/*
 * ============LICENSE_START==========================================
 * org.onap.music
 * ===================================================================
 *  Copyright (c) 2017 AT&T Intellectual Property
 * ===================================================================
 *  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.
 * 
 * ============LICENSE_END=============================================
 * ====================================================================
 */
package org.onap.music.client;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.onap.music.datastore.jsonobjects.JsonInsert;
import org.onap.music.datastore.jsonobjects.JsonKeySpace;
import org.onap.music.datastore.jsonobjects.JsonTable;
import org.onap.music.eelf.logging.EELFLoggerDelegate;
import org.onap.music.lockingservice.MusicLockingService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ColumnDefinitions;
import com.datastax.driver.core.ColumnDefinitions.Definition;
import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.core.DataType;
import com.datastax.driver.core.KeyspaceMetadata;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Row;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.SimpleStatement;
import com.datastax.driver.core.Statement;
import com.datastax.driver.core.TableMetadata;
import com.datastax.driver.core.querybuilder.Clause;
import com.datastax.driver.core.querybuilder.Delete;
import com.datastax.driver.core.querybuilder.QueryBuilder;
import com.datastax.driver.core.querybuilder.Select;

/**
 * A MUSIC client that talks directly to Cassandra/ZooKeeper. This was taken, and slightly modified,
 * from the REST version of the code.
 *
 * @author Robert Eby
 */
public class MusicClient {
    private EELFLoggerDelegate LOG = EELFLoggerDelegate.getLogger(MusicClient.class);

    private final String[] music_hosts; // array of hosts in the music cluster
    private Cluster cluster; // MUSIC Cassandra cluster
    private Session session; // MUSIC Cassandra session
    private MusicLockingService mls; // ZooKeeper
    private final Set<String> lockNames;// set of active lock names

    /**
     * Create a MUSIC client that talks to MUSIC on localhost.
     */
    public MusicClient() {
        this("127.0.0.1");
    }

    /**
     * Create a MUSIC client that talks to MUSIC on a remote host. The string <i>hosts</i> is a
     * comma-separated list of IP addresses for remote instances of Cassandra/ZooKeeper.
     * 
     * @param hosts the list of hostnames
     */
    public MusicClient(String hosts) {
        music_hosts = hosts.split(",");
        if (cluster == null) {
            LOG.debug("Initializing MUSIC Client with endpoints " + hosts);
            cluster = Cluster.builder().addContactPoints(music_hosts).build();
        }
        session = cluster.connect();
        mls = null;
        lockNames = new HashSet<String>();
    }

    /**
     * Close the connection to MUSIC.
     */
    public void close() {
        if (session != null) {
            session.close();
            session = null;
        }
        if (cluster != null) {
            cluster.close();
            cluster = null;
        }
    }

    /**
     * Be sure to close the connection to MUSIC when this object is GC-ed.
     */
    @Override
    protected void finalize() {
        close();
    }

    /**
     * Return a String representation of the music hosts used by this object.
     * 
     * @return the string
     */
    @Override
    public String toString() {
        List<String> t = Arrays.asList(music_hosts);
        return "MUSIC hosts=" + t.toString();
    }

    /**
     * Create a lock.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#createLock(String)
     * @param lockName the lock name
     * @return FILL IN
     */
    public String createLock(String lockName) {
        String ln = "/" + lockName;
        synchronized (lockNames) {
            lockNames.add(ln);
        }
        return getLockingService().createLockId(ln);
    }

    /**
     * Acquire a lock.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#lock(String)
     * @param lockName the lock name
     * @return FILL IN
     */
    public boolean acquireLock(String lockName) {
        return getLockingService().isMyTurn(lockName);
    }

    /**
     * Get the lock holder.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#currentLockHolder(String)
     * @param lockName the lock name
     * @return FILL IN
     */
    public String getLockHolder(String lockName) {
        return getLockingService().whoseTurnIsIt("/" + lockName);
    }

    /**
     * Unlock a lock.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#unlock(String)
     * @param lockName the lock name
     */
    public void unlockLock(String lockName) {
        getLockingService().unlockAndDeleteId(lockName);
    }

    /**
     * Delete a lock.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#deleteLock(String)
     * @param lockName the lock name
     */
    public void deleteLock(String lockName) {
        String ln = "/" + lockName;
        synchronized (lockNames) {
            lockNames.remove(ln);
        }
        getLockingService().deleteLock(ln);
    }

    /**
     * Delete all locks.
     * 
     * @see org.onap.music.lockingservice.MusicLockingService#deleteLock(String)
     * @return true
     */
    public boolean deleteAllLocks() {
        synchronized (lockNames) {
            for (String lockName : lockNames) {
                deleteLock(lockName);
            }
            lockNames.clear();
        }
        return true;
    }

