/*
 * Copyright 2019-present Open Networking Foundation
 *
 * 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.onosproject.k8snode.web;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.collect.Sets;
import org.onosproject.k8snode.api.K8sNode;
import org.onosproject.k8snode.api.K8sNodeAdminService;
import org.onosproject.rest.AbstractWebResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.ws.rs.Consumes;
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.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriBuilder;
import javax.ws.rs.core.UriInfo;
import java.io.InputStream;
import java.util.Set;

import static com.fasterxml.jackson.databind.SerializationFeature.INDENT_OUTPUT;
import static javax.ws.rs.core.Response.created;
import static org.onlab.util.Tools.nullIsIllegal;
import static org.onlab.util.Tools.readTreeFromStream;

/**
 * Handles REST API call of kubernetes node config.
 */

@Path("configure")
public class K8sNodeWebResource extends AbstractWebResource {

    private final Logger log = LoggerFactory.getLogger(getClass());

    private static final String MESSAGE_NODE = "Received node %s request";
    private static final String NODES = "nodes";
    private static final String CREATE = "CREATE";
    private static final String UPDATE = "UPDATE";
    private static final String NODE_ID = "NODE_ID";
    private static final String DELETE = "DELETE";

    private static final String HOST_NAME = "hostname";
    private static final String ERROR_MESSAGE = " cannot be null";

    private final K8sNodeAdminService adminService = get(K8sNodeAdminService.class);

    @Context
    private UriInfo uriInfo;

    /**
     * Creates a set of kubernetes nodes' config from the JSON input stream.
     *
     * @param input kubernetes nodes JSON input stream
     * @return 201 CREATED if the JSON is correct, 400 BAD_REQUEST if the JSON
     * is malformed
     * @onos.rsModel K8sNode
     */
    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public Response createNodes(InputStream input) {
        log.trace(String.format(MESSAGE_NODE, CREATE));

        readNodeConfiguration(input).forEach(node -> {
            K8sNode existing = adminService.node(node.hostname());
            if (existing == null) {
                adminService.createNode(node);
            }
        });

        UriBuilder locationBuilder = uriInfo.getBaseUriBuilder()
                .path(NODES)
                .path(NODE_ID);

        return created(locationBuilder.build()).build();
    }

    /**
     * Updates a set of kubernetes nodes' config from the JSON input stream.
     *
     * @param input kubernetes nodes JSON input stream
     * @return 200 OK with the updated kubernetes node's config, 400 BAD_REQUEST
     * if the JSON is malformed, and 304 NOT_MODIFIED without the updated config
     * @onos.rsModel K8sNode
     */
    @PUT
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public Response updateNodes(InputStream input) {
        log.trace(String.format(MESSAGE_NODE, UPDATE));

        Set<K8sNode> nodes = readNodeConfiguration(input);
        for (K8sNode node: nodes) {
            K8sNode existing = adminService.node(node.hostname());
            if (existing == null) {
                log.warn("There is no node configuration to update : {}", node.hostname());
                return Response.notModified().build();
            } else if (!existing.equals(node)) {
                adminService.updateNode(node);
            }
        }

        return Response.ok().build();
    }

    /**
     * Removes a set of kubernetes nodes' config from the JSON input stream.
     *
     * @param hostname host name contained in kubernetes nodes configuration
     * @return 204 NO_CONTENT, 400 BAD_REQUEST if the JSON is malformed, and
     * 304 NOT_MODIFIED without the updated config
     * @onos.rsModel K8sNode
     */
    @javax.ws.rs.DELETE
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    @Path("{hostname}")
    public Response deleteNodes(@PathParam("hostname") String hostname) {
        log.trace(String.format(MESSAGE_NODE, DELETE));

        K8sNode existing =
                adminService.node(nullIsIllegal(hostname, HOST_NAME + ERROR_MESSAGE));

        if (existing == null) {
            log.warn("There is no node configuration to delete : {}", hostname);
            return Response.notModified().build();
        } else {
            adminService.removeNode(hostname);
        }

        return Response.noContent().build();
    }

    private Set<K8sNode> readNodeConfiguration(InputStream input) {
        Set<K8sNode> nodeSet = Sets.newHashSet();
        try {
            JsonNode jsonTree = readTreeFromStream(mapper().enable(INDENT_OUTPUT), input);
            ArrayNode nodes = (ArrayNode) jsonTree.path(NODES);
            nodes.forEach(node -> {
                try {
                    ObjectNode objectNode = node.deepCopy();
                    K8sNode k8sNode =
                            codec(K8sNode.class).decode(objectNode, this);

                    nodeSet.add(k8sNode);
                } catch (Exception e) {
                    log.error("Exception occurred due to {}", e);
                    throw new IllegalArgumentException();
                }
            });
        } catch (Exception e) {
            throw new IllegalArgumentException(e);
        }

        return nodeSet;
    }
}