/*
 * Copyright 2002-2012 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.springframework.web.portlet.mvc.annotation;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;
import javax.portlet.ActionRequest;
import javax.portlet.ClientDataRequest;
import javax.portlet.Event;
import javax.portlet.EventRequest;
import javax.portlet.PortletException;
import javax.portlet.PortletMode;
import javax.portlet.PortletRequest;
import javax.portlet.ResourceRequest;
import javax.portlet.WindowState;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.stereotype.Controller;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.portlet.bind.PortletRequestBindingException;
import org.springframework.web.portlet.bind.annotation.ActionMapping;
import org.springframework.web.portlet.bind.annotation.EventMapping;
import org.springframework.web.portlet.bind.annotation.RenderMapping;
import org.springframework.web.portlet.bind.annotation.ResourceMapping;
import org.springframework.web.portlet.handler.AbstractMapBasedHandlerMapping;
import org.springframework.web.portlet.handler.PortletRequestMethodNotSupportedException;

/**
 * Implementation of the {@link org.springframework.web.portlet.HandlerMapping}
 * interface that maps handlers based on portlet modes expressed through the
 * {@link RequestMapping} annotation at the type or method level.
 *
 * <p>Registered by default in {@link org.springframework.web.portlet.DispatcherPortlet}.
 * <b>NOTE:</b> If you define custom HandlerMapping beans in your DispatcherPortlet context,
 * you need to add a DefaultAnnotationHandlerMapping bean explicitly, since custom
 * HandlerMapping beans replace the default mapping strategies. Defining a
 * DefaultAnnotationHandlerMapping also allows for registering custom interceptors:
 *
 * <pre class="code">
 * &lt;bean class="org.springframework.web.portlet.mvc.annotation.DefaultAnnotationHandlerMapping"&gt;
 *   &lt;property name="interceptors"&gt;
 *     ...
 *   &lt;/property&gt;
 * &lt;/bean&gt;</pre>
 *
 * Annotated controllers are usually marked with the {@link Controller} stereotype
 * at the type level. This is not strictly necessary when {@link RequestMapping} is
 * applied at the type level (since such a handler usually implements the
 * {@link org.springframework.web.portlet.mvc.Controller} interface). However,
 * {@link Controller} is required for detecting {@link RequestMapping} annotations
 * at the method level.
 *
 * <p><b>NOTE:</b> Method-level mappings are only allowed to narrow the mapping
 * expressed at the class level (if any). A portlet mode in combination with specific
 * parameter conditions needs to uniquely map onto one specific handler bean,
 * not spread across multiple handler beans. It is strongly recommended to
 * co-locate related handler methods into the same bean.
 *
 * <p>The {@link AnnotationMethodHandlerAdapter} is responsible for processing
 * annotated handler methods, as mapped by this HandlerMapping. For
 * {@link RequestMapping} at the type level, specific HandlerAdapters such as
 * {@link org.springframework.web.portlet.mvc.SimpleControllerHandlerAdapter} apply.
 *
 * @author Juergen Hoeller
 * @since 2.5
 * @see RequestMapping
 * @see AnnotationMethodHandlerAdapter
 */
public class DefaultAnnotationHandlerMapping extends AbstractMapBasedHandlerMapping<PortletMode> {

	/**
	 * Calls the {@code registerHandlers} method in addition
	 * to the superclass's initialization.
	 * @see #detectHandlers
	 */
	@Override
	public void initApplicationContext() throws BeansException {
		super.initApplicationContext();
		detectHandlers();
	}

