/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * 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.
 */

using System;
using System.Reflection;
using System.Collections.Generic;
using OpenMetaverse;
using OpenSim.Framework;
using log4net;
using OpenSim.Region.Framework.Interfaces;
using OpenSim.Region.Framework.Scenes;
using OpenSim.Region.ScriptEngine.Shared;
using OpenSim.Region.ScriptEngine.Shared.Api;

namespace OpenSim.Region.ScriptEngine.Shared.Api.Plugins
{
    public class SensorRepeat
    {
//        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        /// <summary>
        /// Used by one-off and repeated sensors
        /// </summary>
        public class SensorInfo
        {
            public uint localID;
            public UUID itemID;
            public double interval;
            public DateTime next;

            public string name;
            public UUID keyID;
            public int type;
            public double range;
            public double arc;
            public SceneObjectPart host;

            public SensorInfo Clone()
            {
                return (SensorInfo)this.MemberwiseClone();
            }
        }

        public AsyncCommandManager m_CmdManager;

        /// <summary>
        /// Number of sensors active.
        /// </summary>
        public int SensorsCount
        {
            get
            {
                return SenseRepeaters.Count;
            }
        }

        public SensorRepeat(AsyncCommandManager CmdManager)
        {
            m_CmdManager = CmdManager;
            maximumRange = CmdManager.m_ScriptEngine.Config.GetDouble("SensorMaxRange", 96.0d);
            maximumToReturn = CmdManager.m_ScriptEngine.Config.GetInt("SensorMaxResults", 16);
            m_npcModule = m_CmdManager.m_ScriptEngine.World.RequestModuleInterface<INPCModule>();
        }

        private INPCModule m_npcModule;

        private Object SenseLock = new Object();

        private const int AGENT = 1;
        private const int AGENT_BY_USERNAME = 0x10;
        private const int NPC = 0x20;
        private const int ACTIVE = 2;
        private const int PASSIVE = 4;
        private const int SCRIPTED = 8;

        private double maximumRange = 96.0;
        private int maximumToReturn = 16;

        //
        // Sensed entity
        //
        private class SensedEntity : IComparable
        {
            public SensedEntity(double detectedDistance, UUID detectedID)
            {
                distance = detectedDistance;
                itemID = detectedID;
            }
            public int CompareTo(object obj)
            {
                if (!(obj is SensedEntity)) throw new InvalidOperationException();
                SensedEntity ent = (SensedEntity)obj;
                if (ent == null || ent.distance < distance) return 1;
                if (ent.distance > distance) return -1;
                return 0;
            }
            public UUID itemID;
            public double distance;
        }

        /// <summary>
        /// Sensors to process.
        /// </summary>
        /// <remarks>
        /// Do not add or remove sensors from this list directly.  Instead, copy the list and substitute the updated
        /// copy.  This is to avoid locking the list for the duration of the sensor sweep, which increases the danger
        /// of deadlocks with future code updates.
        ///
        /// Always lock SenseRepeatListLock when updating this list.
        /// </remarks>
        private List<SensorInfo> SenseRepeaters = new List<SensorInfo>();
        private object SenseRepeatListLock = new object();

        public void SetSenseRepeatEvent(uint m_localID, UUID m_itemID,
                                        string name, UUID keyID, int type, double range,
                                        double arc, double sec, SceneObjectPart host)
        {
            // Always remove first, in case this is a re-set
            UnSetSenseRepeaterEvents(m_localID, m_itemID);

            if (sec == 0) // Disabling timer
                return;

            // Add to timer
            SensorInfo ts = new SensorInfo();
            ts.localID = m_localID;
            ts.itemID = m_itemID;
            ts.interval = sec;
            ts.name = name;
            ts.keyID = keyID;
            ts.type = type;
            if (range > maximumRange)
                ts.range = maximumRange;
            else
                ts.range = range;
            ts.arc = arc;
            ts.host = host;

            ts.next = DateTime.Now.ToUniversalTime().AddSeconds(ts.interval);

