package j2html.utils;

/*
 * JSMin.java 2006-02-13
 *
 * Copyright (c) 2006 John Reilly (www.inconspicuous.org)
 *
 * This work is a translation from C to Java of jsmin.c published by
 * Douglas Crockford.  Permission is hereby granted to use the Java
 * version under the same conditions as the jsmin.c on which it is
 * based.
 *
 *
 *
 *
 * jsmin.c 2003-04-21
 *
 * Copyright (c) 2002 Douglas Crockford (www.crockford.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * The Software shall be used for Good, not Evil.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;

public class JSMin {

    private static final int EOF = -1;
    private PushbackInputStream in;
    private OutputStream out;
    private int theA;
    private int theB;
    private JSMin(InputStream in, OutputStream out) {
        this.in = new PushbackInputStream(in);
        this.out = out;
    }

    /**
     * Compress a JS-string
     *
     * @param code the js-code you want to compress
     * @return the compressed code
     */
    public static String compressJs(String code) {
        InputStream inStream = new ByteArrayInputStream(code.getBytes());
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        JSMin jsmin = new JSMin(inStream, outStream);
        try {
            jsmin.jsmin();
            return outStream.toString().trim();
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    /**
     * isAlphanum -- return true if the character is a letter, digit,
     * underscore, dollar sign, or non-ASCII character.
     */
    private static boolean isAlphanum(int c) {
        return ((c >= 'a' && c <= 'z') ||
            (c >= '0' && c <= '9') ||
            (c >= 'A' && c <= 'Z') ||
            c == '_' ||
            c == '$' ||
            c == '\\' ||
            c > 126);
    }

    /**
     * get -- return the next character from stdin. Watch out for lookahead. If
     * the character is a control character, translate it to a space or
     * linefeed.
     */
    private int get() throws IOException {
        int c = in.read();

        if (c >= ' ' || c == '\n' || c == EOF) {
            return c;
        }

        if (c == '\r') {
            return '\n';
        }

        return ' ';
    }


    /**
     * Get the next character without getting it.
     */
    private int peek() throws IOException {
        int lookaheadChar = in.read();
        in.unread(lookaheadChar);
        return lookaheadChar;
    }

    /**
     * next -- get the next character, excluding comments. peek() is used to see
     * if a '/' is followed by a '/' or '*'.
     */
    private int next() throws IOException, UnterminatedCommentException {
        int c = get();
        if (c == '/') {
            switch (peek()) {
                case '/':
                    for (; ; ) {
                        c = get();
                        if (c <= '\n') {
                            return c;
                        }
                    }

                case '*':
                    get();
                    for (; ; ) {
                        switch (get()) {
                            case '*':
                                if (peek() == '/') {
                                    get();
                                    return ' ';
                                }
                                break;
                            case EOF:
                                throw new UnterminatedCommentException();
                        }
                    }

                default:
                    return c;
            }

        }
        return c;
    }

    /**
     * action -- do something! What you do is determined by the argument: 1
     * Output A. Copy B to A. Get the next B. 2 Copy B to A. Get the next B.
     * (Delete A). 3 Get the next B. (Delete B). action treats a string as a
     * single character. Wow! action recognizes a regular expression if it is
     * preceded by ( or , or =.
     */

    private void action(int d) throws IOException, UnterminatedRegExpLiteralException,
        UnterminatedCommentException, UnterminatedStringLiteralException {
        switch (d) {
            case 1:
                out.write(theA);
            case 2:
                theA = theB;

                if (theA == '\'' || theA == '"') {
                    for (; ; ) {
                        out.write(theA);
                        theA = get();
                        if (theA == theB) {
                            break;
                        }
                        if (theA <= '\n') {
                            throw new UnterminatedStringLiteralException();
                        }
                        if (theA == '\\') {
                            out.write(theA);
                            theA = get();
                        }
                    }
                }

            case 3:
                theB = next();
                if (theB == '/' && (theA == '(' || theA == ',' || theA == '=')) {
                    out.write(theA);
                    out.write(theB);
                    for (; ; ) {
                        theA = get();
                        if (theA == '/') {
                            break;
                        } else if (theA == '\\') {
                            out.write(theA);
                            theA = get();
                        } else if (theA <= '\n') {
                            throw new UnterminatedRegExpLiteralException();
                        }
                        out.write(theA);
                    }
                    theB = next();
                }
        }
    }

    /**
     * jsmin -- Copy the input to the output, deleting the characters which are
     * insignificant to JavaScript. Comments will be removed. Tabs will be
     * replaced with spaces. Carriage returns will be replaced with linefeeds.
     * Most spaces and linefeeds will be removed.
     */
    public void jsmin() throws IOException, UnterminatedRegExpLiteralException, UnterminatedCommentException, UnterminatedStringLiteralException {
        theA = '\n';
        action(3);
        while (theA != EOF) {
            switch (theA) {
                case ' ':
                    if (isAlphanum(theB)) {
                        action(1);
                    } else {
                        action(2);
                    }
                    break;
                case '\n':
                    switch (theB) {
                        case '{':
                        case '[':
                        case '(':
                        case '+':
                        case '-':
                            action(1);
                            break;
                        case ' ':
                            action(3);
                            break;
                        default:
                            if (isAlphanum(theB)) {
                                action(1);
                            } else {
                                action(2);
                            }
                    }
                    break;
                default:
                    switch (theB) {
                        case ' ':
                            if (isAlphanum(theA)) {
                                action(1);
                                break;
                            }
                            action(3);
                            break;
                        case '\n':
                            switch (theA) {
                                case '}':
                                case ']':
                                case ')':
                                case '+':
                                case '-':
                                case '"':
                                case '\'':
                                    action(1);
                                    break;
                                default:
                                    if (isAlphanum(theA)) {
                                        action(1);
                                    } else {
                                        action(3);
                                    }
                            }
                            break;
                        default:
                            action(1);
                            break;
                    }
            }
        }
        out.flush();
    }

    public class UnterminatedCommentException extends Exception {
    }

    public class UnterminatedStringLiteralException extends Exception {
    }

    public class UnterminatedRegExpLiteralException extends Exception {
    }

}
