/*
 * 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.flink.runtime.rest.handler.job;

import org.apache.flink.api.common.time.Time;
import org.apache.flink.runtime.executiongraph.AccessExecution;
import org.apache.flink.runtime.executiongraph.AccessExecutionVertex;
import org.apache.flink.runtime.executiongraph.ExecutionHistory;
import org.apache.flink.runtime.rest.handler.HandlerRequest;
import org.apache.flink.runtime.rest.handler.RestHandlerException;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.messages.EmptyRequestBody;
import org.apache.flink.runtime.rest.messages.JobIDPathParameter;
import org.apache.flink.runtime.rest.messages.JobVertexIdPathParameter;
import org.apache.flink.runtime.rest.messages.MessageHeaders;
import org.apache.flink.runtime.rest.messages.ResponseBody;
import org.apache.flink.runtime.rest.messages.SubtaskIndexPathParameter;
import org.apache.flink.runtime.rest.messages.job.SubtaskAttemptMessageParameters;
import org.apache.flink.runtime.rest.messages.job.SubtaskAttemptPathParameter;
import org.apache.flink.runtime.webmonitor.RestfulGateway;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;

import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;

import java.util.Collection;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.Executor;

/**
 * Base class for request handlers whose response depends on a specific attempt (defined via the
 * "{@link SubtaskAttemptPathParameter#KEY}" of a specific subtask (defined via the "{@link
 * SubtaskIndexPathParameter#KEY}" in a specific job vertex, (defined via the "{@link
 * JobVertexIdPathParameter#KEY}" parameter) in a specific job, defined via (defined via the "{@link
 * JobIDPathParameter#KEY}" parameter).
 *
 * @param <R> the response type
 * @param <M> the message parameters type
 */
public abstract class AbstractSubtaskAttemptHandler<
                R extends ResponseBody, M extends SubtaskAttemptMessageParameters>
        extends AbstractSubtaskHandler<R, M> {
    /**
     * Instantiates a new Abstract job vertex handler.
     *
     * @param leaderRetriever the leader retriever
     * @param timeout the timeout
     * @param responseHeaders the response headers
     * @param messageHeaders the message headers
     * @param executionGraphCache the execution graph cache
     * @param executor the executor
     */
    protected AbstractSubtaskAttemptHandler(
            GatewayRetriever<? extends RestfulGateway> leaderRetriever,
            Time timeout,
            Map<String, String> responseHeaders,
            MessageHeaders<EmptyRequestBody, R, M> messageHeaders,
            ExecutionGraphCache executionGraphCache,
            Executor executor) {

        super(
                leaderRetriever,
                timeout,
                responseHeaders,
                messageHeaders,
                executionGraphCache,
                executor);
    }

    @Override
    protected R handleRequest(
            HandlerRequest<EmptyRequestBody> request, AccessExecutionVertex executionVertex)
            throws RestHandlerException {
        final Integer attemptNumber = request.getPathParameter(SubtaskAttemptPathParameter.class);

        final Collection<AccessExecution> currentExecutions =
                executionVertex.getCurrentExecutions();
        final ExecutionHistory executionHistory = executionVertex.getExecutionHistory();

        for (AccessExecution currentExecution : currentExecutions) {
            if (attemptNumber == currentExecution.getAttemptNumber()) {
                return handleRequest(request, currentExecution);
            }
        }

        if (executionHistory.isValidAttemptNumber(attemptNumber)) {
            final Optional<? extends AccessExecution> execution =
                    executionHistory.getHistoricalExecution(attemptNumber);

            if (execution.isPresent()) {
                return handleRequest(request, execution.get());
            } else {
                throw new RestHandlerException(
                        "Attempt "
                                + attemptNumber
                                + " not found in subtask "
                                + executionVertex.getTaskNameWithSubtaskIndex(),
                        HttpResponseStatus.NOT_FOUND);
            }
        } else {
            throw new RestHandlerException(
                    "Invalid attempt num " + attemptNumber, HttpResponseStatus.NOT_FOUND);
        }
    }

    /**
     * Called for each request after the corresponding {@link AccessExecution} has been retrieved
     * from the {@link AccessExecutionVertex}.
     *
     * @param request the request
     * @param execution the execution
     * @return the response
     * @throws RestHandlerException the rest handler exception
     */
    protected abstract R handleRequest(
            HandlerRequest<EmptyRequestBody> request, AccessExecution execution)
            throws RestHandlerException;
}
