package org.apidesign.vm4brwsr;

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.Writer;

import java.net.URL;

import java.util.Arrays;

import java.util.Enumeration;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.Set;

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

 *

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

 */

final class GenJS {

    private GenJS() {}

    public static void main(String... args) throws IOException {

        if (args.length < 2) {

            System.err.println("Usage: java -cp ... -jar ... <file_to_generate_js_code_to> java/lang/Class org/your/App ...");

            return;

        }

        Writer w = new BufferedWriter(new FileWriter(args[0]));

        List<String> classes = Arrays.asList(args).subList(1, args.length);

        compile(w, classes);

        w.close();

    }

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

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

    }

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

        Set<String> processed = new HashSet<String>();

        LinkedList<String> toProcess = new LinkedList<String>(names);

        for (;;) {

            toProcess.removeAll(processed);

            if (toProcess.isEmpty()) {

                break;

            }

            String name = toProcess.getFirst();

            processed.add(name);

            if (name.startsWith("java/")

                && !name.equals("java/lang/Object")

                && !name.equals("java/lang/Class")

                && !name.equals("java/lang/Number")

                && !name.equals("java/lang/Integer")

                && !name.equals("java/lang/Throwable")

                && !name.equals("java/lang/Exception")

                && !name.equals("java/lang/RuntimeException")

                && !name.equals("java/lang/UnsupportedOperationException")

                && !name.equals("java/lang/String")

                && !name.equals("java/lang/String$CaseInsensitiveComparator")

                && !name.equals("java/lang/StringBuilder")

                && !name.equals("java/lang/AbstractStringBuilder")

            ) {

                continue;

            }            

            InputStream is = loadClass(name);

            if (is == null) {

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

            }

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

            try {

                ByteCodeToJavaScript.compile(is, out, toProcess, scripts);

            } 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) {

                InputStream emul = GenJS.class.getResourceAsStream(resource);

                if (emul == null) {

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

                }

                readResource(emul, out);

            }

        }

    }

    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(String name) throws IOException {

        Enumeration<URL> en = ClassLoader.getSystemClassLoader().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();

    }

}