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/*

 * Copyright 2009 Electronic Business Systems Ltd.

 *

 * This file is part of GSS.

 *

 * GSS is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * GSS is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with GSS.  If not, see <http://www.gnu.org/licenses/>.

 */

package gr.ebs.gss.client.rest;

import gr.ebs.gss.client.GSS;

import gr.ebs.gss.client.SessionExpiredDialog;

import com.google.gwt.http.client.RequestBuilder;

import com.google.gwt.user.client.IncrementalCommand;

/**

 * @author kman

 */

public abstract class RestCommand implements IncrementalCommand {

        protected boolean showLoadingIndicator = true;

        protected void handleHeaders(String username, RequestBuilder requestBuilder, String path){

                String date = getDate();

                requestBuilder.setHeader("X-GSS-Date", date);

                GSS app = GSS.get();

                String token = app.getToken();

                if (token == null)

                        token = "aa";

                String resource = path.substring(app.getApiPath().length()-1,path.length());

                String sig = calculateSig(requestBuilder.getHTTPMethod(), date, resource, base64decode(token));

                requestBuilder.setHeader("Authorization", username + " " + sig);

                requestBuilder.setHeader("Accept", "application/json; charset=utf-8");

        }

        protected void handleHeaders(RequestBuilder requestBuilder, String path) {

                if (GSS.get().getCurrentUserResource() != null) {

                        String username = GSS.get().getCurrentUserResource().getUsername();

                        handleHeaders(username, requestBuilder, path);

                } else

                        GSS.get().displayError("no username");

        }

        public static native String getDate()/*-{

                return (new Date()).toUTCString();

        }-*/;

        public static native String calculateSig(String method, String date, String resource, String token)/*-{

                $wnd.b64pad = "=";

                var q = resource.indexOf('?');

                var res = q == -1? resource: resource.substring(0, q);

                var data = method + date + res;

                var sig = $wnd.b64_hmac_sha1(token, data);

                return sig;

        }-*/;

        public static native String base64decode(String encStr)/*-{

                if (typeof atob === 'function') {

           return atob(encStr);

        }

        var base64s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

        var bits;

        var decOut = "";

        var i = 0;

        for(; i<encStr.length; i += 4){

            bits = (base64s.indexOf(encStr.charAt(i)) & 0xff) <<18 | (base64s.indexOf(encStr.charAt(i +1)) & 0xff) <<12 | (base64s.indexOf(encStr.charAt(i +2)) & 0xff) << 6 | base64s.indexOf(encStr.charAt(i +3)) & 0xff;

            decOut += String.fromCharCode((bits & 0xff0000) >>16, (bits & 0xff00) >>8, bits & 0xff);

        }

        if(encStr.charCodeAt(i -2) == 61){

            return(decOut.substring(0, decOut.length -2));

        }

        else if(encStr.charCodeAt(i -1) == 61){

            return(decOut.substring(0, decOut.length -1));

        }

        else {

            return(decOut);

        }

        }-*/;

        /**

         * An overridden RequestBuilder that allows us to use DELETE, HEAD and PUT methods.

         */

        protected class RestRequestBuilder extends RequestBuilder {

                public RestRequestBuilder(String httpMethod, String url) {

                        super(httpMethod, url);

                }

        }

        public void onComplete(){}

        public abstract void onError(Throwable t);

        public String fixPath(String pathToFix){

                if(pathToFix.endsWith("/"))

                        return pathToFix;

                return pathToFix+"/";

        }

        /**

         * Retrieve the showLoadingIndicator.

         *

         * @return the showLoadingIndicator

         */

        public boolean isShowLoadingIndicator() {

                return showLoadingIndicator;

        }

        /**

         * Modify the showLoadingIndicator.

         *

         * @param newShowLoadingIndicator the showLoadingIndicator to set

         */

        public void setShowLoadingIndicator(boolean newShowLoadingIndicator) {

                showLoadingIndicator = newShowLoadingIndicator;

        }

        static void sessionExpired(){

                SessionExpiredDialog dlg = new SessionExpiredDialog();

                dlg.center();

        }

}