package com.relationinfo.webapp.taglib;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.jsp.tagext.TagData;
import javax.servlet.jsp.tagext.TagExtraInfo;
import javax.servlet.jsp.tagext.VariableInfo;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.relationinfo.Constants;


/**
 * Implementation of <code>TagExtraInfo</code> for the <b>constants</b>
 * tag, identifying the scripting object(s) to be made visible.
 *
 * @author cao guangxin
 * @version $Revision: 1.4 $ $Date: 2004/08/19 00:13:58 $
 */
public class ConstantsTei extends TagExtraInfo {
    private final Log log = LogFactory.getLog(ConstantsTei.class);

    /**
     * Return information about the scripting variables to be created.
     */
    public VariableInfo[] getVariableInfo(TagData data) {
        // loop through and expose all attributes
        List vars = new ArrayList();

        try {
            String clazz = data.getAttributeString("className");

            if (clazz == null) {
                clazz = Constants.class.getName();
            }

            Class c = Class.forName(clazz);

            // if no var specified, get all
            if (data.getAttributeString("var") == null) {
                Field[] fields = c.getDeclaredFields();

                AccessibleObject.setAccessible(fields, true);

                for (int i = 0; i < fields.length; i++) {
                    vars.add(new VariableInfo(fields[i].getName(),
                                              "java.lang.String", true,
                                              VariableInfo.AT_END));
                }
            } else {
                String var = data.getAttributeString("var");
                vars.add(new VariableInfo(c.getField(var).getName(),
                                          "java.lang.String", true,
                                          VariableInfo.AT_END));
            }
        } catch (Exception cnf) {
            log.error(cnf.getMessage());
            cnf.printStackTrace();
        }

        return (VariableInfo[]) vars.toArray(new VariableInfo[] {  });
    }
}