<?php

declare(strict_types=1);

namespace KTXM\ServiceDav;

use DI\Attribute\Inject;
use KTXC\Http\Request\Request;
use KTXC\Http\Response\Response;
use KTXC\Http\Response\StreamedResponse;
use KTXC\Service\SecurityService;
use KTXC\SessionIdentity;
use KTXC\SessionTenant;
use KTXM\ChronoManager\Conversion\IcalDecoder;
use KTXM\ChronoManager\Conversion\IcalEncoder;
use KTXM\ChronoManager\Manager as ChronoManager;
use KTXM\DocumentsManager\Manager as DocumentsManager;
use KTXM\PeopleManager\Manager as PeopleManager;
use KTXM\ServiceDav\Auth\DavAuthBackend;
use KTXM\ServiceDav\Backends\CalDavBackend;
use KTXM\ServiceDav\Backends\CardDavBackend;
use KTXM\ServiceDav\Backends\FilesRootNode;
use KTXM\ServiceDav\Backends\PrincipalBackend;
use Sabre\CalDAV\CalendarRoot;
use Sabre\CalDAV\Plugin as CalDAVPlugin;
use Sabre\CardDAV\AddressBookRoot;
use Sabre\CardDAV\Plugin as CardDAVPlugin;
use Sabre\CardDAV\VCFExportPlugin;
use Sabre\DAV\Auth\Plugin as AuthPlugin;
use Sabre\DAV\Browser\Plugin as BrowserPlugin;
use Sabre\DAV\Locks\Backend\File as LocksBackendFile;
use Sabre\DAV\Locks\Plugin as LocksPlugin;
use Sabre\DAV\Server;
use Sabre\DAVACL\Plugin as DavACLPlugin;
use Sabre\DAVACL\PrincipalCollection;
use Sabre\HTTP\Request as SabreRequest;
use Sabre\HTTP\Response as SabreResponse;

class DavServer
{
    private const BASE_URI = '/dav/';

    public function __construct(
        private readonly SessionTenant $tenant,
        private readonly SessionIdentity $identity,
        private readonly SecurityService $securityService,
        private readonly DocumentsManager $documentsManager,
        private readonly ChronoManager $chronoManager,
        private readonly PeopleManager $peopleManager,
        private readonly DavUriMap $uriMap,
        #[Inject('rootDir')] private readonly string $rootDir,
        #[Inject('kernel.debug')] private readonly bool $debug = false,
    ) {}

    public function process(Request $request): Response
    {
        $server = $this->getServer();

        $sabreRequest = new SabreRequest(
            $request->getMethod(),
            $this->normalizeRequestUri($request->getRequestUri()),
            $this->normalizeHeaders($request->headers->all()),
        );

        $body = $request->getContent(asResource: false);
        if (!empty($body)) {
            $sabreRequest->setBody($body);
        }

        $sabreResponse = new SabreResponse();

        $sabreRequest->setBaseUrl($server->getBaseUri());

        $server->httpRequest  = $sabreRequest;
        $server->httpResponse = $sabreResponse;

        try {
            $server->invokeMethod($sabreRequest, $sabreResponse, false);
        } catch (\Sabre\DAV\Exception $e) {
            try { $server->emit('exception', [$e]); } catch (\Throwable $ignore) {}
            $sabreResponse->setStatus($e->getHTTPCode());
            foreach ($e->getHTTPHeaders($server) as $name => $value) {
                $sabreResponse->setHeader($name, $value);
            }
            $sabreResponse->setBody($this->serializeException($e, $server));
        } catch (\Throwable $e) {
            try { $server->emit('exception', [$e]); } catch (\Throwable $ignore) {}
            $sabreResponse->setStatus(500);
            $sabreResponse->setBody($this->serializeException($e, $server));
        }

        return $this->buildKtxcResponse($sabreResponse);
    }

    private function getServer(): Server
    {
        return $this->buildServer();
    }

    private function buildServer(): Server
    {
        $principalBackend = new PrincipalBackend($this->identity, $this->tenant);
        $calDavBackend    = new CalDavBackend($this->chronoManager, $this->identity, $this->tenant, $this->uriMap, new IcalEncoder(), new IcalDecoder());
        $cardDavBackend   = new CardDavBackend($this->peopleManager, $this->identity, $this->tenant, $this->uriMap);

