<?php

namespace Kernel;

use Exception;

class ModuleLoader
{
    protected string $modulesPath;
    protected array $modules = [];
    protected array $loaded = [];

    public function __construct(string $modulesPath)
    {
        $this->modulesPath = rtrim($modulesPath, '/');
    }

    /**
     * Registers the autoloader for module classes
     * Pattern: Modules\{Module}\{Class} -> modules/{module}/classes/{Class}.php
     */
    public function registerAutoload(): void
    {
        spl_autoload_register(function ($class) {
            // Base prefix
            $prefix = 'Modules\\';

            // Checks if the class uses the prefix
            $len = strlen($prefix);
            if (strncmp($prefix, $class, $len) !== 0) {
                return;
            }

            // Gets the relative class name without the prefix
            $relativeClass = substr($class, $len);

            // Separates the module name (first part of the namespace)
            $parts = explode('\\', $relativeClass);
            $moduleName = array_shift($parts);

            if (empty($moduleName)) {
                return;
            }
            
            // Converts the module name to lowercase to match the folder
            $moduleDir = strtolower($moduleName);

            // Rebuilds the class path
            $classPath = implode('/', $parts);

            // File path
            $file = $this->modulesPath . '/' . $moduleDir . '/classes/' . $classPath . '.php';

            // If the file exists, load it
            if (file_exists($file)) {
                require $file;
            }
        });
    }

    /**
     * Loads all modules
     */
    public function loadAll(): void
    {
        $dirs = glob($this->modulesPath . '/*', GLOB_ONLYDIR);

        foreach ($dirs as $dir) {
            $moduleName = basename($dir);
            $this->load($moduleName);
        }
    }

    /**
     * Loads a specific module
     */
    public function load(string $moduleName): void
    {
        if (isset($this->loaded[$moduleName])) {
            return; // already loaded
        }

        $modulePath = $this->modulesPath . '/' . $moduleName;

        // Checks if it exists
        if (!is_dir($modulePath)) {
            throw new Exception("Módulo '{$moduleName}' não encontrado.");
        }

        // Checks module.json
        $jsonFile = $modulePath . '/module.json';

        if (!file_exists($jsonFile)) {
            throw new Exception("O módulo '{$moduleName}' não possui um module.json válido.");
        }

        $config = json_decode(file_get_contents($jsonFile), true);

        if (!is_array($config)) {
            throw new Exception("module.json inválido no módulo '{$moduleName}'.");
        }

        $this->modules[$moduleName] = $config;

        // Load Service Providers
        $this->registerProviders($config);

        // Load Routes
        $this->registerRoutes($moduleName, $modulePath, $config);

        // Register Views and Locales
        $this->registerResources($moduleName, $modulePath, $config);

        $this->loaded[$moduleName] = true;
    }

    /**
     * Registers Service Providers
     */
    protected function registerProviders(array $config): void
    {
        if (!isset($config['providers'])) {
            return;
        }

        foreach ($config['providers'] as $class) {
            if (class_exists($class)) {
                $provider = new $class();
                if (method_exists($provider, 'register')) {
                    $provider->register();
                }
                if (method_exists($provider, 'boot')) {
                    $provider->boot();
                }
            }
        }
    }

    /**
     * Loads route files
     */
    protected function registerRoutes(string $module, string $path, array $config): void
    {
        if (!isset($config['routes'])) {
            return;
        }

        // Get the application instance to register routes
        $app = \Kernel\Application::getInstance();

        if (isset($config['routes']['web'])) {
            $file = $path . '/' . $config['routes']['web'];
            if (file_exists($file)) {
                $routeLoader = require $file;
                if (is_callable($routeLoader) && $app) {
                    $routeLoader($app);
                }
            }
        }

        if (isset($config['routes']['api'])) {
            $file = $path . '/' . $config['routes']['api'];
            if (file_exists($file)) {
                $routeLoader = require $file;
                if (is_callable($routeLoader) && $app) {
                    $routeLoader($app);
                }
            }
        }
    }

    /**
     * Registers views and translations
     */
    protected function registerResources(string $module, string $path, array $config): void
    {
        // Views
        if (isset($config['views'])) {
            $viewsPath = $path . '/' . $config['views'];
            if (is_dir($viewsPath)) {
                View::addPath($module, $viewsPath);
            }
        }

        // Locales
        if (isset($config['locales'])) {
            $localesPath = $path . '/' . $config['locales'];
            if (is_dir($localesPath)) {
                Translator::addNamespace($module, $localesPath);
            }
        }
    }

    /**
     * Returns the list of loaded modules
     */
    public function getModules(): array
    {
        return $this->modules;
    }
}