/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program 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, version 2 of the License.

 *

 * This program 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 this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.launcher;

import java.io.Closeable;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InterruptedIOException;

import java.io.OutputStream;

import java.io.UnsupportedEncodingException;

import java.io.Writer;

import java.net.URI;

import java.net.URISyntaxException;

import java.net.URL;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Enumeration;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Set;

import java.util.concurrent.BlockingQueue;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.LinkedBlockingQueue;

import java.util.concurrent.TimeUnit;

import java.util.logging.Level;

import java.util.logging.Logger;

import org.apidesign.bck2brwsr.launcher.InvocationContext.Resource;

import org.apidesign.vm4brwsr.Bck2Brwsr;

import org.glassfish.grizzly.PortRange;

import org.glassfish.grizzly.http.server.HttpHandler;

import org.glassfish.grizzly.http.server.HttpServer;

import org.glassfish.grizzly.http.server.NetworkListener;

import org.glassfish.grizzly.http.server.Request;

import org.glassfish.grizzly.http.server.Response;

import org.glassfish.grizzly.http.server.ServerConfiguration;

import org.glassfish.grizzly.http.util.HttpStatus;

/**

 * Lightweight server to launch Bck2Brwsr applications and tests.

 * Supports execution in native browser as well as Java's internal 

 * execution engine.

 */

final class Bck2BrwsrLauncher extends Launcher implements Closeable {

    private static final Logger LOG = Logger.getLogger(Bck2BrwsrLauncher.class.getName());

    private static final InvocationContext END = new InvocationContext(null, null, null);

    private final Set<ClassLoader> loaders = new LinkedHashSet<>();

    private final BlockingQueue<InvocationContext> methods = new LinkedBlockingQueue<>();

    private long timeOut;

    private final Res resources = new Res();

    private final String cmd;

    private Object[] brwsr;

    private HttpServer server;

    private CountDownLatch wait;

    public Bck2BrwsrLauncher(String cmd) {

        this.cmd = cmd;

    }

    @Override

    InvocationContext runMethod(InvocationContext c) throws IOException {

        loaders.add(c.clazz.getClassLoader());

        methods.add(c);

        try {

            c.await(timeOut);

        } catch (InterruptedException ex) {

            throw new IOException(ex);

        }

        return c;

    }

    public void setTimeout(long ms) {

        timeOut = ms;

    }

    public void addClassLoader(ClassLoader url) {

        this.loaders.add(url);

    }

    public void showURL(String startpage) throws IOException {

        if (!startpage.startsWith("/")) {

            startpage = "/" + startpage;

        }

        HttpServer s = initServer(".", true);

        int last = startpage.lastIndexOf('/');

        String prefix = startpage.substring(0, last);

        String simpleName = startpage.substring(last);

        s.getServerConfiguration().addHttpHandler(new SubTree(resources, prefix), "/");

        try {

            launchServerAndBrwsr(s, simpleName);

        } catch (URISyntaxException | InterruptedException ex) {

            throw new IOException(ex);

        }

    }

    void showDirectory(File dir, String startpage) throws IOException {

        if (!startpage.startsWith("/")) {

            startpage = "/" + startpage;

        }

        HttpServer s = initServer(dir.getPath(), false);

        try {

            launchServerAndBrwsr(s, startpage);

        } catch (URISyntaxException | InterruptedException ex) {

            throw new IOException(ex);

        }

    }

    @Override

    public void initialize() throws IOException {

        try {

            executeInBrowser();

        } catch (InterruptedException ex) {

            final InterruptedIOException iio = new InterruptedIOException(ex.getMessage());

            iio.initCause(ex);

            throw iio;

        } catch (Exception ex) {

            if (ex instanceof IOException) {

                throw (IOException)ex;

            }

            if (ex instanceof RuntimeException) {

                throw (RuntimeException)ex;

            }

            throw new IOException(ex);

        }

    }

    private HttpServer initServer(String path, boolean addClasses) throws IOException {

        HttpServer s = HttpServer.createSimpleServer(path, new PortRange(8080, 65535));

        final ServerConfiguration conf = s.getServerConfiguration();

        if (addClasses) {

            conf.addHttpHandler(new VM(resources), "/bck2brwsr.js");

            conf.addHttpHandler(new Classes(resources), "/classes/");

        }

        return s;

