/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.sling.scripting.jsp.jasper;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletContext;
import javax.servlet.jsp.tagext.TagInfo;

import org.apache.sling.commons.compiler.source.JavaEscapeHelper;
import org.apache.sling.scripting.jsp.jasper.compiler.Compiler;
import org.apache.sling.scripting.jsp.jasper.compiler.JDTCompiler;
import org.apache.sling.scripting.jsp.jasper.compiler.JspRuntimeContext;
import org.apache.sling.scripting.jsp.jasper.compiler.Localizer;
import org.apache.sling.scripting.jsp.jasper.compiler.ServletWriter;

/**
 * A place holder for various things that are used through out the JSP
 * engine. This is a per-request/per-context data structure. Some of
 * the instance variables are set at different points.
 *
 * Most of the path-related stuff is here - mangling names, versions, dirs,
 * loading resources and dealing with uris.
 *
 * @author Anil K. Vijendran
 * @author Harish Prabandham
 * @author Pierre Delisle
 * @author Costin Manolache
 * @author Kin-man Chung
 */
public class JspCompilationContext {

    private Map<String, URL> tagFileJarUrls;

    private String className;
    private String jspUri;
    private boolean isErrPage;
    private String basePackageName;
    private String derivedPackageName;
    private String servletJavaFileName;
    private String javaPath;
    private String classFileName;
    private String contentType;
    private ServletWriter writer;
    private Options options;
    private Compiler jspCompiler;

    private String baseURI;
    private String outputDir;
    private ServletContext context;

    private JspRuntimeContext rctxt;

    private boolean isTagFile;
    private boolean protoTypeMode;
    private TagInfo tagInfo;
    private URL tagFileJarUrl;

    private final boolean defaultIsSession;

    // jspURI _must_ be relative to the context
    public JspCompilationContext(String jspUri,
                                 boolean isErrPage,
                                 Options options,
                                 ServletContext context,
                                 JspRuntimeContext rctxt,
                                 boolean defaultIsSession) {

        this.jspUri = canonicalURI(jspUri);
        this.isErrPage = isErrPage;
        this.options = options;
        this.context = context;

        this.baseURI = jspUri.substring(0, jspUri.lastIndexOf('/') + 1);
        // hack fix for resolveRelativeURI
        if (baseURI == null) {
            baseURI = "/";
        } else if (baseURI.charAt(0) != '/') {
            // strip the basde slash since it will be combined with the
            // uriBase to generate a file
            baseURI = "/" + baseURI;
        }
        if (baseURI.charAt(baseURI.length() - 1) != '/') {
            baseURI += '/';
        }

        this.rctxt = rctxt;
        this.tagFileJarUrls = new HashMap<>();
        this.basePackageName = Constants.JSP_PACKAGE_NAME;
        this.defaultIsSession = defaultIsSession;
    }

    public JspCompilationContext(String tagfile,
                                 TagInfo tagInfo,
                                 Options options,
                                 ServletContext context,
                                 JspRuntimeContext rctxt,
                                 boolean defaultIsSession,
                                 URL tagFileJarUrl) {
        this(tagfile, false, options, context, rctxt, defaultIsSession);
        this.isTagFile = true;
        this.tagInfo = tagInfo;
        this.tagFileJarUrl = tagFileJarUrl;
    }

    /**
     * What class loader to use for loading classes while compiling
     * this JSP?
     */
    public ClassLoader getClassLoader() {
        return getRuntimeContext().getIOProvider().getClassLoader();
    }

    /** ---------- Input/Output  ---------- */

    /**
     * Creates an output stream to the given file
     * @param fileName The path to the file to write to
     * @return The OutputStream to the file
     * @throws IOException If an error occurrs creating the output stream.
     */
    public OutputStream getOutputStream(String fileName) throws IOException {
        return getRuntimeContext().getIOProvider().getOutputStream(fileName);
    }

    /**
     * Creates an input stream from the given file
     * @param fileName The path to the file to read from
     * @return The InputStream from the file
     * @throws FileNotFoundException If the file cannot be found
     * @throws IOException If an error occurrs creating the intput stream.
     */
    public InputStream getInputStream(String fileName)
            throws FileNotFoundException, IOException {
        return getRuntimeContext().getIOProvider().getInputStream(fileName);
    }

