/*
 * 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.wicket.extensions.ajax;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.fileupload2.core.FileItem;
import org.apache.commons.fileupload2.core.FileUploadException;
import org.apache.wicket.Component;
import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.ajax.AjaxEventBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.attributes.AjaxCallListener;
import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
import org.apache.wicket.ajax.attributes.AjaxRequestAttributes.Method;
import org.apache.wicket.core.util.string.CssUtils;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.head.JavaScriptHeaderItem;
import org.apache.wicket.markup.html.form.upload.FileUpload;
import org.apache.wicket.protocol.http.servlet.MultipartServletWebRequest;
import org.apache.wicket.protocol.http.servlet.ServletWebRequest;
import org.apache.wicket.request.resource.PackageResourceReference;
import org.apache.wicket.request.resource.ResourceReference;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.lang.Bytes;

/**
 * Uploads files from a drop event.
 *
 * @author Andrew Kondratev
 * @author svenmeier
 */
public class AjaxFileDropBehavior extends AjaxEventBehavior
{

        public static final String DRAG_OVER_CLASS_KEY = CssUtils.key(AjaxFileDropBehavior.class, "dragover");

        private static final ResourceReference JS = new PackageResourceReference(
                AjaxFileDropBehavior.class, "wicket-ajaxupload.js");

        /**
         * Maximum size of all uploaded files in bytes in a request.
         */
        private Bytes maxSize;

        /**
         * Maximum size of file of upload in bytes (if there are more than one) in a request.
         */
        private Bytes fileMaxSize;

        /**
         * Maximum amount of files in request.
         * A value of -1 indicates no maximum.
         */
        private long fileCountMax = -1L;

        private String parameterName = "f";

        /**
         * Listen for 'dragover' and 'drop' events and prevent them, only 'drop' will initiate
         * an Ajax request.
         */
        public AjaxFileDropBehavior()
        {
                super("dragenter dragover dragleave drop");
        }

        @Override
        public void renderHead(Component component, IHeaderResponse response)
        {
                super.renderHead(component, response);

                response.render(JavaScriptHeaderItem.forReference(JS));
        }

        @Override
        protected void updateAjaxAttributes(AjaxRequestAttributes attributes)
        {
                super.updateAjaxAttributes(attributes);

                attributes.setMultipart(true);
                attributes.setMethod(Method.POST);
                // default must be prevented, otherwise browser will consume the dataTransfer
                attributes.setPreventDefault(true);

                attributes.getAjaxCallListeners().add(new AjaxCallListener() {
                        @Override
                        public CharSequence getPrecondition(Component component)
                        {
                                String css = getComponent().getString(DRAG_OVER_CLASS_KEY);

                                return String.format("jQuery('#' + attrs.c).toggleClass('%s', attrs.event.type === 'dragover'); return (attrs.event.type === 'drop');", css);
                        }
                });

                attributes.getDynamicExtraParameters()
                        .add(String.format(
                                "return Wicket.DataTransfer.getFilesAsParamArray(attrs.event.originalEvent, '%s');",
                                parameterName));
        }

        @Override
        protected void onEvent(AjaxRequestTarget target)
        {
                try
                {
                        ServletWebRequest request = (ServletWebRequest)getComponent().getRequest();
                        final MultipartServletWebRequest multipartWebRequest = request
                                .newMultipartWebRequest(getMaxSize(), getComponent().getPage().getId());
                        multipartWebRequest.setFileMaxSize(getFileMaxSize());
                        multipartWebRequest.setFileCountMax(getFileCountMax());
                        multipartWebRequest.parseFileParts();

                        // TODO: Can't this be detected from header?
                        getComponent().getRequestCycle().setRequest(multipartWebRequest);

                        ArrayList<FileUpload> fileUploads = new ArrayList<>();

                        // Get the item for the path
                        final List<FileItem> fileItems = multipartWebRequest.getFile(parameterName);

                        if (fileItems != null)
                        {
                                for (FileItem item : fileItems)
                                {
                                        fileUploads.add(new FileUpload(item));
                                }
                        }

                        onFileUpload(target, fileUploads);
                }
                catch (final FileUploadException fux)
                {
                        onError(target, fux);
                }
        }

        public Bytes getMaxSize()
        {
                if (maxSize == null)
                {
                        maxSize = getComponent().getApplication().getApplicationSettings()
                                .getDefaultMaximumUploadSize();
                }
                return maxSize;
        }

        /**
         * Set the maximum upload size.
         *
         * @param maxSize maximum size, must not be null
         */
        public void setMaxSize(Bytes maxSize)
        {
                Args.notNull(maxSize, "maxSize");
                this.maxSize = maxSize;
        }

        public Bytes getFileMaxSize()
        {
                return fileMaxSize;
        }

        /**
         * Set an optional maximum size per file.
         *
         * @param fileMaxSize maximum size for each uploaded file
         */
        public void setFileMaxSize(Bytes fileMaxSize)
        {
                this.fileMaxSize = fileMaxSize;
        }

        /**
         * Gets maximum count of files
         *
         * @return
         */
        public long getFileCountMax()
        {
                return fileCountMax;
        }

        /**
         * Sets maximum amount of files in upload request.
         *
         * @param fileCountMax
         */
        public void setFileCountMax(long fileCountMax)
        {
                this.fileCountMax = fileCountMax;
        }

        /**
         * Hook method called after a file was uploaded.
         * <p>
         * Note: {@link #onError(AjaxRequestTarget, FileUploadException)} is called instead when
         * uploading failed
         *
         * @param target
         *            the current request handler
         * @param files
         *            uploaded files
         */
        protected void onFileUpload(AjaxRequestTarget target, List<FileUpload> files)
        {
        }

        /**
         * Hook method called to handle any error during uploading of the file.
         * <p>
         * Default implementation re-throws the exception.
         *
         * @param target
         *            the current request handler
         * @param fux
         *            the error that occurred
         */
        protected void onError(AjaxRequestTarget target, FileUploadException fux)
        {
                throw new WicketRuntimeException(fux);
        }
}