    }

    private void executeInBrowser() throws InterruptedException, URISyntaxException, IOException {

        wait = new CountDownLatch(1);

        server = initServer(".", true);

        final ServerConfiguration conf = server.getServerConfiguration();

        class DynamicResourceHandler extends HttpHandler {

            private final InvocationContext ic;

            public DynamicResourceHandler(InvocationContext ic) {

                if (ic == null || ic.resources.isEmpty()) {

                    throw new NullPointerException();

                }

                this.ic = ic;

                for (Resource r : ic.resources) {

                    conf.addHttpHandler(this, r.httpPath);

                }

            }

            public void close() {

                conf.removeHttpHandler(this);

            }

            @Override

            public void service(Request request, Response response) throws Exception {

                for (Resource r : ic.resources) {

                    if (r.httpPath.equals(request.getRequestURI())) {

                        LOG.log(Level.INFO, "Serving HttpResource for {0}", request.getRequestURI());

                        response.setContentType(r.httpType);

                        r.httpContent.reset();

                        copyStream(r.httpContent, response.getOutputStream(), null);

                    }

                }

            }

        }

        conf.addHttpHandler(new Page(resources, 

            "org/apidesign/bck2brwsr/launcher/harness.xhtml"

        ), "/execute");

        conf.addHttpHandler(new HttpHandler() {

            int cnt;

            List<InvocationContext> cases = new ArrayList<>();

            DynamicResourceHandler prev;

            @Override

            public void service(Request request, Response response) throws Exception {

                String id = request.getParameter("request");

                String value = request.getParameter("result");

                if (value != null && value.indexOf((char)0xC5) != -1) {

                    value = toUTF8(value);

                }

                InvocationContext mi = null;

                int caseNmbr = -1;

                if (id != null && value != null) {

                    LOG.log(Level.INFO, "Received result for case {0} = {1}", new Object[]{id, value});

                    value = decodeURL(value);

                    int indx = Integer.parseInt(id);

                    cases.get(indx).result(value, null);

                    if (++indx < cases.size()) {

                        mi = cases.get(indx);

                        LOG.log(Level.INFO, "Re-executing case {0}", indx);

                        caseNmbr = indx;

                    }

                } else {

                    if (!cases.isEmpty()) {

                        LOG.info("Re-executing test cases");

                        mi = cases.get(0);

                        caseNmbr = 0;

                    }

                }

                if (prev != null) {

                    prev.close();

                    prev = null;

                }

                if (mi == null) {

                    mi = methods.take();

                    caseNmbr = cnt++;

                }

                if (mi == END) {

                    response.getWriter().write("");

                    wait.countDown();

                    cnt = 0;

                    LOG.log(Level.INFO, "End of data reached. Exiting.");

                    return;

                }

                if (!mi.resources.isEmpty()) {

                    prev = new DynamicResourceHandler(mi);

                }

                cases.add(mi);

                final String cn = mi.clazz.getName();

                final String mn = mi.methodName;

                LOG.log(Level.INFO, "Request for {0} case. Sending {1}.{2}", new Object[]{caseNmbr, cn, mn});

                response.getWriter().write("{"

                    + "className: '" + cn + "', "

                    + "methodName: '" + mn + "', "

                    + "request: " + caseNmbr

                );

                if (mi.html != null) {

                    response.getWriter().write(", html: '");

                    response.getWriter().write(encodeJSON(mi.html));

                    response.getWriter().write("'");

                }

                response.getWriter().write("}");

            }

        }, "/data");

        this.brwsr = launchServerAndBrwsr(server, "/execute");

    }

    private static String encodeJSON(String in) {

        StringBuilder sb = new StringBuilder();

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

            char ch = in.charAt(i);

            if (ch < 32 || ch == '\'' || ch == '"') {

                sb.append("\\u");

                String hs = "0000" + Integer.toHexString(ch);

                hs = hs.substring(hs.length() - 4);

                sb.append(hs);

            } else {

                sb.append(ch);

            }

        }

        return sb.toString();

    }

    @Override

    public void shutdown() throws IOException {

        methods.offer(END);

        for (;;) {

            int prev = methods.size();

            try {

                if (wait != null && wait.await(timeOut, TimeUnit.MILLISECONDS)) {

                    break;

                }

            } catch (InterruptedException ex) {

                throw new IOException(ex);

