/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.management.data;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.MessageBodyReader;

import org.exoplatform.management.ValueWrapper;
import org.exoplatform.management.annotations.ImpactType;
import org.exoplatform.management.invocation.MethodInvoker;
import org.exoplatform.management.spi.ManagedMethodMetaData;
import org.exoplatform.management.spi.ManagedPropertyMetaData;
import org.exoplatform.management.spi.ManagedResource;
import org.exoplatform.management.spi.ManagedTypeMetaData;
import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;
import org.exoplatform.services.rest.impl.ApplicationContextImpl;
import org.exoplatform.services.rest.impl.MultivaluedMapImpl;


/**
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class RestResource {

    /** . */
    final Map<String, RestResourceProperty> properties;

    /** . */
    private final List<RestResourceMethod> methods;

    /** . */
    private final ManagedResource managedResource;

    /** . */
    private final String name;

    /** . */
    private final String description;

    /** . */
    private final Log                     log = ExoLogger.getLogger(RestResource.class);

    public RestResource(String name, ManagedResource managedResource) {
        ManagedTypeMetaData managedType = managedResource.getMetaData();

        //
        HashMap<String, RestResourceProperty> properties = new HashMap<String, RestResourceProperty>();
        for (ManagedPropertyMetaData managedProperty : managedType.getProperties()) {
            RestResourceProperty resourceProperty = new RestResourceProperty(managedProperty);
            properties.put(resourceProperty.getName(), resourceProperty);
        }

        //
        List<RestResourceMethod> methods = new ArrayList<RestResourceMethod>();
        for (ManagedMethodMetaData managedMethod : managedType.getMethods()) {
            RestResourceMethod resourceMethod = new RestResourceMethod(managedMethod);
            methods.add(resourceMethod);
        }

        //
        this.name = name;
        this.description = managedType.getDescription();
        this.managedResource = managedResource;
        this.properties = Collections.unmodifiableMap(properties);
        this.methods = methods;
    }

    public String getName() {
        return name;
    }

    public String getDescription() {
        return description;
    }

    public Collection<RestResourceProperty> getProperties() {
        return properties.values();
    }

    public Collection<RestResourceMethod> getMethods() {
        return methods;
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public RestResource get() {
        return this;
    }

    @GET
    @Path("{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public Response get(@Context UriInfo info, @PathParam("name") String name) {
        MultivaluedMap<String, String> parameters = info.getQueryParameters();

        // Try first to get a property
        RestResourceProperty property = properties.get(name);
        if (property != null) {
            MethodInvoker getter = property.getGetterInvoker();
            if (getter != null) {
                return safeInvoke(getter, parameters);
            }
        }

        //
        return tryInvoke(name, parameters, ImpactType.READ);
    }

    @PUT
    @Path("{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public Response put(@Context UriInfo info, @PathParam("name") String name) {
        MultivaluedMap<String, String> parameters = getParameters(info);
        // Try first to get a property
        RestResourceProperty property = properties.get(name);
        if (property != null) {
            MethodInvoker setter = property.getSetterInvoker();
            if (setter != null) {
                return safeInvoke(setter, parameters);
            }
        }

        //
        return tryInvoke(name, parameters, ImpactType.IDEMPOTENT_WRITE);
    }

    @POST
    @Path("{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public Response post(@Context UriInfo info, @PathParam("name") String name) {
        return tryInvoke(name, getParameters(info), ImpactType.WRITE);
    }

    /**
     * Try to invoke a method with matching parameters from the query string
     *
     * @param methodName the method name to invoke
     * @param parameters the parameters
     * @param impact the expected impact
     * @return a suitable response
     */
    private Response tryInvoke(String methodName, MultivaluedMap<String, String> parameters, ImpactType impact) {
        //
        RestResourceMethod method = lookupMethod(methodName, parameters.keySet(), impact);

        //
        if (method != null) {
            MethodInvoker invoker = method.getMethodInvoker();
            return safeInvoke(invoker, parameters);
        }

        //
        return null;
    }

    private RestResourceMethod lookupMethod(String methodName, Set<String> argNames, ImpactType impact) {
        for (RestResourceMethod method : methods) {
            if (method.getName().equals(methodName) && method.metaData.getImpact() == impact
                    && method.parameterNames.equals(argNames)) {
                return method;
            }
        }
        return null;
    }

    /**
     * Invoke safely a method.
     *
     * @param invoker the method to invoke
     * @param argMap the arguments
     * @return the ok response or an object returned by the method wrapped by {@link ValueWrapper}
     */
    private Response safeInvoke(MethodInvoker invoker, Map<String, List<String>> argMap) {
        Object resource = managedResource.getResource();

        //
        managedResource.beforeInvoke(resource);

        //
        try {
            Object ret = invoker.invoke(resource, argMap);
            Response.ResponseBuilder rb = ret == null ? Response.ok() : Response.ok(ValueWrapper.wrap(ret));
            return rb.build();
        } catch (IllegalAccessException e) {
            log.error("Could not invoke "+ (invoker == null ? "null" : invoker.getClass().getName()) + ": " + e.getMessage(), e);
            throw new WebApplicationException(Response.serverError().entity(e.getMessage()).build());
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (!(cause instanceof IllegalArgumentException)) {
                /* IllegalArgumentExceptions can happen when there is a missing or invalid parameter
                 * there is no need to log them. We'll log exceptions with all other causes. */
                log.error("Could not invoke "+ (invoker == null ? "null" : invoker.getClass().getName()) + ": " + e.getMessage(), e);
            }
            /* because e.getMessage() is null in InvocationTargetException, we use cause.getMessage() if available */
            throw new WebApplicationException(Response.serverError().entity(cause != null ? cause.getMessage() : e.getMessage()).build());
        } finally {
            managedResource.afterInvoke(resource);
        }
    }

    @SuppressWarnings("unchecked")
    private MultivaluedMap<String, String> getParameters(UriInfo info) {
        MultivaluedMap<String, String> parameters = info.getQueryParameters();
        ApplicationContextImpl context = (ApplicationContextImpl) info;

        Type formType = MultivaluedMapImpl.class.getGenericInterfaces()[0];
        MediaType contentType = context.getHttpHeaders().getMediaType();
        if (contentType == null) {
            contentType = MediaType.APPLICATION_FORM_URLENCODED_TYPE;
        }

        MultivaluedMap<String, String> form = new MultivaluedMapImpl();
        try {
            MessageBodyReader reader = context.getProviders().getMessageBodyReader(MultivaluedMap.class, formType, null,
                    contentType);
            if (reader != null) {
                form = (MultivaluedMap<String, String>) reader.readFrom(MultivaluedMap.class, formType, null, contentType,
                        context.getHttpHeaders().getRequestHeaders(), context.getContainerRequest().getEntityStream());
            }
        } catch (IllegalStateException e) {
            if (log.isTraceEnabled()) {
                log.trace(e.getMessage(), e);
            }
        } catch (WebApplicationException e) {
            if (log.isTraceEnabled()) {
                log.trace(e.getMessage(), e);
            }
        } catch (IOException e) {
            if (log.isTraceEnabled()) {
                log.trace(e.getMessage(), e);
            }
        }

        parameters.putAll(form);
        return parameters;
    }

}
