/*
 * 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.commons.fileupload;

import static java.lang.String.format;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.MultipartStream.ItemInputStream;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.servlet.ServletRequestContext;
import org.apache.commons.fileupload.util.Closeable;
import org.apache.commons.fileupload.util.FileItemHeadersImpl;
import org.apache.commons.fileupload.util.LimitedInputStream;
import org.apache.commons.fileupload.util.Streams;
import org.apache.commons.io.IOUtils;

/**
 * High level API for processing file uploads.
 *
 * <p>
 * This class handles multiple files per single HTML widget, sent using {@code multipart/mixed} encoding type, as specified by
 * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>. Use {@link #parseRequest(RequestContext)} 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>
 */
public abstract class FileUploadBase {

    /**
     * The iterator, which is returned by
     * {@link FileUploadBase#getItemIterator(RequestContext)}.
     */
    private class FileItemIteratorImpl implements FileItemIterator {

        /**
         * Default implementation of {@link FileItemStream}.
         */
        private final class FileItemStreamImpl implements FileItemStream {

            /**
             * The file items content type.
             */
            private final String contentType;

            /**
             * The file items field name.
             */
            private final String fieldName;

            /**
             * The file items file name.
             */
            private final String name;

            /**
             * Whether the file item is a form field.
             */
            private final boolean formField;

            /**
             * The file items input stream.
             */
            private final InputStream inputStream;

            /**
             * The headers, if any.
             */
            private FileItemHeaders headers;

            /**
             * Creates a new instance.
             *
             * @param name          The items file name, or null.
             * @param fieldName     The items field name.
             * @param contentType   The items content type, or null.
             * @param formField     Whether the item is a form field.
             * @param contentLength The items content length, if known, or -1
             * @throws IOException Creating the file item failed.
             */
            FileItemStreamImpl(final String name, final String fieldName, final String contentType, final boolean formField, final long contentLength)
                    throws IOException {
                this.name = name;
                this.fieldName = fieldName;
                this.contentType = contentType;
                this.formField = formField;
                // Check if limit is already exceeded
                if (fileSizeMax != -1 && contentLength != -1 && contentLength > fileSizeMax) {
                    final FileSizeLimitExceededException e = new FileSizeLimitExceededException(
                            format("The field %s exceeds its maximum permitted size of %s bytes.", fieldName, Long.valueOf(fileSizeMax)), contentLength,
                            fileSizeMax);
                    e.setFileName(name);
                    e.setFieldName(fieldName);
                    throw new FileUploadIOException(e);
                }
                // OK to construct stream now
                final ItemInputStream itemStream = multi.newInputStream();
                InputStream istream = itemStream;
                if (fileSizeMax != -1) {
                    istream = new LimitedInputStream(istream, fileSizeMax) {

                        @Override
                        protected void raiseError(final long sizeMax, final long count) throws IOException {
                            itemStream.close(true);
                            final FileSizeLimitExceededException e = new FileSizeLimitExceededException(
                                    format("The field %s exceeds its maximum permitted size of %s bytes.", fieldName, Long.valueOf(sizeMax)), count, sizeMax);
                            e.setFieldName(fieldName);
                            e.setFileName(name);
                            throw new FileUploadIOException(e);
                        }
                    };
                }
                inputStream = istream;
            }

            /**
             * Closes the file item.
             *
             * @throws IOException An I/O error occurred.
             */
            void close() throws IOException {
                inputStream.close();
            }

            /**
             * Returns the items content type, or null.
             *
             * @return Content type, if known, or null.
             */
            @Override
            public String getContentType() {
                return contentType;
            }

            /**
             * Returns the items field name.
             *
             * @return Field name.
             */
            @Override
            public String getFieldName() {
                return fieldName;
            }

            /**
             * Returns the file item headers.
             *
             * @return The items header object
             */
            @Override
            public FileItemHeaders getHeaders() {
                return headers;
            }

            /**
             * Returns the items file name.
             *
             * @return File name, if known, or null.
             * @throws InvalidFileNameException The file name contains a NUL character,
             *   which might be an indicator of a security attack. If you intend to
             *   use the file name anyways, catch the exception and use
             *   InvalidFileNameException#getName().
             */
            @Override
            public String getName() {
                return Streams.checkFileName(name);
            }

            /**
             * Returns, whether this is a form field.
             *
             * @return True, if the item is a form field,
             *   otherwise false.
             */
            @Override
            public boolean isFormField() {
                return formField;
            }

            /**
             * Returns an input stream, which may be used to
             * read the items contents.
             *
             * @return Opened input stream.
             * @throws IOException An I/O error occurred.
             */
            @Override
            public InputStream openStream() throws IOException {
                if (((Closeable) inputStream).isClosed()) {
                    throw new FileItemStream.ItemSkippedException();
                }
                return inputStream;
            }