            AddSenseRepeater(ts);
        }

        private void AddSenseRepeater(SensorInfo senseRepeater)
        {
            lock (SenseRepeatListLock)
            {
                List<SensorInfo> newSenseRepeaters = new List<SensorInfo>(SenseRepeaters);
                newSenseRepeaters.Add(senseRepeater);
                SenseRepeaters = newSenseRepeaters;
            }
        }

        public void UnSetSenseRepeaterEvents(uint m_localID, UUID m_itemID)
        {
            // Remove from timer
            lock (SenseRepeatListLock)
            {
                List<SensorInfo> newSenseRepeaters = new List<SensorInfo>();
                foreach (SensorInfo ts in SenseRepeaters)
                {
                    if (ts.localID != m_localID || ts.itemID != m_itemID)
                    {
                        newSenseRepeaters.Add(ts);
                    }
                }

                SenseRepeaters = newSenseRepeaters;
            }
        }

        public void CheckSenseRepeaterEvents()
        {
            // Go through all timers
            foreach (SensorInfo ts in SenseRepeaters)
            {
                // Time has passed?
                if (ts.next.ToUniversalTime() < DateTime.Now.ToUniversalTime())
                {
                    SensorSweep(ts);
                    // set next interval
                    ts.next = DateTime.Now.ToUniversalTime().AddSeconds(ts.interval);
                }
            }
        }

        public void SenseOnce(uint m_localID, UUID m_itemID,
                              string name, UUID keyID, int type,
                              double range, double arc, SceneObjectPart host)
        {
            // Add to timer
            SensorInfo ts = new SensorInfo();
            ts.localID = m_localID;
            ts.itemID = m_itemID;
            ts.interval = 0;
            ts.name = name;
            ts.keyID = keyID;
            ts.type = type;
            if (range > maximumRange)
                ts.range = maximumRange;
            else
                ts.range = range;
            ts.arc = arc;
            ts.host = host;
            SensorSweep(ts);
        }

        private void SensorSweep(SensorInfo ts)
        {
            if (ts.host == null)
            {
                return;
            }

            List<SensedEntity> sensedEntities = new List<SensedEntity>();

            // Is the sensor type is AGENT and not SCRIPTED then include agents
            if ((ts.type & (AGENT | AGENT_BY_USERNAME | NPC)) != 0 && (ts.type & SCRIPTED) == 0)
            {
                sensedEntities.AddRange(doAgentSensor(ts));
            }

            // If SCRIPTED or PASSIVE or ACTIVE check objects
            if ((ts.type & SCRIPTED) != 0 || (ts.type & PASSIVE) != 0 || (ts.type & ACTIVE) != 0)
            {
                sensedEntities.AddRange(doObjectSensor(ts));
            }

            lock (SenseLock)
            {
                if (sensedEntities.Count == 0)
                {
                    // send a "no_sensor"
                    // Add it to queue
                    m_CmdManager.m_ScriptEngine.PostScriptEvent(ts.itemID,
                            new EventParams("no_sensor", new Object[0],
                            new DetectParams[0]));
                }
                else
                {
                    // Sort the list to get everything ordered by distance
                    sensedEntities.Sort();
                    int count = sensedEntities.Count;
                    int idx;
                    List<DetectParams> detected = new List<DetectParams>();
                    for (idx = 0; idx < count; idx++)
                    {
                        try
                        {
                            DetectParams detect = new DetectParams();
                            detect.Key = sensedEntities[idx].itemID;
                            detect.Populate(m_CmdManager.m_ScriptEngine.World);
                            detected.Add(detect);
                        }
                        catch (Exception)
                        {
                            // Ignore errors, the object has been deleted or the avatar has gone and
                            // there was a problem in detect.Populate so nothing added to the list
                        }
                        if (detected.Count == maximumToReturn)
                            break;
                    }

                    if (detected.Count == 0)
                    {
                        // To get here with zero in the list there must have been some sort of problem
                        // like the object being deleted or the avatar leaving to have caused some
                        // difficulty during the Populate above so fire a no_sensor event
                        m_CmdManager.m_ScriptEngine.PostScriptEvent(ts.itemID,
                                new EventParams("no_sensor", new Object[0],
                                new DetectParams[0]));
                    }
                    else
                    {
                        m_CmdManager.m_ScriptEngine.PostScriptEvent(ts.itemID,
                                new EventParams("sensor",
                                new Object[] {new LSL_Types.LSLInteger(detected.Count) },
                                detected.ToArray()));
                    }
                }
            }
        }

        private List<SensedEntity> doObjectSensor(SensorInfo ts)
        {
            List<EntityBase> Entities;
            List<SensedEntity> sensedEntities = new List<SensedEntity>();

