/*
 * [FileFacts.java]
 *
 * Summary: Facts we record on each file in a directory.
 *
 * Copyright: (c) 2009-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.7 2009-01-11 round all file timestamps to nearest milli so original/copied/untouched timestamps will match.
 */
package com.mindprod.untouch;

import java.io.Serializable;

/**
 * Facts we record on each file in a directory.
 * <p/>
 * Thes fact lets us set LastChangeDate back to what it was if files have not really changed.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.7 2009-01-11 round all file timestamps to nearest milli so original/copied/untouched timestamps will
 * match.
 * @since 2003
 */
public final class FileFacts implements Serializable
    {
    /**
     * to prevent spurious InvalidClassExceptions.
     */
    static final long serialVersionUID = 2L;

    static final long SLOP = 1000 /* treat stamps this close in ms as equal */;

    /**
     * name of the file, converted to lower case.
     */
    public final String filename;

    /**
     * Adlerian 32 bit checksum the file used to be.
     */
    public final int digest;

    /**
     * length the file used to be in bytes.
     */
    public final long fileLength;

    /**
     * The lastChangeDate the file used to have.
     */
    public final long lastChangeDate;

    /**
     * standard Constructor.
     *
     * @param filename       name of the file
     * @param fileLength     length of the file
     * @param lastChangeDate timestamp when file last changed milliseconds since 1970.
     * @param digest         Adlerian 32 bit checksum of the file.
     */
    public FileFacts( String filename,
                      long fileLength,
                      long lastChangeDate,
                      int digest )
        {
        this.filename = filename;
        this.fileLength = fileLength;
        this.lastChangeDate = lastChangeDate;
        this.digest = digest;
        }

    /**
     * Compare another FileFacts object with this one.
     *
     * @param other FileFacts to compare with this one.
     *
     * @return true if the same fields.
     */
    @SuppressWarnings( { "BooleanMethodIsAlwaysInverted" } )
    public boolean equals( FileFacts other )
        {
        return digest == other.digest
               && fileLength == other.fileLength
               && Math.abs( lastChangeDate - other.lastChangeDate ) <= SLOP
               && filename.equals( other.filename );
        }
    }