/**
 *    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.velocity;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;

import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.log.Log;
import org.apache.velocity.runtime.parser.node.Node;

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

/**
 * Velocity directive that compresses an JavaScript content within #compressJs ... #end block. 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 JavaScriptCompressorDirective extends Directive {

    /** The log. */
    private Log     log;

    /** 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 String getName() {
        return "compressJs";
    }

    @Override
    public int getType() {
        return BLOCK;
    }

    @Override
    public void init(RuntimeServices rs, InternalContextAdapter context, Node node) throws TemplateInitException {
        super.init(rs, context, node);
        log = rs.getLog();

        // set compressor properties
        enabled = rs.getBoolean("userdirective.compressJs.enabled", true);
        jsCompressor = rs.getString("userdirective.compressHtml.jsCompressor", HtmlCompressor.JS_COMPRESSOR_YUI);
        yuiJsNoMunge = rs.getBoolean("userdirective.compressJs.yuiJsNoMunge", false);
        yuiJsPreserveAllSemiColons = rs.getBoolean("userdirective.compressJs.yuiJsPreserveAllSemiColons", false);
        yuiJsLineBreak = rs.getInt("userdirective.compressJs.yuiJsLineBreak", -1);
        closureOptLevel = rs.getString("userdirective.compressHtml.closureOptLevel",
                ClosureJavaScriptCompressor.COMPILATION_LEVEL_SIMPLE);
    }

    @Override
    public boolean render(InternalContextAdapter context, Writer writer, Node node) throws IOException,
            MethodInvocationException {

        // render content
        StringWriter content = new StringWriter();
        node.jjtGetChild(0).render(context, content);

        // compress
        if (enabled) {
            try {
                String result = content.toString();

                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(result);

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

                    result = yuiCompressor.compress(result);
                }

                writer.write(result);
            } catch (Exception e) {
                writer.write(content.toString());
                String msg = "Failed to compress content: " + content.toString();
                log.error(msg, e);
                throw new RuntimeException(msg, e);

            }
        } else {
            writer.write(content.toString());
        }

        return true;

    }

}
