package at.asitplus.eidas.specific.connector.gui;

import java.util.Locale;
import java.util.Map;

import javax.annotation.Nullable;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.ViewResolver;

import at.gv.egiz.eaaf.core.api.gui.IGuiBuilderConfiguration;
import at.gv.egiz.eaaf.core.api.gui.ISpringMvcGuiFormBuilder;
import at.gv.egiz.eaaf.core.exceptions.GuiBuildException;

public class SpringMvcGuiFormBuilderImpl implements ISpringMvcGuiFormBuilder {
	private static final Logger log = LoggerFactory.getLogger(SpringMvcGuiFormBuilderImpl.class);
	
	private @Autowired(required=false) ViewResolver[] viewResolvers;
	private @Autowired(required=false) LocaleResolver localeResolver;
	
	@Override
	public void build(HttpServletRequest httpReq, HttpServletResponse httpResp, IGuiBuilderConfiguration config,
			String loggerName) throws GuiBuildException {
		build(httpReq, httpResp, config, null, loggerName);

	}

	@Override
	public void build(HttpServletRequest httpReq, HttpServletResponse httpResp, IGuiBuilderConfiguration config,
			String contentType, String loggerName) throws GuiBuildException {
		try {
			final ModelAndView mav = new ModelAndView(config.getViewName());		
			if (config.getViewParameters() != null)
				mav.addAllObjects(config.getViewParameters());
					
			render(mav, httpReq, httpResp);
			
		} catch (final Exception e) {
			log.info("Can NOT generate GUI for illustration", e);
			throw new GuiBuildException(e.getMessage(), e);
			
		}

	}
	
	protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception {
		// Determine locale for request and apply it to the response.
		final Locale locale =
				(this.localeResolver != null ? this.localeResolver.resolveLocale(request) : request.getLocale());
		response.setLocale(locale);

		View view;
		final String viewName = mv.getViewName();
		if (viewName != null) {
			// We need to resolve the view name.
			view = resolveViewName(viewName, mv.getModelMap(), locale, request);
			if (view == null)
				throw new ServletException("Could not resolve view with name '" + mv.getViewName() + "' ");
			
		} else {
			// No need to lookup: the ModelAndView object contains the actual View object.
			view = mv.getView();
			if (view == null)
				throw new ServletException("ModelAndView [" + mv + "] neither contains a view name nor a " + "View object ");
				
		}

		// Delegate to the View object for rendering.
		if (log.isTraceEnabled())
			log.trace("Rendering view [" + view + "] ");
			
		try {
			if (mv.getStatus() != null)
				response.setStatus(mv.getStatus().value());
				
			view.render(mv.getModelMap(), request, response);
			
		} catch (final Exception ex) {
			if (log.isDebugEnabled())
				log.debug("Error rendering view [" + view + "]", ex);
			
			throw ex;
			
		}
		
	}
	
	protected View resolveViewName(String viewName, @Nullable Map<String, Object> model,
			Locale locale, HttpServletRequest request) throws Exception {
		if (viewResolvers != null) {
			for (final ViewResolver viewResolver : this.viewResolvers) {
				final View view = viewResolver.resolveViewName(viewName, locale);
				if (view != null)
					return view;
				
			}
		}
		
		return null;
	}

}