            /**
             * Sets the file item headers.
             *
             * @param headers The items header object
             */
            @Override
            public void setHeaders(final FileItemHeaders headers) {
                this.headers = headers;
            }

        }

        /**
         * The multi part stream to process.
         */
        private final MultipartStream multi;

        /**
         * The notifier, which used for triggering the
         * {@link ProgressListener}.
         */
        private final MultipartStream.ProgressNotifier notifier;

        /**
         * The boundary, which separates the various parts.
         */
        private final byte[] boundary;

        /**
         * The item, which we currently process.
         */
        private FileItemStreamImpl currentItem;

        /**
         * The current items field name.
         */
        private String currentFieldName;

        /**
         * Whether we are currently skipping the preamble.
         */
        private boolean skipPreamble;

        /**
         * Whether the current item may still be read.
         */
        private boolean itemValid;

        /**
         * Whether we have seen the end of the file.
         */
        private boolean eof;

        /**
         * Is this a multipart/related Request.
         */
        private final boolean multipartRelated;

        /**
         * Creates a new instance.
         *
         * @param ctx The request context.
         * @throws FileUploadException An error occurred while
         *   parsing the request.
         * @throws IOException An I/O error occurred.
         */
        FileItemIteratorImpl(final RequestContext ctx) throws FileUploadException, IOException {
            Objects.requireNonNull(ctx, "ctx");
            final String contentType = ctx.getContentType();
            if (null == contentType || !contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART)) {
                throw new InvalidContentTypeException(format("the request neither contains a %s nor a %s nor a %s stream, content type header is %s",
                        MULTIPART_FORM_DATA, MULTIPART_MIXED, MULTIPART_RELATED, contentType));
            }
            multipartRelated = contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART_RELATED);
            @SuppressWarnings("deprecation") // still has to be backward compatible
            final int contentLengthInt = ctx.getContentLength();
            final long requestSize = UploadContext.class.isAssignableFrom(ctx.getClass())
                    // Inline conditional is OK here CHECKSTYLE:OFF
                    ? ((UploadContext) ctx).contentLength()
                    : contentLengthInt;
            // CHECKSTYLE:ON
            final InputStream input; // this is eventually closed in MultipartStream processing
            if (sizeMax >= 0) {
                if (requestSize != -1 && requestSize > sizeMax) {
                    throw new SizeLimitExceededException(format("the request was rejected because its size (%s) exceeds the configured maximum (%s)",
                            Long.valueOf(requestSize), Long.valueOf(sizeMax)), requestSize, sizeMax);
                }
                // this is eventually closed in MultipartStream processing
                input = new LimitedInputStream(ctx.getInputStream(), sizeMax) {

                    @Override
                    protected void raiseError(final long sizeMax, final long count) throws IOException {
                        final FileUploadException ex = new SizeLimitExceededException(
                                format("the request was rejected because its size (%s) exceeds the configured maximum (%s)", Long.valueOf(count),
                                        Long.valueOf(sizeMax)),
                                count, sizeMax);
                        throw new FileUploadIOException(ex);
                    }
                };
            } else {
                input = ctx.getInputStream();
            }
            String charEncoding = headerEncoding;
            if (charEncoding == null) {
                charEncoding = ctx.getCharacterEncoding();
            }
            boundary = getBoundary(contentType);
            if (boundary == null) {
                IOUtils.closeQuietly(input); // avoid possible resource leak
                throw new FileUploadException("the request was rejected because no multipart boundary was found");
            }
            notifier = new MultipartStream.ProgressNotifier(listener, requestSize);
            try {
                multi = new MultipartStream(input, boundary, notifier);
            } catch (final IllegalArgumentException iae) {
                IOUtils.closeQuietly(input); // avoid possible resource leak
                throw new InvalidContentTypeException(format("The boundary specified in the %s header is too long", CONTENT_TYPE), iae);
            }
            multi.setHeaderEncoding(charEncoding);
            multi.setPartHeaderSizeMax(getPartHeaderSizeMax());
            skipPreamble = true;
            findNextItem();
        }

