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

import org.litesoft.GWT.client.*;
import org.litesoft.GWT.client.widgets.*;
import org.litesoft.bo.views.*;
import org.litesoft.commonfoundation.typeutils.*;
import org.litesoft.core.*;
import org.litesoft.security.*;
import org.litesoft.uispecification.*;

import com.google.gwt.event.logical.shared.*;
import com.google.gwt.user.client.*;
import com.google.gwt.user.client.ui.*;

/**
 * Controls which screen is showing. Coordinates w/ the GWT {@link History}
 * mechanism.
 */
public class ViewManagerImpl extends AbstractViewManager implements ValueChangeHandler<String>,
                                                                    SecurityIssueable
{
    private final TransientScreenProperties mNextScreenProperties = new TransientScreenProperties();

    public ViewManagerImpl( ViewAccessControlManager pAccessControlManager, ViewFactory... pFactories )
    {
        super( pAccessControlManager, pFactories );
    }

    public void initialize()
    {
        History.addValueChangeHandler( this );
        onValueChangeImpl( History.getToken() );
    }

    @Override
    public void showDialog( ViewDef pViewDef, Object pParams )
    {
        Objects.assertNotNull( "(Dialog) ViewDef", pViewDef );
        ViewFactory zFactory = getViewFactory( pViewDef );
        if ( zFactory instanceof DialogViewFactory )
        {
            new DialogViewDialog( ((DialogViewFactory) zFactory).createDialog( ClientContext.get(), pParams ) ).show();
        }
        else
        {
            AlertManager.alert( "ViewManager", "No Dialog Factory", "No Dialog for: " + pViewDef );
        }
    }

    @Override
    public void showScreen( ViewDef pViewDef, UriFragmentIdParams pParams, TransientScreenProperties pNextScreenProperties )
    {
        UtilsGwt.busyCursor();
        Objects.assertNotNull( "(Screen) ViewDef", pViewDef );
        mNextScreenProperties.putAll( pNextScreenProperties );
        ParameterizedUriFragmentId zFragmentId = new ParameterizedUriFragmentId( pViewDef.getFragmentID(), //
                                                                                 UriFragmentIdParams.toParamsString( pParams ) );
        History.newItem( zFragmentId.toNewUriFragmentId( History.getToken() ), true ); // will "eventually" cause an AttachScreenCommand to be issued
    }

    void showScreen( String pHistoryToken, TransientScreenProperties pNextScreenProperties )
    {
        mNextScreenProperties.putAll( pNextScreenProperties );
        onValueChangeImpl( pHistoryToken );
    }

    void onValueChangeImpl( final String pHistoryToken ) // Everything that follows the '#' in the url.
    {
        String zUriFragmentId = ParameterizedUriFragmentId.removePrefix( pHistoryToken );
        ParameterizedUriFragmentId zFragmentId;
        try
        {
            zFragmentId = new ParameterizedUriFragmentId( zUriFragmentId );
        }
        catch ( IllegalArgumentException e )
        {
            LOGGER.warn.log( e, zUriFragmentId );
            zFragmentId = ParameterizedUriFragmentId.DEFAULT;
        }

        if ( mAccessControlManager.loginRequired() )
        {
            LoginServerStateChecker zChecker = ClientContext.get().checkGet( LoginServerStateChecker.class );
            if ( zChecker == null )
            {
                requestUserLogin( pHistoryToken, null );
            }
            else
            {
                zChecker.checkServerLogin( new SimpleDataProviderCallBack()
                {
                    @Override
                    public void error( String pError )
                    {
                        if ( mAccessControlManager.loginRequired() )
                        {
                            requestUserLogin( pHistoryToken, pError );
                        }
                        else
                        {
                            new LoginSuccessCommand( pHistoryToken, mNextScreenProperties ).execute();
                        }
                    }
                } );
            }
            return;
        }

