/*
 * 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.
 */
package com.facebook.presto.jdbc;

import com.facebook.presto.client.ClientSession;
import com.facebook.presto.client.ServerInfo;
import com.facebook.presto.client.StatementClient;
import com.google.common.collect.ImmutableMap;
import io.airlift.units.Duration;

import java.net.URI;
import java.nio.charset.CharsetEncoder;
import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;

import static com.google.common.base.MoreObjects.firstNonNull;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Maps.fromProperties;
import static java.nio.charset.StandardCharsets.US_ASCII;
import static java.util.Objects.requireNonNull;
import static java.util.concurrent.TimeUnit.MINUTES;

public class PrestoConnection
        implements Connection
{
    private final AtomicBoolean closed = new AtomicBoolean();
    private final AtomicReference<String> catalog = new AtomicReference<>();
    private final AtomicReference<String> schema = new AtomicReference<>();
    private final AtomicReference<String> timeZoneId = new AtomicReference<>();
    private final AtomicReference<Locale> locale = new AtomicReference<>();
    private final AtomicReference<ServerInfo> serverInfo = new AtomicReference<>();

    private final URI jdbcUri;
    private final URI httpUri;
    private final String user;
    private final Map<String, String> clientInfo = new ConcurrentHashMap<>();
    private final Map<String, String> sessionProperties = new ConcurrentHashMap<>();
    private final AtomicReference<String> transactionId = new AtomicReference<>();
    private final QueryExecutor queryExecutor;

    PrestoConnection(PrestoDriverUri uri, QueryExecutor queryExecutor)
            throws SQLException
    {
        requireNonNull(uri, "uri is null");
        this.jdbcUri = uri.getJdbcUri();
        this.httpUri = uri.getHttpUri();
        this.schema.set(uri.getSchema());
        this.catalog.set(uri.getCatalog());
        this.user = uri.getUser();

        this.queryExecutor = requireNonNull(queryExecutor, "queryExecutor is null");

        timeZoneId.set(TimeZone.getDefault().getID());
        locale.set(Locale.getDefault());
    }

    @Override
    public Statement createStatement()
            throws SQLException
    {
        checkOpen();
        return new PrestoStatement(this);
    }

    @Override
    public PreparedStatement prepareStatement(String sql)
            throws SQLException
    {
        checkOpen();
        throw new NotImplementedException("Connection", "prepareStatement");
    }

    @Override
    public CallableStatement prepareCall(String sql)
            throws SQLException
    {
        throw new NotImplementedException("Connection", "prepareCall");
    }

    @Override
    public String nativeSQL(String sql)
            throws SQLException
    {
        checkOpen();
        return sql;
    }

    @Override
    public void setAutoCommit(boolean autoCommit)
            throws SQLException
    {
        checkOpen();
        if (!autoCommit) {
            throw new SQLFeatureNotSupportedException("Disabling auto-commit mode not supported");
        }
    }

    @Override
    public boolean getAutoCommit()
            throws SQLException
    {
        checkOpen();
        return true;
    }

    @Override
    public void commit()
            throws SQLException
    {
        checkOpen();
        if (getAutoCommit()) {
            throw new SQLException("Connection is in auto-commit mode");
        }
        throw new NotImplementedException("Connection", "commit");
    }

    @Override
    public void rollback()
            throws SQLException
    {
        checkOpen();
        if (getAutoCommit()) {
            throw new SQLException("Connection is in auto-commit mode");
        }
        throw new NotImplementedException("Connection", "rollback");
    }

    @Override
    public void close()
            throws SQLException
    {
        closed.set(true);
    }

    @Override
    public boolean isClosed()
            throws SQLException
    {
        return closed.get();
    }

    @Override
    public DatabaseMetaData getMetaData()
            throws SQLException
    {
        return new PrestoDatabaseMetaData(this);
    }

    @Override
    public void setReadOnly(boolean readOnly)
            throws SQLException
    {
        checkOpen();
        // TODO: implement this
    }

    @Override
    public boolean isReadOnly()
            throws SQLException
    {
        return false;
    }

    @Override
    public void setCatalog(String catalog)
            throws SQLException
    {
        checkOpen();
        this.catalog.set(catalog);
    }

