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/*
 * Firebird Open Source JDBC Driver
 *
 * Distributable under LGPL license.
 * You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * LGPL License for more details.
 *
 * This file was created by members of the firebird development team.
 * All individual contributions remain the Copyright (C) of those
 * individuals.  Contributors to this file are either listed here or
 * can be obtained from a source control history command.
 *
 * All rights reserved.
 */
package org.firebirdsql.gds.ng.wire;

import org.firebirdsql.gds.ISCConstants;
import org.firebirdsql.gds.impl.wire.WireProtocolConstants;
import org.firebirdsql.gds.impl.wire.XdrInputStream;
import org.firebirdsql.gds.impl.wire.XdrOutputStream;
import org.firebirdsql.gds.ng.AbstractFbStatement;
import org.firebirdsql.gds.ng.DeferredResponse;
import org.firebirdsql.gds.ng.FbDatabase;
import org.firebirdsql.gds.ng.FbStatement;
import org.firebirdsql.gds.ng.FbTransaction;
import org.firebirdsql.gds.ng.LockCloseable;
import org.firebirdsql.gds.ng.StatementState;
import org.firebirdsql.gds.ng.fields.BlrCalculator;
import org.firebirdsql.gds.ng.fields.RowDescriptor;
import org.firebirdsql.gds.ng.fields.RowValue;
import org.firebirdsql.gds.ng.listeners.DatabaseListener;
import org.firebirdsql.gds.ng.listeners.StatementListener;
import org.firebirdsql.jaybird.util.Cleaners;

import java.io.IOException;
import java.lang.ref.Cleaner;
import java.sql.SQLException;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.function.Function;

import static java.util.Objects.requireNonNull;

/**
 * @author Mark Rotteveel
 * @since 3.0
 */
public abstract class AbstractFbWireStatement extends AbstractFbStatement implements FbWireStatement {

    private final Map blrCache = new WeakHashMap<>();
    private volatile int handle = WireProtocolConstants.INVALID_OBJECT;
    private final FbWireDatabase database;
    private Cleaner.Cleanable cleanable = Cleaners.getNoOp();

    protected AbstractFbWireStatement(FbWireDatabase database) {
        this.database = requireNonNull(database, "database");
    }

    @Override
    public final LockCloseable withLock() {
        return database.withLock();
    }

    /**
     * Gets the XdrInputStream.
     *
     * @return Instance of XdrInputStream
     * @throws SQLException
     *         If no connection is opened or when exceptions occur
     *         retrieving the InputStream
     */
    protected final XdrInputStream getXdrIn() throws SQLException {
        return getXdrStreamAccess().getXdrIn();
    }

    /**
     * Gets the XdrOutputStream.
     *
     * @return Instance of XdrOutputStream
     * @throws SQLException
     *         If no connection is opened or when exceptions occur
     *         retrieving the OutputStream
     */
    protected final XdrOutputStream getXdrOut() throws SQLException {
        return getXdrStreamAccess().getXdrOut();
    }

    private XdrStreamAccess getXdrStreamAccess() throws SQLException {
        if (database != null) {
            return database.getXdrStreamAccess();
        } else {
            throw new SQLException("Connection closed or no connection available");
        }
    }

    @Override
    public final FbWireDatabase getDatabase() {
        return database;
    }

    @Override
    public final int getHandle() {
        return handle;
    }

    protected final void setHandle(int handle) {
        this.handle = handle;
        cleanable = Cleaners.getJbCleaner().register(this, new CleanupAction(this));
    }

    /**
     * Returns the (possibly cached) blr byte array for a {@link RowDescriptor}, or {@code null} if the parameter is null.
     *
     * @param rowDescriptor
     *         The row descriptor.
     * @return blr byte array or {@code null} when {@code rowDescriptor} is {@code null}
     * @throws SQLException
     *         When the {@link RowDescriptor} contains an unsupported field type.
     */
    @SuppressWarnings("java:S1168")
    protected final byte[] calculateBlr(RowDescriptor rowDescriptor) throws SQLException {
        if (rowDescriptor == null) return null;
        byte[] blr = blrCache.get(rowDescriptor);
        if (blr == null) {
            blr = getBlrCalculator().calculateBlr(rowDescriptor);
            blrCache.put(rowDescriptor, blr);
        }
        return blr;
    }

    /**
     * Returns the blr byte array for a {@link RowValue}, or {@code null} if the parameter is null.
     * 
     * Contrary to {@link #calculateBlr(org.firebirdsql.gds.ng.fields.RowDescriptor)}, it is not allowed
     * to cache this value as it depends on the actual row value.
     * 
     *
     * @param rowValue
     *         The row value.
     * @return blr byte array or {@code null} when {@code rowValue} is {@code null}
     * @throws SQLException
     *         When the {@link RowValue} contains an unsupported field type.
     */
    @SuppressWarnings("java:S1168")
    protected final byte[] calculateBlr(RowDescriptor rowDescriptor, RowValue rowValue) throws SQLException {
        if (rowDescriptor == null || rowValue == null) return null;
        return getBlrCalculator().calculateBlr(rowDescriptor, rowValue);
    }