	/**
	 * Register all handlers specified in the Portlet mode map for the corresponding modes.
	 * @throws org.springframework.beans.BeansException if the handler couldn't be registered
	 */
	protected void detectHandlers() throws BeansException {
		ApplicationContext context = getApplicationContext();
		String[] beanNames = context.getBeanNamesForType(Object.class);
		for (String beanName : beanNames) {
			Class<?> handlerType = context.getType(beanName);
			RequestMapping mapping = context.findAnnotationOnBean(beanName, RequestMapping.class);
			if (mapping != null) {
				// @RequestMapping found at type level
				String[] modeKeys = mapping.value();
				String[] params = mapping.params();
				boolean registerHandlerType = true;
				if (modeKeys.length == 0 || params.length == 0) {
					registerHandlerType = !detectHandlerMethods(handlerType, beanName, mapping);
				}
				if (registerHandlerType) {
					AbstractParameterMappingPredicate predicate = new TypeLevelMappingPredicate(
							params, mapping.headers(), mapping.method());
					for (String modeKey : modeKeys) {
						registerHandler(new PortletMode(modeKey), beanName, predicate);
					}
				}
			}
			else if (AnnotationUtils.findAnnotation(handlerType, Controller.class) != null) {
				detectHandlerMethods(handlerType, beanName, mapping);
			}
		}
	}

	/**
	 * Derive portlet mode mappings from the handler's method-level mappings.
	 * @param handlerType the handler type to introspect
	 * @param beanName the name of the bean introspected
	 * @param typeMapping the type level mapping (if any)
	 * @return {@code true} if at least 1 handler method has been registered;
	 * {@code false} otherwise
	 */
	protected boolean detectHandlerMethods(Class<?> handlerType, final String beanName, final RequestMapping typeMapping) {
		final Set<Boolean> handlersRegistered = new HashSet<Boolean>(1);
		Set<Class<?>> handlerTypes = new LinkedHashSet<Class<?>>();
		handlerTypes.add(handlerType);
		handlerTypes.addAll(Arrays.asList(handlerType.getInterfaces()));
		for (Class<?> currentHandlerType : handlerTypes) {
			ReflectionUtils.doWithMethods(currentHandlerType, new ReflectionUtils.MethodCallback() {
				public void doWith(Method method) {
					PortletRequestMappingPredicate predicate = null;
					String[] modeKeys = new String[0];
					String[] params = new String[0];
					if (typeMapping != null) {
						params = StringUtils.mergeStringArrays(typeMapping.params(), params);
					}
					ActionMapping actionMapping = AnnotationUtils.findAnnotation(method, ActionMapping.class);
					RenderMapping renderMapping = AnnotationUtils.findAnnotation(method, RenderMapping.class);
					ResourceMapping resourceMapping = AnnotationUtils.findAnnotation(method, ResourceMapping.class);
					EventMapping eventMapping = AnnotationUtils.findAnnotation(method, EventMapping.class);
					RequestMapping requestMapping = AnnotationUtils.findAnnotation(method, RequestMapping.class);
					if (actionMapping != null) {
						params = StringUtils.mergeStringArrays(params, actionMapping.params());
						predicate = new ActionMappingPredicate(actionMapping.value(), params);
					}
					else if (renderMapping != null) {
						params = StringUtils.mergeStringArrays(params, renderMapping.params());
						predicate = new RenderMappingPredicate(renderMapping.value(), params);
					}
					else if (resourceMapping != null) {
						predicate = new ResourceMappingPredicate(resourceMapping.value());
					}
					else if (eventMapping != null) {
						predicate = new EventMappingPredicate(eventMapping.value());
					}
					if (requestMapping != null) {
						modeKeys = requestMapping.value();
						if (typeMapping != null) {
							if (!PortletAnnotationMappingUtils.validateModeMapping(modeKeys, typeMapping.value())) {
								throw new IllegalStateException("Mode mappings conflict between method and type level: " +
										Arrays.asList(modeKeys) + " versus " + Arrays.asList(typeMapping.value()));
							}
						}
						params = StringUtils.mergeStringArrays(params, requestMapping.params());
						if (predicate == null) {
							predicate = new MethodLevelMappingPredicate(params);
						}
					}
					if (predicate != null) {
						if (modeKeys.length == 0) {
							if (typeMapping != null) {
								modeKeys = typeMapping.value();
							}
							if (modeKeys.length == 0) {
								throw new IllegalStateException(
										"No portlet mode mappings specified - neither at type nor at method level");
							}
						}
						for (String modeKey : modeKeys) {
							registerHandler(new PortletMode(modeKey), beanName, predicate);
							handlersRegistered.add(Boolean.TRUE);
						}
					}
				}
			}, ReflectionUtils.USER_DECLARED_METHODS);
		}
		return !handlersRegistered.isEmpty();
	}

