// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.uispecification;

import org.litesoft.commonfoundation.typeutils.*;

import java.util.*;

import org.litesoft.encryption.symmetric.*;
import org.litesoft.logger.*;

/**
 * Parameter object for initializing screens. We will have many screens, so it
 * is easier to add new parameters to subclasses than to modify every factory.
 */
public abstract class UriFragmentIdParams
{
    public interface ScreenParamsFactory
    {
        UriFragmentIdParams create( ViewDef pTarget );
    }

    public static final Logger LOGGER = LoggerFactory.getLogger( UriFragmentIdParams.class );

    public static String toParamsString( UriFragmentIdParams pParams )
    {
        return (pParams != null) ? pParams.toParamsString() : null;
    }

    public static UriFragmentIdParams fromParamsString( String pFromFragmentIdParams )
    {
        if ( null == (pFromFragmentIdParams = Strings.noEmpty( pFromFragmentIdParams )) )
        {
            return null;
        }
        String zClearText;
        try
        {
            zClearText = ENCRYPTOR.decrypt( pFromFragmentIdParams );
        }
        catch ( SymmetricEncryptor.DecryptFailureException e )
        {
            LOGGER.warn().log( e, "From: '", pFromFragmentIdParams, "'" );
            return null;
        }
        int zAt = zClearText.lastIndexOf( ':' );
        if ( zAt == -1 )
        {
            LOGGER.warn().log( "No RegistrationID in: '", zClearText, "'" );
            return null;
        }
        String zRegistrationID = zClearText.substring( zAt + 1 );
        Factory zFactory = FACTORIES.get( zRegistrationID );
        if ( zFactory == null )
        {
            LOGGER.warn().log( "No Factory for RegistrationID (", zRegistrationID, ") in: '", zClearText, "'" );
            return null;
        }
        try
        {
            return zFactory.create( zClearText.substring( 0, zAt ) );
        }
        catch ( RuntimeException e )
        {
            LOGGER.warn().log( e, "create Failed in ", zFactory.getClass(), " with: '", zClearText, "'" );
            return null;
        }
    }

    public final String toParamsString()
    {
        return ENCRYPTOR.encrypt( Strings.deNull( LLtoParamsString() ) + ":" + getRegistrationID() );
    }

    abstract protected String getRegistrationID();

    abstract protected String LLtoParamsString();

    public static abstract class Factory
    {
        private String mRegistrationID;

        protected Factory( String pRegistrationID )
        {
            mRegistrationID = Strings.assertNotNullNotEmpty( "RegistrationID", pRegistrationID );
        }

        public void register()
        {
            Factory zFactory = FACTORIES.get( mRegistrationID );
            if ( this != zFactory )
            {
                if ( zFactory != null )
                {
                    throw new IllegalStateException( "Duplicate Factory Registration for: " + mRegistrationID );
                }
                FACTORIES.put( mRegistrationID, this );
            }
        }

        public String getRegistrationID()
        {
            return mRegistrationID;
        }

        protected abstract UriFragmentIdParams create( String pLLtoParamsString );
    }

    private static final Map<String, Factory> FACTORIES = new HashMap<String, Factory>();

    private static final SymmetricEncryptor ENCRYPTOR = AlphaNumericConstrainedSymmetricEncryptor.INSTANCE;
}