/*
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution, if
 *  any, must include the following acknowlegement:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowlegement may appear in the software itself,
 *  if and wherever such third-party acknowlegements normally appear.
 *
 *  4. The names "The Jakarta Project", "Ant", and "Apache Software
 *  Foundation" must not be used to endorse or promote products derived
 *  from this software without prior written permission. For written
 *  permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache"
 *  nor may "Apache" appear in their names without prior written
 *  permission of the Apache Group.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package org.apache.tools.ant.filters.util;

import org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.filters.BaseFilterReader;
import org.apache.tools.ant.filters.ChainableReader;
import org.apache.tools.ant.types.AntFilterReader;
import org.apache.tools.ant.types.FilterChain;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Parameter;
import org.apache.tools.ant.types.Parameterizable;
import org.apache.tools.ant.util.FileUtils;

import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Vector;

/**
 * Process a FilterReader chain.
 *
 * @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
 */
public final class ChainReaderHelper {

    /**
     * The primary reader to which the reader chain is to be attached.
     */
    public Reader primaryReader;

    /**
     * The size of the buffer to be used.
     */
    public int bufferSize = 8192;

    /**
     * Chain of filters
     */
    public Vector filterChains = new Vector();

    /** The Ant project */
    private Project project = null;

    /**
     * Sets the primary reader
     */
    public final void setPrimaryReader(Reader rdr) {
        primaryReader = rdr;
    }

    /**
     * Set the project to work with
     */
    public final void setProject(final Project project) {
        this.project = project;
    }

    /**
     * Get the project
     */
    public final Project getProject() {
        return project;
    }

    /**
     * Sets the buffer size to be used.  Defaults to 4096,
     * if this method is not invoked.
     */
    public final void setBufferSize(int size) {
        bufferSize = size;
    }

    /**
     * Sets the collection of filter reader sets
     */
    public final void setFilterChains(Vector fchain) {
        filterChains = fchain;
    }

    /**
     * Assemble the reader
     */
    public final Reader getAssembledReader() throws BuildException {
        if (primaryReader == null) {
            throw new BuildException("primaryReader must not be null.");
        }

        Reader instream = primaryReader;
        final int filterReadersCount = filterChains.size();
        final Vector finalFilters = new Vector();

        for (int i = 0; i < filterReadersCount; i++) {
            final FilterChain filterchain =
                (FilterChain) filterChains.elementAt(i);
            final Vector filterReaders = filterchain.getFilterReaders();
            final int readerCount = filterReaders.size();
            for (int j = 0; j < readerCount; j++) {
                finalFilters.addElement(filterReaders.elementAt(j));
            }
        }

        final int filtersCount = finalFilters.size();

        if (filtersCount > 0) {
            for (int i = 0; i < filtersCount; i++) {
                Object o = finalFilters.elementAt(i);

                if (o instanceof AntFilterReader) {
                    final AntFilterReader filter = (AntFilterReader) finalFilters.elementAt(i);
                    final String className = filter.getClassName();
                    final Path classpath = filter.getClasspath();
                    final Project project = filter.getProject();
                    if (className != null) {
                        try {
                            Class clazz = null;
                            if (classpath == null) {
                                clazz = Class.forName(className);
                            } else {
                                AntClassLoader al = new AntClassLoader(project,
                                                                       classpath);
                                clazz = al.loadClass(className);
                                AntClassLoader.initializeClass(clazz);
                            }
                            if (clazz != null) {
                                if (!FilterReader.class.isAssignableFrom(clazz)) {
                                    throw new BuildException(className +
                                        " does not extend java.io.FilterReader");
                                }
                                final Constructor[] constructors =
                                    clazz.getConstructors();
                                int j = 0;
                                for (; j < constructors.length; j++) {
                                    Class[] types = constructors[j]
                                                      .getParameterTypes();
                                    if (types.length == 1 &&
                                        types[0].isAssignableFrom(Reader.class)) {
                                        break;
                                    }
                                }
                                final Reader[] rdr = {instream};
                                instream =
                                    (Reader) constructors[j].newInstance(rdr);
                                if (Parameterizable.class.isAssignableFrom(clazz)) {
                                    final Parameter[] params = filter.getParams();
                                    ((Parameterizable)
                                        instream).setParameters(params);
                                }
                            }
                        } catch (final ClassNotFoundException cnfe) {
                            throw new BuildException(cnfe);
                        } catch (final InstantiationException ie) {
                            throw new BuildException(ie);
                        } catch (final IllegalAccessException iae) {
                            throw new BuildException(iae);
                        } catch (final InvocationTargetException ite) {
                            throw new BuildException(ite);
                        }
                    }
                } else if (o instanceof ChainableReader &&
                           o instanceof Reader) {
                    if (project != null && o instanceof BaseFilterReader) {
                        ((BaseFilterReader) o).setProject(project);
                    }
                    instream = ((ChainableReader) o).chain(instream);
                }
            }
        }
        return instream;
    }

    /**
     * Read data from the reader and return the
     * contents as a string.
     */
    public final String readFully(Reader rdr)
        throws IOException {
        return FileUtils.readFully(rdr, bufferSize);
    }
}
