/*
 *  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.tools.ant.types.resources;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.types.Resource;

/**
 * Exposes a string as a Resource.
 * @since Ant 1.7
 */
public class StringResource extends Resource {

    /** Magic number */
    private static final int STRING_MAGIC
        = Resource.getMagicNumber("StringResource".getBytes());

    private static final String DEFAULT_ENCODING = "UTF-8";
    private String encoding = DEFAULT_ENCODING;

    /**
     * Default constructor.
     */
    public StringResource() {
    }

    /**
     * Construct a StringResource with the supplied value.
     * @param value the value of this StringResource.
     */
    public StringResource(String value) {
        this(null, value);
    }

    /**
     * Construct a StringResource with the supplied project and value,
     * doing property replacement against the project if non-null.
     * @param project the owning Project.
     * @param value the value of this StringResource.
     */
    public StringResource(Project project, String value) {
        setProject(project);
        setValue(project == null ? value : project.replaceProperties(value));
    }

    /**
     * Enforce String immutability.
     * @param s the new name/value for this StringResource.
     */
    @Override
    public synchronized void setName(String s) {
        if (getName() != null) {
            throw new BuildException(new ImmutableResourceException());
        }
        super.setName(s);
    }

    /**
     * The value attribute is a semantically superior alias for the name attribute.
     * @param s the String's value.
     */
    public synchronized void setValue(String s) {
        setName(s);
    }

    /**
     * Synchronize access.
     * @return the name/value of this StringResource.
     */
    @Override
    public synchronized String getName() {
        return super.getName();
    }

    /**
     * Get the value of this StringResource, resolving to the root reference if needed.
     * @return the represented String.
     */
    public synchronized String getValue() {
        return getName();
    }

    /**
     * The exists attribute tells whether a resource exists.
     *
     * @return true if this resource exists.
     */
    @Override
    public boolean isExists() {
        return getValue() != null;
    }

    /**
     * Add nested text to this resource.
     * Properties will be expanded during this process.
     * @since Ant 1.7.1
     * @param text text to use as the string resource
     */
    public void addText(String text) {
        checkChildrenAllowed();
        setValue(getProject().replaceProperties(text));
    }

    /**
     * Set the encoding to be used for this StringResource.
     * @param s the encoding name.
     */
    public synchronized void setEncoding(String s) {
        checkAttributesAllowed();
        encoding = s;
    }

    /**
     * Get the encoding used by this StringResource.
     * @return the encoding name.
     */
    public synchronized String getEncoding() {
        return encoding;
    }

    /**
     * Get the size of this Resource.
     * @return the size, as a long, 0 if the Resource does not exist (for
     *         compatibility with java.io.File), or UNKNOWN_SIZE if not known.
     */
    @Override
    public synchronized long getSize() {
        return isReference() ? getRef().getSize()
            : getContent().length();
    }

    /**
     * Get the hash code for this Resource.
     * @return hash code as int.
     */
    @Override
    public synchronized int hashCode() { //NOSONAR
        // super.equals + super.compareTo are consistent with this implementation
        if (isReference()) {
            return getRef().hashCode();
        }
        return super.hashCode() * STRING_MAGIC;
    }

    /**
     * Get the string. See {@link #getContent()}
     *
     * @return the string contents of the resource.
     * @since Ant 1.7
     */
    @Override
    public String toString() {
        return String.valueOf(getContent());
    }

    /**
     * Get an InputStream for the Resource.
     * @return an InputStream containing this Resource's content.
     * @throws IOException if unable to provide the content of this
     *         Resource as a stream.
     * @throws UnsupportedOperationException if InputStreams are not
     *         supported for this Resource type.
     */
    @Override
    public synchronized InputStream getInputStream() throws IOException {
        if (isReference()) {
            return getRef().getInputStream();
        }
        String content = getContent();
        if (content == null) {
            throw new IllegalStateException("unset string value");
        }
        return new ByteArrayInputStream(encoding == null
                ? content.getBytes() : content.getBytes(encoding));
    }

    /**
     * Get an OutputStream for the Resource.
     * @return an OutputStream to which content can be written.
     * @throws IOException if unable to provide the content of this
     *         Resource as a stream.
     * @throws UnsupportedOperationException if OutputStreams are not
     *         supported for this Resource type.
     */
    @Override
    public synchronized OutputStream getOutputStream() throws IOException {
        if (isReference()) {
            return getRef().getOutputStream();
        }
        if (getValue() != null) {
            throw new ImmutableResourceException();
        }
        return new StringResourceFilterOutputStream();
    }

    /**
     * Overrides the super version.
     * @param r the Reference to set.
     */
    @Override
    public void setRefid(Reference r) {
        if (encoding != DEFAULT_ENCODING) {
            throw tooManyAttributes();
        }
        super.setRefid(r);
    }

    /**
     * Get the content of this StringResource. See {@link #getValue()}
     * @return a String or null if there is no value.
     */
    protected synchronized String getContent() {
        return getValue();
    }

    @Override
    protected StringResource getRef() {
        return getCheckedRef(StringResource.class);
    }

    private class StringResourceFilterOutputStream extends FilterOutputStream {
        private final ByteArrayOutputStream baos;

        public StringResourceFilterOutputStream() {
            super(new ByteArrayOutputStream());
            baos = (ByteArrayOutputStream) out;
        }

        @Override
        public void close() throws IOException {
            super.close();
            String result = encoding == null
                    ? baos.toString() : baos.toString(encoding);

            setValueFromOutputStream(result);
        }

        private void setValueFromOutputStream(String output) {
            String value;
            if (getProject() != null) {
                value = getProject().replaceProperties(output);
            } else {
                value = output;
            }
            setValue(value);
        }

    }
}
