EDIT

package eu.etaxonomy.cdm.model.media;

import java.awt.Dimension;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.LinkedHashMap;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.SortedMap;

import java.util.TreeMap;

import java.util.regex.Pattern;

import java.util.stream.Collectors;

import org.apache.log4j.Logger;

import eu.etaxonomy.cdm.model.common.CdmBase;

public class MediaUtils {

    private static final Logger logger = Logger.getLogger(MediaUtils.class);

    public static MediaRepresentation findBestMatchingRepresentation(Media media,

            Class<? extends MediaRepresentationPart> representationPartType, Integer size, Integer height,

            Integer widthOrDuration, String[] mimeTypes, MissingValueStrategy missingValStrategy){

        // find best matching representations of each media

        Set<MediaRepresentation> representations = media.getRepresentations();

        return findBestMatchingRepresentation(representations, representationPartType, size, height, widthOrDuration,

                mimeTypes, missingValStrategy);

    }

    public static MediaRepresentation findBestMatchingRepresentation(

            Set<MediaRepresentation> representations, Class<? extends MediaRepresentationPart> representationPartType, Integer size,

            Integer height, Integer widthOrDuration, String[] mimeTypes,

            MissingValueStrategy missingValStrategy) {

        SortedMap<Long, MediaRepresentation> prefRepresentations

                = filterAndOrderMediaRepresentations(representations, representationPartType, mimeTypes,

                        size, widthOrDuration, height, missingValStrategy);

        if(prefRepresentations.size() > 0){

            MediaRepresentation prefOne = prefRepresentations.get(prefRepresentations.firstKey());

            return prefOne;

        }

        return null;

    }

    /**

     * Return the first {@link MediaRepresentationPart} found for the given {@link Media}

     * or <code>null</code> otherwise.

     * @param media the media which is searched for the first part

     * @return the first part found or <code>null</code>

     */

    public static MediaRepresentationPart getFirstMediaRepresentationPart(Media media){

        if(media==null){

            return null;

        }

        MediaRepresentationPart mediaRepresentationPart = null;

        Set<MediaRepresentation> representations = media.getRepresentations();

        if(representations!=null && representations.size()>0){

            MediaRepresentation mediaRepresentation = representations.iterator().next();

            List<MediaRepresentationPart> parts = mediaRepresentation.getParts();

            if(parts!=null && parts.size()>0){

                mediaRepresentationPart = parts.iterator().next();

            }

        }

        return mediaRepresentationPart;

    }

    /**

     * Creates one single {@link MediaRepresentationPart} for the given {@link Media}

     * if it does not already exists. Otherwise the first part found is returned.<br>

     * @param media the media for which the representation part should be created

     * @return the first or newly created representation part

     */

    public static MediaRepresentationPart initFirstMediaRepresentationPart(Media media, boolean isImage) {

        MediaRepresentationPart mediaRepresentationPart = getFirstMediaRepresentationPart(media);

        if(mediaRepresentationPart==null){

            Set<MediaRepresentation> representations = media.getRepresentations();

            if(representations!=null && representations.size()>0){

                MediaRepresentation mediaRepresentation = representations.iterator().next();

                if(isImage){

                    mediaRepresentationPart = ImageFile.NewInstance(null, null);

                }

                else{

                    mediaRepresentationPart = MediaRepresentationPart.NewInstance(null, null);

                }

                mediaRepresentation.addRepresentationPart(mediaRepresentationPart);

            }

            else{

                if(isImage){

                    mediaRepresentationPart = ImageFile.NewInstance(null, null);

                }

                else{

                    mediaRepresentationPart = MediaRepresentationPart.NewInstance(null, null);

                }

                MediaRepresentation mediaRepresentation = MediaRepresentation.NewInstance();

                mediaRepresentation.addRepresentationPart(mediaRepresentationPart);

                media.addRepresentation(mediaRepresentation);

            }

        }

        return mediaRepresentationPart;

    }

    /**

     * Filters the given List of Media by the supplied filter parameters <code>representationPartType</code>,

     * <code>mimeTypes</code>, <code>widthOrDuration</code>, <code>height</code>, <code>size</code>.

     * Only best matching MediaRepresentation remains attached to the Media entities.

     * A Media entity may be completely omitted in the resulting list if  {@link #filterAndOrderMediaRepresentations(Set, Class, String[], Integer, Integer, Integer)}

     * is not returning any matching representation. This can be the case if a <code>representationPartType</code> is supplied.

