package org.openautonomousconnection.luascript.runtime;

import javafx.concurrent.Worker;
import javafx.scene.web.WebEngine;
import org.luaj.vm2.Globals;
import org.openautonomousconnection.luascript.fx.FxDomHost;
import org.openautonomousconnection.luascript.fx.FxEventHost;
import org.openautonomousconnection.luascript.fx.FxUiHost;
import org.openautonomousconnection.luascript.fx.FxWebViewResourceHost;
import org.openautonomousconnection.luascript.hosts.AudioHost;
import org.openautonomousconnection.luascript.hosts.HostServices;
import org.openautonomousconnection.luascript.security.LuaExecutionPolicy;
import org.openautonomousconnection.luascript.utils.LuaGlobalsFactory;

import java.util.Objects;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * JavaFX WebView integration entry point for LuaScript (no JavaScript).
 *
 * <p>Hard rule: every HTML script tag is treated as Lua.</p>
 */
public final class FxLuaScriptEngine implements AutoCloseable {

    private final WebEngine engine;
    private final LuaExecutionPolicy policy;

    private final AtomicBoolean bootstrapped = new AtomicBoolean(false);

    private LuaRuntime runtime;

    /**
     * Creates an integration engine with default UI execution policy.
     *
     * @param engine web engine
     */
    public FxLuaScriptEngine(WebEngine engine) {
        this(engine, LuaExecutionPolicy.uiDefault());
    }

    /**
     * Creates an integration engine with a custom execution policy.
     *
     * @param engine web engine
     * @param policy execution policy
     */
    public FxLuaScriptEngine(WebEngine engine, LuaExecutionPolicy policy) {
        this.engine = Objects.requireNonNull(engine, "engine");
        this.policy = Objects.requireNonNull(policy, "policy");
    }

    /**
     * Installs a load hook that bootstraps Lua when a page finished loading.
     */
    public void install() {
        engine.getLoadWorker().stateProperty().addListener((obs, oldState, newState) -> {
            if (newState == Worker.State.SUCCEEDED) {
                bootstrapped.set(false);
                bootstrap();
            } else if (newState == Worker.State.CANCELLED || newState == Worker.State.FAILED) {
                bootstrapped.set(false);
                closeRuntimeQuietly();
            }
        });
    }

    /**
     * Bootstraps Lua for the currently loaded document.
     */
    public void bootstrap() {
        if (!bootstrapped.compareAndSet(false, true)) return;

        closeRuntimeQuietly();

        // DOM host must exist before event/UI tables, and must ensure stable ids.
        FxDomHost dom = new FxDomHost(engine);
        dom.ensureAllElementsHaveId();

        // Create per-page globals; harden sandbox in production.
        Globals globals = LuaGlobalsFactory.create(
                new LuaGlobalsFactory.Options()
                        .enableDebug(false)
                        .sandbox(true)
        );

        HostServices.StdoutConsole console = new HostServices.StdoutConsole("[lua] ");
        FxUiHost uiHost = new FxUiHost(engine, dom);
        FxWebViewResourceHost resourceHost = new FxWebViewResourceHost(engine);
        FxEventHost eventHost = new FxEventHost(dom);
        // TODO: Default implementation or parameter for "audioHost"
        HostServices services = new HostServices.Default(uiHost, dom, eventHost, resourceHost, console, audioHost);
        LuaRuntime rt = new LuaRuntime(globals, services, policy);
        eventHost.setRouter(rt.eventRouter());

        rt.installStdTables(true);
        rt.bootstrapFromDom();

        this.runtime = rt;
    }

    /**
     * Returns active runtime or null if not bootstrapped.
     *
     * @return runtime or null
     */
    public LuaRuntime runtimeOrNull() {
        return runtime;
    }

    @Override
    public void close() {
        closeRuntimeQuietly();
    }

    private void closeRuntimeQuietly() {
        LuaRuntime rt = this.runtime;
        this.runtime = null;
        if (rt != null) {
            try {
                rt.close();
            } catch (Exception ignored) {
                // Best-effort shutdown.
            }
        }
    }
}