/**
 * 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.oozie.command;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.apache.oozie.WorkflowJobBean;
import org.apache.oozie.ErrorCode;
import org.apache.oozie.XException;
import org.apache.oozie.executor.jpa.BundleJobsDeleteJPAExecutor;
import org.apache.oozie.executor.jpa.BundleJobsGetForPurgeJPAExecutor;
import org.apache.oozie.executor.jpa.CoordActionsDeleteJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobQueryExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobQueryExecutor.WorkflowJobQuery;
import org.apache.oozie.executor.jpa.CoordJobsCountNotForPurgeFromParentIdJPAExecutor;
import org.apache.oozie.executor.jpa.CoordJobsDeleteJPAExecutor;
import org.apache.oozie.executor.jpa.CoordJobsGetForPurgeJPAExecutor;
import org.apache.oozie.executor.jpa.CoordJobsGetFromParentIdJPAExecutor;
import org.apache.oozie.executor.jpa.JPAExecutorException;
import org.apache.oozie.executor.jpa.WorkflowJobsCountNotForPurgeFromCoordParentIdJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobsCountNotForPurgeFromWorkflowParentIdJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobsDeleteJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobsGetFromWorkflowParentIdJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobsGetForPurgeJPAExecutor;
import org.apache.oozie.executor.jpa.WorkflowJobsGetFromCoordParentIdJPAExecutor;
import org.apache.oozie.service.JPAService;
import org.apache.oozie.service.Services;

/**
 * This class is used to purge workflows, coordinators, and bundles.  It takes into account the relationships between workflows and
 * coordinators, and coordinators and bundles.  It also only acts on 'limit' number of items at a time to not overtax the DB and in
 * case something gets rolled back.  Also, children are always deleted before their parents in case of a rollback.
 */
public class PurgeXCommand extends XCommand<Void> {
    private JPAService jpaService = null;
    private int wfOlderThan;
    private int coordOlderThan;
    private int bundleOlderThan;
    private boolean purgeOldCoordAction = false;
    private final int limit;
    private List<String> wfList;
    private List<String> coordActionList;
    private List<String> coordList;
    private List<String> bundleList;
    private int wfDel;
    private int coordDel;
    private int coordActionDel;
    private int bundleDel;

    public PurgeXCommand(int wfOlderThan, int coordOlderThan, int bundleOlderThan, int limit) {
        this(wfOlderThan, coordOlderThan, bundleOlderThan, limit, false);
    }

    public PurgeXCommand(int wfOlderThan, int coordOlderThan, int bundleOlderThan, int limit, boolean purgeOldCoordAction) {
        super("purge", "purge", 0);
        this.wfOlderThan = wfOlderThan;
        this.coordOlderThan = coordOlderThan;
        this.bundleOlderThan = bundleOlderThan;
        this.purgeOldCoordAction = purgeOldCoordAction;
        this.limit = limit;
        wfList = new ArrayList<String>();
        coordActionList = new ArrayList<String>();
        coordList = new ArrayList<String>();
        bundleList = new ArrayList<String>();
        wfDel = 0;
        coordDel = 0;
        bundleDel = 0;
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.XCommand#loadState()
     */
    @Override
    protected void loadState() throws CommandException {
        try {
            jpaService = Services.get().get(JPAService.class);

            if (jpaService != null) {
                // Get the lists of workflows, coordinators, and bundles that can be purged (and have no parents)
                int size;
                do {
                    size = wfList.size();
                    wfList.addAll(jpaService.execute(new WorkflowJobsGetForPurgeJPAExecutor(wfOlderThan, wfList.size(), limit)));
                } while(size != wfList.size());
                if (purgeOldCoordAction) {
                    LOG.debug("Purging workflows of long running coordinators is turned on");
                    do {
                        size = coordActionList.size();
                        long olderThan = wfOlderThan;
                        List<WorkflowJobBean> jobBeans = WorkflowJobQueryExecutor.getInstance().getList(
                                WorkflowJobQuery.GET_COMPLETED_COORD_WORKFLOWS_OLDER_THAN, olderThan,
                                coordActionList.size(), limit);
                        for (WorkflowJobBean bean : jobBeans) {
                            coordActionList.add(bean.getParentId());
                            wfList.add(bean.getId());
                        }
                    } while(size != coordActionList.size());
                }
                do {
                    size = coordList.size();
                    coordList.addAll(jpaService.execute(
                            new CoordJobsGetForPurgeJPAExecutor(coordOlderThan, coordList.size(), limit)));
                } while(size != coordList.size());
                do {
                    size = bundleList.size();
                    bundleList.addAll(jpaService.execute(
                            new BundleJobsGetForPurgeJPAExecutor(bundleOlderThan, bundleList.size(), limit)));
                } while(size != bundleList.size());
            }
            else {
                throw new CommandException(ErrorCode.E0610);
            }
        }
        catch (XException ex) {
            throw new CommandException(ex);
        }
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.XCommand#execute()
     */
    @Override
    protected Void execute() throws CommandException {
        LOG.info("STARTED Purge to purge Workflow Jobs older than [{0}] days, Coordinator Jobs older than [{1}] days, and Bundle"
                + "jobs older than [{2}] days.", wfOlderThan, coordOlderThan, bundleOlderThan);

