/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 2000-2016. All Rights Reserved.
 *
 * 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.
 *
 * %CopyrightEnd%
 */
package com.ericsson.otp.erlang;

import java.io.IOException;

/**
 * <p>
 * Maintains a connection between a Java process and a remote Erlang, Java or C
 * node. The object maintains connection state and allows data to be sent to and
 * received from the peer.
 * </p>
 *
 * <p>
 * Once a connection is established between the local node and a remote node,
 * the connection object can be used to send and receive messages between the
 * nodes.
 * </p>
 *
 * <p>
 * The various receive methods are all blocking and will return only when a
 * valid message has been received or an exception is raised.
 * </p>
 *
 * <p>
 * If an exception occurs in any of the methods in this class, the connection
 * will be closed and must be reopened in order to resume communication with the
 * peer.
 * </p>
 *
 * <p>
 * The message delivery methods in this class deliver directly to
 * {@link OtpMbox mailboxes} in the {@link OtpNode OtpNode} class.
 * </p>
 *
 * <p>
 * It is not possible to create an instance of this class directly.
 * OtpCookedConnection objects are created as needed by the underlying mailbox
 * mechanism.
 * </p>
 */
public class OtpCookedConnection extends AbstractConnection {
    protected OtpNode self;

    /*
     * The connection needs to know which local pids have links that pass
     * through here, so that they can be notified in case of connection failure
     */
    protected Links links = null;

    /*
     * Accept an incoming connection from a remote node. Used by {@link
     * OtpSelf#accept() OtpSelf.accept()} to create a connection based on data
     * received when handshaking with the peer node, when the remote node is the
     * connection intitiator.
     *
     * @exception java.io.IOException if it was not possible to connect to the
     * peer.
     *
     * @exception OtpAuthException if handshake resulted in an authentication
     * error
     */
    // package scope
    OtpCookedConnection(final OtpNode self, final OtpTransport s)
            throws IOException, OtpAuthException {
        super(self, s);
        this.self = self;
        links = new Links(25);
        start();
    }

    /*
     * Intiate and open a connection to a remote node.
     *
     * @exception java.io.IOException if it was not possible to connect to the
     * peer.
     *
     * @exception OtpAuthException if handshake resulted in an authentication
     * error.
     */
    // package scope
    OtpCookedConnection(final OtpNode self, final OtpPeer other)
            throws IOException, OtpAuthException {
        super(self, other);
        this.self = self;
        links = new Links(25);
        start();
    }

    // pass the error to the node
    @Override
    public void deliver(final Exception e) {
        self.deliverError(this, e);
        return;
    }

    /*
     * pass the message to the node for final delivery. Note that the connection
     * itself needs to know about links (in case of connection failure), so we
     * snoop for link/unlink too here.
     */
    @Override
    public void deliver(final OtpMsg msg) {
        final boolean delivered = self.deliver(msg);

        switch (msg.type()) {
        case OtpMsg.linkTag:
            if (delivered) {
                links.addLink(msg.getRecipientPid(), msg.getSenderPid());
            } else {
                try {
                    // no such pid - send exit to sender
                    super.sendExit(msg.getRecipientPid(), msg.getSenderPid(),
                            new OtpErlangAtom("noproc"));
                } catch (final IOException e) {
                }
            }
            break;

        case OtpMsg.unlinkTag:
        case OtpMsg.exitTag:
            links.removeLink(msg.getRecipientPid(), msg.getSenderPid());
            break;

        case OtpMsg.exit2Tag:
            break;
        }

        return;
    }

    /*
     * send to pid
     */
    @SuppressWarnings("resource")
    void send(final OtpErlangPid from, final OtpErlangPid dest,
            final OtpErlangObject msg) throws IOException {
        // encode and send the message
        sendBuf(from, dest, new OtpOutputStream(msg));
    }

    /*
     * send to remote name dest is recipient's registered name, the nodename is
     * implied by the choice of connection.
     */
    @SuppressWarnings("resource")
    void send(final OtpErlangPid from, final String dest,
            final OtpErlangObject msg) throws IOException {
        // encode and send the message
        sendBuf(from, dest, new OtpOutputStream(msg));
    }

    @Override
    public void close() {
        super.close();
        breakLinks();
    }

    @Override
    protected void finalize() {
        close();
    }

    /*
     * this one called by dying/killed process
     */
    void exit(final OtpErlangPid from, final OtpErlangPid to,
            final OtpErlangObject reason) {
        try {
            super.sendExit(from, to, reason);
        } catch (final Exception e) {
        }
    }

    /*
     * this one called explicitely by user code => use exit2
     */
    void exit2(final OtpErlangPid from, final OtpErlangPid to,
            final OtpErlangObject reason) {
        try {
            super.sendExit2(from, to, reason);
        } catch (final Exception e) {
        }
    }

    /*
     * snoop for outgoing links and update own table
     */
    synchronized void link(final OtpErlangPid from, final OtpErlangPid to)
            throws OtpErlangExit {
        try {
            super.sendLink(from, to);
            links.addLink(from, to);
        } catch (final IOException e) {
            throw new OtpErlangExit("noproc", to);
        }
    }

    /*
     * snoop for outgoing unlinks and update own table
     */
    synchronized void unlink(final OtpErlangPid from, final OtpErlangPid to) {
        links.removeLink(from, to);
        try {
            super.sendUnlink(from, to);
        } catch (final IOException e) {
        }
    }

    /*
     * When the connection fails - send exit to all local pids with links
     * through this connection
     */
    synchronized void breakLinks() {
        if (links != null) {
            final Link[] l = links.clearLinks();

            if (l != null) {
                final int len = l.length;

                for (int i = 0; i < len; i++) {
                    // send exit "from" remote pids to local ones
                    self.deliver(new OtpMsg(OtpMsg.exitTag, l[i].remote(), l[i]
                            .local(), new OtpErlangAtom("noconnection")));
                }
            }
        }
    }
}