        /**
         * Called for finding the next item, if any.
         *
         * @return True, if an next item was found, otherwise false.
         * @throws IOException An I/O error occurred.
         */
        private boolean findNextItem() throws IOException {
            if (eof) {
                return false;
            }
            if (currentItem != null) {
                currentItem.close();
                currentItem = null;
            }
            for (;;) {
                final boolean nextPart;
                if (skipPreamble) {
                    nextPart = multi.skipPreamble();
                } else {
                    nextPart = multi.readBoundary();
                }
                if (!nextPart) {
                    if (currentFieldName == null) {
                        // Outer multipart terminated -> No more data
                        eof = true;
                        return false;
                    }
                    // Inner multipart terminated -> Return to parsing the outer
                    multi.setBoundary(boundary);
                    currentFieldName = null;
                    continue;
                }
                final FileItemHeaders headers = getParsedHeaders(multi.readHeaders());
                if (multipartRelated) {
                    currentFieldName = "";
                    currentItem = new FileItemStreamImpl(null, null, headers.getHeader(CONTENT_TYPE), false, getContentLength(headers));
                    currentItem.setHeaders(headers);
                    notifier.noteItem();
                    itemValid = true;
                    return true;
                }
                if (currentFieldName == null) {
                    // We're parsing the outer multipart
                    final String fieldName = getFieldName(headers);
                    if (fieldName != null) {
                        final String subContentType = headers.getHeader(CONTENT_TYPE);
                        if (subContentType != null && subContentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART_MIXED)) {
                            currentFieldName = fieldName;
                            // Multiple files associated with this field name
                            final byte[] subBoundary = getBoundary(subContentType);
                            multi.setBoundary(subBoundary);
                            skipPreamble = true;
                            continue;
                        }
                        final String fileName = getFileName(headers);
                        currentItem = new FileItemStreamImpl(fileName, fieldName, headers.getHeader(CONTENT_TYPE), fileName == null, getContentLength(headers));
                        currentItem.setHeaders(headers);
                        notifier.noteItem();
                        itemValid = true;
                        return true;
                    }
                } else {
                    final String fileName = getFileName(headers);
                    if (fileName != null) {
                        currentItem = new FileItemStreamImpl(fileName, currentFieldName, headers.getHeader(CONTENT_TYPE), false, getContentLength(headers));
                        currentItem.setHeaders(headers);
                        notifier.noteItem();
                        itemValid = true;
                        return true;
                    }
                }
                multi.discardBodyData();
            }
        }

        private long getContentLength(final FileItemHeaders headers) {
            try {
                return Long.parseLong(headers.getHeader(CONTENT_LENGTH));
            } catch (final Exception e) {
                return -1;
            }
        }

        /**
         * Returns, whether another instance of {@link FileItemStream}
         * is available.
         *
         * @throws FileUploadException Parsing or processing the
         *   file item failed.
         * @throws IOException Reading the file item failed.
         * @return True, if one or more additional file items
         *   are available, otherwise false.
         */
        @Override
        public boolean hasNext() throws FileUploadException, IOException {
            if (eof) {
                return false;
            }
            if (itemValid) {
                return true;
            }
            try {
                return findNextItem();
            } catch (final FileUploadIOException e) {
                // unwrap encapsulated SizeException
                throw (FileUploadException) e.getCause();
            }
        }

        /**
         * Returns the next available {@link FileItemStream}.
         *
         * @throws java.util.NoSuchElementException No more items are
         *   available. Use {@link #hasNext()} to prevent this exception.
         * @throws FileUploadException Parsing or processing the
         *   file item failed.
         * @throws IOException Reading the file item failed.
         * @return FileItemStream instance, which provides
         *   access to the next file item.
         */
        @Override
        public FileItemStream next() throws FileUploadException, IOException {
            if (eof || !itemValid && !hasNext()) {
                throw new NoSuchElementException();
            }
            itemValid = false;
            return currentItem;
        }

    }

    /**
     * Thrown to indicate that A files size exceeds the configured maximum.
     */
    public static class FileSizeLimitExceededException
            extends SizeException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = 8150776562029630058L;

        /**
         * File name of the item, which caused the exception.
         */
        private String fileName;

        /**
         * Field name of the item, which caused the exception.
         */
        private String fieldName;

        /**
         * Constructs a {@code SizeExceededException} with
         * the specified detail message, and actual and permitted sizes.
         *
         * @param message   The detail message.
         * @param actual    The actual request size.
         * @param permitted The maximum permitted request size.
         */
        public FileSizeLimitExceededException(final String message, final long actual,
                final long permitted) {
            super(message, actual, permitted);
        }

        /**
         * Returns the field name of the item, which caused the
         * exception.
         *
         * @return Field name, if known, or null.
         */
        public String getFieldName() {
            return fieldName;
        }

        /**
         * Returns the file name of the item, which caused the
         * exception.
         *
         * @return File name, if known, or null.
         */
        public String getFileName() {
            return fileName;
        }

        /**
         * Sets the field name of the item, which caused the
         * exception.
         *
         * @param fieldName the field name of the item,
         *        which caused the exception.
         */
        public void setFieldName(final String fieldName) {
            this.fieldName = fieldName;
        }