        // Process parentless workflows to purge them and their children
        if (!wfList.isEmpty()) {
            try {
                processWorkflows(wfList);
            }
            catch (JPAExecutorException je) {
                throw new CommandException(je);
            }
        }

        // Process coordinator actions of long running coordinators and purge them
        if (!coordActionList.isEmpty()) {
            try {
                purgeCoordActions(coordActionList);
            }
            catch (JPAExecutorException je) {
                throw new CommandException(je);
            }
        }
        // Processs parentless coordinators to purge them and their children
        if (!coordList.isEmpty()) {
            try {
                processCoordinators(coordList);
            }
            catch (JPAExecutorException je) {
                throw new CommandException(je);
            }
        }

        // Process bundles to purge them and their children
        if (!bundleList.isEmpty()) {
            try {
                processBundles(bundleList);
            }
            catch (JPAExecutorException je) {
                throw new CommandException(je);
            }
        }

        LOG.info("ENDED Purge deleted [{0}] workflows, [{1}] coordinatorActions, [{2}] coordinators, [{3}] bundles",
                wfDel, coordActionDel, coordDel, bundleDel);
        return null;
    }

    /**
     * Process workflows to purge them and their children.  Uses the processWorkflowsHelper method to help via recursion to make
     * sure that the workflow children are deleted before their parents.
     *
     * @param wfs List of workflows to process
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void processWorkflows(List<String> wfs) throws JPAExecutorException {
        List<String> wfsToPurge = processWorkflowsHelper(wfs);
        for (String id: wfsToPurge) {
            LOG.debug("Purging workflow " + id);
        }
        purgeWorkflows(wfsToPurge);
    }

    /**
     * Used by the processWorkflows method and via recursion.
     *
     * @param wfs List of workflows to process
     * @return List of workflows to purge
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private List<String> processWorkflowsHelper(List<String> wfs) throws JPAExecutorException {
        // If the list is empty, then we've finished recursing
        if (wfs.isEmpty()) {
            return wfs;
        }
        List<String> subwfs = new ArrayList<String>();
        List<String> wfsToPurge = new ArrayList<String>();
        for (String wfId : wfs) {
            // We only purge the workflow and its children if they are all ready to be purged
            long numChildrenNotReady = jpaService.execute(
                    new WorkflowJobsCountNotForPurgeFromWorkflowParentIdJPAExecutor(wfOlderThan, wfId));
            if (numChildrenNotReady == 0) {
                wfsToPurge.add(wfId);
                // Get all of the direct children for this workflow
                List<String> children = new ArrayList<String>();
                int size;
                do {
                    size = children.size();
                    children.addAll(jpaService.execute(
                            new WorkflowJobsGetFromWorkflowParentIdJPAExecutor(wfId, children.size(), limit)));
                } while (size != children.size());
                subwfs.addAll(children);
            }
        }
        // Recurse on the children we just found to process their children
        wfsToPurge.addAll(processWorkflowsHelper(subwfs));
        return wfsToPurge;
    }

    /**
     * Process coordinators to purge them and their children.
     *
     * @param coords List of coordinators to process
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void processCoordinators(List<String> coords) throws JPAExecutorException {
        List<String> wfsToPurge = new ArrayList<String>();
        List<String> coordsToPurge = new ArrayList<String>();
        for (String coordId : coords) {
            // We only purge the coord and its children if they are all ready to be purged
            long numChildrenNotReady = jpaService.execute(
                    new WorkflowJobsCountNotForPurgeFromCoordParentIdJPAExecutor(wfOlderThan, coordId));
            if (numChildrenNotReady == 0) {
                coordsToPurge.add(coordId);
                LOG.debug("Purging coordinator " + coordId);
                // Get all of the direct children for this coord
                List<String> children = new ArrayList<String>();
                int size;
                do {
                    size = children.size();
                    children.addAll(jpaService.execute(
                            new WorkflowJobsGetFromCoordParentIdJPAExecutor(coordId, children.size(), limit)));
                } while (size != children.size());
                wfsToPurge.addAll(children);
            }
        }
        // Process the children
        processWorkflows(wfsToPurge);
        // Now that all children have been purged, we can purge the coordinators
        purgeCoordinators(coordsToPurge);
    }