            }

            if (prev == methods.size()) {

                LOG.log(

                    Level.WARNING, 

                    "Timeout and no test has been executed meanwhile (at {0}). Giving up.", 

                    methods.size()

                );

                break;

            }

            LOG.log(Level.INFO, 

                "Timeout, but tests got from {0} to {1}. Trying again.", 

                new Object[]{prev, methods.size()}

            );

        }

        stopServerAndBrwsr(server, brwsr);

    }

    static void copyStream(InputStream is, OutputStream os, String baseURL, String... params) throws IOException {

        for (;;) {

            int ch = is.read();

            if (ch == -1) {

                break;

            }

            if (ch == '$' && params.length > 0) {

                int cnt = is.read() - '0';

                if (cnt == 'U' - '0') {

                    os.write(baseURL.getBytes("UTF-8"));

                } else {

                    if (cnt >= 0 && cnt < params.length) {

                        os.write(params[cnt].getBytes("UTF-8"));

                    } else {

                        os.write('$');

                        os.write(cnt + '0');

                    }

                }

            } else {

                os.write(ch);

            }

        }

    }

    private Object[] launchServerAndBrwsr(HttpServer server, final String page) throws IOException, URISyntaxException, InterruptedException {

        server.start();

        NetworkListener listener = server.getListeners().iterator().next();

        int port = listener.getPort();

        URI uri = new URI("http://localhost:" + port + page);

        LOG.log(Level.INFO, "Showing {0}", uri);

        if (cmd == null) {

            try {

                LOG.log(Level.INFO, "Trying Desktop.browse on {0} {2} by {1}", new Object[] {

                    System.getProperty("java.vm.name"),

                    System.getProperty("java.vm.vendor"),

                    System.getProperty("java.vm.version"),

                });

                java.awt.Desktop.getDesktop().browse(uri);

                LOG.log(Level.INFO, "Desktop.browse successfully finished");

                return null;

            } catch (UnsupportedOperationException ex) {

                LOG.log(Level.INFO, "Desktop.browse not supported: {0}", ex.getMessage());

                LOG.log(Level.FINE, null, ex);

            }

        }

        {

            String cmdName = cmd == null ? "xdg-open" : cmd;

            String[] cmdArr = { 

                cmdName, uri.toString()

            };

            LOG.log(Level.INFO, "Launching {0}", Arrays.toString(cmdArr));

            final Process process = Runtime.getRuntime().exec(cmdArr);

            return new Object[] { process, null };

        }

    }

    private static String toUTF8(String value) throws UnsupportedEncodingException {

        byte[] arr = new byte[value.length()];

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

            arr[i] = (byte)value.charAt(i);

        }

        return new String(arr, "UTF-8");

    }

    private static String decodeURL(String s) {

        for (;;) {

            int pos = s.indexOf('%');

            if (pos == -1) {

                return s;

            }

            int i = Integer.parseInt(s.substring(pos + 1, pos + 2), 16);

            s = s.substring(0, pos) + (char)i + s.substring(pos + 2);

        }

    }

    private void stopServerAndBrwsr(HttpServer server, Object[] brwsr) throws IOException {

        if (brwsr == null) {

            return;

        }

        Process process = (Process)brwsr[0];

        server.stop();

        InputStream stdout = process.getInputStream();

        InputStream stderr = process.getErrorStream();

        drain("StdOut", stdout);

        drain("StdErr", stderr);

        process.destroy();

        int res;

        try {

            res = process.waitFor();

        } catch (InterruptedException ex) {

            throw new IOException(ex);

        }

        LOG.log(Level.INFO, "Exit code: {0}", res);

        deleteTree((File)brwsr[1]);

    }

    private static void drain(String name, InputStream is) throws IOException {

        int av = is.available();

        if (av > 0) {

            StringBuilder sb = new StringBuilder();

            sb.append("v== ").append(name).append(" ==v\n");

            while (av-- > 0) {

                sb.append((char)is.read());

            }

            sb.append("\n^== ").append(name).append(" ==^");

            LOG.log(Level.INFO, sb.toString());

        }

    }

    private void deleteTree(File file) {

        if (file == null) {

            return;

        }

        File[] arr = file.listFiles();

        if (arr != null) {

            for (File s : arr) {

                deleteTree(s);

