/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2024-2025 3A Systems, LLC.
 */
package org.opends.server.backends.jdbc;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.i18n.slf4j.LocalizedLogger;
import org.forgerock.opendj.config.server.ConfigChangeResult;
import org.forgerock.opendj.config.server.ConfigException;
import org.forgerock.opendj.config.server.ConfigurationChangeListener;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.server.config.server.JDBCBackendCfg;
import org.opends.server.backends.pluggable.spi.*;
import org.opends.server.core.ServerContext;
import org.opends.server.types.BackupConfig;
import org.opends.server.types.BackupDirectory;
import org.opends.server.types.DirectoryException;
import org.opends.server.types.RestoreConfig;
import org.opends.server.util.BackupManager;

import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.sql.*;
import java.util.*;
import java.util.concurrent.ExecutionException;

import static org.opends.server.backends.pluggable.spi.StorageUtils.addErrorMessage;
import static org.opends.server.util.StaticUtils.stackTraceToSingleLineString;

public class Storage implements org.opends.server.backends.pluggable.spi.Storage, ConfigurationChangeListener<JDBCBackendCfg>{
	
	private static final LocalizedLogger logger = LocalizedLogger.getLoggerForThisClass();

    private JDBCBackendCfg config;
	  
	public Storage(JDBCBackendCfg cfg, ServerContext serverContext) {
        this.config = cfg;
	    cfg.addJDBCChangeListener(this);
	}

	//config
	@Override
	public boolean isConfigurationChangeAcceptable(JDBCBackendCfg configuration,List<LocalizableMessage> unacceptableReasons) {
		return true;
	}

	@Override
	public ConfigChangeResult applyConfigurationChange(JDBCBackendCfg cfg) {
		final ConfigChangeResult ccr = new ConfigChangeResult();
	    try
	    {
	    	this.config = cfg;
	    }
	    catch (Exception e)
	    {
	      addErrorMessage(ccr, LocalizableMessage.raw(stackTraceToSingleLineString(e)));
	    }
	    return ccr;
	}

	ResultSet executeResultSet(PreparedStatement statement) throws SQLException {
		if (logger.isTraceEnabled()) {
			logger.trace(LocalizableMessage.raw("jdbc: %s",statement));
		}
		return statement.executeQuery();
	}

	int execute(PreparedStatement statement) throws SQLException {
		if (logger.isTraceEnabled()) {
			logger.trace(LocalizableMessage.raw("jdbc: %s",statement));
		}
		return statement.executeUpdate();
	}

    Connection getConnection() throws Exception {
		return CachedConnection.getConnection(config.getDBDirectory());
	}


	AccessMode accessMode=AccessMode.READ_ONLY;
	@Override
	public void open(AccessMode accessMode) throws Exception {
		try (final Connection con=getConnection()) {
			this.accessMode = accessMode;
			storageStatus = StorageStatus.working();
		}
	}

	private StorageStatus storageStatus = StorageStatus.lockedDown(LocalizableMessage.raw("closed"));
	@Override
	public StorageStatus getStorageStatus() {
		return storageStatus;
	}
	
	@Override
	public void close() {
		storageStatus = StorageStatus.lockedDown(LocalizableMessage.raw("closed"));
	}

	final LoadingCache<TreeName,String> tree2table= CacheBuilder.newBuilder()
			.build(new CacheLoader<TreeName, String>() {
				@Override
				public String load(TreeName treeName) throws Exception {
					final MessageDigest md = MessageDigest.getInstance("SHA-224");
					final byte[] messageDigest = md.digest(treeName.toString().getBytes());
					final StringBuilder hashtext = new StringBuilder(56);
					for (byte b : messageDigest) {
						String hex = Integer.toHexString(0xff & b);
						if (hex.length() == 1) hashtext.append('0');
						hashtext.append(hex);
					}
					return "opendj_"+hashtext;
				}
			});

	String getTableName(TreeName treeName) {
        try {
            return tree2table.get(treeName);
        } catch (ExecutionException e) {
            throw new RuntimeException(e);
        }
    }