        /**
         * Sets the file name of the item, which caused the
         * exception.
         *
         * @param fileName the file name of the item, which caused the exception.
         */
        public void setFileName(final String fileName) {
            this.fileName = fileName;
        }

    }

    /**
     * Signals that a FileUpload I/O exception of some sort has occurred. This class is the general class of exceptions produced by failed or interrupted
     * FileUpload I/O operations.
     *
     * This exception wraps a {@link FileUploadException}.
     */
    public static class FileUploadIOException extends IOException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = -7047616958165584154L;

        /**
         * Creates a {@code FileUploadIOException} with the given cause.
         *
         * @param cause The exceptions cause, if any, or null.
         */
        public FileUploadIOException(final FileUploadException cause) {
            super(cause);
        }
    }

    /**
     * Thrown to indicate that the request is not a multipart request.
     */
    public static class InvalidContentTypeException
            extends FileUploadException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = -9073026332015646668L;

        /**
         * Constructs a {@code InvalidContentTypeException} with no
         * detail message.
         */
        public InvalidContentTypeException() {
        }

        /**
         * Constructs an {@code InvalidContentTypeException} with
         * the specified detail message.
         *
         * @param message The detail message.
         */
        public InvalidContentTypeException(final String message) {
            super(message);
        }

        /**
         * Constructs an {@code InvalidContentTypeException} with
         * the specified detail message and cause.
         *
         * @param message The detail message.
         * @param cause the original cause
         * @since 1.3.1
         */
        public InvalidContentTypeException(final String message, final Throwable cause) {
            super(message, cause);
        }
    }

    /**
     * Thrown to indicate an IOException.
     */
    public static class IOFileUploadException extends FileUploadException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = 1749796615868477269L;

        /**
         * Creates a new instance with the given cause.
         *
         * @param message The detail message.
         * @param cause The exceptions cause.
         */
        public IOFileUploadException(final String message, final IOException cause) {
            super(message, cause);
        }

    }

    /**
     * This exception is thrown, if a requests permitted size
     * is exceeded.
     */
    protected abstract static class SizeException extends FileUploadException {

        /**
         * Serial version UID, being used, if serialized.
         */
        private static final long serialVersionUID = -8776225574705254126L;

        /**
         * The actual size of the request.
         */
        private final long actual;

        /**
         * The maximum permitted size of the request.
         */
        private final long permitted;

        /**
         * Creates a new instance.
         *
         * @param message The detail message.
         * @param actual The actual number of bytes in the request.
         * @param permitted The requests size limit, in bytes.
         */
        protected SizeException(final String message, final long actual, final long permitted) {
            super(message);
            this.actual = actual;
            this.permitted = permitted;
        }

        /**
         * Gets the actual size of the request.
         *
         * @return The actual size of the request.
         * @since 1.3
         */
        public long getActualSize() {
            return actual;
        }

        /**
         * Gets the permitted size of the request.
         *
         * @return The permitted size of the request.
         * @since 1.3
         */
        public long getPermittedSize() {
            return permitted;
        }

    }

    /**
     * Thrown to indicate that the request size exceeds the configured maximum.
     */
    public static class SizeLimitExceededException
            extends SizeException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = -2474893167098052828L;

        /**
         * @deprecated 1.2 Replaced by
         * {@link #SizeLimitExceededException(String, long, long)}
         */
        @Deprecated
        public SizeLimitExceededException() {
            this(null, 0, 0);
        }

        /**
         * @deprecated 1.2 Replaced by
         * {@link #SizeLimitExceededException(String, long, long)}
         * @param message The exceptions detail message.
         */
        @Deprecated
        public SizeLimitExceededException(final String message) {
            this(message, 0, 0);
        }

        /**
         * Constructs a {@code SizeExceededException} with
         * the specified detail message, and actual and permitted sizes.
         *
         * @param message   The detail message.
         * @param actual    The actual request size.
         * @param permitted The maximum permitted request size.
         */
        public SizeLimitExceededException(final String message, final long actual,
                final long permitted) {
            super(message, actual, permitted);
        }

    }

    /**
     * Thrown to indicate that the request size is not specified. In other
     * words, it is thrown, if the content-length header is missing or
     * contains the value -1.
     *
     * @deprecated 1.2 As of commons-fileupload 1.2, the presence of a
     *   content-length header is no longer required.
     */
    @Deprecated
    public static class UnknownSizeException extends FileUploadException {

        /**
         * The exceptions UID, for serializing an instance.
         */
        private static final long serialVersionUID = 7062279004812015273L;

