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/*
* Copyright 2013 Jeanfrancois Arcand
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/

package org.atmosphere.gwt.client.impl;

import com.google.gwt.core.client.JsArrayString;
import com.google.gwt.dom.client.BodyElement;
import com.google.gwt.dom.client.IFrameElement;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.NodeList;
import com.google.gwt.user.client.rpc.SerializationException;
import com.google.gwt.user.client.rpc.StatusCodeException;
import org.atmosphere.gwt.client.AtmosphereClient;
import org.atmosphere.gwt.client.AtmosphereClientException;
import org.atmosphere.gwt.client.AtmosphereListener;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

/**
 * @author p.havelaar
 */
public class IFrameCometTransport extends BaseCometTransport {

    private String domain;
    private IFrameElement iframe;
    private BodyElement body;
    private boolean connected;
    private boolean expectingDisconnection;

    @Override
    public void initiate(AtmosphereClient client, AtmosphereListener listener) {
        super.initiate(client, listener);

    }

    @Override
    public void connect(int connectionCount) {
        domain = getDomain(getDocumentDomain(), client.getUrl());

        StringBuilder html = new StringBuilder("");
        if (domain != null) {
            html.append("");
        }
        html.append("");

        iframe = createIFrame(html.toString());

        expectingDisconnection = false;
        String url = getUrl(connectionCount);
        if (domain != null) {
            url += "&d=" + domain;
        }
        iframe.setSrc(url);
    }

    @Override
    public void disconnect() {
        // TODO this does not seem to close the connection immediately.
        expectingDisconnection = true;
        super.disconnect();
        iframe.setSrc("");
        // perhaps this will fix disconnecting properly
        destroyIFrame();
        iframe = null;
        body = null;
        if (connected) {
            onDisconnected();
        }
        connected = false;
    }

    protected IFrameElement createIFrame(String html) {
        return createIFrameImpl(this, html);
    }

    protected void destroyIFrame() {
    }

    private static native IFrameElement createIFrameImpl(IFrameCometTransport client, String domain) /*-{
        var div = document.createElement('div'),
                iframe = document.createElement("iframe"),
                span = document.createElement('span');
        iframe.id = '--endless-iframe-comet-transport';
        iframe.setAttribute('name', '--endless-iframe-comet-transport');
        iframe.name = '--endless-iframe-comet-transport';
        iframe.style.visibility = 'hidden';

        span.innerHTML += '';

        div.id = '--endless-iframe-comet-transport-div';
        div.style.position = 'absolute';
        div.style.left = iframe.style.top = '0px';
        div.style.width = iframe.style.height = '1px';
        div.style.visibility = 'hidden';
        div.appendChild(span);
        div.appendChild(iframe);
        document.getElementsByTagName('body')[0].appendChild(div);

        window.m = $entry(function(message) {
            [email protected]::onMessages(Lcom/google/gwt/core/client/JsArrayString;)(arguments);
        });
        window.c = $entry(function(heartbeat, connectionID) {
            [email protected]::onConnected(II)(heartbeat, connectionID);
        });
        window.d = $entry(function() {
            [email protected]::onDisconnected()();
        });
        window.e = $entry(function(statusCode, message) {
            [email protected]::onError(ILjava/lang/String;)(statusCode, message);
        });
        window.h = $entry(function() {
            [email protected]::onHeartbeat()();
        });
        window.r = $entry(function() {
            [email protected]::onRefresh()();
        });
        // no $entry() because no user code is reachable
        window.t = function() {
            [email protected]::onTerminate()();
        };

        return iframe;
    }-*/;

    private native static String getDocumentDomain() /*-{
        return $doc.domain;
    }-*/;

    private native static String getDomain(String documentDomain, String url) /*-{
        var urlParts = /(^https?:)?(\/\/(([^:\/\?#]+)(:(\d+))?))?([^\?#]*)/.exec(url);
        var urlDomain = urlParts[4];

        if (!urlDomain || documentDomain == urlDomain) {
            return null;
        }

        var documentDomainParts = documentDomain.split('.');
        var urlDomainParts = urlDomain.split('.');

        var d = documentDomainParts.length - 1;
        var u = urlDomainParts.length - 1;
        var resultDomainParts = [];

        while (d >= 0 && u >= 0 && documentDomainParts[d] == urlDomainParts[u]) {
            resultDomainParts.push(urlDomainParts[u]);
            d--;
            u--;
        }
        return resultDomainParts.reverse().join('.')
    }-*/;

    private void collect() {
        if (body != null) {
            NodeList childNodes = body.getChildNodes();
            if (childNodes.getLength() > 1) {
                body.removeChild(childNodes.getItem(0));
            }
        }
    }

    @SuppressWarnings("unused")
    private void onMessages(JsArrayString arguments) {
        collect();
        int length = arguments.length();
        List messages = new ArrayList(length);
        for (int i = 0; i < length; i++) {
            String message = arguments.get(i);
            switch (message.charAt(0)) {
                case ']':
                    messages.add(message.substring(1));
                    break;
                case '[':
                case 'R':
                case 'r':
                case 'f':
                    try {
                        messages.add(parse(message));
                    } catch (SerializationException e) {
                        listener.onError(e, true);
                    }
                    break;
                default:
                    listener.onError(new AtmosphereClientException("Invalid message received: " + message), true);
            }
        }

        listener.onMessage(messages);
    }

    @SuppressWarnings("unused")
    private void onConnected(int heartbeat, int connectionID) {
        connected = true;
        body = iframe.getContentDocument().getBody();
        collect();
        this.connectionId = connectionID;
        listener.onConnected(heartbeat, connectionID);
    }

    private void onDisconnected() {
        connected = false;
        body = null;
        if (expectingDisconnection) {
            listener.onDisconnected();
        } else {
            listener.onError(new AtmosphereClientException("Unexpected disconnection"), false);
        }
    }

    @SuppressWarnings("unused")
    private void onError(int statusCode, String message) {
        listener.onError(new StatusCodeException(statusCode, message), false);
    }

    @SuppressWarnings("unused")
    private void onHeartbeat() {
        collect();
        listener.onHeartbeat();
    }

    @SuppressWarnings("unused")
    private void onRefresh() {
        collect();
        listener.onRefresh();
    }

    @SuppressWarnings("unused")
    private void onTerminate() {
        collect();
        disconnect();
    }
}