/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * 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 org.apache.jasper.compiler;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.List;

import org.apache.jasper.JasperException;
import org.apache.jasper.JspCompilationContext;
import org.apache.jasper.Options;
import org.apache.jasper.servlet.JspServletWrapper;

/**
 * Main JSP compiler class. This class uses Ant for compiling.
 *
 * @author Anil K. Vijendran
 * @author Mandar Raje
 * @author Pierre Delisle
 * @author Kin-man Chung
 * @author Remy Maucherat
 * @author Mark Roth
 */
public abstract class Compiler {
    protected static org.apache.commons.logging.Log log=
        org.apache.commons.logging.LogFactory.getLog( Compiler.class );

    // ----------------------------------------------------------------- Static


    // Some javac are not thread safe; use a lock to serialize compilation, 
    static Object javacLock = new Object();


    // ----------------------------------------------------- Instance Variables


    protected JspCompilationContext ctxt;

    protected ErrorDispatcher errDispatcher;
    protected PageInfo pageInfo;
    protected JspServletWrapper jsw;
    protected TagFileProcessor tfp;

    protected Options options;

    protected Node.Nodes pageNodes;
    // ------------------------------------------------------------ Constructor

    public void init(JspCompilationContext ctxt, JspServletWrapper jsw) {
        this.jsw = jsw;
        this.ctxt = ctxt;
        this.options = ctxt.getOptions();
    }

    // --------------------------------------------------------- Public Methods


    /** 
     * Compile the jsp file into equivalent servlet in .java file
     * @return a smap for the current JSP page, if one is generated,
     *         null otherwise
     */
    protected String[] generateJava() throws Exception {

        String[] smapStr = null;

        long t1=System.currentTimeMillis();

        // Setup page info area
        pageInfo = new PageInfo(new BeanRepository(ctxt.getClassLoader(),
                                                   errDispatcher),
                                ctxt.getJspFile());

        JspConfig jspConfig = options.getJspConfig();
        JspConfig.JspProperty jspProperty =
            jspConfig.findJspProperty(ctxt.getJspFile());

        /*
         * If the current uri is matched by a pattern specified in
         * a jsp-property-group in web.xml, initialize pageInfo with
         * those properties.
         */
        pageInfo.setELIgnored(JspUtil.booleanValue(
                                            jspProperty.isELIgnored()));
        pageInfo.setScriptingInvalid(JspUtil.booleanValue(
                                            jspProperty.isScriptingInvalid()));
        if (jspProperty.getIncludePrelude() != null) {
            pageInfo.setIncludePrelude(jspProperty.getIncludePrelude());
        }
        if (jspProperty.getIncludeCoda() != null) {
	    pageInfo.setIncludeCoda(jspProperty.getIncludeCoda());
        }

        String javaFileName = ctxt.getServletJavaFileName();
        ServletWriter writer = null;

        try {
            // Setup the ServletWriter
            String javaEncoding = ctxt.getOptions().getJavaEncoding();
            OutputStreamWriter osw = null; 

            try {
                osw = new OutputStreamWriter(
                            new FileOutputStream(javaFileName), javaEncoding);
            } catch (UnsupportedEncodingException ex) {
                errDispatcher.jspError("jsp.error.needAlternateJavaEncoding",
                                       javaEncoding);
            }

            writer = new ServletWriter(new PrintWriter(osw));
            ctxt.setWriter(writer);

            // Reset the temporary variable counter for the generator.
            JspUtil.resetTemporaryVariableName();

	    // Parse the file
	    ParserController parserCtl = new ParserController(ctxt, this);
	    pageNodes = parserCtl.parse(ctxt.getJspFile());

	    if (ctxt.isPrototypeMode()) {
                // generate prototype .java file for the tag file
                Generator.generate(writer, this, pageNodes);
                writer.close();
                writer = null;
                return null;
            }

            // Validate and process attributes
            Validator.validate(this, pageNodes);

            long t2=System.currentTimeMillis();
            // Dump out the page (for debugging)
            // Dumper.dump(pageNodes);

            // Collect page info
            Collector.collect(this, pageNodes);