        LoginPasswordResetAccessor zAccessor = ClientContext.get().get( LoginPasswordResetAccessor.class );
        if ( zAccessor.isPasswordResetRequired() )
        {
            LoginPasswordResetDialogViewFactory zFactory = ClientContext.get().get( LoginPasswordResetDialogViewFactory.class );
            if ( zFactory != null )
            {
                DialogView zView = zFactory.createDialog( ClientContext.get(), new LoginSuccessCommand( pHistoryToken, mNextScreenProperties, "Password updated" ) );
                ClientContext.get().get( SingleWidgetPanel.class ).setWidget( new SizeableSpacer().stretchable() );
                new DialogViewDialog( zView ).show();
                return;
            }
        }

        String viewDefId = zFragmentId.getFragmentReference();
        String viewParams = zFragmentId.getParameters();
        ViewDef zViewDef = getViewDef( viewDefId );

        UriFragmentIdParams zParams = UriFragmentIdParams.fromParamsString( viewParams );
        if ( zViewDef == null )
        {
            zViewDef = ViewDef.HOME;
            zParams = null;
            if ( Strings.isNotNullOrEmpty( viewDefId ) )
            {
                mNextScreenProperties.ERROR.set( "No Screen for: " + viewDefId );
            }
        }
        ViewFactory zFactory = getViewFactory( zViewDef );
        if ( !(zFactory instanceof ScreenViewFactory) )
        {
            zParams = null;
            mNextScreenProperties.ERROR.set( "No Screen for: " + viewDefId );
            zFactory = getViewFactory( zViewDef = ViewDef.HOME );
        }

        if ( zFactory == null )
        {
            throw new IllegalStateException( "No Screen for: " + zViewDef );
        }

        StatusMessageSinc zMessageSinc = ClientContext.get().checkGet( StatusMessageSinc.class );
        if ( zMessageSinc != null )
        {
            zMessageSinc.setErrorMessage( mNextScreenProperties.ERROR.get() );
            if ( Strings.isNullOrEmpty( mNextScreenProperties.ERROR.get() ) )
            {
                zMessageSinc.setWarningMessage( mNextScreenProperties.WARNING.get() );
            }
        }
        mNextScreenProperties.clear();

        ScreenView zView = ((ScreenViewFactory) zFactory).createScreen( ClientContext.get(), zParams );
        Widget zViewWidget = zView.augmentView( zView.getTopBar(), null );
        ClientContext.get().get( SingleWidgetPanel.class ).setWidget( zViewWidget ); // This line MUST BE last!
    }

    @Override
    public void handleSecurityIssue( String pError )
    {
        requestUserLogin( ViewDef.HOME.getFragmentID(), pError );
    }

    private void requestUserLogin( String pHistoryToken, String pError )
    {
        LoginDialogViewFactory zFactory = ClientContext.get().get( LoginDialogViewFactory.class );
        DialogView zView = zFactory.createDialog( false, new LoginSuccessCommand( pHistoryToken, mNextScreenProperties ) );
        zView.setDialogErrorMessage( pError );
        ClientContext.get().get( SingleWidgetPanel.class ).setWidget( new SizeableSpacer().stretchable() );
        new DialogViewDialog( zView ).show();
    }

    @Override
    public void onValueChange( ValueChangeEvent<String> pEvent )
    {
        onValueChangeImpl( pEvent.getValue() );
    }

    private class LoginSuccessCommand implements Command
    {
        private final String mHistoryToken;
        private final TransientScreenProperties mNextScreenProperties;

        public LoginSuccessCommand( String pHistoryToken, TransientScreenProperties pNextScreenProperties )
        {
            this( pHistoryToken, pNextScreenProperties, null );
        }

        private LoginSuccessCommand( String pHistoryToken, TransientScreenProperties pNextScreenProperties, String pWarning )
        {
            mHistoryToken = pHistoryToken;
            mNextScreenProperties = pNextScreenProperties.copy();
            if ( pWarning != null )
            {
                mNextScreenProperties.WARNING.set( pWarning );
            }
        }

        @Override
        public void execute()
        {
            showScreen( mHistoryToken, mNextScreenProperties );
        }
    }
}