        /**
         * Constructs a {@code UnknownSizeException} with no
         * detail message.
         */
        public UnknownSizeException() {
        }

        /**
         * Constructs an {@code UnknownSizeException} with
         * the specified detail message.
         *
         * @param message The detail message.
         */
        public UnknownSizeException(final String message) {
            super(message);
        }

    }

    /**
     * Line feed.
     */
    private static final char LF = '\n';

    /**
     * Carriage return.
     */
    private static final char CR = '\r';

    /**
     * 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";

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

    /**
     * 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";

    /**
     * HTTP content type header for multiple related data.
     *
     * @since 1.6.0
     */
    public static final String MULTIPART_RELATED = "multipart/related";

    /**
     * The maximum length of a single header line that will be parsed
     * (1024 bytes).
     * @deprecated This constant is no longer used. As of commons-fileupload
     *   1.6, the applicable limit is the total size of a single part's headers,
     *   {@link #getPartHeaderSizeMax()} in bytes.
     */
    @Deprecated
    public static final int MAX_HEADER_SIZE = 1024;

    /**
     * Default per part header size limit in bytes.
     *
     * @since 1.6.0
     */
    public static final int DEFAULT_PART_HEADER_SIZE_MAX = 512;


    /**
     * 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} if the request is multipart;
     *         {@code false} otherwise.
     *
     * @deprecated 1.1 Use the method on {@code ServletFileUpload} instead.
     */
    @Deprecated
    public static boolean isMultipartContent(final HttpServletRequest req) {
        return ServletFileUpload.isMultipartContent(req);
    }

    /**
     * <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} 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} if the request is multipart;
     *         {@code false} otherwise.
     */
    public static final boolean isMultipartContent(final RequestContext ctx) {
        final String contentType = ctx.getContentType();
        if (contentType == null) {
            return false;
        }
        return contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART);
    }

    /**
     * The maximum size permitted for the complete request, as opposed to
     * {@link #fileSizeMax}. A value of -1 indicates no maximum.
     */
    private long sizeMax = -1;

    /**
     * The maximum size permitted for a single uploaded file, as opposed
     * to {@link #sizeMax}. A value of -1 indicates no maximum.
     */
    private long fileSizeMax = -1;

    /**
     * The maximum permitted number of files that may be uploaded in a single
     * request. A value of -1 indicates no maximum.
     */
    private long fileCountMax = -1;

    /**
     * The maximum permitted size of the headers provided with a single part in bytes.
     */
    private int partHeaderSizeMax = DEFAULT_PART_HEADER_SIZE_MAX;

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

    /**
     * The progress listener.
     */
    private ProgressListener listener;

    /**
     * Constructs a new instance.
     */
    public FileUploadBase() {
        // empty
    }

    /**
     * Creates a new {@link FileItem} instance.
     *
     * @param headers       A {@code Map} containing the HTTP request
     *                      headers.
     * @param isFormField   Whether or not this item is a form field, as
     *                      opposed to a file.
     *
     * @return A newly created {@code FileItem} instance.
     * @deprecated 1.2 This method is no longer used in favor of
     *   internally created instances of {@link FileItem}.
     */
    @Deprecated
    protected FileItem createItem(final Map<String, String> headers, final boolean isFormField) {
        return getFileItemFactory().createItem(getFieldName(headers), getHeader(headers, CONTENT_TYPE), isFormField, getFileName(headers));
    }

    /**
     * Gets the boundary from the {@code Content-type} header.
     *
     * @param contentType The value of the content type header from which to
     *                    extract the boundary value.
     *
     * @return The boundary, as a byte array.
     */
    protected byte[] getBoundary(final String contentType) {
        final ParameterParser parser = new ParameterParser();
        parser.setLowerCaseNames(true);
        // Parameter parser can handle null input
        final Map<String, String> params = parser.parse(contentType, new char[] { ';', ',' });
        final String boundaryStr = params.get("boundary");
        if (boundaryStr == null) {
            return null; // NOPMD
        }
        return boundaryStr.getBytes(StandardCharsets.ISO_8859_1);
    }

    /**
     * Gets the field name from the {@code Content-disposition}
     * header.
     *
     * @param headers A {@code Map} containing the HTTP request headers.
     * @return The field name for the current {@code encapsulation}.
     */
    protected String getFieldName(final FileItemHeaders headers) {
        return getFieldName(headers.getHeader(CONTENT_DISPOSITION));
    }

    /**
     * Gets the field name from the {@code Content-disposition}
     * header.
     *
     * @param headers A {@code Map} containing the HTTP request headers.
     * @return The field name for the current {@code encapsulation}.
     * @deprecated 1.2.1 Use {@link #getFieldName(FileItemHeaders)}.
     */
    @Deprecated
    protected String getFieldName(final Map<String, String> headers) {
        return getFieldName(getHeader(headers, CONTENT_DISPOSITION));
    }

