/*
 * BufferBody.java February 2012
 *
 * Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
 *
 * 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.simpleframework.http.message;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.List;

import org.simpleframework.http.Part;
import org.simpleframework.util.buffer.Buffer;

/**
 * The <code>Body</code> interface is used to represent the body of a HTTP
 * entity. It contains the information that is delivered with the request. The
 * body is represented by a stream of bytes. In order to access the entity body
 * this interface provides a stream which can be used to read it. Also, should
 * the message be encoded as a multipart message the individual parts can be
 * read using the <code>Attachment</code> instance for it.
 * 
 * @author Niall Gallagher
 */
class BufferBody implements Body {

    /**
     * This is used to hold the attachments for the HTTP body.
     */
    private final PartSeries series;

    /**
     * This is usd to hold the bytes representing the HTTP body.
     */
    private final Buffer buffer;

    /**
     * Constructor for the <code>BufferBody</code> object. This is used to
     * create a body that represents a HTTP payload. The body enables the
     * payload to be either read in a stream or as an encoded string. Also the
     * attachments are available.
     */
    public BufferBody() {
        this(null);
    }

    /**
     * Constructor for the <code>BufferBody</code> object. This is used to
     * create a body that represents a HTTP payload. The body enables the
     * payload to be either read in a stream or as an encoded string. Also the
     * attachments are available.
     * 
     * @param buffer
     *            this is the buffer representing the body
     */
    public BufferBody(Buffer buffer) {
        this(buffer, null);
    }

    /**
     * Constructor for the <code>BufferBody</code> object. This is used to
     * create a body that represents a HTTP payload. The body enables the
     * payload to be either read in a stream or as an encoded string. Also the
     * attachments are available.
     * 
     * @param buffer
     *            this is the buffer representing the body
     * @param series
     *            this is the list of parts for this body
     */
    public BufferBody(Buffer buffer, PartSeries series) {
        this.buffer = buffer;
        this.series = series;
    }

    /**
     * This method is used to acquire a <code>Part</code> from the HTTP request
     * using a known name for the part. This is typically used when there is a
     * file upload with a multipart POST request. All parts that are not files
     * can be acquired as string values from the attachment object.
     * 
     * @param name
     *            this is the name of the part object to acquire
     * 
     * @return the named part or null if the part does not exist
     */
    @Override
    public Part getPart(String name) {
        if (this.series != null) return this.series.getPart(name);
        return null;
    }

    /**
     * This method is used to get all <code>Part</code> objects that are
     * associated with the request. Each attachment contains the body and
     * headers associated with it. If the request is not a multipart POST
     * request then this will return an empty list.
     * 
     * @return the list of parts associated with this request
     */
    @Override
    public List<Part> getParts() {
        if (this.series != null) return this.series.getParts();
        return Collections.emptyList();
    }

    /**
     * This will acquire the contents of the body in UTF-8. If there is no
     * content encoding and the user of the request wants to deal with the body
     * as a string then this method can be used. It will simply create a UTF-8
     * string using the body bytes.
     * 
     * @return returns a UTF-8 string representation of the body
     */
    @Override
    public String getContent() throws IOException {
        if (this.buffer == null) return new String();
        return this.buffer.encode();
    }

    /**
     * This will acquire the contents of the body in the specified charset.
     * Typically this will be given the charset as taken from the HTTP
     * Content-Type header. Although any encoding can be specified to convert
     * the body to a string representation.
     * 
     * @return returns an encoded string representation of the body
     */
    @Override
    public String getContent(String charset) throws IOException {
        if (this.buffer == null) return new String();
        return this.buffer.encode(charset);
    }

    /**
     * This is used to acquire the contents of the body as a stream. Each time
     * this method is invoked a new stream is created that will read the
     * contents of the body from the first byte. This ensures that the stream
     * can be acquired several times without any issues arising from previous
     * reads.
     * 
     * @return this returns a new string used to read the body
     */
    @Override
    public InputStream getInputStream() throws IOException {
        if (this.buffer == null) return new EmptyInputStream();
        return this.buffer.getInputStream();
    }
}