	@Override
	public void removeStorageFiles() throws StorageRuntimeException {
		final boolean isOpen=getStorageStatus().isWorking();
		if (!isOpen) {
			try {
				open(AccessMode.READ_WRITE);
			}catch (Exception e) {
				throw new StorageRuntimeException(e);
			}
		}
		final Set<TreeName> trees=listTrees();
		if (!trees.isEmpty()) {
			try (final Connection con = getConnection()) {
				try {
					for (final TreeName treeName : trees) {
						try (final PreparedStatement statement = con.prepareStatement("drop table " + getTableName(treeName))) {
							execute(statement);
						}
					}
					con.commit();
				} catch (SQLException e) {
					try {
						con.rollback();
					} catch (SQLException e2) {}
					throw new StorageRuntimeException(e);
				}
			} catch (Exception e) {
				throw new StorageRuntimeException(e);
			}
		}
		if (!isOpen) {
			close();
		}
	}
	
	//operation
	@Override
	public <T> T read(ReadOperation<T> readOperation) throws Exception {
		try(final Connection con=getConnection()) {
			return readOperation.run(new ReadableTransactionImpl(con));
		}
	}

	@Override
	public void write(WriteOperation writeOperation) throws Exception {
		try (final Connection con=getConnection()) {
			try {
				writeOperation.run(new WriteableTransactionTransactionImpl(con));
				con.commit();
			} catch (Exception e) {
				try {
					con.rollback();
				} catch (SQLException ex) {}
				throw e;
			}
		}
	}

	final static byte[] NULL=new byte[]{(byte)0};

	static byte[] real2db(byte[] real) {
		return real.length==0?NULL:real;
	}
	static byte[] db2real(byte[] db) {
		return Arrays.equals(NULL,db)?new byte[0]:db;
	}

	final LoadingCache<ByteBuffer,String> key2hash= CacheBuilder.newBuilder()
			.softValues()
			.build(new CacheLoader<ByteBuffer, String>() {
				@Override
				public String load(ByteBuffer key) throws Exception {
					final MessageDigest md = MessageDigest.getInstance("SHA-512");
					final byte[] messageDigest = md.digest(key.array());
					final StringBuilder hashtext = new StringBuilder(128);
					for (byte b : messageDigest) {
						String hex = Integer.toHexString(0xff & b);
						if (hex.length() == 1) hashtext.append('0');
						hashtext.append(hex);
					}
					return hashtext.toString();
				}
			});
	private class ReadableTransactionImpl implements ReadableTransaction {
		final Connection con;
		boolean isReadOnly=true;

		public ReadableTransactionImpl(Connection con) {
			this.con=con;
		}

		@Override
		public ByteString read(TreeName treeName, ByteSequence key) {
			try (final PreparedStatement statement=con.prepareStatement("select v from "+getTableName(treeName)+" where h=? and k=?")){
				statement.setString(1,key2hash.get(ByteBuffer.wrap(key.toByteArray())));
				statement.setBytes(2,real2db(key.toByteArray()));
				try(ResultSet rc=executeResultSet(statement)) {
					return rc.next() ? ByteString.wrap(rc.getBytes("v")) : null;
				}
			}catch (SQLException|ExecutionException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public Cursor<ByteString, ByteString> openCursor(TreeName treeName) {
			return new CursorImpl(isReadOnly,con,treeName);
		}

		@Override
		public long getRecordCount(TreeName treeName) {
			try (final PreparedStatement statement=con.prepareStatement("select count(*) from "+getTableName(treeName));
				 final ResultSet rc=executeResultSet(statement)){
				return rc.next() ? rc.getLong(1) : 0;
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}
	}
	private final class WriteableTransactionTransactionImpl extends ReadableTransactionImpl implements WriteableTransaction {

		public WriteableTransactionTransactionImpl(Connection con) {
			super(con);
			if (!accessMode.isWriteable()) {
				throw new ReadOnlyStorageException();
			}
			isReadOnly = false;
		}

		boolean isExistsTable(TreeName treeName) {
			try (final ResultSet rs = con.getMetaData().getTables(null, null, null, new String[]{"TABLE"})) {
				while (rs.next()) {
					if (tree2table.get(treeName).equalsIgnoreCase(rs.getString("TABLE_NAME"))) {
						return true;
					}
				}
			} catch (Exception e) {
				throw new StorageRuntimeException(e);
			}
			return false;
		}

