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

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

import java.util.*;

/**
 * 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 = ConstrainTo.significantOrNull( 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( ConstrainTo.notNull( LLtoParamsString() ) + ":" + getRegistrationID() );
    }

    abstract protected String getRegistrationID();

    abstract protected String LLtoParamsString();

    public static abstract class Factory {
        private String mRegistrationID;

        protected Factory( String pRegistrationID ) {
            mRegistrationID = Confirm.significant( "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;
}