            // If this is an object sense by key try to get it directly
            // rather than getting a list to scan through
            if (ts.keyID != UUID.Zero)
            {
                EntityBase e = null;
                m_CmdManager.m_ScriptEngine.World.Entities.TryGetValue(ts.keyID, out e);
                if (e == null)
                    return sensedEntities;
                Entities = new List<EntityBase>();
                Entities.Add(e);
            }
            else
            {
                Entities = new List<EntityBase>(m_CmdManager.m_ScriptEngine.World.GetEntities());
            }
            SceneObjectPart SensePoint = ts.host;

            Vector3 fromRegionPos = SensePoint.GetWorldPosition();

            // pre define some things to avoid repeated definitions in the loop body
            Vector3 toRegionPos;
            double dis;
            int objtype;
            SceneObjectPart part;
            float dx;
            float dy;
            float dz;

//            Quaternion q = SensePoint.RotationOffset;
            Quaternion q = SensePoint.GetWorldRotation();		// non-attached prim Sensor *always* uses World rotation!
            if (SensePoint.ParentGroup.IsAttachment)
            {
                // In attachments, rotate the sensor cone with the
                // avatar rotation. This may include a nonzero elevation if
                // in mouselook.
                // This will not include the rotation and position of the
                // attachment point (e.g. your head when a sensor is in your
                // hair attached to your scull. Your hair  will turn with
                // your head but the sensor will stay with your (global)
                // avatar rotation and position.
                // Position of a sensor in a child prim attached to an avatar
                // will be still wrong. 
                ScenePresence avatar = m_CmdManager.m_ScriptEngine.World.GetScenePresence(SensePoint.ParentGroup.AttachedAvatar);
                fromRegionPos = avatar.AbsolutePosition;
                q = avatar.Rotation;
            }

            LSL_Types.Quaternion r = new LSL_Types.Quaternion(q);
            LSL_Types.Vector3 forward_dir = (new LSL_Types.Vector3(1, 0, 0) * r);
            double mag_fwd = LSL_Types.Vector3.Mag(forward_dir);

            Vector3 ZeroVector = new Vector3(0, 0, 0);

            bool nameSearch = (ts.name != null && ts.name != "");

            foreach (EntityBase ent in Entities)
            {
                bool keep = true;

                if (nameSearch && ent.Name != ts.name) // Wrong name and it is a named search
                    continue;

                if (ent.IsDeleted) // taken so long to do this it has gone from the scene
                    continue;

                if (!(ent is SceneObjectGroup)) // dont bother if it is a pesky avatar
                    continue;
                toRegionPos = ent.AbsolutePosition;

                // Calculation is in line for speed
                dx = toRegionPos.X - fromRegionPos.X;
                dy = toRegionPos.Y - fromRegionPos.Y;
                dz = toRegionPos.Z - fromRegionPos.Z;

                // Weed out those that will not fit in a cube the size of the range
                // no point calculating if they are within a sphere the size of the range
                // if they arent even in the cube
                if (Math.Abs(dx) > ts.range || Math.Abs(dy) > ts.range || Math.Abs(dz) > ts.range)
                    dis = ts.range + 1.0;
                else
                    dis = Math.Sqrt(dx * dx + dy * dy + dz * dz);

                if (keep && dis <= ts.range && ts.host.UUID != ent.UUID)
                {
                    // In Range and not the object containing the script, is it the right Type ?
                    objtype = 0;