    /**
     * Returns the field name, which is given by the content-disposition
     * header.
     * @param contentDisposition The content-dispositions header value.
     * @return The field name.
     */
    private String getFieldName(final String contentDisposition) {
        String fieldName = null;
        if (contentDisposition != null && contentDisposition.toLowerCase(Locale.ROOT).startsWith(FORM_DATA)) {
            final ParameterParser parser = new ParameterParser();
            parser.setLowerCaseNames(true);
            // Parameter parser can handle null input
            final Map<String, String> params = parser.parse(contentDisposition, ';');
            fieldName = params.get("name");
            if (fieldName != null) {
                fieldName = fieldName.trim();
            }
        }
        return fieldName;
    }

    /**
     * Returns the maximum number of files allowed in a single request.
     *
     * @return The maximum number of files allowed in a single request.
     */
    public long getFileCountMax() {
        return fileCountMax;
    }

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

    /**
     * Gets the file name from the {@code Content-disposition}
     * header.
     *
     * @param headers The HTTP headers object.
     * @return The file name for the current {@code encapsulation}.
     */
    protected String getFileName(final FileItemHeaders headers) {
        return getFileName(headers.getHeader(CONTENT_DISPOSITION));
    }

    /**
     * Gets the file name from the {@code Content-disposition}
     * header.
     *
     * @param headers A {@code Map} containing the HTTP request headers.
     * @return The file name for the current {@code encapsulation}.
     * @deprecated 1.2.1 Use {@link #getFileName(FileItemHeaders)}.
     */
    @Deprecated
    protected String getFileName(final Map<String, String> headers) {
        return getFileName(getHeader(headers, CONTENT_DISPOSITION));
    }

    /**
     * Returns the given content-disposition headers file name.
     * @param contentDisposition The content-disposition headers value.
     * @return The file name
     */
    private String getFileName(final String contentDisposition) {
        String fileName = null;
        if (contentDisposition != null) {
            final String cdl = contentDisposition.toLowerCase(Locale.ROOT);
            if (cdl.startsWith(FORM_DATA) || cdl.startsWith(ATTACHMENT)) {
                final ParameterParser parser = new ParameterParser();
                parser.setLowerCaseNames(true);
                // Parameter parser can handle null input
                final Map<String, String> params = parser.parse(contentDisposition, ';');
                if (params.containsKey("filename")) {
                    fileName = params.get("filename");
                    if (fileName != null) {
                        fileName = fileName.trim();
                    } else {
                        // Even if there is no value, the parameter is present,
                        // so we return an empty file name rather than no file
                        // name.
                        fileName = "";
                    }
                }
            }
        }
        return fileName;
    }

    /**
     * Returns the maximum allowed size of a single uploaded file,
     * as opposed to {@link #getSizeMax()}.
     *
     * @see #setFileSizeMax(long)
     * @return Maximum size of a single uploaded file.
     */
    public long getFileSizeMax() {
        return fileSizeMax;
    }

    /**
     * Returns the header with the specified name from the supplied map. The
     * header lookup is case-insensitive.
     *
     * @param headers A {@code Map} containing the HTTP request headers.
     * @param name    The name of the header to return.
     * @return The value of specified header, or a comma-separated list if
     *         there were multiple headers of that name.
     * @deprecated 1.2.1 Use {@link FileItemHeaders#getHeader(String)}.
     */
    @Deprecated
    protected final String getHeader(final Map<String, String> headers,
            final String name) {
        return headers.get(name.toLowerCase(Locale.ROOT));
    }

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

    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant {@code multipart/form-data} stream.
     *
     * @param ctx The context for the request to be parsed.
     * @return An iterator to instances of {@code FileItemStream}
     *         parsed from the request, in the order that they were
     *         transmitted.
     *
     * @throws FileUploadException if there are problems reading/parsing
     *                             the request or storing files.
     * @throws IOException An I/O error occurred. This may be a network
     *   error while communicating with the client or a problem while
     *   storing the uploaded content.
     */
    public FileItemIterator getItemIterator(final RequestContext ctx)
    throws FileUploadException, IOException {
        try {
            return new FileItemIteratorImpl(ctx);
        } catch (final FileUploadIOException e) {
            // unwrap encapsulated SizeException
            throw (FileUploadException) e.getCause();
        }
    }