    /**
     * Removes a (generated) file.
     * @param fileName The path to the file to remove.
     * @return <code>true</code> if the file has been removed.
     */
    public boolean delete(String fileName) {
        return getRuntimeContext().getIOProvider().delete(fileName);
    }

    /**
     * Renams then old file to the new file
     * @return <code>true</code> if the file has been renamed
     *
     */
    public boolean rename(String oldFileName, String newFileName) {
        return getRuntimeContext().getIOProvider().rename(oldFileName, newFileName);
    }

    /**
     * The output directory to generate code into.  The output directory
     * is make up of the scratch directory, which is provide in Options,
     * plus the directory derived from the package name.
     */
    public String getOutputDir() {
    	if (outputDir == null) {
	        createOutputDir();
	    }

        return outputDir;
    }

    /**
     * Create a "Compiler" object based on some init param data. This
     * is not done yet. Right now we're just hardcoding the actual
     * compilers that are created.
     */
    private Compiler createCompiler() {
        if (jspCompiler != null ) {
            return jspCompiler;
        }
        jspCompiler = new JDTCompiler(defaultIsSession);
        jspCompiler.init(this);
        return jspCompiler;
    }

    public Compiler getCompiler() {
        return jspCompiler;
    }

    /** ---------- Access resources in the webapp ---------- */

    /**
     * Get the full value of a URI relative to this compilations context
     * uses current file as the base.
     */
    public String resolveRelativeUri(String uri) {
        // sometimes we get uri's massaged from File(String), so check for
        // a root directory deperator char
        if (uri.startsWith("/") || uri.startsWith(File.separator)) {
            return uri;
        }
        return baseURI + uri;
    }

    /**
     * Gets a resource as a stream, relative to the meanings of this
     * context's implementation.
     * @return a null if the resource cannot be found or represented
     *         as an InputStream.
     */
    public java.io.InputStream getResourceAsStream(String res) {
        return context.getResourceAsStream(canonicalURI(res));
    }


    public URL getResource(String res) throws MalformedURLException {
        return context.getResource(canonicalURI(res));
    }

    @SuppressWarnings("unchecked")
    public Set<String> getResourcePaths(String path) {
        return context.getResourcePaths(canonicalURI(path));
    }

    /**
     * Gets the actual path of a URI relative to the context of
     * the compilation.
     */
    public String getRealPath(String path) {
        if (context != null) {
            return context.getRealPath(path);
        }
        return path;
    }

    /**
     * Returns the tag-file-name-to-JAR-file map of this compilation unit,
     * which maps tag file names to the JAR files in which the tag files are
     * packaged.
     *
     * The map is populated when parsing the tag-file elements of the TLDs
     * of any imported taglibs.
     */
    public URL getTagFileJarUrl(String tagFile) {
        return this.tagFileJarUrls.get(tagFile);
    }

    public void setTagFileJarUrl(String tagFile, URL tagFileURL) {
        this.tagFileJarUrls.put(tagFile, tagFileURL);
    }

    public URL getTagFileUrl(String tagFile) {
        return this.tagFileJarUrls.get("tagfile:" + tagFile);
    }

    public void setTagFileUrl(String tagFile, URL tagFileURL) {
        this.tagFileJarUrls.put("tagfile:" + tagFile, tagFileURL);
    }

    /**
     * Returns the JAR file in which the tag file for which this
     * JspCompilationContext was created is packaged, or null if this
     * JspCompilationContext does not correspond to a tag file, or if the
     * corresponding tag file is not packaged in a JAR.
     */
    public URL getTagFileJarUrl() {
        return this.tagFileJarUrl;
    }

    public void setTagFileUrls(final JspCompilationContext ctxt) {
        this.tagFileJarUrls.putAll(ctxt.tagFileJarUrls);
    }
    /* ==================== Common implementation ==================== */

    /**
     * Just the class name (does not include package name) of the
     * generated class.
     */
    public String getServletClassName() {

        if (className != null) {
            return className;
        }

        if (isTagFile) {
            className = tagInfo.getTagClassName();
            int lastIndex = className.lastIndexOf('.');
            if (lastIndex != -1) {
                className = className.substring(lastIndex + 1);
            }
        } else {
            int iSep = jspUri.lastIndexOf('/') + 1;
            className = JavaEscapeHelper.getJavaIdentifier(jspUri.substring(iSep));
        }
        return className;
    }