    @Override
    public String getCatalog()
            throws SQLException
    {
        checkOpen();
        return catalog.get();
    }

    @Override
    public void setTransactionIsolation(int level)
            throws SQLException
    {
        checkOpen();
        throw new SQLFeatureNotSupportedException("Transactions are not yet supported");
    }

    @Override
    public int getTransactionIsolation()
            throws SQLException
    {
        checkOpen();
        return TRANSACTION_NONE;
    }

    @Override
    public SQLWarning getWarnings()
            throws SQLException
    {
        checkOpen();
        return null;
    }

    @Override
    public void clearWarnings()
            throws SQLException
    {
        checkOpen();
    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency)
            throws SQLException
    {
        checkResultSet(resultSetType, resultSetConcurrency);
        return createStatement();
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
            throws SQLException
    {
        checkResultSet(resultSetType, resultSetConcurrency);
        return prepareStatement(sql);
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency)
            throws SQLException
    {
        checkResultSet(resultSetType, resultSetConcurrency);
        throw new SQLFeatureNotSupportedException("prepareCall");
    }

    @Override
    public Map<String, Class<?>> getTypeMap()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("getTypeMap");
    }

    @Override
    public void setTypeMap(Map<String, Class<?>> map)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("setTypeMap");
    }

    @Override
    public void setHoldability(int holdability)
            throws SQLException
    {
        checkOpen();
        if (holdability != ResultSet.HOLD_CURSORS_OVER_COMMIT) {
            throw new SQLFeatureNotSupportedException("Changing holdability not supported");
        }
    }

    @Override
    public int getHoldability()
            throws SQLException
    {
        checkOpen();
        return ResultSet.HOLD_CURSORS_OVER_COMMIT;
    }

    @Override
    public Savepoint setSavepoint()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("setSavepoint");
    }

    @Override
    public Savepoint setSavepoint(String name)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("setSavepoint");
    }

    @Override
    public void rollback(Savepoint savepoint)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("rollback");
    }

    @Override
    public void releaseSavepoint(Savepoint savepoint)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("releaseSavepoint");
    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
            throws SQLException
    {
        checkHoldability(resultSetHoldability);
        return createStatement(resultSetType, resultSetConcurrency);
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
            throws SQLException
    {
        checkHoldability(resultSetHoldability);
        return prepareStatement(sql, resultSetType, resultSetConcurrency);
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
            throws SQLException
    {
        checkHoldability(resultSetHoldability);
        return prepareCall(sql, resultSetType, resultSetConcurrency);
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys)
            throws SQLException
    {
        if (autoGeneratedKeys != Statement.RETURN_GENERATED_KEYS) {
            throw new SQLFeatureNotSupportedException("Auto generated keys must be NO_GENERATED_KEYS");
        }
        return prepareStatement(sql);
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int[] columnIndexes)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("prepareStatement");
    }

    @Override
    public PreparedStatement prepareStatement(String sql, String[] columnNames)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("prepareStatement");
    }

    @Override
    public Clob createClob()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createClob");
    }

    @Override
    public Blob createBlob()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createBlob");
    }

    @Override
    public NClob createNClob()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createNClob");
    }

    @Override
    public SQLXML createSQLXML()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createSQLXML");
    }

    @Override
    public boolean isValid(int timeout)
            throws SQLException
    {
        if (timeout < 0) {
            throw new SQLException("Timeout is negative");
        }
        return !isClosed();
    }

    @Override
    public void setClientInfo(String name, String value)
            throws SQLClientInfoException
    {
        requireNonNull(name, "name is null");
        if (value != null) {
            clientInfo.put(name, value);
        }
        else {
            clientInfo.remove(name);
        }
    }

    @Override
    public void setClientInfo(Properties properties)
            throws SQLClientInfoException
    {
        clientInfo.putAll(fromProperties(properties));
    }

    @Override
    public String getClientInfo(String name)
            throws SQLException
    {
        return clientInfo.get(name);
    }

    @Override
    public Properties getClientInfo()
            throws SQLException
    {
        Properties properties = new Properties();
        for (Map.Entry<String, String> entry : clientInfo.entrySet()) {
            properties.setProperty(entry.getKey(), entry.getValue());
        }
        return properties;
    }

    @Override
    public Array createArrayOf(String typeName, Object[] elements)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createArrayOf");
    }