    /**
     * <p> Parses the {@code header-part} and returns as key/value
     * pairs.
     *
     * <p> If there are multiple headers of the same names, the name
     * will map to a comma-separated list containing the values.
     *
     * @param headerPart The {@code header-part} of the current
     *                   {@code encapsulation}.
     *
     * @return A {@code Map} containing the parsed HTTP request headers.
     */
    protected FileItemHeaders getParsedHeaders(final String headerPart) {
        final int len = headerPart.length();
        final FileItemHeadersImpl headers = newFileItemHeaders();
        int start = 0;
        for (;;) {
            int end = parseEndOfLine(headerPart, start);
            if (start == end) {
                break;
            }
            final StringBuilder header = new StringBuilder(headerPart.substring(start, end));
            start = end + 2;
            while (start < len) {
                int nonWs = start;
                while (nonWs < len) {
                    final char c = headerPart.charAt(nonWs);
                    if (c != ' '  &&  c != '\t') {
                        break;
                    }
                    ++nonWs;
                }
                if (nonWs == start) {
                    break;
                }
                // Continuation line found
                end = parseEndOfLine(headerPart, nonWs);
                header.append(' ').append(headerPart, nonWs, end);
                start = end + 2;
            }
            parseHeaderLine(headers, header.toString());
        }
        return headers;
    }

    /**
     * Obtain the per part size limit for headers.
     *
     * @return The maximum size of the headers for a single part in bytes.
     *
     * @since 1.6.0
     */
    public int getPartHeaderSizeMax() {
        return partHeaderSizeMax;
    }

    /**
     * Returns the progress listener.
     *
     * @return The progress listener, if any, or null.
     */
    public ProgressListener getProgressListener() {
        return listener;
    }

    /**
     * Returns the maximum allowed size of a complete request, as opposed
     * to {@link #getFileSizeMax()}.
     *
     * @return The maximum allowed size, in bytes. The default value of
     *   -1 indicates, that there is no limit.
     *
     * @see #setSizeMax(long)
     *
     */
    public long getSizeMax() {
        return sizeMax;
    }

    /**
     * Creates a new instance of {@link FileItemHeaders}.
     * @return The new instance.
     */
    protected FileItemHeadersImpl newFileItemHeaders() {
        return new FileItemHeadersImpl();
    }

    /**
     * Skips bytes until the end of the current line.
     * @param headerPart The headers, which are being parsed.
     * @param end Index of the last byte, which has yet been
     *   processed.
     * @return Index of the \r\n sequence, which indicates
     *   end of line.
     */
    private int parseEndOfLine(final String headerPart, final int end) {
        int index = end;
        for (;;) {
            final int offset = headerPart.indexOf(CR, index);
            if (offset == -1  ||  offset + 1 >= headerPart.length()) {
                throw new IllegalStateException(
                    "Expected headers to be terminated by an empty line.");
            }
            if (headerPart.charAt(offset + 1) == LF) {
                return offset;
            }
            index = offset + 1;
        }
    }

    /**
     * Reads the next header line.
     * @param headers String with all headers.
     * @param header Map where to store the current header.
     */
    private void parseHeaderLine(final FileItemHeadersImpl headers, final String header) {
        final int colonOffset = header.indexOf(':');
        if (colonOffset == -1) {
            // This header line is malformed, skip it.
            return;
        }
        final String headerName = header.substring(0, colonOffset).trim();
        final String headerValue = header.substring(colonOffset + 1).trim();
        headers.addHeader(headerName, headerValue);
    }

    /**
     * <p> Parses the {@code header-part} and returns as key/value
     * pairs.
     *
     * <p> If there are multiple headers of the same names, the name
     * will map to a comma-separated list containing the values.
     *
     * @param headerPart The {@code header-part} of the current
     *                   {@code encapsulation}.
     *
     * @return A {@code Map} containing the parsed HTTP request headers.
     * @deprecated 1.2.1 Use {@link #getParsedHeaders(String)}
     */
    @Deprecated
    protected Map<String, String> parseHeaders(final String headerPart) {
        final FileItemHeaders headers = getParsedHeaders(headerPart);
        final Map<String, String> result = new HashMap<>();
        for (final Iterator<String> iter = headers.getHeaderNames();  iter.hasNext();) {
            final String headerName = iter.next();
            final Iterator<String> iter2 = headers.getHeaders(headerName);
            final StringBuilder headerValue = new StringBuilder(iter2.next());
            while (iter2.hasNext()) {
                headerValue.append(",").append(iter2.next());
            }
            result.put(headerName, headerValue.toString());
        }
        return result;
    }

