/**
 *    Copyright 2009-2017 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package com.googlecode.htmlcompressor.taglib;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.javascript.jscomp.CompilationLevel;
import com.googlecode.htmlcompressor.compressor.ClosureJavaScriptCompressor;
import com.googlecode.htmlcompressor.compressor.HtmlCompressor;
import com.googlecode.htmlcompressor.compressor.YuiJavaScriptCompressor;

/**
 * JSP tag that compresses an JavaScript content within &lt;compress:js&gt; tags. All JavaScript-related properties from
 * {@link HtmlCompressor} are supported.
 *
 * @author <a href="mailto:serg472@gmail.com">Sergiy Kovalchuk</a>
 * @see HtmlCompressor
 * @see <a href="http://developer.yahoo.com/yui/compressor/">Yahoo YUI Compressor</a>
 * @see <a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a>
 */
public class JavaScriptCompressorTag extends BodyTagSupport {

    /** The Constant serialVersionUID. */
    private static final long   serialVersionUID = 1L;

    /** The Constant logger. */
    private static final Logger logger           = LoggerFactory.getLogger(JavaScriptCompressorTag.class);

    /** The enabled. */
    private boolean             enabled          = true;

    /** The js compressor. */
    private String              jsCompressor     = HtmlCompressor.JS_COMPRESSOR_YUI;

    // YUICompressor settings

    /** The yui js no munge. */
    private boolean             yuiJsNoMunge;

    /** The yui js preserve all semi colons. */
    private boolean             yuiJsPreserveAllSemiColons;

    /** The yui js disable optimizations. */
    private boolean             yuiJsDisableOptimizations;

    /** The yui js line break. */
    private int                 yuiJsLineBreak   = -1;

    // Closure compressor settings

    /** The closure opt level. */
    private String              closureOptLevel  = ClosureJavaScriptCompressor.COMPILATION_LEVEL_SIMPLE;

    @Override
    public int doEndTag() throws JspException {

        BodyContent bodyContent = getBodyContent();
        String content = bodyContent.getString();

        try {
            if (enabled) {

                String result;

                if (jsCompressor.equalsIgnoreCase(HtmlCompressor.JS_COMPRESSOR_CLOSURE)) {
                    // call Closure compressor
                    ClosureJavaScriptCompressor closureCompressor = new ClosureJavaScriptCompressor();
                    if (closureOptLevel.equalsIgnoreCase(ClosureJavaScriptCompressor.COMPILATION_LEVEL_ADVANCED)) {
                        closureCompressor.setCompilationLevel(CompilationLevel.ADVANCED_OPTIMIZATIONS);
                    } else if (closureOptLevel
                            .equalsIgnoreCase(ClosureJavaScriptCompressor.COMPILATION_LEVEL_WHITESPACE)) {
                        closureCompressor.setCompilationLevel(CompilationLevel.WHITESPACE_ONLY);
                    } else {
                        closureCompressor.setCompilationLevel(CompilationLevel.SIMPLE_OPTIMIZATIONS);
                    }

                    result = closureCompressor.compress(content);

                } else {
                    // call YUICompressor
                    YuiJavaScriptCompressor yuiCompressor = new YuiJavaScriptCompressor();
                    yuiCompressor.setDisableOptimizations(yuiJsDisableOptimizations);
                    yuiCompressor.setLineBreak(yuiJsLineBreak);
                    yuiCompressor.setNoMunge(yuiJsNoMunge);
                    yuiCompressor.setPreserveAllSemiColons(yuiJsPreserveAllSemiColons);

                    result = yuiCompressor.compress(content);
                }

                bodyContent.clear();
                bodyContent.append(result);
                bodyContent.writeOut(pageContext.getOut());
            } else {
                bodyContent.clear();
                bodyContent.append(content);
                bodyContent.writeOut(pageContext.getOut());
            }

        } catch (IOException e) {
            logger.error("", e);
        }

        return super.doEndTag();
    }

    /**
     * Sets the yui js no munge.
     *
     * @param yuiJsNoMunge
     *            the new yui js no munge
     * @see HtmlCompressor#setYuiJsNoMunge(boolean)
     */
    public void setYuiJsNoMunge(boolean yuiJsNoMunge) {
        this.yuiJsNoMunge = yuiJsNoMunge;
    }

    /**
     * Sets the yui js preserve all semi colons.
     *
     * @param yuiJsPreserveAllSemiColons
     *            the new yui js preserve all semi colons
     * @see HtmlCompressor#setYuiJsPreserveAllSemiColons(boolean)
     */
    public void setYuiJsPreserveAllSemiColons(boolean yuiJsPreserveAllSemiColons) {
        this.yuiJsPreserveAllSemiColons = yuiJsPreserveAllSemiColons;
    }

    /**
     * Sets the yui js disable optimizations.
     *
     * @param yuiJsDisableOptimizations
     *            the new yui js disable optimizations
     * @see HtmlCompressor#setYuiJsDisableOptimizations(boolean)
     */
    public void setYuiJsDisableOptimizations(boolean yuiJsDisableOptimizations) {
        this.yuiJsDisableOptimizations = yuiJsDisableOptimizations;
    }

    /**
     * Sets the yui js line break.
     *
     * @param yuiJsLineBreak
     *            the new yui js line break
     * @see HtmlCompressor#setYuiJsLineBreak(int)
     */
    public void setYuiJsLineBreak(int yuiJsLineBreak) {
        this.yuiJsLineBreak = yuiJsLineBreak;
    }

    /**
     * Sets the enabled.
     *
     * @param enabled
     *            the new enabled
     * @see HtmlCompressor#setEnabled(boolean)
     */
    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }

    /**
     * Sets JavaScript compressor implementation that will be used to compress inline JavaScript in HTML.
     * 
     * @param jsCompressor
     *            Could be either <code>"yui"</code> for using {@link YuiJavaScriptCompressor} (used by default if none
     *            provided) or <code>"closure"</code> for using {@link ClosureJavaScriptCompressor}
     * 
     * @see YuiJavaScriptCompressor
     * @see ClosureJavaScriptCompressor
     * @see <a href="http://developer.yahoo.com/yui/compressor/">Yahoo YUI Compressor</a>
     * @see <a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a>
     */
    public void setJsCompressor(String jsCompressor) {
        this.jsCompressor = jsCompressor;
    }

    /**
     * Sets level of optimization if <a href="http://code.google.com/closure/compiler/">Google Closure Compiler</a> is
     * used for compressing inline JavaScript.
     * 
     * @param closureOptLevel
     *            Could be either <code>"simple"</code> (used by default), <code>"whitespace"</code> or
     *            <code>"advanced"</code>
     * 
     * @see ClosureJavaScriptCompressor#setCompilationLevel(CompilationLevel)
     */
    public void setClosureOptLevel(String closureOptLevel) {
        this.closureOptLevel = closureOptLevel;
    }

}