/*
 * Copyright 2004-2005 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 
package org.codehaus.groovy.grails.plugins.web;


import javax.servlet.http.HttpServletRequest
import javax.servlet.http.HttpServletResponse
import javax.servlet.http.HttpSession
import org.springframework.web.util.WebUtils
import javax.servlet.ServletContext

/**
* <p>This plug-in adds methods to the Servlet API interfaces to make them more Grailsy. For example all classes that implement
* HttpServletRequest will get new methods that allow access to attributes via subscript operator
*
* @author Graeme Rocher
* @since 0.5.5
*/
class ServletsGrailsPlugin {


	def version = grails.util.GrailsUtil.getGrailsVersion()
	def dependsOn = [core:version]



	def doWithDynamicMethods = { ctx ->

        def getAttributeClosure = { String name ->
            def mp = delegate.class.metaClass.getMetaProperty(name)
            def result = null
            if(mp) result = mp.getProperty(delegate)
            else {
                result = delegate.getAttribute(name)
            }
            result
        }
        def setAttributeClosure = { String name, value ->
            def mp = delegate.class.metaClass.getMetaProperty(name)
            if(mp) mp.setProperty(delegate, value)
            else {
                delegate.setAttribute(name, value)
            }
        }

        def getAttributeSubscript = { String key ->
	        delegate.getAttribute(key)
	    }
	    def setAttributeSubScript = { String key, Object val ->
	        delegate.setAttribute(key, val)
	    }

        // enables acces to servlet context with servletContext.foo syntax
        ServletContext.metaClass.getProperty = getAttributeClosure
        ServletContext.metaClass.setProperty = setAttributeClosure
        ServletContext.metaClass.getAt = getAttributeSubscript
        ServletContext.metaClass.putAt = setAttributeSubScript

        // enables access to session attributes using session.foo syntax
        HttpSession.metaClass.getProperty = getAttributeClosure
        HttpSession.metaClass.setProperty = setAttributeClosure
		// enables access to session attributes with session["foo"] syntax
	    HttpSession.metaClass.getAt =  getAttributeSubscript
	    // enables setting of session attributes with session["foo"] = "bar" syntax
	    HttpSession.metaClass.putAt =  setAttributeSubScript

        // retrieve the forwardURI for the request
	    HttpServletRequest.metaClass.getForwardURI = {->
            org.codehaus.groovy.grails.web.util.WebUtils.getForwardURI(delegate)
	    }
	
		// test whether the current request is an XHR request
        HttpServletRequest.metaClass.isXhr = {->
             delegate.getHeader('X-Requested-With') != null                
        }	

        // enables access to request attributes with request["foo"] syntax
	    HttpServletRequest.metaClass.getAt = { String key ->
	        delegate.getAttribute(key)
	    }         
	    // enables setting of request attributes with request["foo"] = "bar" syntax
	    HttpServletRequest.metaClass.putAt = { String key, Object val ->
	        delegate.setAttribute(key, val)
	    }
	    // enables access to request attributes using property syntax
        HttpServletRequest.metaClass.getProperty = getAttributeClosure
        HttpServletRequest.metaClass.setProperty = setAttributeClosure

        HttpServletRequest.metaClass.isGet = {->
            delegate.method == "GET"
        }        
        HttpServletRequest.metaClass.isPost = {->
            delegate.method == "POST"
        }   
		// enables searching of request attributes with request.find { it.key == 'foo' }
		HttpServletRequest.metaClass.find = { Closure c ->
		   def request = delegate
		   def result = [:]
		   for(name in request.attributeNames) {
				def match = false
				switch(c.parameterTypes.length) {
					case 0:
					  match = c.call()
					break
					case 1:
					   match = c.call(key:name, value:request.getAttribute(name))
					break
					default:
				  	   match =  c.call(name, request.getAttribute(name))
				}
				if(match) {
						result[name] = request.getAttribute(name)
						break
				}
		   }
		   result
		}
		// enables searching of for a number of request attributes using request.findAll { it.key.startsWith('foo') }  
		HttpServletRequest.metaClass.findAll = { Closure c ->
		   def request = delegate 
		   def results = [:]
		   for(name in request.attributeNames) {
				def match = false
				switch(c.parameterTypes.length) {
					case 0:
					  match = c.call()
					break
					case 1: 
					   match = c.call(key:name, value:request.getAttribute(name))
					break
					default:
				  	   match =  c.call(name, request.getAttribute(name))  										
				}                                                                           
				if(match) { results[name] = request.getAttribute(name) }
		   }                                                            
		   results
		}  
		// enables iteration over request attributes with each method request.each { name, value -> }  
		HttpServletRequest.metaClass.each = { Closure c ->
			def request = delegate 
			for(name in request.attributeNames) {
				switch(c.parameterTypes.length) {
					case 0:
					  c.call()
					break
					case 1: 
					   c.call(key:name, value:request.getAttribute(name))
					break
					default:
				  		c.call(name, request.getAttribute(name))  					
				}				
			}
		}   
		// allows the syntax response << "foo"		
		HttpServletResponse.metaClass.leftShift = { Object o ->
			delegate.writer << o
		}
	}
}