/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.apache.isis.viewer.restfulobjects.server;

import java.io.InputStream;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.SecurityContext;
import javax.ws.rs.core.UriInfo;

import org.apache.isis.applib.annotation.Where;
import org.apache.isis.applib.profiles.Localization;
import org.apache.isis.core.commons.authentication.AuthenticationSession;
import org.apache.isis.core.commons.config.IsisConfiguration;
import org.apache.isis.core.metamodel.adapter.ObjectAdapter;
import org.apache.isis.core.metamodel.adapter.mgr.AdapterManager;
import org.apache.isis.core.metamodel.spec.SpecificationLoader;
import org.apache.isis.core.runtime.system.persistence.PersistenceSession;
import org.apache.isis.viewer.restfulobjects.applib.JsonRepresentation;
import org.apache.isis.viewer.restfulobjects.applib.RepresentationType;
import org.apache.isis.viewer.restfulobjects.applib.client.RestfulRequest.DomainModel;
import org.apache.isis.viewer.restfulobjects.applib.client.RestfulRequest.RequestParameter;
import org.apache.isis.viewer.restfulobjects.applib.client.RestfulResponse.HttpStatusCode;
import org.apache.isis.viewer.restfulobjects.rendering.RendererContext;
import org.apache.isis.viewer.restfulobjects.server.resources.DomainResourceHelper;

import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

public class ResourceContext implements RendererContext {

    private final HttpHeaders httpHeaders;
    private final UriInfo uriInfo;
    private final Request request;
    private final HttpServletRequest httpServletRequest;
    private final HttpServletResponse httpServletResponse;
    private final SecurityContext securityContext;
    private final Localization localization;

    @SuppressWarnings("unused")
    private final IsisConfiguration configuration;
    private final AuthenticationSession authenticationSession;
    private final PersistenceSession persistenceSession;
    private final AdapterManager adapterManager;
    private final SpecificationLoader specificationLookup;

    private List<List<String>> followLinks;

    private final Where where;
    private final String queryString;
    private JsonRepresentation readQueryStringAsMap;

    //////////////////////////////////////////////////////////////////
    // constructor and init
    //////////////////////////////////////////////////////////////////

    public ResourceContext(
            final RepresentationType representationType, 
            final HttpHeaders httpHeaders, 
            final UriInfo uriInfo, 
            final Request request, 
            final Where where, 
            final String queryStringIfAny,
            final HttpServletRequest httpServletRequest, 
            final HttpServletResponse httpServletResponse,
            final SecurityContext securityContext, 
            final Localization localization, final AuthenticationSession authenticationSession, 
            final PersistenceSession persistenceSession, 
            final AdapterManager objectAdapterLookup, 
            final SpecificationLoader specificationLookup, 
            final IsisConfiguration configuration) {

        this.httpHeaders = httpHeaders;
        this.uriInfo = uriInfo;
        this.request = request;
        this.queryString = queryStringIfAny;
        this.httpServletRequest = httpServletRequest;
        this.httpServletResponse = httpServletResponse;
        this.securityContext = securityContext;
        this.localization = localization;
        this.configuration = configuration;
        this.authenticationSession = authenticationSession;
        this.persistenceSession = persistenceSession;
        this.adapterManager = objectAdapterLookup;
        this.specificationLookup = specificationLookup;
        this.where = where;

        init(representationType);
    }

    
    void init(final RepresentationType representationType) {
        getQueryStringAsJsonRepr(); // force it to be cached
        
        ensureCompatibleAcceptHeader(representationType);
        ensureDomainModelQueryParamSupported();
        
        this.followLinks = Collections.unmodifiableList(getArg(RequestParameter.FOLLOW_LINKS));
    }

    private void ensureDomainModelQueryParamSupported() {
        final DomainModel domainModel = getArg(RequestParameter.DOMAIN_MODEL);
        if(domainModel != DomainModel.FORMAL) {
            throw RestfulObjectsApplicationException.createWithMessage(HttpStatusCode.BAD_REQUEST,  
                                           "x-ro-domain-model of '%s' is not supported", domainModel);
        }
    }

    private void ensureCompatibleAcceptHeader(final RepresentationType representationType) {
        if (representationType == null) {
            return;
        }