     *

     * @param mediaList

     * @param representationPartType any subclass of {@link MediaRepresentationPart}

     * @param mimeTypes

     * @param widthOrDuration

     * @param height

     * @param size

     * @return

     */

    public static Map<Media, MediaRepresentation> findPreferredMedia(List<Media> mediaList,

            Class<? extends MediaRepresentationPart> representationPartType, String[] mimeTypes, Integer widthOrDuration,

            Integer height, Integer size, MissingValueStrategy missingValStrat) {

        if(mimeTypes != null) {

            for(int i=0; i<mimeTypes.length; i++){

                mimeTypes[i] = mimeTypes[i].replace(':', '/');

            }

        }

        Map<Media, MediaRepresentation> returnMediaList;

        if(mediaList != null){

            returnMediaList = new LinkedHashMap<>(mediaList.size());

            for(Media media : mediaList){

                Set<MediaRepresentation> candidateRepresentations = new LinkedHashSet<>();

                candidateRepresentations.addAll(media.getRepresentations());

                SortedMap<Long, MediaRepresentation> prefRepresentations

                    = filterAndOrderMediaRepresentations(candidateRepresentations, representationPartType,

                            mimeTypes, size, widthOrDuration, height, missingValStrat);

                if(prefRepresentations.size() > 0){

                    // Media.representations is a set

                    // so it cannot retain the sorting which has been found by filterAndOrderMediaRepresentations()

                    // thus we take first one and remove all other representations

                    returnMediaList.put(media, prefRepresentations.get(prefRepresentations.firstKey()));

                }

            }

        }

        else{

            returnMediaList = new HashMap<>();

        }

        return returnMediaList;

    }

    /**

     * @see also cdm-dataportal: cdm-api.module#cdm_preferred_media_representations()

     *

     * @param mediaRepresentations

     * @param representationPartType

     * @param mimeTypeRegexes

     * @param size

     *  Applies to all {@link MediaRepresentationPart}s (value = <code>null</code> means ignore, for maximum size use {@link Integer#MAX_VALUE})

     * @param widthOrDuration

     *   Applied to {@link ImageFile#getWidth()}, or {@link {@link MovieFile#getDuration()},

     *   or {@link {@link AudioFile#getDuration()} (value = <code>null</code> means ignore,

     *   for maximum use {@link Integer#MAX_VALUE})

     * @param height

     *   The height is only applied to {@link ImageFile}s (value = <code>null</code> means ignore,

     *   for maximum height use {@link Integer#MAX_VALUE})

     * @return

     */

    public static SortedMap<Long, MediaRepresentation> filterAndOrderMediaRepresentations(

            Set<MediaRepresentation> mediaRepresentations,

            Class<? extends MediaRepresentationPart> representationPartType, String[] mimeTypeRegexes,

            Integer size, Integer widthOrDuration, Integer height,

            MissingValueStrategy missingValStrat) {

        SortedMap<Long, MediaRepresentation> prefRepr = new TreeMap<>();

        Dimension preferredImageDimensions = dimensionsFilter(widthOrDuration, height, null);

        long preferredExpansion = expanse(preferredImageDimensions);

        logger.debug("preferredExpansion: " + preferredExpansion);

        mimeTypeRegexes = (mimeTypeRegexes == null ? new String[]{".*"} : mimeTypeRegexes);

        for (String mimeTypeRegex : mimeTypeRegexes) {

            // getRepresentationByMimeType

            Pattern mimeTypePattern = Pattern.compile(mimeTypeRegex);

            int representationCnt = 0;

            for (MediaRepresentation representation : mediaRepresentations) {

                List<MediaRepresentationPart> matchingParts = new ArrayList<>();

                // check MIME type

                boolean isMimeTypeMatch = representation.getMimeType() == null

                        || mimeTypePattern.matcher(representation.getMimeType()).matches();

                if(logger.isDebugEnabled()){

                    logger.debug("isMimeTypeMatch: " + Boolean.valueOf(isMimeTypeMatch).toString());

                }

                long dimensionsDeltaAllParts = 0;

                //first the size is used for comparison

                for (MediaRepresentationPart part : representation.getParts()) {

                    // check representationPartType

                    boolean isRepresentationPartTypeMatch = representationPartType == null

                            || part.getClass().isAssignableFrom(representationPartType);

                    if(logger.isDebugEnabled()){

                        logger.debug("isRepresentationPartTypeMatch: " + Boolean.valueOf(isRepresentationPartTypeMatch).toString());

                    }

                    if ( !(isRepresentationPartTypeMatch && isMimeTypeMatch) ) {

                        continue;

                    }

                    if(logger.isDebugEnabled()){

                        logger.debug(part + " matches");

                    }

                    matchingParts.add(part);

                    Integer sizeOfPart = part.getSize();

                    if(isUndefined(sizeOfPart)){

                        sizeOfPart = missingValStrat.applyTo(sizeOfPart);

                    }

                    if (size != null && sizeOfPart != null){

                        int distance = sizeOfPart - size;

                        if (distance < 0) {

                            distance *= -1;

                        }

                        dimensionsDeltaAllParts += distance;

                    }

                    //if height and width/duration is defined, add this information, too

                    if (preferredImageDimensions != null || widthOrDuration != null){

                        long expansionDelta = 0;

                        if (part.isInstanceOf(ImageFile.class)) {

                            if (preferredImageDimensions != null){

                                ImageFile image = CdmBase.deproxy(part, ImageFile.class);

                                Dimension imageDimension = dimensionsFilter(image.getWidth(), image.getHeight(), missingValStrat);

                                if (imageDimension != null){

                                    expansionDelta = Math.abs(expanse(imageDimension) - preferredExpansion);

                                }

                                if(logger.isDebugEnabled()){

                                    if(logger.isDebugEnabled()){

                                        logger.debug("part [" + part.getUri() + "; " + imageDimension + "] : preferredImageDimensions= " + preferredImageDimensions + ", size= "  + size+ " >>" + expansionDelta );

                                    }

                                }

                            }

                        }

                        else if (part.isInstanceOf(MovieFile.class)){

                             MovieFile movie = CdmBase.deproxy(part, MovieFile.class);

                             Integer durationOfMovie = movie.getDuration();

                             if(isUndefined(durationOfMovie)){

                                 durationOfMovie = null; // convert potential 0 to null!

