/*
 *  ============LICENSE_START=======================================================
 *  Copyright (C) 2022 Nordix Foundation
 *  Modifications Copyright (C) 2022 Bell Canada
 *  ================================================================================
 *  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.
 *
 *  SPDX-License-Identifier: Apache-2.0
 *  ============LICENSE_END=========================================================
 */

package org.onap.cps.ncmp.api.inventory.sync;

import com.fasterxml.jackson.databind.JsonNode;
import java.security.SecureRandom;
import java.time.Duration;
import java.time.OffsetDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.onap.cps.ncmp.api.impl.operations.DmiDataOperations;
import org.onap.cps.ncmp.api.impl.operations.DmiOperations;
import org.onap.cps.ncmp.api.impl.utils.YangDataConverter;
import org.onap.cps.ncmp.api.impl.yangmodels.YangModelCmHandle;
import org.onap.cps.ncmp.api.inventory.CmHandleState;
import org.onap.cps.ncmp.api.inventory.CompositeState;
import org.onap.cps.ncmp.api.inventory.DataStoreSyncState;
import org.onap.cps.ncmp.api.inventory.InventoryPersistence;
import org.onap.cps.ncmp.api.inventory.LockReasonCategory;
import org.onap.cps.spi.FetchDescendantsOption;
import org.onap.cps.spi.model.DataNode;
import org.onap.cps.utils.JsonObjectMapper;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;

@Slf4j
@Service
@RequiredArgsConstructor
public class SyncUtils {

    private static final SecureRandom secureRandom = new SecureRandom();

    private final InventoryPersistence inventoryPersistence;

    private final DmiDataOperations dmiDataOperations;

    private final JsonObjectMapper jsonObjectMapper;

    private static final Pattern retryAttemptPattern = Pattern.compile("^Attempt #(\\d+) failed:");

    /**
     * Query data nodes for cm handles with an "ADVISED" cm handle state, and select a random entry for processing.
     *
     * @return a random yang model cm handle with an ADVISED state, return null if not found
     */
    public YangModelCmHandle getAnAdvisedCmHandle() {
        final List<DataNode> advisedCmHandles = inventoryPersistence.getCmHandlesByState(CmHandleState.ADVISED);
        if (advisedCmHandles.isEmpty()) {
            return null;
        }
        final int randomElementIndex = secureRandom.nextInt(advisedCmHandles.size());
        final String cmHandleId = advisedCmHandles.get(randomElementIndex).getLeaves()
            .get("id").toString();
        return inventoryPersistence.getYangModelCmHandle(cmHandleId);
    }

    /**
     * First query data nodes for cm handles with CM Handle Operational Sync State in "UNSYNCHRONIZED" and
     * randomly select a CM Handle and query the data nodes for CM Handle State in "READY".
     *
     * @return a random yang model cm handle with State in READY and Operation Sync State in "UNSYNCHRONIZED",
     *         return null if not found
     */
    public YangModelCmHandle getAnUnSynchronizedReadyCmHandle() {
        final List<DataNode> unSynchronizedCmHandles = inventoryPersistence
                .getCmHandlesByOperationalSyncState(DataStoreSyncState.UNSYNCHRONIZED);
        if (unSynchronizedCmHandles.isEmpty()) {
            return null;
        }
        Collections.shuffle(unSynchronizedCmHandles);
        for (final DataNode cmHandle : unSynchronizedCmHandles) {
            final String cmHandleId = cmHandle.getLeaves().get("id").toString();
            final List<DataNode> readyCmHandles = inventoryPersistence
                    .getCmHandlesByIdAndState(cmHandleId, CmHandleState.READY);
            if (!readyCmHandles.isEmpty()) {
                return inventoryPersistence.getYangModelCmHandle(cmHandleId);
            }
        }
        return null;
    }

