/**
 * 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.hcatalog.templeton;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.ws.rs.core.Response;
 
import org.apache.commons.exec.ExecuteException;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hcatalog.templeton.tool.TempletonUtils;


/**
 * Run hcat on the local server using the ExecService.  This is
 * the backend of the ddl web service.
 */
public class HcatDelegator extends LauncherDelegator {
    private static final Log LOG = LogFactory.getLog(HcatDelegator.class);
    private ExecService execService;

    public HcatDelegator(AppConfig appConf, ExecService execService) {
        super(appConf);
        this.execService = execService;
    }

    /**
     * Run the local hcat executable.
     */
    public ExecBean run(String user, String exec, boolean format,
                        String group, String permissions)
        throws NotAuthorizedException, BusyException, ExecuteException, IOException {
        SecureProxySupport proxy = new SecureProxySupport();
        try {
            List<String> args = makeArgs(exec, format, group, permissions);
            proxy.open(user, appConf);

            // Setup the hadoop vars to specify the user.
            String cp = makeOverrideClasspath(appConf);
            Map<String, String> env = TempletonUtils.hadoopUserEnv(user, cp);
            proxy.addEnv(env);
            proxy.addArgs(args);
            return execService.run(appConf.clusterHcat(), args, env);
        } catch (InterruptedException e) {
            throw new IOException(e);
        } finally {
            if (proxy != null)
                proxy.close();
        }
    }

    private List<String> makeArgs(String exec, boolean format,
                                  String group, String permissions) {
        ArrayList<String> args = new ArrayList<String>();
        args.add("-e");
        args.add(exec);
        if (TempletonUtils.isset(group)) {
            args.add("-g");
            args.add(group);
        }
        if (TempletonUtils.isset(permissions)) {
            args.add("-p");
            args.add(permissions);
        }
        if (format) {
            args.add("-D");
            args.add("hive.ddl.output.format=json");
            // Use both args to ease development.  Delete this one on
            // May 1.
            args.add("-D");
            args.add("hive.format=json");
        }

        return args;
    }

    /**
     * Return a json description of the database.
     */
    public Response descDatabase(String user, String db, boolean extended)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "desc database " + db + "; ";
        if (extended)
            exec = "desc database extended " + db + "; ";

        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(res).build();
        } catch (HcatException e) {
            if (e.execBean.stderr.contains("SemanticException")) {
                return JsonBuilder.create().
                    put("error", "Database " + db + " does not exist")
                    .put("errorCode", "404")
                    .put("database", db).build();
            }
            throw new HcatException("unable to describe database: " + db,
                e.execBean, exec);
        }
    }

    /**
     * Return a json "show databases like".  This will return a list of
     * databases.
     */
    public Response listDatabases(String user, String dbPattern)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("show databases like '%s';", dbPattern);
        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(res)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to show databases for: " + dbPattern,
                e.execBean, exec);
        }
    }

    /**
     * Create a database with the given name
     */
    public Response createDatabase(String user, DatabaseDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "create database";
        if (desc.ifNotExists)
            exec += " if not exists";
        exec += " " + desc.database;
        if (TempletonUtils.isset(desc.comment))
            exec += String.format(" comment '%s'", desc.comment);
        if (TempletonUtils.isset(desc.location))
            exec += String.format(" location '%s'", desc.location);
        if (TempletonUtils.isset(desc.properties))
            exec += String.format(" with dbproperties (%s)",
                makePropertiesStatement(desc.properties));
        exec += ";";

        String res = jsonRun(user, exec, desc.group, desc.permissions);
        return JsonBuilder.create(res)
            .put("database", desc.database)
            .build();
    }

    /**
     * Drop the given database
     */
    public Response dropDatabase(String user, String db,
                                 boolean ifExists, String option,
                                 String group, String permissions)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "drop database";
        if (ifExists)
            exec += " if exists";
        exec += " " + db;
        if (TempletonUtils.isset(option))
            exec += " " + option;
        exec += ";";

        String res = jsonRun(user, exec, group, permissions);
        return JsonBuilder.create(res)
            .put("database", db)
            .build();
    }

    /**
     * Create a table.
     */
    public Response createTable(String user, String db, TableDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = makeCreateTable(db, desc);

        try {
            String res = jsonRun(user, exec, desc.group, desc.permissions, true);