                             }

                             durationOfMovie = missingValStrat.applyTo(durationOfMovie);

                             if(widthOrDuration != null){

                                expansionDelta = durationOfMovie - widthOrDuration;

                            }

                             if(logger.isDebugEnabled()){

                                 logger.debug("part MovieFile[" + part.getUri() + "; duration=" + movie.getDuration() + "-> " + durationOfMovie + "] : preferrdDuration= " + widthOrDuration + ", size= "  + size+ " >>" + expansionDelta );

                             }

                        } else if (part.isInstanceOf(AudioFile.class)){

                            AudioFile audio = CdmBase.deproxy(part, AudioFile.class);

                            Integer durationOfAudio = audio.getDuration();

                            if(isUndefined(durationOfAudio)){

                                durationOfAudio = null;  // convert potential 0 to null!

                            }

                            durationOfAudio = missingValStrat.applyTo(durationOfAudio);

                            if(widthOrDuration != null) {

                                expansionDelta = durationOfAudio - widthOrDuration;

                            }

                            if(logger.isDebugEnabled()){

                                logger.debug("part AudioFile[" + part.getUri() + "; duration=" +  audio.getDuration() + "-> " + durationOfAudio + "] : preferrdDuration= " + widthOrDuration + ", size= "  + size + " >>" + expansionDelta );

                            }

                        }

                        // the expansionDelta is summed up since the parts together for the whole

                        // which is bigger than only a part. By simply summing up images splitted

                        // into parts have too much weight compared to the single image but since

                        // parts are not used at all this is currently not a problem

                        dimensionsDeltaAllParts += expansionDelta;

                    }

                } // loop parts

                logger.debug("matchingParts.size():" + matchingParts.size());

                if(matchingParts.size() > 0 ){

                    representation.getParts().clear();

                    representation.getParts().addAll(matchingParts);

                    prefRepr.put((dimensionsDeltaAllParts + representationCnt++), representation);

                }

            } // loop representations

        } // loop mime types

        if(logger.isDebugEnabled()){

            String text =  prefRepr.keySet().stream()

            .map(key -> key + ": " + prefRepr.get(key).getParts().get(0).getUri().toString())

            .collect(Collectors.joining(", ", "{", "}"));

            logger.debug("resulting representations: " + text);

        }

        return prefRepr;

    }

    /**

     * @param imageDimension

     * @return

     */

    static long expanse(Dimension imageDimension) {

        if(imageDimension != null){

            return (long)imageDimension.height * (long)imageDimension.width;

        } else {

            return -1;

        }

    }

    /**

     * @param widthOrDuration

     * @param height

     * @param mvs Will be applied when both, width and height, are <code>null</code>

     */

    static Dimension dimensionsFilter(Integer width, Integer height, MissingValueStrategy mvs) {

        Dimension imageDimensions = null;

        if(!isUndefined(height) || !isUndefined(width)){

            imageDimensions = new Dimension();

            if (!isUndefined(height) && isUndefined(width)){

                imageDimensions.setSize(1, height);

            } else if(isUndefined(height) && !isUndefined(width)) {

                imageDimensions.setSize(width, 1); // --> height will be respected and width is ignored

            } else {

                imageDimensions.setSize(width, height);

            }

        } else {

            // both, width and height, are undefined

            if(mvs != null){

                // set both values to null so that the MissingValueStrategy can be applied

                // the MissingValueStrategy only get effective when the supplied value  is NULL

                width = null;

                height = null;

                imageDimensions = new Dimension(mvs.applyTo(width), mvs.applyTo(height));

            }

        }

        return imageDimensions;

    }

    static private boolean isUndefined(Integer val) {

        return val == null || val == 0;

    }

    /**

     * Strategies for replacing <code>null</code> values with a numeric value.

     *

     * @author a.kohlbecker

     */

    public enum MissingValueStrategy {

        /**

         * replace <code>null</code> by {@link Integer#MAX_VALUE}

         */

        MAX(Integer.MAX_VALUE),

        /**

         * replace <code>null</code> by <code>0</code>

         */

        ZERO(0);

        private Integer defaultValue;

        MissingValueStrategy(Integer defaultValue){

            this.defaultValue = defaultValue;

        }

        public Integer applyTo(Integer val){

            if(val == null){

                return defaultValue;

            } else {

                return val;

            }

        }

    }

  }