    @Override
    public Struct createStruct(String typeName, Object[] attributes)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("createStruct");
    }

    @Override
    public void setSchema(String schema)
            throws SQLException
    {
        checkOpen();
        this.schema.set(schema);
    }

    @Override
    public String getSchema()
            throws SQLException
    {
        checkOpen();
        return schema.get();
    }

    public String getTimeZoneId()
    {
        return timeZoneId.get();
    }

    public void setTimeZoneId(String timeZoneId)
    {
        requireNonNull(timeZoneId, "timeZoneId is null");
        this.timeZoneId.set(timeZoneId);
    }

    public Locale getLocale()
    {
        return locale.get();
    }

    public void setLocale(Locale locale)
    {
        this.locale.set(locale);
    }

    /**
     * Adds a session property (experimental).
     */
    public void setSessionProperty(String name, String value)
    {
        requireNonNull(name, "name is null");
        requireNonNull(value, "value is null");
        checkArgument(!name.isEmpty(), "name is empty");

        CharsetEncoder charsetEncoder = US_ASCII.newEncoder();
        checkArgument(name.indexOf('=') < 0, "Session property name must not contain '=': %s", name);
        checkArgument(charsetEncoder.canEncode(name), "Session property name is not US_ASCII: %s", name);
        checkArgument(charsetEncoder.canEncode(value), "Session property value is not US_ASCII: %s", value);

        sessionProperties.put(name, value);
    }

    @Override
    public void abort(Executor executor)
            throws SQLException
    {
        close();
    }

    @Override
    public void setNetworkTimeout(Executor executor, int milliseconds)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("setNetworkTimeout");
    }

    @Override
    public int getNetworkTimeout()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("getNetworkTimeout");
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T unwrap(Class<T> iface)
            throws SQLException
    {
        if (isWrapperFor(iface)) {
            return (T) this;
        }
        throw new SQLException("No wrapper for " + iface);
    }

    @Override
    public boolean isWrapperFor(Class<?> iface)
            throws SQLException
    {
        return iface.isInstance(this);
    }

    URI getURI()
    {
        return jdbcUri;
    }

    String getUser()
    {
        return user;
    }

    ServerInfo getServerInfo()
            throws SQLException
    {
        if (serverInfo.get() == null) {
            try {
                serverInfo.set(queryExecutor.getServerInfo(httpUri));
            }
            catch (RuntimeException e) {
                throw new SQLException("Error fetching version from server", e);
            }
        }
        return serverInfo.get();
    }

    StatementClient startQuery(String sql, Map<String, String> sessionPropertiesOverride)
    {
        String source = firstNonNull(clientInfo.get("ApplicationName"), "presto-jdbc");

        Map<String, String> allProperties = new HashMap<>(sessionProperties);
        allProperties.putAll(sessionPropertiesOverride);

        ClientSession session = new ClientSession(
                httpUri,
                user,
                source,
                clientInfo.get("ClientInfo"),
                catalog.get(),
                schema.get(),
                timeZoneId.get(),
                locale.get(),
                ImmutableMap.copyOf(allProperties),
                transactionId.get(),
                false,
                new Duration(2, MINUTES));

        return queryExecutor.startQuery(session, sql);
    }

    private void checkOpen()
            throws SQLException
    {
        if (isClosed()) {
            throw new SQLException("Connection is closed");
        }
    }

    private static void checkResultSet(int resultSetType, int resultSetConcurrency)
            throws SQLFeatureNotSupportedException
    {
        if (resultSetType != ResultSet.TYPE_FORWARD_ONLY) {
            throw new SQLFeatureNotSupportedException("Result set type must be TYPE_FORWARD_ONLY");
        }
        if (resultSetConcurrency != ResultSet.CONCUR_READ_ONLY) {
            throw new SQLFeatureNotSupportedException("Result set concurrency must be CONCUR_READ_ONLY");
        }
    }

    private static void checkHoldability(int resultSetHoldability)
            throws SQLFeatureNotSupportedException
    {
        if (resultSetHoldability != ResultSet.HOLD_CURSORS_OVER_COMMIT) {
            throw new SQLFeatureNotSupportedException("Result set holdability must be HOLD_CURSORS_OVER_COMMIT");
        }
    }
}