            // Compile (if necessary) and load the tag files referenced in
            // this compilation unit.
            tfp = new TagFileProcessor();
            tfp.loadTagFiles(this, pageNodes);

            long t3=System.currentTimeMillis();
        
            // Determine which custom tag needs to declare which scripting vars
            ScriptingVariabler.set(pageNodes, errDispatcher);

            // Optimizations by Tag Plugins
            TagPluginManager tagPluginManager = options.getTagPluginManager();
            tagPluginManager.apply(pageNodes, errDispatcher, pageInfo);

            // Optimization: concatenate contiguous template texts.
            TextOptimizer.concatenate(this, pageNodes);

            // Generate static function mapper codes.
            ELFunctionMapper.map(this, pageNodes);

            // generate servlet .java file
            Generator.generate(writer, this, pageNodes);
            writer.close();
            writer = null;

            // The writer is only used during the compile, dereference
            // it in the JspCompilationContext when done to allow it
            // to be GC'd and save memory.
            ctxt.setWriter(null);

            long t4=System.currentTimeMillis();
            if( t4-t1 > 500 ) {
                log.debug("Generated "+ javaFileName + " total=" +
                          (t4-t1) + " generate=" + ( t4-t3 ) + " validate=" +
                          ( t2-t1 ));
            }

        } catch (Exception e) {
            if (writer != null) {
                try {
                    writer.close();
                    writer = null;
                } catch (Exception e1) {
                    // do nothing
                }
            }
            // Remove the generated .java file
            new File(javaFileName).delete();
            throw e;
        } finally {
            if (writer != null) {
                try {
                    writer.close();
                } catch (Exception e2) {
                    // do nothing
                }
            }
        }
        
        // JSR45 Support
        if (! options.isSmapSuppressed()) {
            smapStr = SmapUtil.generateSmap(ctxt, pageNodes);
        }

        // If any proto type .java and .class files was generated,
        // the prototype .java may have been replaced by the current
        // compilation (if the tag file is self referencing), but the
        // .class file need to be removed, to make sure that javac would
        // generate .class again from the new .java file just generated.
        tfp.removeProtoTypeFiles(ctxt.getClassFileName());

        return smapStr;
    }

    /** 
     * Compile the servlet from .java file to .class file
     */
    protected abstract void generateClass(String[] smap)
        throws FileNotFoundException, JasperException, Exception;
    
    
    /** 
     * Compile the jsp file from the current engine context
     */
    public void compile()
        throws FileNotFoundException, JasperException, Exception
    {
        compile(true);
    }

    /**
     * Compile the jsp file from the current engine context.  As an side-
     * effect, tag files that are referenced by this page are also compiled.
     * @param compileClass If true, generate both .java and .class file
     *                     If false, generate only .java file
     */
    public void compile(boolean compileClass)
        throws FileNotFoundException, JasperException, Exception
    {
        compile(compileClass, false);
    }

    /**
     * Compile the jsp file from the current engine context.  As an side-
     * effect, tag files that are referenced by this page are also compiled.
     *
     * @param compileClass If true, generate both .java and .class file
     *                     If false, generate only .java file
     * @param jspcMode true if invoked from JspC, false otherwise
     */
    public void compile(boolean compileClass, boolean jspcMode)
        throws FileNotFoundException, JasperException, Exception
    {
        if (errDispatcher == null) {
            this.errDispatcher = new ErrorDispatcher(jspcMode);
        }

        try {
            String[] smap = generateJava();
            if (compileClass) {
                generateClass(smap);
            }
        } finally {
            if (tfp != null) {
                tfp.removeProtoTypeFiles(null);
            }
            // Make sure these object which are only used during the
            // generation and compilation of the JSP page get
            // dereferenced so that they can be GC'd and reduce the
            // memory footprint.
            tfp = null;
            errDispatcher = null;
            pageInfo = null;
            pageNodes = null;
            if (ctxt.getWriter() != null) {
                ctxt.getWriter().close();
                ctxt.setWriter(null);
            }
        }
    }

    /**
     * This is a protected method intended to be overridden by 
     * subclasses of Compiler. This is used by the compile method
     * to do all the compilation. 
     */
    public boolean isOutDated() {
        return isOutDated( true );
    }