            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", desc.table)
                .build();
        } catch (final HcatException e) {
            throw new HcatException("unable to create table: " + desc.table,
                e.execBean, exec);
        }
    }

    /**
     * Create a table like another.
     */
    public Response createTableLike(String user, String db, TableLikeDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; create", db);

        if (desc.external)
            exec += " external";
        exec += String.format(" table %s like %s", desc.newTable, desc.existingTable);
        if (TempletonUtils.isset(desc.location))
            exec += String.format(" location '%s'", desc.location);
        exec += ";";

        try {
            String res = jsonRun(user, exec, desc.group, desc.permissions, true);

            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", desc.newTable)
                .build();
        } catch (final HcatException e) {
            throw new HcatException("unable to create table: " + desc.newTable,
                e.execBean, exec);
        }
    }

    /**
     * Return a json description of the table.
     */
    public Response descTable(String user, String db, String table, boolean extended)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "use " + db + "; ";
        if (extended)
            exec += "desc extended " + table + "; ";
        else
            exec += "desc " + table + "; ";
        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .build();
        } catch (HcatException e) {
            if (e.execBean.stderr.contains("SemanticException") &&
                e.execBean.stderr.contains("Table not found")) {
                return JsonBuilder.create().
                    put("error", "Table" + db + "." + table + " does not exist" )
                    .put("errorCode", "404")
                    .put("table", table)
                    .put("database", db).build();
            }
            throw new HcatException("unable to describe database: " + db,
                e.execBean, exec);
        }
    }

    /**
     * Return a json "show table like".  This will return a list of
     * tables.
     */
    public Response listTables(String user, String db, String tablePattern)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; show tables like '%s';",
            db, tablePattern);
        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(res)
                .put("database", db)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to show tables for: " + tablePattern,
                e.execBean, exec);
        }
    }

    /**
     * Return a json "show table extended like".  This will return
     * only the first single table.
     */
    public Response descExtendedTable(String user, String db, String table)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; show table extended like %s;",
            db, table);
        try {
            String res = jsonRun(user, exec);
            JsonBuilder jb = JsonBuilder.create(singleTable(res, table))
                .remove("tableName")
                .put("database", db)
                .put("table", table);

            // If we can get them from HDFS, add group and permission
            String loc = (String) jb.getMap().get("location");
            if (loc != null && loc.startsWith("hdfs://")) {
                try {
                    FileSystem fs = FileSystem.get(appConf);
                    FileStatus status = fs.getFileStatus(new Path(new URI(loc)));
                    jb.put("group", status.getGroup());
                    jb.put("permission", status.getPermission().toString());
                } catch (Exception e) {
                    LOG.warn(e.getMessage() + " Couldn't get permissions for " + loc);
                }
            }
            return jb.build();
        } catch (HcatException e) {
            throw new HcatException("unable to show table: " + table, e.execBean, exec);
        }
    }

    // Format a list of Columns for a create statement
    private String makeCols(List<ColumnDesc> cols) {
        ArrayList<String> res = new ArrayList<String>();
        for (ColumnDesc col : cols)
            res.add(makeOneCol(col));
        return StringUtils.join(res, ", ");
    }

    // Format a Column for a create statement
    private String makeOneCol(ColumnDesc col) {
        String res = String.format("%s %s", col.name, col.type);
        if (TempletonUtils.isset(col.comment))
            res += String.format(" comment '%s'", col.comment);
        return res;
    }

    // Make a create table statement
    private String makeCreateTable(String db, TableDesc desc) {
        String exec = String.format("use %s; create", db);

        if (desc.external)
            exec += " external";
        exec += " table";
        if (desc.ifNotExists)
            exec += " if not exists";
        exec += " " + desc.table;

        if (TempletonUtils.isset(desc.columns))
            exec += String.format("(%s)", makeCols(desc.columns));
        if (TempletonUtils.isset(desc.comment))
            exec += String.format(" comment '%s'", desc.comment);
        if (TempletonUtils.isset(desc.partitionedBy))
            exec += String.format(" partitioned by (%s)", makeCols(desc.partitionedBy));
        if (desc.clusteredBy != null)
            exec += String.format(" clustered by %s", makeClusteredBy(desc.clusteredBy));
        if (desc.format != null)
            exec += " " + makeStorageFormat(desc.format);
        if (TempletonUtils.isset(desc.location))
            exec += String.format(" location '%s'", desc.location);
        if (TempletonUtils.isset(desc.tableProperties))
            exec += String.format(" tblproperties (%s)",
                makePropertiesStatement(desc.tableProperties));
        exec += ";";

