package pt.ist.fenixWebFramework.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.CharEncoding;
import org.apache.commons.lang.StringUtils;

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

public abstract class AutoCompleteServlet extends HttpServlet {

    private static final String JAVASCRIPT_LIBRARY_ENCODING = CharEncoding.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(JAVASCRIPT_LIBRARY_ENCODING);

        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("application/json; charset=" + JAVASCRIPT_LIBRARY_ENCODING);
        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);
    }
}