    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant {@code multipart/form-data} stream.
     *
     * @param ctx The context for the request to be parsed.
     * @return A map of {@code FileItem} instances parsed from the request.
     * @throws FileUploadException if there are problems reading/parsing
     *                             the request or storing files.
     *
     * @since 1.3
     */
    public Map<String, List<FileItem>> parseParameterMap(final RequestContext ctx) throws FileUploadException {
        final List<FileItem> items = parseRequest(ctx);
        final Map<String, List<FileItem>> itemsMap = new HashMap<>(items.size());
        for (final FileItem fileItem : items) {
            final String fieldName = fileItem.getFieldName();
            List<FileItem> mappedItems = itemsMap.get(fieldName);
            if (mappedItems == null) {
                mappedItems = new ArrayList<>();
                itemsMap.put(fieldName, mappedItems);
            }
            mappedItems.add(fileItem);
        }
        return itemsMap;
    }

    /**
     * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
     * compliant {@code multipart/form-data} stream.
     *
     * @param req The servlet request to be parsed.
     * @return A list of {@code FileItem} 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 1.1 Use {@link ServletFileUpload#parseRequest(HttpServletRequest)} instead.
     */
    @Deprecated
    public List<FileItem> parseRequest(final 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} stream.
     *
     * @param ctx The context for the request to be parsed.
     * @return A list of {@code FileItem} 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(final RequestContext ctx) throws FileUploadException {
        final List<FileItem> items = new ArrayList<>();
        boolean successful = false;
        try {
            final FileItemIterator iter = getItemIterator(ctx);
            final FileItemFactory fileItemFactory = getFileItemFactory();
            Objects.requireNonNull(fileItemFactory, "getFileItemFactory()");
            final byte[] buffer = new byte[Streams.DEFAULT_BUFFER_SIZE];
            while (iter.hasNext()) {
                if (items.size() == fileCountMax) {
                    // The next item will exceed the limit.
                    throw new FileCountLimitExceededException(ATTACHMENT, getFileCountMax());
                }
                final FileItemStream item = iter.next();
                // Don't use getName() here to prevent an InvalidFileNameException.
                final String fileName = ((FileItemIteratorImpl.FileItemStreamImpl) item).name;
                final FileItem fileItem = fileItemFactory.createItem(item.getFieldName(), item.getContentType(), item.isFormField(), fileName);
                items.add(fileItem);
                try {
                    Streams.copy(item.openStream(), fileItem.getOutputStream(), true, buffer);
                } catch (final FileUploadIOException e) {
                    throw (FileUploadException) e.getCause();
                } catch (final IOException e) {
                    throw new IOFileUploadException(format("Processing of %s request failed. %s", MULTIPART_FORM_DATA, e.getMessage()), e);
                }
                final FileItemHeaders fih = item.getHeaders();
                fileItem.setHeaders(fih);
            }
            successful = true;
            return items;
        } catch (final FileUploadIOException e) {
            throw (FileUploadException) e.getCause();
        } catch (final IOException e) {
            throw new FileUploadException(e.getMessage(), e);
        } finally {
            if (!successful) {
                for (final FileItem fileItem : items) {
                    try {
                        fileItem.delete();
                    } catch (final Exception ignored) {
                        // ignored TODO perhaps add to tracker delete failure list somehow?
                    }
                }
            }
        }
    }

    /**
     * Sets the maximum number of files allowed per request.
     *
     * @param fileCountMax The new limit. {@code -1} means no limit.
     */
    public void setFileCountMax(final long fileCountMax) {
        this.fileCountMax = fileCountMax;
    }

    /**
     * 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);

    /**
     * Sets the maximum allowed size of a single uploaded file,
     * as opposed to {@link #getSizeMax()}.
     *
     * @see #getFileSizeMax()
     * @param fileSizeMax Maximum size of a single uploaded file.
     */
    public void setFileSizeMax(final long fileSizeMax) {
        this.fileSizeMax = fileSizeMax;
    }

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

    /**
     * Sets the per part size limit for headers.
     *
     * @param partHeaderSizeMax The maximum size of the headers in bytes.
     *
     * @since 1.6.0
     */
    public void setPartHeaderSizeMax(final int partHeaderSizeMax) {
        this.partHeaderSizeMax = partHeaderSizeMax;
    }

    /**
     * Sets the progress listener.
     *
     * @param listener The progress listener, if any. Defaults to null.
     */
    public void setProgressListener(final ProgressListener listener) {
        this.listener = listener;
    }

    /**
     * Sets the maximum allowed size of a complete request, as opposed
     * to {@link #setFileSizeMax(long)}.
     *
     * @param sizeMax The maximum allowed size, in bytes. The default value of
     *   -1 indicates, that there is no limit.
     *
     * @see #getSizeMax()
     *
     */
    public void setSizeMax(final long sizeMax) {
        this.sizeMax = sizeMax;
    }

}
