/**

 * 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.vm4brwsr;

import java.io.IOException;

import java.io.InputStream;

import java.net.URL;

import java.util.Enumeration;

/** Generator of JavaScript from bytecode of classes on classpath of the VM.

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

class GenJS extends ByteCodeToJavaScript {

    public GenJS(Appendable out) {

        super(out);

    }

    static {

        // uses VMLazy to load dynamic classes

        VMLazy.init();

    }

    static void compile(Appendable out, String... names) throws IOException {

        compile(out, StringArray.asList(names));

    }

    static void compile(ClassLoader l, Appendable out, String... names) throws IOException {

        compile(l, out, StringArray.asList(names));

    }

    static void compile(Appendable out, StringArray names) throws IOException {

        compile(GenJS.class.getClassLoader(), out, names);

    }

    static void compile(ClassLoader l, Appendable out, StringArray names) throws IOException {

        new GenJS(out).doCompile(l, names);

    }

    protected void doCompile(ClassLoader l, StringArray names) throws IOException {

        out.append("(function VM(global) {");

        out.append("\n  var vm = {};");

        StringArray processed = new StringArray();

        StringArray initCode = new StringArray();

        for (String baseClass : names.toArray()) {

            references.add(baseClass);

            for (;;) {

                String name = null;

                for (String n : references.toArray()) {

                    if (processed.contains(n)) {

                        continue;

                    }

                    name = n;

                }

                if (name == null) {

                    break;

                }

                InputStream is = loadClass(l, name);

                if (is == null) {

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

                }

                try {

                    String ic = compile(is);

                    processed.add(name);

                    initCode.add(ic == null ? "" : ic);

                } catch (RuntimeException ex) {

                    if (out instanceof CharSequence) {

                        CharSequence seq = (CharSequence)out;

                        int lastBlock = seq.length();

                        while (lastBlock-- > 0) {

                            if (seq.charAt(lastBlock) == '{') {

                                break;

                            }

                        }

                        throw new IOException("Error while compiling " + name + "\n" 

                            + seq.subSequence(lastBlock + 1, seq.length()), ex

                        );

                    } else {

                        throw new IOException("Error while compiling " + name + "\n" 

                            + out, ex

                        );

                    }

                }

            }

            for (String resource : scripts.toArray()) {

                while (resource.startsWith("/")) {

                    resource = resource.substring(1);

                }

                InputStream emul = l.getResourceAsStream(resource);

                if (emul == null) {

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

                }

                readResource(emul, out);

            }

            scripts = new StringArray();

            StringArray toInit = StringArray.asList(references.toArray());

            toInit.reverse();

            for (String ic : toInit.toArray()) {

                int indx = processed.indexOf(ic);

                if (indx >= 0) {

                    out.append(initCode.toArray()[indx]).append("\n");

                    initCode.toArray()[indx] = "";

                }

            }

        }

        out.append(

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

            + "    var args = arguments;\n"

            + "    var loader = {};\n"

            + "    loader.vm = vm;\n"

            + "    loader.loadClass = function(name) {\n"

            + "      var attr = name.replace__Ljava_lang_String_2CC(name, '.','_');\n"

            + "      var fn = vm[attr];\n"

            + "      if (fn) return fn(false);\n"

            + "      return vm.org_apidesign_vm4brwsr_VMLazy(false).\n"

            + "        load___3Ljava_lang_Object_2Ljava_lang_Object_2Ljava_lang_String_2_3Ljava_lang_Object_2(loader, name, args);\n"

            + "    }\n"

            + "    return loader;\n"

            + "  };\n");

        out.append("}(this));");

    }

    private static void readResource(InputStream emul, Appendable out) throws IOException {

        try {

            int state = 0;

            for (;;) {

                int ch = emul.read();

                if (ch == -1) {

                    break;

                }

                if (ch < 0 || ch > 255) {

                    throw new IOException("Invalid char in emulation " + ch);

                }

                switch (state) {

                    case 0: 

                        if (ch == '/') {

                            state = 1;

                        } else {

                            out.append((char)ch);

                        }

                        break;

                    case 1:

                        if (ch == '*') {

                            state = 2;

                        } else {

                            out.append('/').append((char)ch);

                            state = 0;

                        }

                        break;

                    case 2:

                        if (ch == '*') {

                            state = 3;

                        }

                        break;

                    case 3:

                        if (ch == '/') {

                            state = 0;

                        } else {

                            state = 2;

                        }

                        break;

                }

            }

        } finally {

            emul.close();

        }

    }

    private static InputStream loadClass(ClassLoader l, String name) throws IOException {

        Enumeration<URL> en = l.getResources(name + ".class");

        URL u = null;

        while (en.hasMoreElements()) {

            u = en.nextElement();

        }

        if (u == null) {

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

        }

        if (u.toExternalForm().contains("rt.jar!")) {

            throw new IOException("No emulation for " + u);

        }

        return u.openStream();

    }

    static String toString(String name) throws IOException {

        StringBuilder sb = new StringBuilder();

        compile(sb, name);

        return sb.toString().toString();

    }

    private StringArray scripts = new StringArray();

    private StringArray references = new StringArray();

    @Override

    protected boolean requireReference(String cn) {

        if (references.contains(cn)) {

            return false;

        }

        references.add(cn);

        return true;

    }

    @Override

    protected void requireScript(String resourcePath) {

        scripts.add(resourcePath);

    }

    @Override

    String assignClass(String className) {

        return "vm." + className + " = ";

    }

    @Override

    String accessClass(String className) {

        return "vm." + className;

    }

}