package Torello.Browser;


import javax.json.*;
import java.io.*;

import NeoVisionaries.WebSockets.*;

import Torello.Java.*;
import Torello.Java.Additional.*;

import static Torello.Java.C.*;

import java.util.concurrent.ConcurrentHashMap;
import java.util.List;
import java.util.Objects;
import java.lang.reflect.Constructor;
import java.util.function.Consumer;

/**
 * This class implements a connection to a Web-Browser using the Remote Debug Protocol over
 * Web-Sockets.
 * 
 * <H3 STYLE='background: black; color: white; padding: 0.5em;'>Browser Remote Debug Protocol
 * Connection Class</H3>
 * 
 * <BR />Java is capable of communicating with either a Headless instance of Google Chrome - <I>or
 * any browser that implements the Remote Debuggin Protocol</I>.  It is not mandatory to run the
 * browser in headless mode, but it is more common.
 */
@SuppressWarnings({"rawtypes", "unchecked"})
public class WebSocketSender implements Sender<String>
{
    // ********************************************************************************************
    // ********************************************************************************************
    // Main Fields
    // ********************************************************************************************
    // ********************************************************************************************


    // The Browser Connection
    private final WebSocket webSocket;

    // Stores the lists of promises
    private ConcurrentHashMap<Integer, Promise<JsonObject, ? extends Object>> promises =
        new ConcurrentHashMap<>();


    // ********************************************************************************************
    // ********************************************************************************************
    // User-Provided Handler Fields
    // ********************************************************************************************
    // ********************************************************************************************


    final Consumer<BrowserEvent> eventHandler;

    final Consumer<RDPError> rdpErrorHandler;

    final Consumer<BrowserError> browserErrorHandler;


    // ********************************************************************************************
    // ********************************************************************************************
    // Output Log Text Fields
    // ********************************************************************************************
    // ********************************************************************************************


    private AppendableSafe raw =
        new AppendableSafe(System.out, WebSocketSender::handleLogIOE);

    private AppendableSafe app =
        new AppendableSafe(System.out, WebSocketSender::handleLogIOE);

    private AppendableSafe err =
        new AppendableSafe(System.out, WebSocketSender::handleLogIOE);

    AppendableSafe raw() { return raw; }
    AppendableSafe app() { return app; }
    AppendableSafe err() { return err; }

    /** <EMBED CLASS='external-html' DATA-FILE-ID=WSS_RAW_LOG> */
    public AppendableSafe setRawFrameLog(Appendable a)
    { return this.raw = new AppendableSafe(a, WebSocketSender::handleLogIOE); }

    /** <EMBED CLASS='external-html' DATA-FILE-ID=WSS_APP_LOG> */
    public AppendableSafe setApplicationLayerLog(Appendable a)
    { return this.app = new AppendableSafe(a, WebSocketSender::handleLogIOE); }

    /** <EMBED CLASS='external-html' DATA-FILE-ID=WSS_ERR_LOG> */
    public AppendableSafe setErrorLog(Appendable a)
    { return this.app = new AppendableSafe(a, WebSocketSender::handleLogIOE); }

    private static void handleLogIOE(final IOException ioe)
    {
        System.err.println(
            "There has been an exception throw while attempting to write to an output log.\n" +
            "Cannot Proceed"
        );

        throw new UnreachableError();
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Constructor
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * Opens a Connection to a Web Browser using a Web-Socket.  This class will now be
     * ready to accept {@link #send(int, String, Promise)} messages to the browser.
     * 
     * @param url This is a {@code URL} that is generated by the browser, and has a base
     * {@code URL} that is just {@code 127.0.0.1}, followed by a <B STYLE='color:red'>port
     * number</B>.  There will also be an <B STYLE='color:red;'>identifier-code</B>.
     * 
     * @throws IOException Throws if there are problems connecting the socket.
     * 
     * @throws WebSocketException Throws if the NeoVisionaries Package encounters a problem
     * building the socket connection.
     */
    public WebSocketSender(
            final String                    url,
            final Consumer<BrowserEvent>    eventHandler,
            final Consumer<RDPError>        rdpErrorHandler,
            final Consumer<BrowserError>    browserErrorHandler
        )
        throws IOException, WebSocketException
    {
        Objects.requireNonNull(url,             "Parameter 'url' has been passed null.");
        Objects.requireNonNull(eventHandler,    "Parameter 'eventHandler' has been passed null.");

        this.rdpErrorHandler = (rdpErrorHandler == null)
            ? RDPError.NO_OP
            : rdpErrorHandler;

        this.browserErrorHandler = (browserErrorHandler == null)
            ? (BrowserError be) -> {}
            : browserErrorHandler;

        this.eventHandler = eventHandler;

        final WebSocketListener webSocketListener =
            new WSAdapter(this, this.promises);

        this.webSocket = new WebSocketFactory()
            .createSocket(url)
            .addListener(webSocketListener)
            .connect();

        System.out.println
            (BYELLOW_BKGND + BBLACK + " Web Socket Connection Opened: " + RESET + url);
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Two Instance Methods
    // ********************************************************************************************
    // ********************************************************************************************


    /** Closes the {@link WebSocket} connection to the Browser's Remote Debug Port. */
    public void disconnect() { webSocket.disconnect(); }

    /**
     * This method is the implementation-method for the {@link Sender} Functional-Interface.  This
     * message accepts a <B STYLE='color; red;'>Request &amp; ID</B> pair, and then transmits that
     * request to a Browser's Remote-Debugging Port over the {@code WebSocket}.  It keeps the
     * {@link Promise} that was created by the {@link Script} that sent this request, and saves
     * that {@code Promise} until the Web-Socket receives a response about the request.
     * 
     * @param requestID This may be any number.  It is used to map requests sent over the Web
     * Socket to responses received from it.
     * 
     * @param requestJSON This is the JSON Method Request sent to the Browser
     * 
     * @param promise This is a {@code Promise} which is automatically generated by the 
     * {@link Script} object that is sending the request.
     */
    public void send(int requestID, String requestJSON, Promise promise)
    {
        this.promises.put(requestID, promise);

        // Print the request-message that is about to be sent, and then send it.
        app.append(BGREEN_BKGND + " Sending JSON: " + RESET + '\n' + requestJSON);

        try
            { webSocket.sendText(requestJSON); }

        catch (Exception e)
        {
            throw new AsynchronousException(
                "When attempting to send a JSON Request, an Exception was thrown:\n" + 
                e.getMessage() + "\nSee Exception getCause() for details.", e
            );
        }
    }
}