    /**
     * @return The {@link BlrCalculator} instance for this statement (currently always the one from
     * the {@link FbWireDatabase} instance).
     */
    protected final BlrCalculator getBlrCalculator() {
        return getDatabase().getBlrCalculator();
    }

    @Override
    public final void close() throws SQLException {
        try {
            super.close();
        } finally {
            // TODO Preferably this should be done elsewhere and AbstractFbStatement.close() should be final
            cleanable.clean();
            try (LockCloseable ignored = withLock()) {
                blrCache.clear();
            }
        }
    }

    @Override
    protected boolean isValidTransactionClass(Class transactionClass) {
        return FbWireTransaction.class.isAssignableFrom(transactionClass);
    }

    @Override
    public final RowDescriptor emptyRowDescriptor() {
        return database.emptyRowDescriptor();
    }

    @Override
    public byte[] getSqlInfo(byte[] requestItems, int bufferLength) throws SQLException {
        try {
            checkStatementValid();
            return getInfo(WireProtocolConstants.op_info_sql, requestItems, bufferLength);
        } catch (SQLException e) {
            exceptionListenerDispatcher.errorOccurred(e);
            throw e;
        }
    }

    protected byte[] getInfo(int operation, byte[] requestItems, int bufferLength) throws SQLException {
        return getDatabase().getInfo(operation, getHandle(), requestItems, bufferLength, getStatementWarningCallback());
    }

    /**
     * Wraps a deferred response to produce a deferred action that can be added
     * using {@link FbWireDatabase#enqueueDeferredAction(DeferredAction)}, notifying the exception listener of this
     * statement for exceptions, and forcing the ERROR state for IO errors.
     *
     * @param deferredResponse
     *         deferred response to wrap
     * @param responseMapper
     *         Function to map a {@link Response} to the response object expected by the deferred response
     * @param requiresSync
     *         {@code true} if the deferred response requires a sync action or flush before it can be processed
     * @param 
     *         type of deferred response
     * @return deferred action
     */
    protected final  DeferredAction wrapDeferredResponse(DeferredResponse deferredResponse,
            Function responseMapper, boolean requiresSync) {
        return DeferredAction.wrapDeferredResponse(deferredResponse, responseMapper, getStatementWarningCallback(),
                this::deferredExceptionHandler, requiresSync);
    }

    /**
     * Handler for exceptions to a deferred response.
     * 
     * If the exception is a {@code SQLException}, the exception listener dispatcher is notified. If the exception
     * or its cause is an {@code IOException}, the statement state is forced to {@code ERROR}.
     * 
     *
     * @param exception exception received in a deferred response, or thrown while receiving the deferred response
     */
    private void deferredExceptionHandler(Exception exception) {
        if (exception instanceof SQLException sqle) {
            exceptionListenerDispatcher.errorOccurred(sqle);
        }
        if (exception instanceof IOException || exception.getCause() instanceof IOException) {
            forceState(StatementState.ERROR);
        }
    }

    private static final class CleanupAction implements Runnable, StatementListener, DatabaseListener {

        private final int handle;
        @SuppressWarnings("java:S3077")
        private volatile FbWireDatabase database;

        private CleanupAction(AbstractFbWireStatement statement) {
            // NOTE: Care should be taken not to retain a handle to statement itself here
            handle = statement.getHandle();
            database = statement.getDatabase();
            database.addWeakDatabaseListener(this);
            statement.addWeakStatementListener(this);
        }

        @Override
        public void statementStateChanged(FbStatement sender, StatementState newState, StatementState previousState) {
            if (newState == StatementState.CLOSING) {
                FbDatabase database = this.database;
                if (database != null) {
                    release(database);
                }
                sender.removeStatementListener(this);
            }
        }

        @Override
        public void detaching(FbDatabase database) {
            release(database);
        }

        private void release(FbDatabase database) {
            this.database = null;
            database.removeDatabaseListener(this);
        }

        @Override
        public void run() {
            FbWireDatabase database = this.database;
            if (database == null) return;
            release(database);
            try (LockCloseable ignored = database.withLock()) {
                if (!database.isAttached()) return;
                XdrOutputStream xdrOut = database.getXdrStreamAccess().getXdrOut();
                xdrOut.writeInt(WireProtocolConstants.op_free_statement);
                xdrOut.writeInt(handle);
                xdrOut.writeInt(ISCConstants.DSQL_drop);
                xdrOut.flush();
                database.enqueueDeferredAction(DeferredAction.NO_OP_INSTANCE);
            } catch (SQLException | IOException e) {
                System.getLogger(getClass().getName()).log(System.Logger.Level.TRACE,
                        "Ignored exception during statement clean up", e);
            }
        }
    }

}