        $server = new Server([
            new PrincipalCollection($principalBackend, PrincipalBackend::PRINCIPAL_PREFIX),
            new CalendarRoot($principalBackend, $calDavBackend),
            new AddressBookRoot($principalBackend, $cardDavBackend),
            new FilesRootNode($this->documentsManager, $this->identity, $this->tenant),
        ]);
        $server->setBaseUri(self::BASE_URI);
        $server->debugExceptions = $this->debug;

        // Authentication plugin — short-circuits when JWT/Bearer already populated
        $authBackend = new DavAuthBackend($this->identity, $this->securityService);
        $server->addPlugin(new AuthPlugin($authBackend));

        // DAVACL — required for CalDAV / CardDAV principal resolution
        $aclPlugin = new DavACLPlugin();
        $userId    = (string) ($this->identity->identifier() ?? 'anonymous');
        $aclPlugin->adminPrincipals = [PrincipalBackend::PRINCIPAL_PREFIX . '/' . $userId];
        $server->addPlugin($aclPlugin);

        $server->addPlugin(new CalDAVPlugin());
        $server->addPlugin(new CardDAVPlugin());
        $server->addPlugin(new VCFExportPlugin());

        // File-based lock backend (single-server; swap for DB/Redis in multi-node setups)
        $davDir = $this->rootDir . '/var/dav';
        if (!is_dir($davDir)) {
            mkdir($davDir, 0750, true);
        }
        $server->addPlugin(new LocksPlugin(new LocksBackendFile($davDir . '/locks.db')));

        $server->addPlugin(new BrowserPlugin());

        return $server;
    }

    private function serializeException(\Throwable $e, Server $server): string
    {
        $h = static fn (string $s): string => htmlspecialchars($s, ENT_NOQUOTES, 'UTF-8');

        $dom = new \DOMDocument('1.0', 'utf-8');
        $dom->formatOutput = true;
        $error = $dom->createElementNS('http://sabredav.org/ns', 's:error');
        $error->setAttribute('xmlns:s', 'http://sabredav.org/ns');
        $dom->appendChild($error);
        $error->appendChild($dom->createElement('s:exception', $h(get_class($e))));
        $error->appendChild($dom->createElement('s:message', $h($e->getMessage())));

        if ($this->debug) {
            $error->appendChild($dom->createElement('s:file', $h($e->getFile())));
            $error->appendChild($dom->createElement('s:line', $h((string) $e->getLine())));
            $error->appendChild($dom->createElement('s:code', $h((string) $e->getCode())));
            $error->appendChild($dom->createElement('s:stacktrace', $h($e->getTraceAsString())));
        }

        if ($e instanceof \Sabre\DAV\Exception) {
            $e->serialize($server, $error);
        }

        return $dom->saveXML();
    }

    // -------------------------------------------------------------------------
    // HTTP bridge helpers
    // -------------------------------------------------------------------------

    private function normalizeRequestUri(string $uri): string
    {
        // Ensure requests for the bare base path (e.g. /dav) include the trailing
        // slash so sabre's getPath() keeps them within the base URI /dav/.
        $path = strtok($uri, '?');
        if ($path === rtrim(self::BASE_URI, '/')) {
            return self::BASE_URI . (str_contains($uri, '?') ? '?' . explode('?', $uri, 2)[1] : '');
        }
        return $uri;
    }

    private function normalizeHeaders(array $symfonyHeaders): array
    {
        $normalized = [];
        foreach ($symfonyHeaders as $name => $values) {
            $key = str_replace(' ', '-', ucwords(str_replace('-', ' ', strtolower($name))));
            $normalized[$key] = implode(', ', (array) $values);
        }
        return $normalized;
    }

    private function buildKtxcResponse(SabreResponse $sabreResponse): Response
    {
        $status = $sabreResponse->getStatus();
        $body   = $sabreResponse->getBody();

        // Collect headers; skip security headers that KTXC re-applies by default
        $headers = [];
        foreach ($sabreResponse->getHeaders() as $name => $value) {
            $headers[$name] = $value;
        }


        if (is_resource($body)) {
            // Stream the body to avoid buffering potentially large files
            $stream = $body;
            return new StreamedResponse(
                static function () use ($stream): void {
                    while (!feof($stream)) {
                        echo fread($stream, 8192);
                    }
                },
                $status,
                $headers,
            );
        }

        return new Response((string) ($body ?? ''), $status, $headers);
    }
}