    /**
     * Create a keyspace using the default replication configuration.
     * 
     * @param keyspaceName the name of the keyspace
     * @return always true currently
     * @throws Exception Cassandra exceptions are passed through
     */
    public boolean createKeyspace(String keyspaceName) throws Exception {
        Map<String, Object> repl = new HashMap<String, Object>();
        repl.put("class", "SimpleStrategy");
        repl.put("replication_factor", 1);
        Map<String, String> consistencyInfo = Collections.singletonMap("type", "eventual");
        JsonKeySpace jsonKp = new JsonKeySpace();
        jsonKp.setConsistencyInfo(consistencyInfo);
        jsonKp.setDurabilityOfWrites("true");
        jsonKp.setReplicationInfo(repl);
        return createKeyspace(keyspaceName, jsonKp);
    }

    public boolean createKeyspace(String keyspaceName, JsonKeySpace kspObject) throws Exception {
        String consistency = extractConsistencyInfo(keyspaceName, kspObject.getConsistencyInfo());
        Map<String, Object> replicationInfo = kspObject.getReplicationInfo();
        String durability = "";
        if (kspObject.getDurabilityOfWrites() != null)
            durability = " AND durable_writes = " + kspObject.getDurabilityOfWrites();
        String query = String.format(
                        "CREATE KEYSPACE IF NOT EXISTS %s WITH replication = { %s } %s;",
                        keyspaceName, jsonMaptoSqlString(replicationInfo, ","), durability);
        LOG.info(EELFLoggerDelegate.applicationLogger,query);
        executeCreateQuery(query, consistency);
        return true;
    }

    public boolean dropKeyspace(String keyspaceName, JsonKeySpace kspObject) throws Exception {
        String consistency = extractConsistencyInfo(keyspaceName, kspObject.getConsistencyInfo());
        String query = String.format("DROP KEYSPACE %s;", keyspaceName);
        LOG.info(EELFLoggerDelegate.applicationLogger,query);
        executeCreateQuery(query, consistency);
        return false;
    }

    public boolean createTable(String tablename, Map<String, String> cols) throws Exception {
        JsonTable tableObj = new JsonTable();
        Map<String, String> map = new HashMap<String, String>(); // This should be in the
                                                                 // consutructor!
        map.put("type", "eventual");
        tableObj.setConsistencyInfo(map);
        return createTable(tablename, cols, tableObj);
    }

    public boolean createTable(String tablename, Map<String, String> cols, JsonTable tableObj)
                    throws Exception {
        // Note: https://docs.datastax.com/en/cql/3.0/cql/cql_reference/create_table_r.html

        // first read the information about the table fields
        StringBuilder fields = new StringBuilder();
        String prefix = "";
        for (String key : cols.keySet()) {
            fields.append(prefix).append(key).append(" ").append(cols.get(key));
            prefix = ", ";
        }

        String query = String.format("CREATE TABLE IF NOT EXISTS %s (%s);", tablename,
                        fields.toString());
        
        LOG.debug(query);
        String consistency = extractConsistencyInfo(tablename, tableObj.getConsistencyInfo());
        executeCreateQuery(query, consistency);
        return false;
    }

    public boolean dropTable(String name) {
        // TODO
        return false;
    }

    public boolean insertRow(String name, Map<String, Object> valuesMap) throws Exception {
        Map<String, String> consistencyInfo = Collections.singletonMap("type", "eventual");
        return insertRow(name, valuesMap, consistencyInfo, new JsonInsert());
    }

    public boolean insertRow(String tablename, Map<String, Object> valuesMap,
                    Map<String, String> consistencyInfo, JsonInsert insObj) throws Exception {
        // Note: https://docs.datastax.com/en/cql/3.0/cql/cql_reference/insert_r.html
        String[] parts = tablename.split("\\.");
        KeyspaceMetadata ks = cluster.getMetadata().getKeyspace(parts[0]);
        TableMetadata tableInfo = ks.getTable(parts[1]);

        StringBuilder fields = new StringBuilder();
        StringBuilder values = new StringBuilder();
        String prefix = "";
        for (String key : valuesMap.keySet()) {
            fields.append(prefix).append(key);
            Object valueObj = valuesMap.get(key);
            DataType colType = tableInfo.getColumn(key).getType();
            values.append(prefix).append(convertToSqlDataType(colType, valueObj));
            prefix = ", ";
        }

        String suffix = getTTLSuffix(insObj);
        String query = String.format("INSERT INTO %s (%s) VALUES (%s)%s;", tablename,
                        fields.toString(), values.toString(), suffix);
        LOG.info(EELFLoggerDelegate.applicationLogger,query);

        String consistency = extractConsistencyInfo(tablename, consistencyInfo);
        executeCreateQuery(query, consistency);
        return false;
    }

    public boolean lockRow(String name, Map<String, String> cols) {
        // TODO
        return false;
    }

