    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.imaging.internal;
    018
    019import org.apache.commons.imaging.ImageFormat;
    020import org.apache.commons.imaging.ImageFormats;
    021import org.apache.commons.imaging.ImageParser;
    022import org.apache.commons.imaging.Imaging;
    023import org.apache.commons.imaging.common.bytesource.ByteSource;
    024
    025import java.io.IOException;
    026import java.util.function.Predicate;
    027import java.util.function.Supplier;
    028
    029/**
    030 * Internal utilities.
    031 *
    032 * @since 1.0-alpha3
    033 */
    034public class Util {
    035
    036    private Util() {}
    037
    038    public static ImageParser<?> getImageParser(ImageFormat format) {
    039        return getImageParser((parser) -> parser.canAcceptType(format), () -> new IllegalArgumentException("Unknown Format: " + format));
    040    }
    041
    042    public static ImageParser<?> getImageParser(String fileExtension) {
    043        return getImageParser((parser) -> parser.canAcceptExtension(fileExtension), () -> new IllegalArgumentException("Unknown Extension: " + fileExtension));
    044    }
    045
    046    // This generics suppression is as good as the predicate given. If the predicate violates a generics design,
    047    // then there will be an error during runtime.
    048    private static ImageParser<?> getImageParser(Predicate<ImageParser<?>> pred, Supplier<? extends RuntimeException> supplier) {
    049        return (ImageParser<?>) ImageParser
    050                .getAllImageParsers()
    051                .stream()
    052                .filter(pred)
    053                .findFirst()
    054                .orElseThrow(supplier);
    055    }
    056
    057    public static ImageParser<?> getImageParser(final ByteSource byteSource) throws IOException {
    058        // TODO: circular dependency between Imaging and internal Util class below.
    059        final ImageFormat format = Imaging.guessFormat(byteSource);
    060        if (!format.equals(ImageFormats.UNKNOWN)) {
    061            return Util.getImageParser(format);
    062        }
    063
    064        final String fileName = byteSource.getFileName();
    065        if (fileName != null) {
    066            return Util.getImageParser(fileName);
    067        }
    068
    069        throw new IllegalArgumentException("Can't parse this format.");
    070    }
    071}