            }

        }

        file.delete();

    }

    @Override

    public void close() throws IOException {

        shutdown();

    }

    private class Res implements Bck2Brwsr.Resources {

        @Override

        public InputStream get(String resource) throws IOException {

            for (ClassLoader l : loaders) {

                URL u = null;

                Enumeration<URL> en = l.getResources(resource);

                while (en.hasMoreElements()) {

                    u = en.nextElement();

                }

                if (u != null) {

                    return u.openStream();

                }

            }

            throw new IOException("Can't find " + resource);

        }

    }

    private static class Page extends HttpHandler {

        final String resource;

        private final String[] args;

        private final Res res;

        public Page(Res res, String resource, String... args) {

            this.res = res;

            this.resource = resource;

            this.args = args.length == 0 ? new String[] { "$0" } : args;

        }

        @Override

        public void service(Request request, Response response) throws Exception {

            String r = computePage(request);

            if (r.startsWith("/")) {

                r = r.substring(1);

            }

            String[] replace = {};

            if (r.endsWith(".html")) {

                response.setContentType("text/html");

                LOG.info("Content type text/html");

                replace = args;

            }

            if (r.endsWith(".xhtml")) {

                response.setContentType("application/xhtml+xml");

                LOG.info("Content type application/xhtml+xml");

                replace = args;

            }

            OutputStream os = response.getOutputStream();

            try (InputStream is = res.get(r)) {

                copyStream(is, os, request.getRequestURL().toString(), replace);

            } catch (IOException ex) {

                response.setDetailMessage(ex.getLocalizedMessage());

                response.setError();

                response.setStatus(404);

            }

        }

        protected String computePage(Request request) {

            String r = resource;

            if (r == null) {

                r = request.getHttpHandlerPath();

            }

            return r;

        }

    }

    private static class SubTree extends Page {

        public SubTree(Res res, String resource, String... args) {

            super(res, resource, args);

        }

        @Override

        protected String computePage(Request request) {

            return resource + request.getHttpHandlerPath();

        }

    }

    private static class VM extends HttpHandler {

        private final String bck2brwsr;

        public VM(Res loader) throws IOException {

            StringBuilder sb = new StringBuilder();

            Bck2Brwsr.generate(sb, loader);

            sb.append(

                  "(function WrapperVM(global) {"

                + "  function ldCls(res) {\n"

                + "    var request = new XMLHttpRequest();\n"

                + "    request.open('GET', '/classes/' + res, false);\n"

                + "    request.send();\n"

                + "    if (request.status !== 200) return null;\n"

                + "    var arr = eval('(' + request.responseText + ')');\n"

                + "    return arr;\n"

                + "  }\n"

                + "  var prevvm = global.bck2brwsr;\n"

                + "  global.bck2brwsr = function() {\n"

                + "    var args = Array.prototype.slice.apply(arguments);\n"

                + "    args.unshift(ldCls);\n"

                + "    return prevvm.apply(null, args);\n"

                + "  };\n"

                + "})(this);\n"

            );

            this.bck2brwsr = sb.toString();

        }

        @Override

        public void service(Request request, Response response) throws Exception {

            response.setCharacterEncoding("UTF-8");

            response.setContentType("text/javascript");

            response.getWriter().write(bck2brwsr);

        }

    }

    private static class Classes extends HttpHandler {

        private final Res loader;

        public Classes(Res loader) {

            this.loader = loader;

        }

        @Override

        public void service(Request request, Response response) throws Exception {

            String res = request.getHttpHandlerPath();

            if (res.startsWith("/")) {

                res = res.substring(1);

            }

            try (InputStream is = loader.get(res)) {

                response.setContentType("text/javascript");

                Writer w = response.getWriter();

                w.append("[");

                for (int i = 0;; i++) {

                    int b = is.read();

                    if (b == -1) {

                        break;

                    }

                    if (i > 0) {

                        w.append(", ");

                    }

                    if (i % 20 == 0) {

                        w.write("\n");

                    }

                    if (b > 127) {

                        b = b - 256;

                    }

                    w.append(Integer.toString(b));

                }

                w.append("\n]");

            } catch (IOException ex) {

                response.setStatus(HttpStatus.NOT_FOUND_404);

                response.setError();

                response.setDetailMessage(ex.getMessage());

            }

        }

    }

}