                    part = ((SceneObjectGroup)ent).RootPart;
                    if (part.ParentGroup.RootPart.Shape.PCode != (byte)PCode.Tree &&
                        part.ParentGroup.RootPart.Shape.PCode != (byte)PCode.NewTree &&
                        part.ParentGroup.AttachmentPoint != 0) // Attached so ignore
                        continue;

                    if (part.Inventory.ContainsScripts())
                    {
                        objtype |= ACTIVE | SCRIPTED; // Scripted and active. It COULD have one hidden ...
                    }
                    else
                    {
                        if (ent.Velocity.Equals(ZeroVector))
                        {
                            objtype |= PASSIVE; // Passive non-moving
                        }
                        else
                        {
                            objtype |= ACTIVE; // moving so active
                        }
                    }

                    // If any of the objects attributes match any in the requested scan type
                    if (((ts.type & objtype) != 0))
                    {
                        // Right type too, what about the other params , key and name ?
                        if (ts.arc < Math.PI)
                        {
                            // not omni-directional. Can you see it ?
                            // vec forward_dir = llRot2Fwd(llGetRot())
                            // vec obj_dir = toRegionPos-fromRegionPos
                            // dot=dot(forward_dir,obj_dir)
                            // mag_fwd = mag(forward_dir)
                            // mag_obj = mag(obj_dir)
                            // ang = acos(dot /(mag_fwd*mag_obj))
                            double ang_obj = 0;
                            try
                            {
                                Vector3 diff = toRegionPos - fromRegionPos;
                                double dot = LSL_Types.Vector3.Dot(forward_dir, diff);
                                double mag_obj = LSL_Types.Vector3.Mag(diff);
                                ang_obj = Math.Acos(dot / (mag_fwd * mag_obj));
                            }
                            catch
                            {
                            }

                            if (ang_obj > ts.arc) keep = false;
                        }

                        if (keep == true)
                        {
                            // add distance for sorting purposes later
                            sensedEntities.Add(new SensedEntity(dis, ent.UUID));
                        }
                    }
                }
            }
            return sensedEntities;
        }

        private List<SensedEntity> doAgentSensor(SensorInfo ts)
        {
            List<SensedEntity> sensedEntities = new List<SensedEntity>();

            // If nobody about quit fast
            if (m_CmdManager.m_ScriptEngine.World.GetRootAgentCount() == 0)
                return sensedEntities;

            SceneObjectPart SensePoint = ts.host;
            Vector3 fromRegionPos = SensePoint.GetWorldPosition();
            
            Quaternion q = SensePoint.GetWorldRotation();
            if (SensePoint.ParentGroup.IsAttachment)
            {
                // In attachments, rotate the sensor cone with the
                // avatar rotation. This may include a nonzero elevation if
                // in mouselook.
                // This will not include the rotation and position of the
                // attachment point (e.g. your head when a sensor is in your
                // hair attached to your scull. Your hair  will turn with
                // your head but the sensor will stay with your (global)
                // avatar rotation and position.
                // Position of a sensor in a child prim attached to an avatar
                // will be still wrong. 
                ScenePresence avatar = m_CmdManager.m_ScriptEngine.World.GetScenePresence(SensePoint.ParentGroup.AttachedAvatar);
                if (avatar == null)
                    return sensedEntities;
                fromRegionPos = avatar.AbsolutePosition;
                q = avatar.Rotation;
            }

            LSL_Types.Quaternion r = new LSL_Types.Quaternion(q);
            LSL_Types.Vector3 forward_dir = (new LSL_Types.Vector3(1, 0, 0) * r);
            double mag_fwd = LSL_Types.Vector3.Mag(forward_dir);
            bool attached = (SensePoint.ParentGroup.AttachmentPoint != 0);
            Vector3 toRegionPos;
            double dis;
            