    /**
     * Path of the JSP URI. Note that this is not a file name. This is
     * the context rooted URI of the JSP file.
     */
    public String getJspFile() {
        return jspUri;
    }

    /**
     * Are we processing something that has been declared as an
     * errorpage?
     */
    public boolean isErrorPage() {
        return isErrPage;
    }

    public void setErrorPage(boolean isErrPage) {
        this.isErrPage = isErrPage;
    }

    public boolean isTagFile() {
        return isTagFile;
    }

    public TagInfo getTagInfo() {
        return tagInfo;
    }

    public void setTagInfo(TagInfo tagi) {
        tagInfo = tagi;
    }

    /**
     * True if we are compiling a tag file in prototype mode.
     * ie we only generate codes with class for the tag handler with empty
     * method bodies.
     */
    public boolean isPrototypeMode() {
        return protoTypeMode;
    }

    public void setPrototypeMode(boolean pm) {
        protoTypeMode = pm;
    }

    /**
     * Package name for the generated class is make up of the base package
     * name, which is user settable, and the derived package name.  The
     * derived package name directly mirrors the file heirachy of the JSP page.
     */
    public String getServletPackageName() {
        if (isTagFile()) {
            String className = tagInfo.getTagClassName();
            int lastIndex = className.lastIndexOf('.');
            String pkgName = "";
            if (lastIndex != -1) {
                pkgName = className.substring(0, lastIndex);
            }
            return pkgName;
        } else if (basePackageName == null || basePackageName.length() == 0) {
            return getDerivedPackageName();
        } else {
            String dPackageName = getDerivedPackageName();
            if (dPackageName.length() == 0) {
                return basePackageName;
            }
            return basePackageName + '.' + getDerivedPackageName();
        }
    }

    protected String getDerivedPackageName() {
        if (derivedPackageName == null) {
            int iSep = jspUri.lastIndexOf('/');
            derivedPackageName = (iSep > 0) ?
                    JavaEscapeHelper.makeJavaPackage(jspUri.substring(1,iSep)) : "";
        }
        return derivedPackageName;
    }

    /**
     * Full path name of the Java file into which the servlet is being
     * generated.
     */
    public String getServletJavaFileName() {
        if (servletJavaFileName == null) {
            servletJavaFileName = getOutputDir() + getServletClassName() + ".java";
        }
        return servletJavaFileName;
    }

    /**
     * Get hold of the Options object for this context.
     */
    public Options getOptions() {
        return options;
    }

    public ServletContext getServletContext() {
        return context;
    }

    public JspRuntimeContext getRuntimeContext() {
        return rctxt;
    }

    /**
     * Path of the Java file relative to the work directory.
     */
    public String getJavaPath() {

        if (javaPath != null) {
            return javaPath;
        }

        if (isTagFile()) {
	    String tagName = tagInfo.getTagClassName();
            javaPath = tagName.replace('.', '/') + ".java";
        } else {
            javaPath = getServletPackageName().replace('.', '/') + '/' +
                       getServletClassName() + ".java";
	}
        return javaPath;
    }

    public String getClassFileName() {
        if (classFileName == null) {
            classFileName = getOutputDir() + getServletClassName() + ".class";
        }
        return classFileName;
    }

    /**
     * Get the content type of this JSP.
     *
     * Content type includes content type and encoding.
     */
    public String getContentType() {
        return contentType;
    }

    public void setContentType(String contentType) {
        this.contentType = contentType;
    }

    /**
     * Where is the servlet being generated?
     */
    public ServletWriter getWriter() {
        return writer;
    }

    public void setWriter(ServletWriter writer) {
        this.writer = writer;
    }

    /**
     * Gets the 'location' of the TLD associated with the given taglib 'uri'.
     *
     * @return An array of two Strings: The first element denotes the real
     * path to the TLD. If the path to the TLD points to a jar file, then the
     * second element denotes the name of the TLD entry in the jar file.
     * Returns null if the given uri is not associated with any tag library
     * 'exposed' in the web application.
     */
    public String[] getTldLocation(String uri) throws JasperException {
        String[] location =
            getOptions().getTldLocationsCache().getLocation(uri);
        return location;
    }