        return exec;
    }

    // Format a clustered by statement
    private String makeClusteredBy(TableDesc.ClusteredByDesc desc) {
        String res = String.format("(%s)", StringUtils.join(desc.columnNames, ", "));
        if (TempletonUtils.isset(desc.sortedBy))
            res += String.format(" sorted by (%s)", makeClusterSortList(desc.sortedBy));
        res += String.format(" into %s buckets", desc.numberOfBuckets);

        return res;
    }

    // Format a sorted by statement
    private String makeClusterSortList(List<TableDesc.ClusterSortOrderDesc> descs) {
        ArrayList<String> res = new ArrayList<String>();
        for (TableDesc.ClusterSortOrderDesc desc : descs)
            res.add(makeOneClusterSort(desc));
        return StringUtils.join(res, ", ");
    }

    // Format a single cluster sort statement
    private String makeOneClusterSort(TableDesc.ClusterSortOrderDesc desc) {
        return String.format("%s %s", desc.columnName, desc.order.toString());
    }

    // Format the storage format statements
    private String makeStorageFormat(TableDesc.StorageFormatDesc desc) {
        String res = "";

        if (desc.rowFormat != null)
            res += makeRowFormat(desc.rowFormat);
        if (TempletonUtils.isset(desc.storedAs))
            res += String.format(" stored as %s", desc.storedAs);
        if (desc.storedBy != null)
            res += " " + makeStoredBy(desc.storedBy);

        return res;
    }

    // Format the row format statement
    private String makeRowFormat(TableDesc.RowFormatDesc desc) {
        String res =
            makeTermBy(desc.fieldsTerminatedBy, "fields")
                + makeTermBy(desc.collectionItemsTerminatedBy, "collection items")
                + makeTermBy(desc.mapKeysTerminatedBy, "map keys")
                + makeTermBy(desc.linesTerminatedBy, "lines");

        if (TempletonUtils.isset(res))
            return "row format delimited" + res;
        else if (desc.serde != null)
            return makeSerdeFormat(desc.serde);
        else
            return "";
    }

    // A row format terminated by clause
    private String makeTermBy(String sep, String fieldName) {

        if (TempletonUtils.isset(sep))
            return String.format(" %s terminated by '%s'", fieldName, sep);
        else
            return "";
    }

    // Format the serde statement
    private String makeSerdeFormat(TableDesc.SerdeDesc desc) {
        String res = "row format serde " + desc.name;
        if (TempletonUtils.isset(desc.properties))
            res += String.format(" with serdeproperties (%s)",
                makePropertiesStatement(desc.properties));
        return res;
    }

    // Format the properties statement
    private String makePropertiesStatement(Map<String, String> properties) {
        ArrayList<String> res = new ArrayList<String>();
        for (Map.Entry<String, String> e : properties.entrySet())
            res.add(String.format("'%s'='%s'", e.getKey(), e.getValue()));
        return StringUtils.join(res, ", ");
    }

    // Format the stored by statement
    private String makeStoredBy(TableDesc.StoredByDesc desc) {
        String res = String.format("stored by '%s'", desc.className);
        if (TempletonUtils.isset(desc.properties))
            res += String.format(" with serdeproperties (%s)",
                makePropertiesStatement(desc.properties));
        return res;
    }

    // Pull out the first table from the "show extended" json.
    private String singleTable(String json, String table)
        throws IOException {
        Map obj = JsonBuilder.jsonToMap(json);
        if (JsonBuilder.isError(obj))
            return json;

        List tables = (List) obj.get("tables");
        if (TempletonUtils.isset(tables))
            return JsonBuilder.mapToJson(tables.get(0));
        else {
            return JsonBuilder
                .createError(String.format("Table %s does not exist", table),
                    JsonBuilder.MISSING).
                    buildJson();
        }
    }

