCDOmRQD4ID1EVWw9fyDHC');
}

function admin_has_custom_password(): bool
{
    return app_setting('admin_password_hash') !== '';
}

function save_admin_password(string $password): void
{
    save_setting('admin_password_hash', password_hash($password, PASSWORD_DEFAULT));
}

function verify_admin_login(string $username, string $password): bool
{
    $expectedUser = admin_username();
    $normalizedUsername = trim($username);

    return hash_equals($expectedUser, $normalizedUsername) && password_verify($password, admin_password_hash());
}