    /**
     * Select ALL rows in the table.
     * 
     * @param tablename the name of the table
     * @return a list of maps, one map per row
     */
    public List<Map<String, Object>> selectRows(final String tablename) {
        return selectRows(tablename, new HashMap<String, String>());
    }

    public List<Map<String, Object>> selectRows(final String tablename, Map<String, String> cols) {
        String ns = "";
        String tbl = tablename;
        int ix = tbl.indexOf('.');
        if (ix >= 0) {
            ns = tablename.substring(0, ix);
            tbl = tablename.substring(ix + 1);
        }
        Select sel = QueryBuilder.select().all().from(ns, tbl);
        Statement stmt = sel;
        if (cols.size() == 1) {
            // only handles 1 WHERE value right now
            String k = cols.keySet().iterator().next();
            Clause eqclause = QueryBuilder.eq(k, cols.get(k));
            stmt = sel.where(eqclause);
        }
        ResultSet resultset = session.execute(stmt);
        List<Map<String, Object>> results = new ArrayList<Map<String, Object>>();
        for (Row row : resultset) {
            Map<String, Object> map = new HashMap<String, Object>();
            for (Definition definition : row.getColumnDefinitions()) {
                map.put(definition.getName(),
                                readRow(row, definition.getName(), definition.getType()));
            }
            results.add(map);
        }
        return results;
    }

    private Object readRow(final Row row, final String name, final DataType colType) {
        switch (colType.getName()) {
            case BIGINT:
                return row.getLong(name);
            case BOOLEAN:
                return row.getBool(name);
            case DOUBLE:
                return row.getDouble(name);
            case FLOAT:
                return row.getFloat(name);
            case INT:
                return row.getInt(name);
            case MAP:
                return row.getMap(name, String.class, String.class);
            case UUID:
                return row.getUUID(name);
            case TEXT:
            case VARCHAR:
                return row.getString(name);
            case VARINT:
                return row.getVarint(name);
            // These are not supported right now....
            // ASCII
            // BLOB
            // COUNTER
            // CUSTOM
            // DECIMAL
            // INET
            // LIST
            // SET
            // TIMESTAMP
            // TIMEUUID
            // TUPLE
            // UDT
            default:
                return null;
        }
    }

    @Deprecated
    public List<Map<String, String>> OLDselectRows(String tablename, Map<String, String> cols) {
        String query = String.format("SELECT * FROM %s", tablename);
        if (cols.size() > 0) {
            // add WHERE clause
            // String[] parts = tablename.split("\\.");
            // KeyspaceMetadata ks = cluster.getMetadata().getKeyspace(parts[0]);
            // TableMetadata tableInfo = ks.getTable(parts[1]);
            String whereclause = " WHERE";
            String prefix = "";
            for (String key : cols.keySet()) {
                String val = cols.get(key);
                // DataType colType = tableInfo.getColumn(key).getType();
                whereclause = String.format("%s%s %s = '%s'", whereclause, prefix, key, val);
                prefix = " AND";
            }
            query += whereclause;
        }
        LOG.debug(query);
        ResultSet resultset = session.execute(query);
        List<Map<String, String>> results = new ArrayList<Map<String, String>>();
        for (Row row : resultset) {
            ColumnDefinitions colInfo = row.getColumnDefinitions();
            Map<String, String> map = new HashMap<String, String>();
            for (Definition definition : colInfo) {
                // map.put(definition.getName(), (String)MusicDataStore.readRow(row,
                // definition.getName(), definition.getType()));
            }
            results.add(map);
        }
        return results;
    }

    public void updateRows(String tablename, Map<String, String> cols, Map<String, Object> vals)
                    throws Exception {
        Map<String, String> consistencyInfo = Collections.singletonMap("type", "eventual");
        updateRows(tablename, cols, vals, consistencyInfo, new JsonInsert());
    }

    public void updateRows(String tablename, Map<String, String> cols, Map<String, Object> vals,
                    Map<String, String> consistencyInfo, JsonInsert insObj) throws Exception {
        // https://docs.datastax.com/en/cql/3.0/cql/cql_reference/update_r.html

        // obtain the field value pairs of the update
        String[] parts = tablename.split("\\.");
        KeyspaceMetadata ks = cluster.getMetadata().getKeyspace(parts[0]);
        TableMetadata tableInfo = ks.getTable(parts[1]);

        StringBuilder fields = new StringBuilder();
        String prefix = "";
        for (String key : vals.keySet()) {
            Object valueObj = vals.get(key);
            String valueString = convertToSqlDataType(tableInfo.getColumn(key).getType(), valueObj);
            fields.append(prefix).append(key).append(" = ").append(valueString);
            prefix = ", ";
        }