    /**
     * Drop a table.
     */
    public Response dropTable(String user, String db,
                              String table, boolean ifExists,
                              String group, String permissions)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; drop table", db);
        if (ifExists)
            exec += " if exists";
        exec += String.format(" %s;", table);

        try {
            String res = jsonRun(user, exec, group, permissions, true);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to drop table: " + table, e.execBean, exec);
        }
    }

    /**
     * Rename a table.
     */
    public Response renameTable(String user, String db,
                                String oldTable, String newTable,
                                String group, String permissions)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; alter table %s rename to %s;",
            db, oldTable, newTable);
        try {
            String res = jsonRun(user, exec, group, permissions, true);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", newTable)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to rename table: " + oldTable,
                e.execBean, exec);
        }
    }

    /**
     * Describe one table property.
     */
    public Response descTableProperty(String user, String db,
                                      String table, String property)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        Response res = descTable(user, db, table, true);
        if (res.getStatus() != JsonBuilder.OK)
            return res;
        Map props = tableProperties(res.getEntity());
        Map found = null;
        if (props != null) {
            String value = (String) props.get(property);
            if (value != null) {
                found = new HashMap<String, String>();
                found.put(property, value);
            }
        }

        return JsonBuilder.create()
            .put("database", db)
            .put("table", table)
            .put("property", found)
            .build();
    }

    /**
     * List the table properties.
     */
    public Response listTableProperties(String user, String db, String table)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        Response res = descTable(user, db, table, true);
        if (res.getStatus() != JsonBuilder.OK)
            return res;
        Map props = tableProperties(res.getEntity());
        return JsonBuilder.create()
            .put("database", db)
            .put("table", table)
            .put("properties", props)
            .build();
    }

    /**
     * Add one table property.
     */
    public Response addOneTableProperty(String user, String db, String table,
                                        TablePropertyDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec
            = String.format("use %s; alter table %s set tblproperties ('%s'='%s');",
                db, table, desc.name, desc.value);
        try {
            String res = jsonRun(user, exec, desc.group, desc.permissions, true);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .put("property", desc.name)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to add table property: " + table,
                e.execBean, exec);
        }
    }

    private Map tableProperties(Object extendedTable) {
        if (!(extendedTable instanceof Map))
            return null;
        Map m = (Map) extendedTable;
        Map tableInfo = (Map) m.get("tableInfo");
        if (tableInfo == null)
            return null;

        return (Map) tableInfo.get("parameters");
    }

    /**
     * Return a json description of the partitions.
     */
    public Response listPartitions(String user, String db, String table)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "use " + db + "; ";
        exec += "show partitions " + table + "; ";
        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to show partitions for table: " + table,
                e.execBean, exec);
        }
    }

    /**
     * Return a json description of one partition.
     */
    public Response descOnePartition(String user, String db, String table,
                                     String partition)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = "use " + db + "; ";
        exec += "show table extended like " + table
            + " partition (" + partition + "); ";
        try {
            String res = jsonRun(user, exec);
            return JsonBuilder.create(singleTable(res, table))
                .remove("tableName")
                .put("database", db)
                .put("table", table)
                .put("partition", partition)
                .build();
        } catch (HcatException e) {
            if (e.execBean.stderr.contains("SemanticException") &&
                e.execBean.stderr.contains("Partition not found")) {
                String emsg = "Partition " + partition + " for table " 
                    + table + " does not exist" + db + "." + table + " does not exist";
                return JsonBuilder.create()
                    .put("error", emsg)
                    .put("errorCode", "404")
                    .put("database", db)
                    .put("table", table)
                    .put("partition", partition)
                    .build();
            }

            throw new HcatException("unable to show partition: "
                + table + " " + partition,
                e.execBean,
                exec);
        }
    }

    /**
     * Add one partition.
     */
    public Response addOnePartition(String user, String db, String table,
                                    PartitionDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; alter table %s add", db, table);
        if (desc.ifNotExists)
            exec += " if not exists";
        exec += String.format(" partition (%s)", desc.partition);
        if (TempletonUtils.isset(desc.location))
            exec += String.format(" location '%s'", desc.location);
        exec += ";";
        try {
            String res = jsonRun(user, exec, desc.group, desc.permissions, true);
            if (res.indexOf("AlreadyExistsException") > -1) {
                return JsonBuilder.create().
                    put("error", "Partition already exists")
                    .put("errorCode", "409")
                    .put("database", db)
                    .put("table", table)
                    .put("partition", desc.partition).build();
            }
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .put("partition", desc.partition)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to add partition: " + desc,
                e.execBean, exec);
        }
    }

