/**

 * 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.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedHashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

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

 *

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

 */

final class GenJS {

    private GenJS() {}

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

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

    }

    static void compile(Appendable out, List<String> names) throws IOException {

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

    }

    static void compile(ClassLoader l, Appendable out, List<String> names) throws IOException {

        final Map<String,String> processed = new HashMap<String, String>();

        for (String baseClass : names) {

            LinkedHashSet<String> toProcess = new LinkedHashSet<String>() {

                @Override

                public boolean add(String e) {

                    if (processed.containsKey(e)) {

                        return false;

                    }

                    return super.add(e);

                }

            };

            toProcess.add(baseClass);

            for (;;) {

                String name = null;

                Iterator<String> it = toProcess.iterator();

                while (it.hasNext() && name == null) {

                    String n = it.next();

                    if (processed.get(n) != null) {

                        continue;

                    }

                    name = n;

                }

                if (name == null) {

                    break;

                }

                if (name.startsWith("sun/")) {

                    processed.put(name, "");

                    continue;

                }            

                InputStream is = loadClass(l, name);

                if (is == null) {

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

                }

                LinkedList<String> scripts = new LinkedList<String>();

                try {

                    String initCode = ByteCodeToJavaScript.compile(is, out, toProcess, scripts);

                    processed.put(name, initCode == null ? "" : initCode);

                } 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) {

                    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);

                }

            }

            List<String> toInit = new ArrayList<String>(toProcess);

            Collections.reverse(toInit);

            for (String clazz : toInit) {

                String initCode = processed.get(clazz);

                if (initCode != null && !initCode.isEmpty()) {

                    out.append(initCode).append("\n");

                    processed.put(clazz, "");

                }

            }

        }

    }

    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);

        }

        return u.openStream();

    }

    static String toString(String name) throws IOException {

        StringBuilder sb = new StringBuilder();

        compile(sb, name);

        return sb.toString().toString();

    }

}