        // RestEasy will check the basic media types...
        // ... so we just need to check the profile paramter
        final String producedProfile = representationType.getMediaTypeProfile();
        if(producedProfile != null) {
            for (MediaType mediaType : httpHeaders.getAcceptableMediaTypes()) {
                String acceptedProfileValue = mediaType.getParameters().get("profile");
                if(acceptedProfileValue == null) {
                    continue;
                }
                if(!producedProfile.equals(acceptedProfileValue)) {
                    throw RestfulObjectsApplicationException.create(HttpStatusCode.NOT_ACCEPTABLE);
                }
            }
        }
    }


    
    //////////////////////////////////////////////////////////////////
    //
    //////////////////////////////////////////////////////////////////
    
    
    public HttpHeaders getHttpHeaders() {
        return httpHeaders;
    }

    /**
     * The {@link HttpServletRequest#getQueryString() query string}, cached
     * after first call.
     * 
     * <p>
     * Note that this can return non-null for <tt>PUT</tt>s as well as <tt>GET</tt>s.
     * It will only have been URL encoded for the latter; the caller should handle both cases.
     */
    public String getQueryString() {
        if(queryString != null) {
            return queryString;
        }
        return getHttpServletRequest().getQueryString();
    }

    public JsonRepresentation getQueryStringAsJsonRepr() {
        
        if (readQueryStringAsMap == null) {
            readQueryStringAsMap = requestArgsAsMap();
        }
        return readQueryStringAsMap;
    }

    protected JsonRepresentation requestArgsAsMap() {
        @SuppressWarnings("unchecked")
        final Map<String,String[]> params = httpServletRequest.getParameterMap();

        if(simpleQueryArgs(params)) {
            // try to process regular params and build up JSON repr 
            final JsonRepresentation map = JsonRepresentation.newMap();
            for(String paramName: params.keySet()) {
                String paramValue = params.get(paramName)[0];
                try {
                    int paramValueAsInt = Integer.parseInt(paramValue);
                    map.mapPut(paramName+".value", paramValueAsInt);
                } catch(Exception ex) {
                    map.mapPut(paramName+".value", paramValue);
                }
            }
            return map;
        } else {
            return DomainResourceHelper.readQueryStringAsMap(getQueryString());
        }
    }

    private static boolean simpleQueryArgs(Map<String, String[]> params) {
        if(params.isEmpty()) {
            return false;
        }
        for(String paramName: params.keySet()) {
            if("x-isis-querystring".equals(paramName) || paramName.startsWith("{")) {
                return false;
            }
        }
        return true;
    }


    public <Q> Q getArg(final RequestParameter<Q> requestParameter) {
        final JsonRepresentation queryStringJsonRepr = getQueryStringAsJsonRepr();
        return requestParameter.valueOf(queryStringJsonRepr);
    }

    public UriInfo getUriInfo() {
        return uriInfo;
    }

    public Request getRequest() {
        return request;
    }

    public HttpServletRequest getHttpServletRequest() {
        return httpServletRequest;
    }

    public HttpServletResponse getServletResponse() {
        return httpServletResponse;
    }

    public SecurityContext getSecurityContext() {
        return securityContext;
    }


    public List<List<String>> getFollowLinks() {
        return followLinks;
    }


    
    public Localization getLocalization() {
        return localization;
    }

    public AuthenticationSession getAuthenticationSession() {
        return authenticationSession;
    }

    public AdapterManager getAdapterManager() {
        return adapterManager;
    }

    public PersistenceSession getPersistenceSession() {
        return persistenceSession;
    }

    public List<ObjectAdapter> getServiceAdapters() {
        return persistenceSession.getServices();
    }

    public SpecificationLoader getSpecificationLookup() {
        return specificationLookup;
    }

    public Where getWhere() {
        return where;
    }


    //////////////////////////////////////////////////////////////////
    //
    //////////////////////////////////////////////////////////////////

    public String urlFor(final String url) {
        return getUriInfo().getBaseUri().toString() + url;
    }

}