/*
 * [Persist.java]
 *
 * Summary: Save and Restore config in registry via Preferences API.
 *
 * Copyright: (c) 2006-2017 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:
 *  1.0 2010-01-17 initial release.
 */
package com.mindprod.htmlreflow;

import java.util.prefs.BackingStoreException;
import java.util.prefs.Preferences;

/**
 * Save and Restore config in registry via Preferences API.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.0 2010-01-17 initial release.
 * @since 2010-01-17
 */
class Persist
    {
    /**
     * sub node for the tag descriptions.
     */
    private static final Preferences persistedTags = Preferences.userNodeForPackage( HtmlReflow.class ).node( "tags" );

    /**
     * where in registry we persist our history
     */
    private static final Preferences persistence = Preferences.userNodeForPackage( HtmlReflow.class );

    /**
     * reflow line length (Unbreakable lines may be considerably shorter or longer.)
     */
    private static int desiredLineLength;

    /**
     * how to end each line CrLf Lf Cr
     */
    private static String lineSeparator;

    /**
     * maximum line length if line longer than this, we break at attributes.
     */
    private static int maxLineLength;

    /**
     * lookup table so we can get information on how to do NLs and indents for a given <tag> </tag>
     */
    private static TagConfig[] tags;

    /**
     * restore the configuration from the registry via the Preferences API
     *
     * @throws java.util.prefs.BackingStoreException on any problem with persistence
     */
    static void restoreConfig() throws BackingStoreException
        {
        long expectedSerialVersionUID = persistence.getLong( "version", 0 );
        if ( expectedSerialVersionUID != TagConfig.serialVersionUID )
            {
            throw new BackingStoreException( "Configuration out of date. Please rerun Configure utility." );
            }
        // all keys must be present or there is a program bug.
        desiredLineLength = persistence.getInt( "desiredLineLength", 0 );
        maxLineLength = persistence.getInt( "maxLineLength", 0 );
        lineSeparator = persistence.get( "lineSeparator", null );
        if ( desiredLineLength < 10 || maxLineLength < 10 || lineSeparator == null )
            {
            throw new BackingStoreException( "Configuration corrupted. Please rerun Configure utility." );
            }
        final String[] keys = persistedTags.keys();
        tags = new TagConfig[ keys.length ];
        int i = 0;
        for ( String key : keys )
            {
            final byte[] byteValues = persistedTags.getByteArray( key, null );
            if ( byteValues == null )
                {
                throw new BackingStoreException( "Configuration corrupted. Please rerun Configure utility." );
                }
            tags[ i++ ] = new TagConfig( key, byteValues );
            } // end for
        }

    /**
     * save the configuration into the registry via the Preferences API
     *
     * @throws java.util.prefs.BackingStoreException on any problem with persistence
     */
    static void saveConfig() throws BackingStoreException
        {
        // must save config as key=value pairs with unique keys.
        persistence.clear();
        persistence.putLong( "version", TagConfig.serialVersionUID );
        persistence.putInt( "desiredLineLength", desiredLineLength );
        persistence.putInt( "maxLineLength", maxLineLength );
        persistence.put( "lineSeparator", lineSeparator );
        for ( TagConfig tag : tags )
            {
            persistedTags.putByteArray( tag.getTagName(), tag.getByteValues() );
            }
        persistence.flush();
        }

    /**
     * get the desiredLineLength
     *
     * @return line length to aim for in reflowing
     */
    public static int getDesiredLineLength()
        {
        return desiredLineLength;
        }

    /**
     * set the desiredLineLength
     *
     * @param desiredLineLength line length to aim for in reflowing
     */
    public static void setDesiredLineLength( final int desiredLineLength )
        {
        Persist.desiredLineLength = desiredLineLength;
        }

    /**
     * get the lineSeparator string
     *
     * @return \r\n \n \r
     */
    public static String getLineSeparator()
        {
        return lineSeparator;
        }

    /**
     * set the lineSeparator string
     *
     * @param lineSeparator \r\n \n \r
     */
    public static void setLineSeparator( final String lineSeparator )
        {
        Persist.lineSeparator = lineSeparator;
        }

    /**
     * get the maxLineLength
     *
     * @return maximum line length if line longer than this, we break at attributes.
     */
    public static int getMaxLineLength()
        {
        return desiredLineLength;
        }

    /**
     * set the maxLineLength
     *
     * @param maxLineLength if line longer than this, we break at attributes.
     */
    public static void setMaxLineLength( final int maxLineLength )
        {
        Persist.maxLineLength = maxLineLength;
        }

    /**
     * get the configuration for all the tags
     *
     * @return tags array of all the tag configurations
     */
    public static TagConfig[] getTags()
        {
        return tags;
        }

    /**
     * set the configuration for all the tags
     *
     * @param tags array of all the tag configurations
     */
    public static void setTags( final TagConfig[] tags )
        {
        Persist.tags = tags;
        }
    }