package org.openautonomousconnection.webserver.runtime;

import org.openautonomousconnection.protocol.packets.v1_0_1.beta.web.impl.resource.WebResourceRequestPacket;
import org.openautonomousconnection.protocol.packets.v1_0_1.beta.web.impl.resource.WebResourceResponsePacket;
import org.openautonomousconnection.protocol.side.server.CustomConnectedClient;
import org.openautonomousconnection.protocol.side.web.ProtocolWebServer;
import org.openautonomousconnection.webserver.WebServer;
import org.openautonomousconnection.webserver.api.WebPage;
import org.openautonomousconnection.webserver.api.WebPageContext;
import org.openautonomousconnection.webserver.utils.HeaderMaps;
import org.openautonomousconnection.webserver.utils.RequestParams;
import org.openautonomousconnection.webserver.utils.WebHasher;
import org.openautonomousconnection.webserver.utils.WebUrlUtil;

import java.nio.charset.StandardCharsets;

/**
 * Dispatches Java WebPages using {@code @Route} annotation (v1.0.1-BETA).
 */
public final class JavaPageDispatcher {

    private static final JavaRouteRegistry ROUTES = new JavaRouteRegistry();
    private static final JavaPageCache CACHE = new JavaPageCache();

    private JavaPageDispatcher() {
    }

    /**
     * Attempts to dispatch a request to a Java WebPage.
     *
     * @param client  connected client
     * @param server  protocol web server
     * @param request request packet
     * @return response packet or {@code null} if no Java route matches
     * @throws Exception on unexpected failures
     */
    public static WebResourceResponsePacket dispatch(
            CustomConnectedClient client,
            ProtocolWebServer server,
            WebResourceRequestPacket request
    ) throws Exception {

        if (request == null || request.getUrl() == null) {
            return null;
        }

        String route = WebUrlUtil.extractPathAndQuery(request.getUrl());
        if (route == null) return null;

        int q = route.indexOf('?');
        if (q >= 0) route = route.substring(0, q);

        route = WebUrlUtil.normalizeRequestPath(route);

        java.io.File contentRoot = server.getContentFolder();
        ROUTES.refreshIfNeeded(contentRoot);

        JavaRouteRegistry.RouteLookupResult found = ROUTES.find(route);
        if (found == null) {
            return null;
        }

        long contentLm = ROUTES.currentContentLastModified(contentRoot);

        JavaPageCache.LoadedClass loaded = CACHE.getOrCompile(contentRoot, found.sourceFile(), contentLm);
        Class<?> clazz = loaded.clazz();

        if (!WebPage.class.isAssignableFrom(clazz)) {
            return error(request, 500, "Class has @Route but is not a WebPage: " + found.fqcn());
        }

        Object instance = clazz.getDeclaredConstructor().newInstance();
        WebPage page = (WebPage) instance;

        WebHasher hasher = (server instanceof WebServer ws) ? ws.getHasher() : null;
        if (hasher == null) {
            return error(request, 500, "WebHasher missing on server instance.");
        }

        WebPageContext ctx = new WebPageContext(client, server, request, new RequestParams(request), hasher);
        return page.handle(ctx);
    }

    private static WebResourceResponsePacket error(WebResourceRequestPacket req, int code, String msg) {
        byte[] body = (msg == null ? "" : msg).getBytes(StandardCharsets.UTF_8);

        // Mirror correlation from the incoming request if possible.
        org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketHeader in =
                (req != null && req.getHeader() != null)
                        ? req.getHeader()
                        : new org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketHeader(
                        0, 0, 0, 0, org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketFlags.RESOURCE, System.currentTimeMillis()
                );

        org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketHeader out =
                new org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketHeader(
                        in.getRequestId(),
                        in.getTabId(),
                        in.getPageId(),
                        in.getFrameId(),
                        in.getFlags() | org.openautonomousconnection.protocol.versions.v1_0_1.beta.WebPacketFlags.RESOURCE,
                        System.currentTimeMillis()
                );

        return new WebResourceResponsePacket(
                out,
                code,
                "text/plain; charset=utf-8",
                HeaderMaps.mutable(),
                body,
                null
        );
    }
}