package com.ly.tag;

import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;

import org.apache.commons.beanutils.PropertyUtils;

/** *//**
 * @author ceun
 * 
 */
public class RequestUtils {
    private static Map scopes = new HashMap();
    static {
        scopes.put("page", new Integer(PageContext.PAGE_SCOPE));
        scopes.put("request", new Integer(PageContext.REQUEST_SCOPE));
        scopes.put("session", new Integer(PageContext.SESSION_SCOPE));
        scopes.put("application", new Integer(PageContext.APPLICATION_SCOPE));
    }
    /** *//**
     * Locate and return the specified bean, from an optionally specified
     * scope, in the specified page context.  If no such bean is found,
     * return <code>null</code> instead.  If an exception is thrown, it will
     * have already been saved via a call to <code>saveException()</code>.
     *
     * @param pageContext Page context to be searched
     * @param name Name of the bean to be retrieved
     * @param scopeName Scope to be searched (page, request, session, application)
     *  or <code>null</code> to use <code>findAttribute()</code> instead
     * @return JavaBean in the specified page context
     * @exception JspException if an invalid scope name
     *  is requested
     * @since ceunUtil 1.2.1
     */
    public static Object lookup(PageContext pageContext, String name, String scopeName)
        throws JspException {
            
        if (scopeName == null) {
            return pageContext.findAttribute(name);
        }
        
        try {
            return pageContext.getAttribute(name, getScope(scopeName));
        
        } catch (JspException e) {
            saveException(pageContext, e);
            throw e;
        }

    }
    
    /** *//**
     * Converts the scope name into its corresponding PageContext constant value.
     * @param scopeName Can be "page", "request", "session", or "application" in any
     * case.
     * @return The constant representing the scope (ie. PageContext.REQUEST_SCOPE).
     * @throws JspException if the scopeName is not a valid name.
     * @since ceunUtil 1.2.1
     */
    public static int getScope(String scopeName) throws JspException {
        Integer scope = (Integer) scopes.get(scopeName.toLowerCase());

        if (scope == null) {
            throw new JspException("未指定范圍");
        }

        return scope.intValue();
    }

    /** *//**
     * Locate and return the specified property of the specified bean, from
     * an optionally specified scope, in the specified page context.  If an
     * exception is thrown, it will have already been saved via a call to
     * <code>saveException()</code>.
     *
     * @param pageContext Page context to be searched
     * @param name Name of the bean to be retrieved
     * @param property Name of the property to be retrieved, or
     *  <code>null</code> to retrieve the bean itself
     * @param scope Scope to be searched (page, request, session, application)
     *  or <code>null</code> to use <code>findAttribute()</code> instead
     * @return property of specified JavaBean
     *
     * @exception JspException if an invalid scope name
     *  is requested
     * @exception JspException if the specified bean is not found
     * @exception JspException if accessing this property causes an
     *  IllegalAccessException, IllegalArgumentException,
     *  InvocationTargetException, or NoSuchMethodException
     */
    public static Object lookup(
        PageContext pageContext,
        String name,
        String property,
        String scope)
        throws JspException {

        // Look up the requested bean, and return if requested
        Object bean = lookup(pageContext, name, scope);
        if (bean == null) {
            JspException e = null;
            if (scope == null) {
                e = new JspException("在指定范圍內找不到對象");
            } else {
                e = new JspException("找不到對象");
            }
            saveException(pageContext, e);
            throw e;
        }
        
        if (property == null) {
            return bean;
        }

        // Locate and return the specified property
        try {
            return PropertyUtils.getProperty(bean, property);
            
        } catch (IllegalAccessException e) {
            saveException(pageContext, e);
            throw new JspException("不能訪問指定對象的屬性");
        
        } catch (InvocationTargetException e) {
            Throwable t = e.getTargetException();
            if (t == null) {
                t = e;
            }
            saveException(pageContext, t);
            throw new JspException("找不到對象");
        
        } catch (NoSuchMethodException e) {
            saveException(pageContext, e);
            throw new JspException("找不到此方法");
        }

    }
    public static void saveException(PageContext pageContext, Throwable exception) {

        pageContext.setAttribute("ceun.tag.error", exception, PageContext.REQUEST_SCOPE);

    }

}