    /**
     * Drop a partition.
     */
    public Response dropPartition(String user, String db,
                                  String table, String partition, boolean ifExists,
                                  String group, String permissions)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; alter table %s drop", db, table);
        if (ifExists)
            exec += " if exists";
        exec += String.format(" partition (%s);", partition);

        try {
            String res = jsonRun(user, exec, group, permissions, true);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .put("partition", partition)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to drop partition: " + partition,
                e.execBean, exec);
        }
    }

    /**
     * Return a json description of the columns.  Same as
     * describeTable.
     */
    public Response listColumns(String user, String db, String table)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        try {
            return descTable(user, db, table, false);
        } catch (HcatException e) {
            throw new HcatException("unable to show columns for table: " + table,
                e.execBean, e.statement);
        }
    }

    /**
     * Return a json description of one column.
     */
    public Response descOneColumn(String user, String db, String table, String column)
        throws SimpleWebException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        Response res = listColumns(user, db, table);
        if (res.getStatus() != JsonBuilder.OK)
            return res;

        Object o = res.getEntity();
        final Map fields = (o != null && (o instanceof Map)) ? (Map) o : null;
        if (fields == null)
            throw new SimpleWebException(500, "Internal error, unable to find column "
                + column);


        List<Map> cols = (List) fields.get("columns");
        Map found = null;
        if (cols != null) {
            for (Map col : cols) {
                if (column.equals(col.get("name"))) {
                    found = col;
                    break;
                }
            }
        }
        if (found == null)
            throw new SimpleWebException(500, "unable to find column " + column,
                new HashMap<String, Object>() {
                    {
                        put("description", fields);
                    }
                });
        fields.remove("columns");
        fields.put("column", found);
        return Response.fromResponse(res).entity(fields).build();
    }

    /**
     * Add one column.
     */
    public Response addOneColumn(String user, String db, String table,
                                 ColumnDesc desc)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        String exec = String.format("use %s; alter table %s add columns (%s %s",
            db, table, desc.name, desc.type);
        if (TempletonUtils.isset(desc.comment))
            exec += String.format(" comment '%s'", desc.comment);
        exec += ");";
        try {
            String res = jsonRun(user, exec, desc.group, desc.permissions, true);
            return JsonBuilder.create(res)
                .put("database", db)
                .put("table", table)
                .put("column", desc.name)
                .build();
        } catch (HcatException e) {
            throw new HcatException("unable to add column: " + desc,
                e.execBean, exec);
        }
    }

    // Check that the hcat result is valid and or has a valid json
    // error
    private boolean isValid(ExecBean eb, boolean requireEmptyOutput) {
        if (eb == null)
            return false;

        try {
            Map m = JsonBuilder.jsonToMap(eb.stdout);
            if (m.containsKey("error")) // This is a valid error message.
                return true;
        } catch (IOException e) {
            return false;
        }

        if (eb.exitcode != 0)
            return false;

        if (requireEmptyOutput)
            if (TempletonUtils.isset(eb.stdout))
                return false;

        return true;
    }

    // Run an hcat expression and return just the json outout.
    private String jsonRun(String user, String exec,
                           String group, String permissions,
                           boolean requireEmptyOutput)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        ExecBean res = run(user, exec, true, group, permissions);

        if (!isValid(res, requireEmptyOutput))
            throw new HcatException("Failure calling hcat: " + exec, res, exec);

        return res.stdout;
    }

    // Run an hcat expression and return just the json outout.  No
    // permissions set.
    private String jsonRun(String user, String exec)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        return jsonRun(user, exec, null, null);
    }

    // Run an hcat expression and return just the json outout.
    private String jsonRun(String user, String exec,
                           String group, String permissions)
        throws HcatException, NotAuthorizedException, BusyException,
        ExecuteException, IOException {
        return jsonRun(user, exec, group, permissions, false);
    }
}