/*
 * Copyright 2001-2005 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 net.myvietnam.mvncore.web.fileupload;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;

import net.myvietnam.mvncore.web.fileupload.servlet.ServletRequestContext;

/**
 * <p>High level API for processing file uploads.</p>
 *
 * <p>This class handles multiple files per single HTML widget, sent using
 * <code>multipart/mixed</code> encoding type, as specified by
 * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>.  Use {@link
 * #parseRequest(HttpServletRequest)} to acquire a list of {@link
 * org.apache.commons.fileupload.FileItem}s associated with a given HTML
 * widget.</p>
 *
 * <p>How the data for individual parts is stored is determined by the factory
 * used to create them; a given part may be in memory, on disk, or somewhere
 * else.</p>
 *
 * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
 * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
 * @author <a href="mailto:jmcnally@collab.net">John McNally</a>
 * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
 * @author Sean C. Sullivan
 *
 * @version $Id: FileUploadBase.java,v 1.3 2006/04/14 18:26:31 minhnn Exp $
 */
public abstract class FileUploadBase {

    // ---------------------------------------------------------- Class methods


    /**
     * <p>Utility method that determines whether the request contains multipart
     * content.</p>
     *
     * <p><strong>NOTE:</strong>This method will be moved to the
     * <code>ServletFileUpload</code> class after the FileUpload 1.1 release.
     * Unfortunately, since this method is static, it is not possible to
     * provide its replacement until this method is removed.</p>
     *
     * @param ctx The request context to be evaluated. Must be non-null.
     *
     * @return <code>true</code> if the request is multipart;
     *         <code>false</code> otherwise.
     */
    public static final boolean isMultipartContent(RequestContext ctx) {
        String contentType = ctx.getContentType();
        if (contentType == null) {
            return false;
        }
        if (contentType.toLowerCase().startsWith(MULTIPART)) {
            return true;
        }
        return false;
    }


    /**
     * Utility method that determines whether the request contains multipart
     * content.
     *
     * @param req The servlet request to be evaluated. Must be non-null.
     *
     * @return <code>true</code> if the request is multipart;
     *         <code>false</code> otherwise.
     *
     * @deprecated Use the method on <code>ServletFileUpload</code> instead.
     */
    public static final boolean isMultipartContent(HttpServletRequest req) {
        if (!"post".equals(req.getMethod().toLowerCase())) {
            return false;
        }
        String contentType = req.getContentType();
        if (contentType == null) {
            return false;
        }
        if (contentType.toLowerCase().startsWith(MULTIPART)) {
            return true;
        }
        return false;
    }


    // ----------------------------------------------------- Manifest constants


    /**
     * HTTP content type header name.
     */
    public static final String CONTENT_TYPE = "Content-type";


    /**
     * HTTP content disposition header name.
     */
    public static final String CONTENT_DISPOSITION = "Content-disposition";


    /**
     * Content-disposition value for form data.
     */
    public static final String FORM_DATA = "form-data";


    /**
     * Content-disposition value for file attachment.
     */
    public static final String ATTACHMENT = "attachment";


    /**
     * Part of HTTP content type header.
     */
    public static final String MULTIPART = "multipart/";


    /**
     * HTTP content type header for multipart forms.
     */
    public static final String MULTIPART_FORM_DATA = "multipart/form-data";


    /**
     * HTTP content type header for multiple uploads.
     */
    public static final String MULTIPART_MIXED = "multipart/mixed";


    /**
     * The maximum length of a single header line that will be parsed
     * (1024 bytes).
     */
    public static final int MAX_HEADER_SIZE = 1024;


    // ----------------------------------------------------------- Data members


    /**
     * The maximum size permitted for an uploaded file. A value of -1 indicates
     * no maximum.
     */
    private long sizeMax = -1;


    /**
     * The content encoding to use when reading part headers.
     */
    private String headerEncoding;


    // ----------------------------------------------------- Property accessors


    /**
     * Returns the factory class used when creating file items.
     *
     * @return The factory class for new file items.
     */
    public abstract FileItemFactory getFileItemFactory();


    /**
     * Sets the factory class to use when creating file items.
     *
     * @param factory The factory class for new file items.
     */
    public abstract void setFileItemFactory(FileItemFactory factory);


    /**
     * Returns the maximum allowed upload size.
     *
     * @return The maximum allowed size, in bytes.
     *
     * @see #setSizeMax(long)
     *
     */
    public long getSizeMax() {
        return sizeMax;
    }


