src/main/java/org/apache/commons/imaging/FormatCompliance.java

/*
 * 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
 *
 *      https://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.imaging;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Provides information about the compliance of a specified data source (byte array, file, etc.) to an image format.
 */
public class FormatCompliance {

    private static final Logger LOGGER = Logger.getLogger(FormatCompliance.class.getName());

    /**
     * Gets the default format compliance instance.
     *
     * @return a default FormatCompliance instance that ignores errors.
     */
    public static FormatCompliance getDefault() {
        return new FormatCompliance("ignore", false);
    }

    private final boolean failOnError;
    private final String description;

    private final List<String> comments = new ArrayList<>();

    /**
     * Constructs a new FormatCompliance with the specified description.
     *
     * @param description the description of the format compliance.
     */
    public FormatCompliance(final String description) {
        this.description = description;
        this.failOnError = false;
    }

    /**
     * Constructs a new FormatCompliance with the specified description and fail-on-error flag.
     *
     * @param description the description of the format compliance.
     * @param failOnError true to throw exceptions on errors, false to only collect comments.
     */
    public FormatCompliance(final String description, final boolean failOnError) {
        this.description = description;
        this.failOnError = failOnError;
    }

    /**
     * Adds a comment about a compliance issue.
     *
     * @param comment the comment to add.
     * @throws ImagingException if failOnError is true.
     */
    public void addComment(final String comment) throws ImagingException {
        comments.add(comment);
        if (failOnError) {
            throw new ImagingException(comment);
        }
    }

    /**
     * Adds a comment about a compliance issue with a value.
     *
     * @param comment the comment to add.
     * @param value the value associated with the comment.
     * @throws ImagingException if failOnError is true.
     */
    public void addComment(final String comment, final int value) throws ImagingException {
        addComment(comment + ": " + getValueDescription(value));
    }

    /**
     * Checks if a value is within specified bounds.
     *
     * @param name the name of the value being checked.
     * @param min the minimum allowed value.
     * @param max the maximum allowed value.
     * @param actual the actual value to check.
     * @return true if the value is within bounds, false otherwise.
     * @throws ImagingException if failOnError is true and the check fails.
     */
    public boolean checkBounds(final String name, final int min, final int max, final int actual) throws ImagingException {
        if (actual < min || actual > max) {
            addComment(name + ": bounds check: " + min + " <= " + actual + " <= " + max + ": false");
            return false;
        }

        return true;
    }

    /**
     * Compares an actual value against a valid value.
     *
     * @param name the name of the value being compared.
     * @param valid the valid value.
     * @param actual the actual value to compare.
     * @return true if the actual value matches the valid value, false otherwise.
     * @throws ImagingException if failOnError is true and the comparison fails.
     */
    public boolean compare(final String name, final int valid, final int actual) throws ImagingException {
        return compare(name, new int[] { valid, }, actual);
    }

    /**
     * Compares an actual value against an array of valid values.
     *
     * @param name the name of the value being compared.
     * @param valid the array of valid values.
     * @param actual the actual value to compare.
     * @return true if the actual value matches any valid value, false otherwise.
     * @throws ImagingException if failOnError is true and the comparison fails.
     */
    public boolean compare(final String name, final int[] valid, final int actual) throws ImagingException {
        for (final int element : valid) {
            if (actual == element) {
                return true;
            }
        }

        final StringBuilder result = new StringBuilder(43);
        result.append(name);
        result.append(": Unexpected value: (valid: ");
        if (valid.length > 1) {
            result.append('{');
        }
        for (int i = 0; i < valid.length; i++) {
            if (i > 0) {
                result.append(", ");
            }
            result.append(getValueDescription(valid[i]));
        }
        if (valid.length > 1) {
            result.append('}');
        }
        result.append(", actual: ").append(getValueDescription(actual)).append(")");
        addComment(result.toString());
        return false;
    }

    /**
     * Compares two byte arrays for equality.
     *
     * @param name the name of the byte arrays being compared.
     * @param expected the expected byte array.
     * @param actual the actual byte array to compare.
     * @return true if the arrays are equal, false otherwise.
     * @throws ImagingException if failOnError is true and the comparison fails.
     */
    public boolean compareBytes(final String name, final byte[] expected, final byte[] actual) throws ImagingException {
        if (expected.length != actual.length) {
            addComment(name + ": Unexpected length: (expected: " + expected.length + ", actual: " + actual.length + ")");
            return false;
        }
        for (int i = 0; i < expected.length; i++) {
            // System.out.println("expected: "
            // + getValueDescription(expected[i]) + ", actual: "
            // + getValueDescription(actual[i]) + ")");
            if (expected[i] != actual[i]) {
                addComment(
                        name + ": Unexpected value: (expected: " + getValueDescription(expected[i]) + ", actual: " + getValueDescription(actual[i]) + ")");
                return false;
            }
        }

        return true;
    }

    /**
     * Dumps the format compliance information to the logger.
     */
    public void dump() {
        try (StringWriter sw = new StringWriter();
                PrintWriter pw = new PrintWriter(sw)) {
            dump(pw);
            pw.flush();
            sw.flush();
            LOGGER.fine(sw.toString());
        } catch (final IOException e) {
            LOGGER.log(Level.SEVERE, e.getMessage(), e);
        }
    }

    /**
     * Dumps the format compliance information to the specified PrintWriter.
     *
     * @param pw the PrintWriter to write to.
     */
    public void dump(final PrintWriter pw) {
        pw.println("Format Compliance: " + description);

        if (comments.isEmpty()) {
            pw.println("\tNo comments.");
        } else {
            for (int i = 0; i < comments.size(); i++) {
                pw.println("\t" + (i + 1) + ": " + comments.get(i));
            }
        }
        pw.println("");
        pw.flush();
    }

    private String getValueDescription(final int value) {
        return value + " (" + Integer.toHexString(value) + ")";
    }

    @Override
    public String toString() {
        final StringWriter sw = new StringWriter();
        final PrintWriter pw = new PrintWriter(sw);

        dump(pw);

        return sw.getBuffer().toString();
    }
}