package org.litesoft.core.util;

/**
 * Takes a 'CamelCased' string and produces a space separated string. 
 */
public class DeCamelizer
{
    public static String resolve( String pID )
    {
        if ( pID != null )
        {
            // remove all leading and trailing spaces and convert multiple spaces to one. (treat '_' as a space)
            int zSpaces = -pID.length();
            StringBuilder sb = new StringBuilder( pID.length() );
            for ( int at = 0; at < pID.length(); at++ )
            {
                char c = pID.charAt( at );
                if ( (c == '_') || (c == ' ') )
                {
                    zSpaces++;
                }
                else
                {
                    if ( zSpaces > 0 )
                    {
                        sb.append( ' ' );
                    }
                    sb.append( c );
                    zSpaces = 0;
                }
            }
            if ( sb.length() != 0 )
            {
                boolean zUpperNext = true;
                boolean zLastUpper = false;
                for ( int at = 0; at < sb.length(); at++ )
                {
                    char c = sb.charAt( at );
                    if ( zUpperNext )
                    {
                        sb.setCharAt( at, Character.toUpperCase( c ) );
                        zLastUpper = true;
                        zUpperNext = false;
                    }
                    else if ( Character.isUpperCase( c ) )
                    {
                        if ( !zLastUpper )
                        {
                            sb.insert( at++, ' ' );
                        }
                        zLastUpper = true;
                    }
                    else
                    {
                        if ( c == ' ' )
                        {
                            zUpperNext = true;
                        }
                        zLastUpper = false;
                    }
                }
                return sb.toString();
            }
        }
        return null;
    }
}