		String getTableDialect() {
			if (((CachedConnection) con).parent.getClass().getName().contains("oracle")) {
				return "h char(128),k raw(2000),v blob,primary key(h,k)";
			}else if (((CachedConnection) con).parent.getClass().getName().contains("mysql")) {
				return "h char(128),k tinyblob,v longblob,primary key(h(128),k(255))";
			}else if (((CachedConnection) con).parent.getClass().getName().contains("microsoft")) {
				return "h char(128),k varbinary(max),v image,primary key(h)";
			}
			return "h char(128),k bytea,v bytea,primary key(h,k)";
		}

		@Override
		public void openTree(TreeName treeName, boolean createOnDemand) {
			if (createOnDemand && !isExistsTable(treeName)) {
				try (final PreparedStatement statement=con.prepareStatement("create table "+getTableName(treeName)+" ("+getTableDialect()+")")){
					execute(statement);
					con.commit();
				}catch (SQLException e) {
					throw new StorageRuntimeException(e);
				}
			}
		}
		
		public void clearTree(TreeName treeName) {
			try (final PreparedStatement statement=con.prepareStatement("delete from "+getTableName(treeName))){
				execute(statement);
				con.commit();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public void deleteTree(TreeName treeName) {
			if (isExistsTable(treeName)) {
				try (final PreparedStatement statement = con.prepareStatement("drop table " + getTableName(treeName))) {
					execute(statement);
					con.commit();
				} catch (SQLException e) {
					throw new StorageRuntimeException(e);
				}
			}
		}

		@Override
		public void put(TreeName treeName, ByteSequence key, ByteSequence value) {
			try {
				upsert(treeName, key, value);
			} catch (SQLException|ExecutionException e) {
				throw new RuntimeException(e);
			}
		}

		boolean upsert(TreeName treeName, ByteSequence key, ByteSequence value) throws SQLException, ExecutionException {
			final String driverName=((CachedConnection) con).parent.getClass().getName();
			if (driverName.contains("postgres")) { //postgres upsert
				try (final PreparedStatement statement = con.prepareStatement("insert into " + getTableName(treeName) + " (h,k,v) values (?,?,?) ON CONFLICT (h, k) DO UPDATE set v=excluded.v")) {
					statement.setString(1, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
					statement.setBytes(2, real2db(key.toByteArray()));
					statement.setBytes(3, value.toByteArray());
					return (execute(statement) == 1 && statement.getUpdateCount() > 0);
				}
			}else if (driverName.contains("mysql")) { //mysql upsert
				try (final PreparedStatement statement = con.prepareStatement("insert into " + getTableName(treeName) + " (h,k,v) values (?,?,?) as new ON DUPLICATE KEY UPDATE v=new.v")) {
					statement.setString(1, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
					statement.setBytes(2, real2db(key.toByteArray()));
					statement.setBytes(3, value.toByteArray());
					return (execute(statement) == 1 && statement.getUpdateCount() > 0);
				}
			}else if (driverName.contains("oracle")) { //ANSI MERGE without ;
				try (final PreparedStatement statement = con.prepareStatement("merge into " + getTableName(treeName) + " old using (select ? h,? k,? v from dual) new on (old.h=new.h and old.k=new.k) WHEN MATCHED THEN UPDATE SET old.v=new.v WHEN NOT MATCHED THEN INSERT (h,k,v) VALUES (new.h,new.k,new.v)")) {
					statement.setString(1, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
					statement.setBytes(2, real2db(key.toByteArray()));
					statement.setBytes(3, value.toByteArray());
					return (execute(statement) == 1 && statement.getUpdateCount() > 0);
				}
			}else if (driverName.contains("microsoft")) { //ANSI MERGE with ;
				try (final PreparedStatement statement = con.prepareStatement("merge into " + getTableName(treeName) + " old using (select ? h,? k,? v) new on (old.h=new.h and old.k=new.k) WHEN MATCHED THEN UPDATE SET old.v=new.v WHEN NOT MATCHED THEN INSERT (h,k,v) VALUES (new.h,new.k,new.v);")) {
					statement.setString(1, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
					statement.setBytes(2, real2db(key.toByteArray()));
					statement.setBytes(3, value.toByteArray());
					return (execute(statement) == 1 && statement.getUpdateCount() > 0);
				}
			}else { //ANSI SQL: try update before insert with not exists
				return update(treeName,key,value) || insert(treeName,key,value);
			}
		}