    /**
     * Sets the maximum allowed upload size. If negative, there is no maximum.
     *
     * @param sizeMax The maximum allowed size, in bytes, or -1 for no maximum.
     *
     * @see #getSizeMax()
     *
     */
    public void setSizeMax(long sizeMax) {
        this.sizeMax = sizeMax;
    }


    /**
     * Retrieves the character encoding used when reading the headers of an
     * individual part. When not specified, or <code>null</code>, the request
     * encoding is used. If that is also not specified, or <code>null</code>,
     * the platform default encoding is used.
     *
     * @return The encoding used to read part headers.
     */
    public String getHeaderEncoding() {
        return headerEncoding;
    }


    /**
     * Specifies the character encoding to be used when reading the headers of
     * individual part. When not specified, or <code>null</code>, the request
     * encoding is used. If that is also not specified, or <code>null</code>,
     * the platform default encoding is used.
     *
     * @param encoding The encoding used to read part headers.
     */
    public void setHeaderEncoding(String encoding) {
        headerEncoding = encoding;
    }


    // --------------------------------------------------------- Public methods


    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant <code>multipart/form-data</code> stream.
     *
     * @param req The servlet request to be parsed.
     *
     * @return A list of <code>FileItem</code> instances parsed from the
     *         request, in the order that they were transmitted.
     *
     * @throws FileUploadException if there are problems reading/parsing
     *                             the request or storing files.
     *
     * @deprecated Use the method in <code>ServletFileUpload</code> instead.
     */
    public List /* FileItem */ parseRequest(HttpServletRequest req)
            throws FileUploadException {
        return parseRequest(new ServletRequestContext(req));
    }

    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant <code>multipart/form-data</code> stream.
     *
     * @param ctx The context for the request to be parsed.
     *
     * @return A list of <code>FileItem</code> instances parsed from the
     *         request, in the order that they were transmitted.
     *
     * @throws FileUploadException if there are problems reading/parsing
     *                             the request or storing files.
     */
    public List /* FileItem */ parseRequest(RequestContext ctx)
            throws FileUploadException {
        if (ctx == null) {
            throw new NullPointerException("ctx parameter");
        }

        ArrayList items = new ArrayList();
        String contentType = ctx.getContentType();

        if ((null == contentType)
            || (!contentType.toLowerCase().startsWith(MULTIPART))) {
            throw new InvalidContentTypeException(
                "the request doesn't contain a "
                + MULTIPART_FORM_DATA
                + " or "
                + MULTIPART_MIXED
                + " stream, content type header is "
                + contentType);
        }
        int requestSize = ctx.getContentLength();

        if (requestSize == -1) {
            throw new UnknownSizeException(
                "the request was rejected because its size is unknown");
        }

        if (sizeMax >= 0 && requestSize > sizeMax) {
            throw new SizeLimitExceededException(
                "the request was rejected because its size (" + requestSize
                + ") exceeds the configured maximum (" + sizeMax + ")",
                requestSize, sizeMax);
        }

        String charEncoding = headerEncoding;
        if (charEncoding == null) {
            charEncoding = ctx.getCharacterEncoding();
        }

        try {
            byte[] boundary = getBoundary(contentType);
            if (boundary == null) {
                throw new FileUploadException(
                        "the request was rejected because "
                        + "no multipart boundary was found");
            }

            InputStream input = ctx.getInputStream();

            MultipartStream multi = new MultipartStream(input, boundary);
            multi.setHeaderEncoding(charEncoding);

            boolean nextPart = multi.skipPreamble();
            while (nextPart) {
                Map headers = parseHeaders(multi.readHeaders());
                String fieldName = getFieldName(headers);
                if (fieldName != null) {
                    String subContentType = getHeader(headers, CONTENT_TYPE);
                    if (subContentType != null && subContentType
                        .toLowerCase().startsWith(MULTIPART_MIXED)) {
                        // Multiple files.
                        byte[] subBoundary = getBoundary(subContentType);
                        multi.setBoundary(subBoundary);
                        boolean nextSubPart = multi.skipPreamble();
                        while (nextSubPart) {
                            headers = parseHeaders(multi.readHeaders());
                            if (getFileName(headers) != null) {
                                FileItem item =
                                        createItem(headers, false);