<?php
/**
 * @author Giancarlo Voci
 * @date 04/12/2018
 * @time 15:22
 */

namespace OpenMind\Admin;

use Base;
use Exception;
use OpenMind\System\OMUtils;
use OpenMind\System\User;
use OpenMind\Web\Controller;
use Template;

class Pages extends Controller
{
	private const CONFIGURATION_BACKUP_FILE = 'cfg/config.bin.old';
	private const CONFIGURATION_FILE = 'cfg/config.bin';
	private const LOAD_CONFIGURATION_METHOD = 'loadconfig';
	private const SAVE_CONFIGURATION_METHOD = 'saveconfig';

	/**
	 * Initializes the admin controller and configures its template directory.
	 *
	 * @param Base $f3 Framework instance.
	 * @return void
	 * @sideEffects Changes the framework UI directory.
	 */
	public function __construct(Base $f3)
	{
		parent::__construct($f3);
		$f3->set('UI', 'ui/admin/');
	}

	/**
	 * Renders the admin landing page.
	 *
	 * @param Base $f3 Framework instance.
	 * @return void
	 * @sideEffects Sends the rendered template to the response.
	 */
	public function Admin(Base $f3): void
	{
		$f3->set('PAGENAME', 'Admin');
		echo Template::instance()->render('masterpage.tpl');
	}

	/**
	 * Renders the encrypted configuration editor.
	 *
	 * @param Base $f3 Framework instance.
	 * @return void
	 * @sideEffects Reads the configuration file and sends the rendered template.
	 * @throws Exception When the configuration file cannot be read.
	 */
	public function OML_Settings(Base $f3): void
	{
		global $frameworkUtils;

		$config = $this->readConfiguration($frameworkUtils);
		$f3->set('PAGENAME', 'OM-Link Settings');
		$f3->set('CONTENT', 'omlsettings.tpl');
		$f3->set('CONFIG_TEXT', $config);
		echo Template::instance()->render('masterpage.tpl');
	}

	/**
	 * Loads or saves configuration data requested by the admin UI.
	 *
	 * @param Base $f3 Framework instance.
	 * @return void
	 * @sideEffects Reads or replaces the encrypted configuration file and sends JSON.
	 */
	public function Config(Base $f3): void
	{
		global $frameworkUtils;

		$request = json_decode($f3->get('BODY'));
		if (!is_object($request) || !isset($request->method)) {
			$this->sendJson(['err' => 'Invalid configuration command']);
			return;
		}

		switch ($request->method) {
			case self::SAVE_CONFIGURATION_METHOD:
				if (!isset($request->value) || !is_string($request->value)) {
					$this->sendJson(['err' => 'Configuration value is required']);
					return;
				}

				$this->saveConfiguration($frameworkUtils->Encrypt($request->value));
				$this->sendJson(['err' => 'Configuration saved']);
				return;

			case self::LOAD_CONFIGURATION_METHOD:
				$this->sendJson([
					'err' => 'Configuration reloaded successfully',
					'value' => $this->readConfiguration($frameworkUtils),
				]);
				return;

			default:
				$this->sendJson(['err' => 'Unsupported configuration command']);
		}
	}

	/**
	 * Renders the user-management page.
	 *
	 * @param Base $f3 Framework instance.
	 * @return void
	 * @sideEffects Reads users from the database and sends the rendered template.
	 */
	public function Users(Base $f3): void
	{
		$users = new User('');
		$f3->set('USERLIST', $users->find());
		$f3->set('PAGENAME', 'User Management');
		$f3->set('CONTENT', 'users.tpl');
		echo Template::instance()->render('masterpage.tpl');
	}

	/**
	 * Reads and decrypts the application configuration.
	 *
	 * @param OMUtils $frameworkUtils Configuration utility service.
	 * @return string Decrypted configuration.
	 * @sideEffects Reads the configuration file.
	 * @throws Exception When the configuration file cannot be read.
	 */
	private function readConfiguration(OMUtils $frameworkUtils): string
	{
		$config = file_get_contents(self::CONFIGURATION_FILE);
		if ($config === false) {
			throw new Exception('Configuration file could not be read');
		}

		return $frameworkUtils->Decrypt($config);
	}

	/**
	 * Replaces the configuration file while retaining the previous version as backup.
	 *
	 * @param string $configuration Encrypted configuration.
	 * @return void
	 * @sideEffects Renames and writes configuration files.
	 * @throws Exception When the backup or write fails.
	 */
	private function saveConfiguration(string $configuration): void
	{
		if (!rename(self::CONFIGURATION_FILE, self::CONFIGURATION_BACKUP_FILE)) {
			throw new Exception('Configuration backup could not be created');
		}

		if (file_put_contents(self::CONFIGURATION_FILE, $configuration) !== false) {
			return;
		}

		rename(self::CONFIGURATION_BACKUP_FILE, self::CONFIGURATION_FILE);
		throw new Exception('Configuration file could not be written');
	}

	/**
	 * Sends a JSON response.
	 *
	 * @param array<string, string> $response Response data.
	 * @return void
	 * @sideEffects Writes JSON to the HTTP response.
	 */
	private function sendJson(array $response): void
	{
		echo json_encode($response);
	}
}