		boolean insert(TreeName treeName, ByteSequence key, ByteSequence value) throws SQLException, ExecutionException {
			try (final PreparedStatement statement = con.prepareStatement("insert into " + getTableName(treeName) + " (h,k,v) select ?,?,? where not exists (select 1 from "+getTableName(treeName)+" where  h=? and k=? )")) {
				statement.setString(1, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
				statement.setBytes(2, real2db(key.toByteArray()));
				statement.setBytes(3, value.toByteArray());
				statement.setString(4, key2hash.get(ByteBuffer.wrap(key.toByteArray())));
				statement.setBytes(5, real2db(key.toByteArray()));
				return (execute(statement)==1 && statement.getUpdateCount()>0);
			}
		}

		boolean update(TreeName treeName, ByteSequence key, ByteSequence value) throws SQLException, ExecutionException {
			try (final PreparedStatement statement=con.prepareStatement("update "+getTableName(treeName)+" set v=? where h=? and k=?")){
				statement.setBytes(1,value.toByteArray());
				statement.setString(2,key2hash.get(ByteBuffer.wrap(key.toByteArray())));
				statement.setBytes(3,real2db(key.toByteArray()));
				return (execute(statement)==1 && statement.getUpdateCount()>0);
			}
		}

		@Override
		public boolean update(TreeName treeName, ByteSequence key, UpdateFunction f) {
			final ByteString oldValue=read(treeName,key);
			final ByteSequence newValue=f.computeNewValue(oldValue);
			if (Objects.equals(newValue, oldValue))
	        {
				return false;
	        }
	        if (newValue == null)
	        {
				return delete(treeName, key);
	        }
	        put(treeName,key,newValue);
			return true;
		}

		@Override
		public boolean delete(TreeName treeName, ByteSequence key) {
			try (final PreparedStatement statement=con.prepareStatement("delete from "+getTableName(treeName)+" where h=? and k=?")){
				statement.setString(1,key2hash.get(ByteBuffer.wrap(key.toByteArray())));
				statement.setBytes(2,real2db(key.toByteArray()));
				return (execute(statement)==1 && statement.getUpdateCount()>0);
			}catch (SQLException|ExecutionException e) {
				throw new StorageRuntimeException(e);
			}
		}
	}
	
	private final class CursorImpl implements Cursor<ByteString, ByteString> {
		final TreeName treeName;

		final PreparedStatement statement;
		final ResultSet rc;
		final boolean isReadOnly;
		public CursorImpl(boolean isReadOnly, Connection con, TreeName treeName) {
			this.treeName=treeName;
			this.isReadOnly=isReadOnly;
			try {
				statement=con.prepareStatement("select h,k,v from "+getTableName(treeName)+" order by k",
						isReadOnly?ResultSet.TYPE_SCROLL_INSENSITIVE:ResultSet.TYPE_SCROLL_SENSITIVE,
						isReadOnly?ResultSet.CONCUR_READ_ONLY:ResultSet.CONCUR_UPDATABLE);
				rc=executeResultSet(statement);
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public boolean next() {
			try {
				return rc.next();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public boolean isDefined() {
			try{
				return rc.getRow()>0;
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public ByteString getKey() throws NoSuchElementException {
			if (!isDefined()) {
				throw new NoSuchElementException();
			}
			try{
				return ByteString.wrap(db2real(rc.getBytes("k")));
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public ByteString getValue() throws NoSuchElementException {
			if (!isDefined()) {
				throw new NoSuchElementException();
			}
			try{
				return ByteString.wrap(rc.getBytes("v"));
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public void delete() throws NoSuchElementException, UnsupportedOperationException {
			if (!isDefined()) {
				throw new NoSuchElementException();
			}
			try{
				rc.deleteRow();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public void close() {
			try{
				rc.close();
				statement.close();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}