        // get the row specifier
        StringBuilder rows = new StringBuilder();
        String primaryKey = "";
        prefix = "";
        for (String key : cols.keySet()) {
            String indValue = cols.get(key);
            DataType colType = tableInfo.getColumn(key).getType();
            String formattedValue = convertToSqlDataType(colType, indValue);
            primaryKey = primaryKey + indValue;
            rows.append(prefix).append(key).append(" = ").append(formattedValue);
            prefix = " AND ";
        }

        String using = getTTLSuffix(insObj);
        String query = String.format("UPDATE %s%s SET %s WHERE %s;", tablename, using,
                        fields.toString(), rows.toString());
        LOG.debug(query);

        String consistency = extractConsistencyInfo(tablename, consistencyInfo);
        executeCreateQuery(query, consistency);
    }

    public void deleteRows(String tablename, Map<String, String> cols) {
        String ns = "";
        String tbl = tablename;
        int ix = tbl.indexOf('.');
        if (ix >= 0) {
            ns = tablename.substring(0, ix);
            tbl = tablename.substring(ix + 1);
        }
        Delete stmt = QueryBuilder.delete().from(ns, tbl);
        if (cols.size() == 1) {
            // only handles 1 WHERE value right now
            String k = cols.keySet().iterator().next();
            Clause eqclause = QueryBuilder.eq(k, cols.get(k));
            session.execute(stmt.where(eqclause));
        } else {
            session.execute(stmt);
        }
    }

    private String getTTLSuffix(JsonInsert insObj) {
        String ttl = insObj.getTtl();
        String timestamp = insObj.getTimestamp();
        if (ttl != null && ttl.length() > 0) {
            if (timestamp != null && timestamp.length() > 0) {
                return " USING TTL " + ttl + " AND TIMESTAMP " + timestamp;
            } else {
                return " USING TTL " + ttl;
            }
        } else if (timestamp != null && timestamp.length() > 0) {
            return " USING TIMESTAMP " + timestamp;
        }
        return "";
    }

    private MusicLockingService getLockingService() {
        if (mls == null) {
            mls = new MusicLockingService(music_hosts[0]);
        }
        return mls;
    }

    private String extractConsistencyInfo(String key, Map<String, String> consistencyInfo)
                    throws Exception {
        String consistency = "";
        if (consistencyInfo.get("type").equalsIgnoreCase("atomic")) {
            String lockId = consistencyInfo.get("lockId");
            String lockName = lockId.substring(lockId.indexOf("$") + 1);
            lockName = lockName.substring(0, lockName.indexOf("$"));

            // first ensure that the lock name is correct before seeing if it has access
            if (!lockName.equalsIgnoreCase(key))
                throw new Exception("THIS LOCK IS NOT FOR THE KEY: " + key);

            String lockStatus = getLockingService().isMyTurn(lockId) + "";
            if (lockStatus.equalsIgnoreCase("false"))
                throw new Exception("YOU DO NOT HAVE THE LOCK");
            return "atomic";
        }
        if (consistencyInfo.get("type").equalsIgnoreCase("eventual"))
            return "eventual";
        throw new Exception("Consistency type " + consistency + " unknown!!");
    }

    // utility function to parse json map into sql like string
    private String jsonMaptoSqlString(Map<String, Object> jMap, String lineDelimiter) {
        String sql = "";
        String prefix = "";
        for (Map.Entry<String, Object> entry : jMap.entrySet()) {
            Object ot = entry.getValue();
            String value = ot + "";
            if (ot instanceof String) {
                value = "'" + value + "'";
            }
            sql = String.format("%s%s'%s': %s", sql, prefix, entry.getKey(), value);
            prefix = lineDelimiter;
        }
        return sql;
    }

    private String convertToSqlDataType(DataType type, Object valueObj) {
        switch (type.getName()) {
            case TEXT:
                String t = valueObj.toString();
                t = t.replaceAll("'", "''");
                return "'" + t + "'";
            case MAP:
                @SuppressWarnings("unchecked")
                Map<String, Object> otMap = (Map<String, Object>) valueObj;
                return "{" + jsonMaptoSqlString(otMap, ",") + "}";
            default:
            case UUID:
                return valueObj.toString();
        }
    }

    private void executeCreateQuery(String query, String consistency) throws Exception {
        Statement statement = new SimpleStatement(query);
        if (consistency.equalsIgnoreCase("atomic"))
            statement.setConsistencyLevel(ConsistencyLevel.ALL);
        else if (consistency.equalsIgnoreCase("eventual"))
            statement.setConsistencyLevel(ConsistencyLevel.ONE);
        else
            throw new Exception("Consistency level " + consistency + " unknown!!");
        session.execute(statement);
    }
}