/*
 * Copyright 2005 the original author or authors.
 * 
 * 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.wamblee.photos.servlet;

import java.io.IOException;
import java.io.InputStream;

import javax.inject.Inject;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.wamblee.photos.model.Album;
import org.wamblee.photos.model.Photo;
import org.wamblee.photos.model.PhotoEntry;
import org.wamblee.photos.model.plumbing.AuthorizedPhotos;

/**
 * Sends an image (either thumbnail or full size) from the photo album.
 * <p/>
 * The returned picture is defined based on
 * {@link javax.servlet.http.HttpServletRequest#getPathInfo}. as follows. If the
 * path info starts with the string defined by {@link #THUMBNAIL_NAME}, then a
 * thumbnail image is served and the rest of the path info is the relative path
 * of the picture. Otherwise the path info is identical to the relative path of
 * the picture.
 */
public class ImageSender extends HttpServlet {

    @Inject
    @AuthorizedPhotos
    private transient Album root;

    static final long serialVersionUID = 4069997717483260853L;

    enum ImageType {
        thumbnail,
        photo,
        resource
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest
     * , javax.servlet.http.HttpServletResponse)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest
     * , javax.servlet.http.HttpServletResponse)
     */
    protected void doPost(HttpServletRequest aRequest, HttpServletResponse aResponse)
            throws ServletException, IOException {

        String entryPath = aRequest.getPathInfo();
        if (entryPath == null) {
            entryPath = "/";
        }

        ImageType type = null;
        for (ImageType t : ImageType.values()) {
            if (entryPath.startsWith("/" + t + "/")) {
                entryPath = entryPath.substring(t.toString().length() + 1);
                type = t;
                break;
            }
        }

        if (type == null) {
            throw new RuntimeException("unsupported URL " + aRequest.getPathInfo());
        }

        switch (type) {
            case thumbnail:
            case photo: {
                if (entryPath.endsWith(".jpg")) {
                    entryPath = entryPath.substring(0, entryPath.length() - ".jpg".length());
                }
                PhotoEntry entry = root.getEntry(entryPath);

                Photo photo = (Photo) entry;
                InputStream is = null;
                if (type == ImageType.thumbnail) {
                    is = photo.getThumbNail();
                } else {
                    is = photo.getPhoto();
                }
                sendImage(aResponse, is);
                break;
            }
            case resource: {
                try (InputStream is = getServletContext().getResourceAsStream("/images/" + entryPath)) {
                    ServletOutputStream os = aResponse.getOutputStream();
                    byte[] buffer = new byte[4096];
                    int n;
                    while ((n = is.read(buffer)) > 0) {
                        os.write(buffer, 0, n);
                    }
                }
                break;
            }

            default: {
                //throw new RuntimeException("Unknown type " + type);
            }
        }
    }

    /**
     * Sends the image.
     *
     * @param response Response
     * @param is       Input stream of the image.
     * @throws IOException In case an IO problem occurs.
     */

    private void sendImage(HttpServletResponse response, InputStream is) throws IOException {
        int c;
        while ((c = is.read()) >= 0) {
            response.getOutputStream().write(c);
        }
    }
}