    /**
     * Query data nodes for cm handles with an "LOCKED" cm handle state with reason LOCKED_MODULE_SYNC_FAILED".
     *
     * @return a random LOCKED yang model cm handle, return null if not found
     */
    public List<YangModelCmHandle> getModuleSyncFailedCmHandles() {
        final List<DataNode> lockedCmHandleAsDataNodeList = inventoryPersistence.getCmHandleDataNodesByCpsPath(
            "//lock-reason[@reason=\"LOCKED_MODULE_SYNC_FAILED\"]/ancestor::cm-handles",
            FetchDescendantsOption.INCLUDE_ALL_DESCENDANTS);
        return lockedCmHandleAsDataNodeList.stream()
            .map(cmHandle -> YangDataConverter.convertCmHandleToYangModel(cmHandle,
                cmHandle.getLeaves().get("id").toString())).collect(Collectors.toList());
    }

    /**
     * Update Composite State attempts counter and set new lock reason and details.
     *
     * @param lockReasonCategory lock reason category
     * @param errorMessage       error message
     */
    public void updateLockReasonDetailsAndAttempts(final CompositeState compositeState,
                                                   final LockReasonCategory lockReasonCategory,
                                                   final String errorMessage) {
        int attempt = 1;
        if (compositeState.getLockReason() != null) {
            final Matcher matcher = retryAttemptPattern.matcher(compositeState.getLockReason().getDetails());
            if (matcher.find()) {
                attempt = 1 + Integer.parseInt(matcher.group(1));
            }
        }
        compositeState.setLockReason(CompositeState.LockReason.builder()
            .details(String.format("Attempt #%d failed: %s", attempt, errorMessage))
            .lockReasonCategory(lockReasonCategory).build());
    }


    /**
     * Check if the retry mechanism should attempt to unlock the cm handle based on the last update time.
     *
     * @param compositeState the composite state currently in the locked state
     * @return if the retry mechanism should be attempted
     */
    public boolean isReadyForRetry(final CompositeState compositeState) {
        int timeInMinutesUntilNextAttempt = 1;
        final OffsetDateTime time =
            OffsetDateTime.parse(compositeState.getLastUpdateTime(),
                DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ"));
        final Matcher matcher = retryAttemptPattern.matcher(compositeState.getLockReason().getDetails());
        if (matcher.find()) {
            timeInMinutesUntilNextAttempt = (int) Math.pow(2, Integer.parseInt(matcher.group(1)));
        } else {
            log.debug("First Attempt: no current attempts found.");
        }
        final int timeSinceLastAttempt = (int) Duration.between(time, OffsetDateTime.now()).toMinutes();
        if (timeInMinutesUntilNextAttempt >= timeSinceLastAttempt) {
            log.info("Time until next attempt is {} minutes: ",
                timeInMinutesUntilNextAttempt - timeSinceLastAttempt);
        }
        return timeSinceLastAttempt > timeInMinutesUntilNextAttempt;
    }

    /**
     * Get the Resourece Data from Node through DMI Passthrough service.
     *
     * @param cmHandleId cm handle id
     * @return optional string containing the resource data
     */
    public String getResourceData(final String cmHandleId) {
        final ResponseEntity<Object> resourceDataResponseEntity = dmiDataOperations.getResourceDataFromDmi(
                cmHandleId, DmiOperations.DataStoreEnum.PASSTHROUGH_OPERATIONAL,
                UUID.randomUUID().toString());
        if (resourceDataResponseEntity.getStatusCode().is2xxSuccessful()) {
            return getFirstResource(resourceDataResponseEntity.getBody());
        }
        return null;
    }

    private String getFirstResource(final Object responseBody) {
        final String jsonObjectAsString = jsonObjectMapper.asJsonString(responseBody);
        final JsonNode overallJsonNode = jsonObjectMapper.convertToJsonNode(jsonObjectAsString);
        final Iterator<Map.Entry<String, JsonNode>> overallJsonTreeMap = overallJsonNode.fields();
        final Map.Entry<String, JsonNode> firstElement = overallJsonTreeMap.next();
        return jsonObjectMapper.asJsonString(Map.of(firstElement.getKey(), firstElement.getValue()));
    }
}