package com.temp.foundation.client.pavment;

import com.temp.common.shared.utils.*;

import java.util.*;

/**
 * Code to support converting a list of Strings to a single String and back.
 *
 * @author georgs
 */
public class PlaceTokenPackaging {

    /**
     * Pack the passed Strings into a single String.
     *
     * @return "" if null passed OR no strings, individual nulls treated as ""
     */
    public static String pack( String... strings ) {
        return pack( (strings != null) ? Arrays.asList( strings ) : null );
    }

    /**
     * Pack the passed Strings into a single String.
     *
     * @return "" if null passed OR no strings, individual nulls treated as ""
     */
    public static String pack( List<String> strings ) {
        if ( null != (strings = normalize( strings )) ) {
            StringBuilder sb = new StringBuilder();
            for ( String string : strings ) {
                appendString( sb, string );
            }
            return sb.toString();
        }
        return "";
    }

    /**
     * Unpack the passed String into multiple Strings.
     *
     * @return empty if minimumListSize < 1 AND null or "" passed, otherwise the
     * list will be at least minimumListSize (or 1 if minimumListSize <
     * 1) and no entries will be null.
     */
    public static List<String> unpack( String packed, int minimumListSize ) {
        List<String> results = new ArrayList<String>();
        if ( packed != null ) {
            if ( (packed = packed.trim()).length() != 0 ) {
                CharSource cs = new CharSource( packed );
                do {
                    results.add( parseString( cs ) );
                } while ( cs.anyRemaining() );
            }
        }
        while ( results.size() < minimumListSize ) {
            results.add( "" );
        }
        return results;
    }

    private static String parseString( CharSource cs ) {
        int length = IntegerCodec.decodePositive( cs );
        if ( length == 0 ) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        while ( length-- > 0 ) {
            sb.append( cs.getRequired() );
        }
        return sb.toString();
    }

    private static void appendString( StringBuilder sb, String string ) {
        sb.append( IntegerCodec.encodePositive( string.length() ) ).append( string );
    }

    private static List<String> normalize( List<String> strings ) {
        if ( strings != null ) {
            List<String> normalized = new ArrayList<String>( strings.size() );
            int empties = 0;
            for ( String string : strings ) {
                string = (string != null) ? string.trim() : "";
                if ( string.isEmpty() ) {
                    empties++;
                } else {
                    for (; empties > 0; empties-- ) {
                        normalized.add( "" );
                    }
                    normalized.add( string );
                }
            }
            if ( !normalized.isEmpty() ) {
                return normalized;
            }
        }
        return null;
    }
}