package pt.ist.renderers.servlets.ajax;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.lang.StringUtils;

import pt.ist.renderers.servlets.json.JsonObject;
import pt.ist.renderers.utils.RenderUtils;

public abstract class AutoCompleteServlet extends HttpServlet {

    private static final String JAVASCRIPT_LIBRARY_ENCODING = "UTF-8";
    private static final int DEFAULT_MAX_COUNT = 20;

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	process(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	process(request, response);
    }

    private void process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

	request.setCharacterEncoding("UTF-8");

	String value = new String(request.getParameter("value").getBytes(), JAVASCRIPT_LIBRARY_ENCODING);
	Map<String, String> argsMap = getArgsMap(request.getParameter("args"));
	int maxCount = getNumber(request.getParameter("maxCount"), DEFAULT_MAX_COUNT);

	Collection result = getSearchResult(argsMap, value, maxCount);

	String labelField = request.getParameter("labelField");
	String format = request.getParameter("format");
	String valueField = request.getParameter("valueField");
	String styleClass = request.getParameter("styleClass");

	response.setContentType("text/html");
	response.getWriter().write(getResponseHtml(result, labelField, format, valueField, styleClass, maxCount));
    }

    private int getNumber(String parameter, int defaultValue) {
	if (parameter == null) {
	    return defaultValue;
	}

	try {
	    return Integer.parseInt(parameter);
	} catch (NumberFormatException e) {
	    return defaultValue;
	}
    }

    protected abstract Collection getSearchResult(Map<String, String> argsMap, String value, int maxCount);

    private Map<String, String> getArgsMap(String encodedServiceArgs) {
	String[] serviceArgsArray = StringUtils.split(encodedServiceArgs, ',');
	Map<String, String> serviceArgsMap = new HashMap<String, String>();

	for (String serviceArg : serviceArgsArray) {
	    String[] argNameArgValue = StringUtils.split(serviceArg, '=');
	    serviceArgsMap.put(argNameArgValue[0], argNameArgValue[1]);
	}

	return serviceArgsMap;
    }

    private String getResponseHtml(Collection result, String labelField, String format, String valueField, String styleClass,
	    int maxCount) {
	List<JsonObject> jsonObjects = new ArrayList<JsonObject>();
	try {
	    int count = 0;
	    for (final Object element : result) {
		if (count++ >= maxCount) {
		    break;
		}

		final String labelProperty = BeanUtils.getProperty(element, labelField);
		if (format == null) {
		    jsonObjects.add(new JsonObject(BeanUtils.getProperty(element, valueField), labelProperty));
		} else {
		    jsonObjects.add(new JsonObject(BeanUtils.getProperty(element, valueField), RenderUtils
			    .getFormattedProperties(format, element)));
		}
	    }
	} catch (Exception ex) {
	    throw new RuntimeException("Error getting field property (see label and value fields)", ex);

	}

	return JsonObject.getJsonArrayString(jsonObjects);
    }
}