/**

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 2013-2014 Oracle and/or its affiliates. All rights reserved.

 *

 * Oracle and Java are registered trademarks of Oracle and/or its affiliates.

 * Other names may be trademarks of their respective owners.

 *

 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

 * specific language governing permissions and limitations under the

 * License.  When distributing the software, include this License Header

 * Notice in each file and include the License file at

 * nbbuild/licenses/CDDL-GPL-2-CP.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the GPL Version 2 section of the License file that

 * accompanied this code. If applicable, add the following below the

 * License Header, with the fields enclosed by brackets [] replaced by

 * your own identifying information:

 * "Portions Copyrighted [year] [name of copyright owner]"

 *

 * Contributor(s):

 *

 * The Original Software is NetBeans. The Initial Developer of the Original

 * Software is Oracle. Portions Copyright 2013-2014 Oracle. All Rights Reserved.

 *

 * If you wish your version of this file to be governed by only the CDDL

 * or only the GPL Version 2, indicate your decision by adding

 * "[Contributor] elects to include this software in this distribution

 * under the [CDDL or GPL Version 2] license." If you do not indicate a

 * single choice of license, a recipient has the option to distribute

 * your version of this file under either the CDDL, the GPL Version 2 or

 * to extend the choice of license to its licensees as provided above.

 * However, if you add GPL Version 2 code and therefore, elected the GPL

 * Version 2 license, then the option applies only if the new code is

 * made subject to such option by the copyright holder.

 */

package org.netbeans.html.xhr4j;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.PushbackInputStream;

import java.io.Reader;

import java.io.UnsupportedEncodingException;

import java.net.HttpURLConnection;

import java.net.URL;

import java.net.URLConnection;

import java.util.concurrent.Callable;

import java.util.concurrent.Executor;

import java.util.concurrent.Executors;

import java.util.concurrent.ThreadFactory;

import java.util.logging.Logger;

import net.java.html.js.JavaScriptBody;

import org.netbeans.html.json.spi.JSONCall;

/** This is an implementation package - just

 * include its JAR on classpath and use official {@link Context} API

 * to access the functionality.

 *

 * @author Jaroslav Tulach

 */

final class LoadJSON implements Runnable {

    private static final Logger LOG = Logger.getLogger(LoadJSON.class.getName());

    private static final Executor REQ = Executors.newCachedThreadPool(new ThreadFactory() {

        @Override

        public Thread newThread(Runnable runnable) {

            Thread thread = Executors.defaultThreadFactory().newThread(runnable);

            thread.setDaemon(true);

            thread.setName("xhr4j daemon");

            return thread;

        }

    });

    private final JSONCall call;

    private final URL base;

    private LoadJSON(JSONCall call) {

        this.call = call;

        this.base = null;

    }

    public static void loadJSON(JSONCall call) {

        assert !"WebSocket".equals(call.getMethod());

        REQ.execute(new LoadJSON((call)));

    }

    @Override

    public void run() {

        final String url;

        Throwable error = null;

        Object json = null;

        if (call.isJSONP()) {

            url = call.composeURL("dummy");

        } else {

            url = call.composeURL(null);

        }

        try {

            final URL u = new URL(base, url.replace(" ", "%20"));

            URLConnection conn = u.openConnection();

            if (call.isDoOutput()) {

                conn.setDoOutput(true);

            }

            String h = call.getHeaders();

            if (h != null) {

                int pos = 0;

                while (pos < h.length()) {

                    int tagEnd = h.indexOf(':', pos);

                    if (tagEnd == -1) {

                        break;

                    }

                    int r = h.indexOf('\r', tagEnd);

                    int n = h.indexOf('\n', tagEnd);

                    if (r == -1) {

                        r = h.length();

                    }

                    if (n == -1) {

                        n = h.length();

                    }

                    String key = h.substring(pos, tagEnd).trim();

                    String val = h.substring(tagEnd + 1, Math.min(r, n)).trim();

                    conn.setRequestProperty(key, val);;

                    pos = Math.max(r, n);

                }

            }

            if (call.getMethod() != null && conn instanceof HttpURLConnection) {

                ((HttpURLConnection) conn).setRequestMethod(call.getMethod());

            }

            if (call.isDoOutput()) {

                final OutputStream os = conn.getOutputStream();

                call.writeData(os);

                os.flush();

            }

            final PushbackInputStream is = new PushbackInputStream(

                conn.getInputStream(), 1

            );

            boolean[] arrayOrString = { false, false };

            detectJSONType(call.isJSONP(), is, arrayOrString);

            String response = readStream(is);

            if (call.isJSONP()) {

                response = '(' + response;

            }

            json = new Result(response, arrayOrString[0], arrayOrString[1]);

        } catch (IOException ex) {

            error = ex;

        } finally {

            if (error != null) {

                call.notifyError(error);

            } else {

                call.notifySuccess(json);

            }

        }

    }

    private static final class Result implements Callable<Object> {

        private final String response;

        private final boolean array;

        private final boolean plain;

        Result(String response, boolean array, boolean plain) {

            this.response = response;

            this.array = array;

            this.plain = plain;

        }

        @Override

        public Object call() throws Exception {

            if (plain) {

                return response;

            } else {

                if (array) {

                    Object r = parse(response);

                    Object[] arr = r instanceof Object[] ? (Object[])r : new Object[] { r };

                    for (int i = 0; i < arr.length; i++) {

                        arr[i] = new JSObjToStr(response, arr[i]);

                    }

                    return arr;

                } else {

                    return new JSObjToStr(response, parse(response));

                }

            }

        }

    }

    private static final class JSObjToStr {

        final String str;

        final Object obj;

        public JSObjToStr(Object str, Object obj) {

            this.str = str == null ? "" : str.toString();

            this.obj = obj;

        }

        @Override

        public String toString() {

            return str;

        }

    }

    static String readStream(InputStream is) throws IOException, UnsupportedEncodingException {

        Reader r = new InputStreamReader(is, "UTF-8");

        StringBuilder sb = new StringBuilder();

        char[] arr = new char[4096];

        for (;;) {

            int len = r.read(arr);

            if (len == -1) {

                break;

            }

            sb.append(arr, 0, len);

        }

        return sb.toString();

    }

    private static void detectJSONType(boolean skipAnything, final PushbackInputStream is, boolean[] arrayOrString) throws IOException {

        for (;;) {

            int ch = is.read();

            if (ch == -1) {

                arrayOrString[1] = true;

                break;

            }

            if (Character.isWhitespace(ch)) {

                continue;

            }

            if (ch == '[') {

                is.unread(ch);

                arrayOrString[0] = true;

                break;

            }

            if (ch == '{') {

                is.unread(ch);

                break;

            }

            if (!skipAnything) {

                is.unread(ch);

                arrayOrString[1] = true;

                break;

            }

        }

    }

    @JavaScriptBody(args = {"object", "property"},

        body

        = "if (property === null) return object;\n"

        + "if (object === null) return null;\n"

        + "var p = object[property]; return p ? p : null;"

    )

    private static Object getProperty(Object object, String property) {

        return null;

    }

    @JavaScriptBody(args = {"s"}, body = "return eval('(' + s + ')');")

    static Object parse(String s) {

        throw new IllegalStateException("No parser context for " + s);

    }

    static void extractJSON(Object js, String[] props, Object[] values) {

        if (js instanceof JSObjToStr) {

            js = ((JSObjToStr)js).obj;

        }

        for (int i = 0; i < props.length; i++) {

            values[i] = getProperty(js, props[i]);

        }

    }

}