    /**
     * Determine if a compilation is necessary by checking the time stamp
     * of the JSP page with that of the corresponding .class or .java file.
     * If the page has dependencies, the check is also extended to its
     * dependeants, and so on.
     * This method can by overidden by a subclasses of Compiler.
     * @param checkClass If true, check against .class file,
     *                   if false, check against .java file.
     */
    public boolean isOutDated(boolean checkClass) {

        boolean outDated = false;
        String jsp = ctxt.getJspFile();

        if ((jsw != null)
            && (ctxt.getOptions().getModificationTestInterval() > 0)
            && ((jsw.getLastModificationTest()
                    + (ctxt.getOptions().getModificationTestInterval() * 1000)) 
                    > System.currentTimeMillis())) {
            return false;
        }
        
        long jspRealLastModified = 0;
        try {
            URL jspUrl = ctxt.getResource(jsp);
            if (jspUrl == null) {
                ctxt.incrementRemoved();
                return false;
            }
            URLConnection uc = jspUrl.openConnection();
            jspRealLastModified = uc.getLastModified();
            uc.getInputStream().close();
        } catch (Exception e) {
            e.printStackTrace();
            return true;
        }

        long targetLastModified = 0;
        File targetFile;
        
        if( checkClass ) {
            targetFile = new File(ctxt.getClassFileName());
        } else {
            targetFile = new File(ctxt.getServletJavaFileName());
        }
        
        if (!targetFile.exists()) {
            outDated = true;
        } else {
            targetLastModified = targetFile.lastModified();
            if (checkClass && jsw != null) {
                jsw.setServletClassLastModifiedTime(targetLastModified);
            }   
            if (targetLastModified < jspRealLastModified) {
                if( log.isDebugEnabled() ) {
                    log.debug("Compiler: outdated: " + targetFile + " " +
                        targetLastModified );
                }
                outDated = true;
            }
        }

        // determine if source dependent files (e.g. includes using include
        // directives) have been changed.
        if( jsw==null ) {
            return outDated;
        }
        jsw.setLastModificationTest(System.currentTimeMillis());
        
        List depends = jsw.getDependants();
        if (depends == null) {
            return outDated;
        }

        Iterator it = depends.iterator();
        while (it.hasNext()) {
            String include = (String)it.next();
            try {
                URL includeUrl = ctxt.getResource(include);
                if (includeUrl == null) {
                    outDated = true;
                }
                if (!outDated) {

                    URLConnection includeUconn = includeUrl.openConnection();
                    long includeLastModified = includeUconn.getLastModified();
                    includeUconn.getInputStream().close();

                    if (includeLastModified > targetLastModified) {
                        outDated = true;
                    }
                }
                if (outDated) {
                    // Remove any potential Wrappers for tag files
                    ctxt.getRuntimeContext().removeWrapper(include);
                }
            } catch (Exception e) {
                e.printStackTrace();
                outDated = true;
            }
        }

        return outDated;

    }

    
    /**
     * Gets the error dispatcher.
     */
    public ErrorDispatcher getErrorDispatcher() {
	return errDispatcher;
    }


    /**
     * Gets the info about the page under compilation
     */
    public PageInfo getPageInfo() {
	return pageInfo;
    }


    public JspCompilationContext getCompilationContext() {
	return ctxt;
    }


    /**
     * Remove generated files
     */
    public void removeGeneratedFiles() {
        try {
            String classFileName = ctxt.getClassFileName();
            if (classFileName != null) {
                File classFile = new File(classFileName);
                if( log.isDebugEnabled() )
                    log.debug( "Deleting " + classFile );
                classFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
        try {
            String javaFileName = ctxt.getServletJavaFileName();
            if (javaFileName != null) {
                File javaFile = new File(javaFileName);
                if( log.isDebugEnabled() )
                    log.debug( "Deleting " + javaFile );
                javaFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
    }

    public void removeGeneratedClassFiles() {
        try {
            String classFileName = ctxt.getClassFileName();
            if (classFileName != null) {
                File classFile = new File(classFileName);
                if( log.isDebugEnabled() )
                    log.debug( "Deleting " + classFile );
                classFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
    }
}