<?php

namespace Franzz\MyThoughts;

use Franzz\Objects\PhpObject;
use Franzz\Objects\ToolBox;

/**
 * Single entry point: parses the request, guards it, dispatches it.
 */
class Controller extends PhpObject {
	//Anything that changes state must arrive as POST with a valid CSRF token.
	private const MUTATING_ACTIONS = [
		'signup',
		'login',
		'logout',
		'account',
		'open_entry',
		'save_entry',
		'close_entry',
		'delete_entry'
	];

	//Actions that need the session lock held while they run.
	private const SESSION_WRITING_ACTIONS = [
		'signup',
		'login',
		'logout'
	];

	private MyThoughts $oMyThoughts;
	private array $asReq = [];
	private string $sCsrfToken = '';

	public function __construct() {
		parent::__construct(__CLASS__);
	}

	public function handle($sProcessPage, array $argv = []): string {
		//Start buffering so warnings/notices can be collected
		ob_start();

		$asReq = ToolBox::getRequest($argv);
		$sAction = $asReq['a'] ?? '';

		$this->asReq = [
			't'			=> (string) ($asReq['t'] ?? ''),
			'id'		=> self::positiveInt($asReq['id'] ?? 0),
			'dir'		=> (string) ($asReq['dir'] ?? ''),
			'date'		=> (string) ($asReq['date'] ?? ''),
			'content'	=> (string) ($asReq['content'] ?? ''),
			'has_content'=> array_key_exists('content', $asReq),
			'name'		=> (string) ($asReq['name'] ?? ''),
			'email'		=> (string) ($asReq['email'] ?? ''),
			'password'	=> (string) ($asReq['password'] ?? ''),
			'remember'	=> !empty($asReq['remember']),
			'field'		=> (string) ($asReq['field'] ?? ''),
			'value'		=> (string) ($asReq['value'] ?? ''),
			//sendBeacon cannot set headers, so the unload close falls back to
			//carrying the token in the body.
			'csrf_token'=> (string) ($_SERVER['HTTP_X_CSRF_TOKEN'] ?? ($_POST['csrf_token'] ?? ''))
		];

		//Authentication and CSRF protection share the same server-side session.
		$this->initCsrfToken();

		$this->oMyThoughts = new MyThoughts($sProcessPage, $this->asReq['t']);

		//Validate CSRF, then release the session lock before long-running work.
		$bValidMutationRequest = $this->validateMutationRequest($sAction);
		if(!$bValidMutationRequest || !in_array($sAction, self::SESSION_WRITING_ACTIONS, true)) $this->closeSession();

		if(!$bValidMutationRequest) $sResult = MyThoughts::getJsonResult(false, MyThoughts::UNAUTHORIZED);
		else $sResult = ($sAction == '') ? $this->oMyThoughts->getAppMainPage($this->getCsrfToken()) : $this->dispatch($sAction);

		//Clean errors
		$sDebug = ob_get_clean();
		if($sDebug != '') $this->oMyThoughts->addUncaughtError($sDebug);
		$this->closeSession();

		return $sResult;
	}

	private function dispatch(string $sAction): string {
		$oJournal = $this->oMyThoughts->getJournal();

		return match($sAction) {
			/* Account */
			'signup'		=> $this->oMyThoughts->signup($this->asReq['name'], $this->asReq['email'], $this->asReq['password'], $this->asReq['t']),
			'login'			=> $this->oMyThoughts->login($this->asReq['email'], $this->asReq['password'], $this->asReq['t'], $this->asReq['remember']),
			'logout'		=> $this->oMyThoughts->logout(),
			'account'		=> $this->oMyThoughts->updateAccount($this->asReq['field'], $this->asReq['value']),

			/* Reading the book */
			'book'			=> $oJournal->getBook(),
			'entries'		=> $oJournal->getEntries($this->asReq['dir'], $this->asReq['id']),
			'date'			=> $oJournal->getEntryIdAtDate($this->asReq['date']),

			/* Writing in it */
			'open_entry'	=> $oJournal->openEntry(),
			'save_entry'	=> $oJournal->saveEntry($this->asReq['id'], $this->asReq['content']),
			'close_entry'	=> $oJournal->closeEntry($this->asReq['id'], $this->asReq['content'], $this->asReq['has_content']),
			'delete_entry'	=> $oJournal->deleteEntry($this->asReq['id']),

			default			=> MyThoughts::getJsonResult(false, MyThoughts::NOT_FOUND)
		};
	}

	/* CSRF & session */

	private function validateMutationRequest(string $sAction): bool {
		return
			PHP_SAPI === 'cli'
			||
			!in_array($sAction, self::MUTATING_ACTIONS, true)
			||
			(($_SERVER['REQUEST_METHOD'] ?? '') === 'POST' && $this->checkCsrfToken($this->asReq['csrf_token']))
		;
	}

	private function getCsrfToken(): string {
		if($this->sCsrfToken === '') $this->initCsrfToken();
		return $this->sCsrfToken;
	}

	private function initCsrfToken(): void {
		if(PHP_SAPI === 'cli') return;

		if(session_status() !== PHP_SESSION_ACTIVE) {
			session_set_cookie_params(['httponly' => true, 'secure' => User::isSecureRequest(), 'samesite' => 'Lax']);
			session_start();
		}

		if(empty($_SESSION['csrf_token'])) $_SESSION['csrf_token'] = bin2hex(random_bytes(32));
		$this->sCsrfToken = $_SESSION['csrf_token'];
	}

	private function checkCsrfToken(string $sClientToken): bool {
		$sServerToken = $this->getCsrfToken();
		return PHP_SAPI === 'cli' || ($sServerToken !== '' && $sClientToken !== '' && hash_equals($sServerToken, $sClientToken));
	}

	private function closeSession(): void {
		if(session_status() === PHP_SESSION_ACTIVE) session_write_close();
	}

	private static function positiveInt($oValue): int {
		return filter_var($oValue, FILTER_VALIDATE_INT, ['options' => ['default' => 0, 'min_range' => 0]]);
	}
}