		@Override
		public boolean positionToKeyOrNext(ByteSequence key) {
			if (!isDefined() || key.compareTo(getKey())<0) { //restart iterator
				try{
					rc.first();
				}catch (SQLException e) {
					throw new StorageRuntimeException(e);
				}
			}
			try{
				if (!isDefined()){
					return false;
				}
				do {
					if (key.compareTo(getKey())<=0) {
						return true;
					}
				}while(rc.next());
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
			return false;
		}
		
		@Override
		public boolean positionToKey(ByteSequence key) {
			if (!isDefined() || key.compareTo(getKey())<0) {  //restart iterator
				try{
					rc.first();
				}catch (SQLException e) {
					throw new StorageRuntimeException(e);
				}
			}
			if (!isDefined()){
				return false;
			}
			if (isDefined() && key.compareTo(getKey())==0) {
				return true;
			}
			try{
				do {
					if (key.compareTo(getKey())==0) {
						return true;
					}
				}while(rc.next());
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
			return false;
		}

		
		@Override
		public boolean positionToLastKey() {
			try{
				return rc.last();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
		}

		@Override
		public boolean positionToIndex(int index) {
			try{
				rc.first();
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
			if (!isDefined()){
				return false;
			}
			int ct=0;
			try{
				do {
					if (ct==index) {
						return true;
					}
					ct++;
				}while(rc.next());
			}catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
			return false;
		}
	}
	
	@Override
	public Set<TreeName> listTrees() {
		return tree2table.asMap().keySet();
	}

	private final class ImporterImpl implements Importer {
		final Connection con;
		final ReadableTransactionImpl txr;
		final WriteableTransactionTransactionImpl txw;

		final Boolean isOpen;
		
		public ImporterImpl() {
			isOpen=getStorageStatus().isWorking();
			if (!isOpen) {
				try {
					open(AccessMode.READ_WRITE);
				}catch (Exception e) {
					throw new StorageRuntimeException(e);
				}
			}
			try {
				con = getConnection();
			}catch (Exception e){
				throw new StorageRuntimeException(e);
			}
			txr =new ReadableTransactionImpl(con);
			txw =new WriteableTransactionTransactionImpl(con);
		}
		
		@Override
		public void close() {
			try {
				con.commit();
				con.close();
			} catch (SQLException e) {
				throw new StorageRuntimeException(e);
			}
			if (!isOpen) {
				Storage.this.close();
			}
		}
		
		@Override
		public void clearTree(TreeName name) {
			txw.clearTree(name);
		}
		
		@Override
		public void put(TreeName treeName, ByteSequence key, ByteSequence value) {
			txw.put(treeName, key, value);
		}
		
		@Override
		public ByteString read(TreeName treeName, ByteSequence key) {
			return txr.read(treeName, key);
		}
		
		@Override
		public SequentialCursor<ByteString, ByteString> openCursor(TreeName treeName) {
			return txr.openCursor(treeName);
		}
	}
	
	//import
	@Override
	public Importer startImport() throws ConfigException, StorageRuntimeException {
		return new ImporterImpl();
	}
	
	//backup
	@Override
	public boolean supportsBackupAndRestore() {
		return true;
	}

	@Override
	public void createBackup(BackupConfig backupConfig) throws DirectoryException
	{
		// TODO backup over snapshot or SQL export
		//new BackupManager(config.getBackendId()).createBackup(this, backupConfig);
	}

	@Override
	public void removeBackup(BackupDirectory backupDirectory, String backupID) throws DirectoryException
	{
		new BackupManager(config.getBackendId()).removeBackup(backupDirectory, backupID);
	}

	@Override
	public void restoreBackup(RestoreConfig restoreConfig) throws DirectoryException
	{
		// TODO restore over snapshot or SQL export
		//new BackupManager(config.getBackendId()).restoreBackup(this, restoreConfig);
	}

}