	/**
	 * Uses the current PortletMode as lookup key.
	 */
	@Override
	protected PortletMode getLookupKey(PortletRequest request) throws Exception {
		return request.getPortletMode();
	}


	private interface SpecialRequestTypePredicate {
	}


	private static abstract class AbstractParameterMappingPredicate implements PortletRequestMappingPredicate {

		private final String[] params;

		public AbstractParameterMappingPredicate(String[] params) {
			this.params = params;
		}

		public boolean match(PortletRequest request) {
			return PortletAnnotationMappingUtils.checkParameters(this.params, request);
		}

		protected int compareParams(AbstractParameterMappingPredicate other) {
			return new Integer(other.params.length).compareTo(this.params.length);
		}

		protected int compareParams(Object other) {
			if (other instanceof AbstractParameterMappingPredicate) {
				return compareParams((AbstractParameterMappingPredicate) other);
			}
			return 0;
		}
	}


	private static class TypeLevelMappingPredicate extends AbstractParameterMappingPredicate {

		private final String[] headers;

		private final Set<String> methods = new HashSet<String>();

		public TypeLevelMappingPredicate(String[] params, String[] headers, RequestMethod[] methods) {
			super(params);
			this.headers = headers;
			if (methods != null) {
				for (RequestMethod method : methods) {
					this.methods.add(method.name());
				}
			}
		}

		public void validate(PortletRequest request) throws PortletException {
			if (!PortletAnnotationMappingUtils.checkHeaders(this.headers, request)) {
				throw new PortletRequestBindingException("Header conditions \"" +
						StringUtils.arrayToDelimitedString(this.headers, ", ") +
						"\" not met for actual request");
			}
			if (!this.methods.isEmpty()) {
				if (!(request instanceof ClientDataRequest)) {
					throw new PortletRequestMethodNotSupportedException(StringUtils.toStringArray(this.methods));
				}
				String method = ((ClientDataRequest) request).getMethod();
				if (!this.methods.contains(method)) {
					throw new PortletRequestMethodNotSupportedException(method, StringUtils.toStringArray(this.methods));
				}
			}
		}

		public int compareTo(Object other) {
			return (other instanceof SpecialRequestTypePredicate ? -1 : compareParams(other));
		}
	}


	private static class MethodLevelMappingPredicate extends AbstractParameterMappingPredicate {

		public MethodLevelMappingPredicate(String[] params) {
			super(params);
		}

		public void validate(PortletRequest request) throws PortletException {
		}

		public int compareTo(Object other) {
			return (other instanceof SpecialRequestTypePredicate ? 1 : compareParams(other));
		}
	}


	private static class ActionMappingPredicate extends AbstractParameterMappingPredicate implements SpecialRequestTypePredicate {

		private final String actionName;

		public ActionMappingPredicate(String actionName, String[] params) {
			super(params);
			this.actionName = actionName;
		}

		@Override
		public boolean match(PortletRequest request) {
			return (PortletRequest.ACTION_PHASE.equals(request.getAttribute(PortletRequest.LIFECYCLE_PHASE)) &&
					("".equals(this.actionName) || this.actionName.equals(request.getParameter(ActionRequest.ACTION_NAME))) &&
					super.match(request));
		}

		public void validate(PortletRequest request) {
		}

		public int compareTo(Object other) {
			if (other instanceof TypeLevelMappingPredicate) {
				return 1;
			}
			else if (other instanceof ActionMappingPredicate) {
				ActionMappingPredicate otherAction = (ActionMappingPredicate) other;
				boolean hasActionName = "".equals(this.actionName);
				boolean otherHasActionName = "".equals(otherAction.actionName);
				if (hasActionName != otherHasActionName) {
					return (hasActionName ? -1 : 1);
				}
				else {
					return compareParams(otherAction);
				}
			}
			if (other instanceof SpecialRequestTypePredicate) {
				return this.getClass().getName().compareTo(other.getClass().getName());
			}
			return -1;
		}
	}


