/*
 * Copyright (c) Citrix Systems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   1) Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2) Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.xensource.xenapi;

import com.xensource.xenapi.Types.BadServerResponse;
import com.xensource.xenapi.Types.VersionException;
import com.xensource.xenapi.Types.XenAPIException;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Date;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.apache.xmlrpc.XmlRpcException;

/**
 * Asynchronous event registration and handling
 *
 * @author Citrix Systems, Inc.
 */
public class Event extends XenAPIObject {

    /**
     * The XenAPI reference (OpaqueRef) to this object.
     */
    protected final String ref;

    /**
     * For internal use only.
     */
    Event(String ref) {
        this.ref = ref;
    }

    /**
     * @return The XenAPI reference (OpaqueRef) to this object.
     */
    public String toWireString() {
        return this.ref;
    }

    /**
     * If obj is a Event, compares XenAPI references for equality.
     */
    @Override
    public boolean equals(Object obj)
    {
        if (obj != null && obj instanceof Event)
        {
            Event other = (Event)obj;
            return other.ref.equals(this.ref);
        } else
        {
            return false;
        }
    }

    @Override
    public int hashCode()
    {
        return ref.hashCode();
    }

    /**
     * Represents all the fields in a Event
     */
    public static class Record implements Types.Record {
        public String toString() {
            StringWriter writer = new StringWriter();
            PrintWriter print = new PrintWriter(writer);
            print.printf("%1$20s: %2$s\n", "id", this.id);
            print.printf("%1$20s: %2$s\n", "timestamp", this.timestamp);
            print.printf("%1$20s: %2$s\n", "clazz", this.clazz);
            print.printf("%1$20s: %2$s\n", "operation", this.operation);
            print.printf("%1$20s: %2$s\n", "ref", this.ref);
            print.printf("%1$20s: %2$s\n", "objUuid", this.objUuid);
            print.printf("%1$20s: %2$s\n", "snapshot", this.snapshot);
            return writer.toString();
        }

        /**
         * Convert a event.Record to a Map
         */
        public Map<String, Object> toMap() {
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("id", this.id == null ? 0 : this.id);
            map.put("timestamp", this.timestamp == null ? new Date(0) : this.timestamp);
            map.put("class", this.clazz == null ? "" : this.clazz);
            map.put("operation", this.operation == null ? Types.EventOperation.UNRECOGNIZED : this.operation);
            map.put("ref", this.ref == null ? "" : this.ref);
            map.put("obj_uuid", this.objUuid == null ? "" : this.objUuid);
            map.put("snapshot", this.snapshot);
            return map;
        }

        /**
         * An ID, monotonically increasing, and local to the current session
         */
        public Long id;
        /**
         * The time at which the event occurred
         */
        public Date timestamp;
        /**
         * The name of the class of the object that changed
         */
        public String clazz;
        /**
         * The operation that was performed
         */
        public Types.EventOperation operation;
        /**
         * A reference to the object that changed
         */
        public String ref;
        /**
         * The uuid of the object that changed
         */
        public String objUuid;
        /**
         * The record of the database object that was added, changed or deleted
         * (the actual type will be VM.Record, VBD.Record or similar)
         */
        public Object snapshot;
    }

    /**
     * Registers this session with the event system.  Specifying * as the desired class will register for all classes.
     *
     * @param classes register for events for the indicated classes
     * @return Task
     */
    public static Task registerAsync(Connection c, Set<String> classes) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "Async.event.register";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toTask(result);
    }

    /**
     * Registers this session with the event system.  Specifying * as the desired class will register for all classes.
     *
     * @param classes register for events for the indicated classes
     */
    public static void register(Connection c, Set<String> classes) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "event.register";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes)};
        Map response = c.dispatch(method_call, method_params);
        return;
    }

    /**
     * Unregisters this session with the event system
     *
     * @param classes remove this session's registration for the indicated classes
     * @return Task
     */
    public static Task unregisterAsync(Connection c, Set<String> classes) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "Async.event.unregister";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toTask(result);
    }

    /**
     * Unregisters this session with the event system
     *
     * @param classes remove this session's registration for the indicated classes
     */
    public static void unregister(Connection c, Set<String> classes) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "event.unregister";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes)};
        Map response = c.dispatch(method_call, method_params);
        return;
    }

    /**
     * Blocking call which returns a (possibly empty) batch of events
     *
     * @return the batch of events
     */
    public static Set<Event.Record> next(Connection c) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException,
        Types.SessionNotRegistered,
        Types.EventsLost {
        String method_call = "event.next";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toSetOfEventRecord(result);
    }

    /**
     * Blocking call which returns a (possibly empty) batch of events
     *
     * @param classes register for events for the indicated classes
     * @param token A token representing the point from which to generate database events. The empty string represents the beginning.
     * @param timeout Return after this many seconds if no events match
     * @return the batch of events
     */
    public static Set<Event.Record> from(Connection c, Set<String> classes, String token, Double timeout) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException,
        Types.SessionNotRegistered,
        Types.EventsLost {
        String method_call = "event.from";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes), Marshalling.toXMLRPC(token), Marshalling.toXMLRPC(timeout)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toSetOfEventRecord(result);
    }

    /**
     * Return the ID of the next event to be generated by the system
     *
     * @return the event ID
     */
    public static Long getCurrentId(Connection c) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "event.get_current_id";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toLong(result);
    }

    /**
     * Injects an artificial event on the given object and return the corresponding ID
     *
     * @param clazz class of the object
     * @param ref A reference to the object that will be changed.
     * @return the event ID
     */
    public static String inject(Connection c, String clazz, String ref) throws
        BadServerResponse,
        XenAPIException,
        XmlRpcException {
        String method_call = "event.inject";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(clazz), Marshalling.toXMLRPC(ref)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        return Types.toString(result);
    }

    public static Map properFrom(Connection c, Set<String> classes, String token, Double timeout) throws BadServerResponse, XenAPIException, XmlRpcException,
            Types.SessionNotRegistered,
            Types.EventsLost {
        String method_call = "event.from";
        String session = c.getSessionReference();
        Object[] method_params = {Marshalling.toXMLRPC(session), Marshalling.toXMLRPC(classes), Marshalling.toXMLRPC(token), Marshalling.toXMLRPC(timeout)};
        Map response = c.dispatch(method_call, method_params);
        Object result = response.get("Value");
        Map value = (Map)result;
        Map<String, Object> from = new HashMap<String, Object>();
        from.put("token", value.get("token"));
        from.put("events", Types.toSetOfEventRecord(value.get("events")));
        return from;
    }

}