package org.springside.core.commons;

import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.propertyeditors.CustomDateEditor;
import org.springframework.beans.propertyeditors.CustomNumberEditor;
import org.springframework.util.Assert;
import org.springframework.validation.BindingResult;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import org.springframework.web.bind.ServletRequestDataBinder;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;
import org.springframework.web.util.WebUtils;
import org.springside.core.utils.DateUtil;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * SpringSide Multiaction Controller的基类.
 * 对Spring的MultiActionController作了少量扩展，主要是对数据绑定校验的扩展,
 * 同时增加了{@link #saveMessage(HttpServletRequest, String) }，一个{@link #rendText(HttpServletResponse,String)}
 *
 * @author calvin
 */
abstract public class BaseController extends MultiActionController {
    /**
     * 不设置任何action参数时的默认 Action.
     * 该函数名由xxx-servlet.xml配置文件中的 methodNameResolver节点配置.
     */
    abstract public ModelAndView index(HttpServletRequest request, HttpServletResponse response) throws Exception;

    /**
     * 初始化binder的回调函数.
     * 默认以DateUtil中的日期格式设置DateEditor及允许Integer,Double的字符串为空.
     *
     * @see MultiActionController#createBinder(HttpServletRequest,Object)
     */
    protected void initBinder(HttpServletRequest request, ServletRequestDataBinder binder) {
        SimpleDateFormat dateFormat = new SimpleDateFormat(DateUtil.getDatePattern());
        binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
        binder.registerCustomEditor(Integer.class, new CustomNumberEditor(Integer.class, true));
        binder.registerCustomEditor(Double.class, new CustomNumberEditor(Double.class, true));
    }

    /**
     * 从Request中绑定对象并进行校验.
     * Spring MVC中的Bind函数未完全符合需求,因此参考原代码进行了扩展
     *
     * @return 校验错误
     * @see #preBind(HttpServletRequest,Object,ServletRequestDataBinder)
     */
    protected BindingResult bindObject(HttpServletRequest request, Object command) throws Exception {
        Assert.notNull(command);

        //创建Binder
        ServletRequestDataBinder binder = createBinder(request, command);
        //回调函数，供子类扩展对binder做出更进一步设置,并进行不能由binder自动完成的绑定
        preBind(request, command, binder);

        //绑定
        binder.bind(request);

        //校验
        Validator[] validators = getValidators();
        if (validators != null) {
            for (Validator validator : validators) {
                if (validator.supports(command.getClass())) {
                    ValidationUtils.invokeValidator(validator, command, binder.getBindingResult());
                }
            }
        }
        return binder.getBindingResult();
    }

    /**
     * 回调函数，在BindObject的最开始调用。负责
     * 1.继续对binder进行设置
     * 2.绑定一些不能由Binder自动绑定的属性.这些属性通常是需要查询数据库来获得对象的绑定.
     * 要注意设置这些属性为disallow. eg.
     * <pre>binder.setDisallowedFields(new String[]{"image","category"});</pre>
     *
     * @see #bindObject(HttpServletRequest, Object)
     * @see org.springframework.web.bind.ServletRequestDataBinder#setDisallowedFields(String[])
     * @see org.springside.bookstore.admin.web.BookManageController#preBind(javax.servlet.http.HttpServletRequest, Object, org.springframework.web.bind.ServletRequestDataBinder)
     */
    protected void preBind(HttpServletRequest request, Object object, ServletRequestDataBinder binder) throws Exception {
        //在子类实现
    }

    /**
     * 回调函数，声明CommandName--对象的名字,默认为首字母小写的类名.
     *
     * @see #bindObject(HttpServletRequest, Object)
     */
    protected String getCommandName(Object command) {
        return StringUtils.uncapitalize(command.getClass().getSimpleName());
    }

    /**
     * 增加validator.
     * 除了Spring配置文件注入的validators数组外,可以用此函数在子类的代码里再添加新的validator.
     */
    protected void addValidator(Validator validator) {
        ArrayUtils.add(getValidators(), validator);
    }

    /**
     * 向View层传递message时将message放入httpSession的messages变量中.
     * 放在session中能保证message即使Redirect也不会消失。需配合{@link org.springside.core.web.MessageFilter MessageFilter}使用
     */
    protected void saveMessage(HttpServletRequest request, String message) {
        if (StringUtils.isNotBlank(message)) {
            List messages = (List) WebUtils.getOrCreateSessionAttribute(request.getSession(), "messages", ArrayList.class);
            messages.add(message);
        }
    }

    /**
     * 直接向客户端返回Content字符串，不用通过View页面渲染.
     */
    protected void rendText(HttpServletResponse response, String content) throws IOException {
        response.setCharacterEncoding("UTF-8");
        response.getWriter().write(content);
    }
}