	private static class RenderMappingPredicate extends AbstractParameterMappingPredicate implements SpecialRequestTypePredicate{

		private final WindowState windowState;

		public RenderMappingPredicate(String windowState, String[] params) {
			super(params);
			this.windowState = ("".equals(windowState) ? null : new WindowState(windowState));
		}

		@Override
		public boolean match(PortletRequest request) {
			return (PortletRequest.RENDER_PHASE.equals(request.getAttribute(PortletRequest.LIFECYCLE_PHASE)) &&
					(this.windowState == null || this.windowState.equals(request.getWindowState())) &&
					super.match(request));
		}

		public void validate(PortletRequest request) {
		}

		public int compareTo(Object other) {
			if (other instanceof TypeLevelMappingPredicate) {
				return 1;
			}
			else if (other instanceof RenderMappingPredicate) {
				RenderMappingPredicate otherRender = (RenderMappingPredicate) other;
				boolean hasWindowState = (this.windowState != null);
				boolean otherHasWindowState = (otherRender.windowState != null);
				if (hasWindowState != otherHasWindowState) {
					return (hasWindowState ? -1 : 1);
				}
				else {
					return compareParams(otherRender);
				}
			}
			if (other instanceof SpecialRequestTypePredicate) {
				return this.getClass().getName().compareTo(other.getClass().getName());
			}
			return -1;
		}
	}


	private static class ResourceMappingPredicate implements PortletRequestMappingPredicate, SpecialRequestTypePredicate {

		private final String resourceId;

		public ResourceMappingPredicate(String resourceId) {
			this.resourceId = resourceId;
		}

		public boolean match(PortletRequest request) {
			return (PortletRequest.RESOURCE_PHASE.equals(request.getAttribute(PortletRequest.LIFECYCLE_PHASE)) &&
					("".equals(this.resourceId) || this.resourceId.equals(((ResourceRequest) request).getResourceID())));
		}

		public void validate(PortletRequest request) {
		}

		public int compareTo(Object other) {
			if (other instanceof ResourceMappingPredicate) {
				boolean hasResourceId = !"".equals(this.resourceId);
				boolean otherHasResourceId = !"".equals(((ResourceMappingPredicate) other).resourceId);
				if (hasResourceId != otherHasResourceId) {
					return (hasResourceId ? -1 : 1);
				}
			}
			if (other instanceof SpecialRequestTypePredicate) {
				return this.getClass().getName().compareTo(other.getClass().getName());
			}
			return -1;
		}
	}


	private static class EventMappingPredicate implements PortletRequestMappingPredicate, SpecialRequestTypePredicate {

		private final String eventName;

		public EventMappingPredicate(String eventName) {
			this.eventName = eventName;
		}

		public boolean match(PortletRequest request) {
			if (!PortletRequest.EVENT_PHASE.equals(request.getAttribute(PortletRequest.LIFECYCLE_PHASE))) {
				return false;
			}
			if ("".equals(this.eventName)) {
				return true;
			}
			Event event = ((EventRequest) request).getEvent();
			return (this.eventName.equals(event.getName()) || this.eventName.equals(event.getQName().toString()));
		}

		public void validate(PortletRequest request) {
		}

		public int compareTo(Object other) {
			if (other instanceof EventMappingPredicate) {
				boolean hasEventName = !"".equals(this.eventName);
				boolean otherHasEventName = !"".equals(((EventMappingPredicate) other).eventName);
				if (hasEventName != otherHasEventName) {
					return (hasEventName ? -1 : 1);
				}
			}
			if (other instanceof SpecialRequestTypePredicate) {
				return this.getClass().getName().compareTo(other.getClass().getName());
			}
			return -1;
		}
	}

}