    /**
     * Are we keeping generated code around?
     */
    public boolean keepGenerated() {
        return getOptions().getKeepGenerated();
    }

    // ==================== Compile and reload ====================

    public JasperException compile() {
        return compile(false);
    }

    public JasperException compile(boolean fromJSPC) {
        final Compiler c = createCompiler();
        try {
            c.removeGeneratedFiles();
            c.compile(true, fromJSPC);
        } catch (final JasperException ex) {
            return ex;
        } catch (final IOException ioe) {
            final JasperException je = new JasperException(
                    Localizer.getMessage("jsp.error.unable.compile"),
                    ioe);
            return je;
        } catch (final Exception ex) {
            JasperException je = new JasperException(
                    Localizer.getMessage("jsp.error.unable.compile"),
                    ex);
            return je;
        } finally {
            c.clean();
        }

        return null;
    }

    // ==================== Manipulating the class ====================

    public Class<?> load()
    throws JasperException {
        try {
            String name;
            if (isTagFile()) {
                name = tagInfo.getTagClassName();
            } else {
                name = getServletPackageName() + "." + getServletClassName();
            }
            final Class<?> servletClass = getClassLoader().loadClass(name);
            return servletClass;
        } catch (ClassNotFoundException cex) {
            throw new JasperException(Localizer.getMessage("jsp.error.unable.load"),
                                      cex);
        } catch (Exception ex) {
            throw new JasperException(Localizer.getMessage("jsp.error.unable.compile"),
                                      ex);
        }
    }

    // ==================== protected methods ====================

    public void checkOutputDir() {
        getOutputDir();
    }

    private boolean makeOutputDir() {
        return getRuntimeContext().getIOProvider().mkdirs(outputDir);
    }

    private void createOutputDir() {
        String path = null;
        if (isTagFile()) {
	        String tagName = tagInfo.getTagClassName();
            path = tagName.replace('.', '/');
	        path = path.substring(0, path.lastIndexOf('/'));
        } else {
            path = getServletPackageName().replace('.', '/');
	    }

        // Append servlet or tag handler path to scratch dir
        outputDir = options.getScratchDir() + File.separator + path + File.separator;
        if (!makeOutputDir()) {
            throw new IllegalStateException(Localizer.getMessage("jsp.error.outputfolder"));
        }
    }

    private static final boolean isPathSeparator(char c) {
       return (c == '/' || c == '\\');
    }

    private static final String canonicalURI(String s) {
       if (s == null) return null;
       StringBuilder result = new StringBuilder();
       final int len = s.length();
       int pos = 0;
       while (pos < len) {
           char c = s.charAt(pos);
           if ( isPathSeparator(c) ) {
               /*
                * multiple path separators.
                * 'foo///bar' -> 'foo/bar'
                */
               while (pos+1 < len && isPathSeparator(s.charAt(pos+1))) {
                   ++pos;
               }

               if (pos+1 < len && s.charAt(pos+1) == '.') {
                   /*
                    * a single dot at the end of the path - we are done.
                    */
                   if (pos+2 >= len) break;

                   switch (s.charAt(pos+2)) {
                       /*
                        * self directory in path
                        * foo/./bar -> foo/bar
                        */
                   case '/':
                   case '\\':
                       pos += 2;
                       continue;

                       /*
                        * two dots in a path: go back one hierarchy.
                        * foo/bar/../baz -> foo/baz
                        */
                   case '.':
                       // only if we have exactly _two_ dots.
                       if (pos+3 < len && isPathSeparator(s.charAt(pos+3))) {
                           pos += 3;
                           int separatorPos = result.length()-1;
                           while (separatorPos >= 0 &&
                                  ! isPathSeparator(result
                                                    .charAt(separatorPos))) {
                               --separatorPos;
                           }
                           if (separatorPos >= 0)
                               result.setLength(separatorPos);
                           continue;
                       }
                   }
               }
           }
           result.append(c);
           ++pos;
       }
       return result.toString();
    }

}