    /**
     * Process bundles to purge them and their children
     *
     * @param bundles List of bundles to process
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void processBundles(List<String> bundles) throws JPAExecutorException {
        List<String> coordsToPurge = new ArrayList<String>();
        List<String> bundlesToPurge = new ArrayList<String>();
        for (Iterator<String> it = bundles.iterator(); it.hasNext(); ) {
            String bundleId = it.next();
            // We only purge the bundle and its children if they are all ready to be purged
            long numChildrenNotReady = jpaService.execute(
                    new CoordJobsCountNotForPurgeFromParentIdJPAExecutor(coordOlderThan, bundleId));
            if (numChildrenNotReady == 0) {
                bundlesToPurge.add(bundleId);
                LOG.debug("Purging bundle " + bundleId);
                // Get all of the direct children for this bundle
                List<String> children = new ArrayList<String>();
                int size;
                do {
                    size = children.size();
                    children.addAll(jpaService.execute(new CoordJobsGetFromParentIdJPAExecutor(bundleId, children.size(), limit)));
                } while (size != children.size());
                coordsToPurge.addAll(children);
            }
        }
        // Process the children
        processCoordinators(coordsToPurge);
        // Now that all children have been purged, we can purge the bundles
        purgeBundles(bundlesToPurge);
    }

    /**
     * Purge the workflows in REVERSE order in batches of size 'limit' (this must be done in reverse order so that children are
     * purged before their parents)
     *
     * @param wfs List of workflows to purge
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void purgeWorkflows(List<String> wfs) throws JPAExecutorException {
        wfDel += wfs.size();
        Collections.reverse(wfs);
        for (int startIndex = 0; startIndex < wfs.size(); ) {
            int endIndex = (startIndex + limit < wfs.size()) ? (startIndex + limit) : wfs.size();
            jpaService.execute(new WorkflowJobsDeleteJPAExecutor(wfs.subList(startIndex, endIndex)));
            startIndex = endIndex;
        }
    }

    /**
     * Purge coordActions of long running coordinators and purge them
     *
     * @param coordActions List of coordActions to purge
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void purgeCoordActions(List<String> coordActions) throws JPAExecutorException {
        coordActionDel = coordActions.size();
        for (int startIndex = 0; startIndex < coordActions.size(); ) {
            int endIndex = (startIndex + limit < coordActions.size()) ? (startIndex + limit) : coordActions.size();
            jpaService.execute(new CoordActionsDeleteJPAExecutor(coordActions.subList(startIndex, endIndex)));
            startIndex = endIndex;
        }
    }
    /**
     * Purge the coordinators in SOME order in batches of size 'limit' (its in reverse order only for convenience)
     *
     * @param coords List of coordinators to purge
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void purgeCoordinators(List<String> coords) throws JPAExecutorException {
        coordDel += coords.size();
        for (int startIndex = 0; startIndex < coords.size(); ) {
            int endIndex = (startIndex + limit < coords.size()) ? (startIndex + limit) : coords.size();
            jpaService.execute(new CoordJobsDeleteJPAExecutor(coords.subList(startIndex, endIndex)));
            startIndex = endIndex;
        }
    }

    /**
     * Purge the bundles in SOME order in batches of size 'limit' (its in reverse order only for convenience)
     *
     * @param bundles List of bundles to purge
     * @throws JPAExecutorException If a JPA executor has a problem
     */
    private void purgeBundles(List<String> bundles) throws JPAExecutorException {
        bundleDel += bundles.size();
        for (int startIndex = 0; startIndex < bundles.size(); ) {
            int endIndex = (startIndex + limit < bundles.size()) ? (startIndex + limit) : bundles.size();
            jpaService.execute(new BundleJobsDeleteJPAExecutor(bundles.subList(startIndex, endIndex)));
            startIndex = endIndex;
        }
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.XCommand#getEntityKey()
     */
    @Override
    public String getEntityKey() {
        return null;
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.XCommand#isLockRequired()
     */
    @Override
    protected boolean isLockRequired() {
        return false;
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.XCommand#verifyPrecondition()
     */
    @Override
    protected void verifyPrecondition() throws CommandException, PreconditionException {
    }
}