            Action<ScenePresence> senseEntity = new Action<ScenePresence>(presence =>
            {
//                m_log.DebugFormat(
//                    "[SENSOR REPEAT]: Inspecting scene presence {0}, type {1} on sensor sweep for {2}, type {3}",
//                    presence.Name, presence.PresenceType, ts.name, ts.type);

                if ((ts.type & NPC) == 0 && presence.PresenceType == PresenceType.Npc)
                {
                    INPC npcData = m_npcModule.GetNPC(presence.UUID, presence.Scene);
                    if (npcData == null || !npcData.SenseAsAgent)
                    {
//                        m_log.DebugFormat(
//                            "[SENSOR REPEAT]: Discarding NPC {0} from agent sense sweep for script item id {1}",
//                            presence.Name, ts.itemID);
                        return;
                    }
                }

                if ((ts.type & AGENT) == 0)
                {
                    if (presence.PresenceType == PresenceType.User)
                    {
                        return;
                    }
                    else
                    {
                        INPC npcData = m_npcModule.GetNPC(presence.UUID, presence.Scene);
                        if (npcData != null && npcData.SenseAsAgent)
                        {
//                            m_log.DebugFormat(
//                                "[SENSOR REPEAT]: Discarding NPC {0} from non-agent sense sweep for script item id {1}",
//                                presence.Name, ts.itemID);
                            return;
                        }
                    }
                }

                if (presence.IsDeleted || presence.IsChildAgent || presence.GodLevel > 0.0)
                    return;
                
                // if the object the script is in is attached and the avatar is the owner
                // then this one is not wanted
                if (attached && presence.UUID == SensePoint.OwnerID)
                    return;

                toRegionPos = presence.AbsolutePosition;
                dis = Math.Abs(Util.GetDistanceTo(toRegionPos, fromRegionPos));

                // Disabled for now since all osNpc* methods check for appropriate ownership permission.
                // Perhaps could be re-enabled as an NPC setting at some point since being able to make NPCs not
                // sensed might be useful.
//                if (presence.PresenceType == PresenceType.Npc && npcModule != null)
//                {
//                    UUID npcOwner = npcModule.GetOwner(presence.UUID);
//                    if (npcOwner != UUID.Zero && npcOwner != SensePoint.OwnerID)
//                        return;
//                }

                // are they in range
                if (dis <= ts.range)
                {
                    // Are they in the required angle of view
                    if (ts.arc < Math.PI)
                    {
                        // not omni-directional. Can you see it ?
                        // vec forward_dir = llRot2Fwd(llGetRot())
                        // vec obj_dir = toRegionPos-fromRegionPos
                        // dot=dot(forward_dir,obj_dir)
                        // mag_fwd = mag(forward_dir)
                        // mag_obj = mag(obj_dir)
                        // ang = acos(dot /(mag_fwd*mag_obj))
                        double ang_obj = 0;
                        try
                        {
                            LSL_Types.Vector3 obj_dir = new LSL_Types.Vector3(
                                toRegionPos - fromRegionPos);
                            double dot = LSL_Types.Vector3.Dot(forward_dir, obj_dir);
                            double mag_obj = LSL_Types.Vector3.Mag(obj_dir);
                            ang_obj = Math.Acos(dot / (mag_fwd * mag_obj));
                        }
                        catch
                        {
                        }
                        if (ang_obj <= ts.arc)
                        {
                            sensedEntities.Add(new SensedEntity(dis, presence.UUID));
                        }
                    }
                    else
                    {
                        sensedEntities.Add(new SensedEntity(dis, presence.UUID));
                    }
                }
            });

            // If this is an avatar sense by key try to get them directly
            // rather than getting a list to scan through
            if (ts.keyID != UUID.Zero)
            {
                ScenePresence sp;
                // Try direct lookup by UUID
                if (!m_CmdManager.m_ScriptEngine.World.TryGetScenePresence(ts.keyID, out sp))
                    return sensedEntities;
                senseEntity(sp);
            }
            else if (ts.name != null && ts.name != "")
            {
                ScenePresence sp;
                // Try lookup by name will return if/when found
                if (((ts.type & AGENT) != 0) && m_CmdManager.m_ScriptEngine.World.TryGetAvatarByName(ts.name, out sp))
                    senseEntity(sp);
                if ((ts.type & AGENT_BY_USERNAME) != 0)
                {
                    m_CmdManager.m_ScriptEngine.World.ForEachRootScenePresence(
                        delegate (ScenePresence ssp)
                        {
                            if (ssp.Lastname == "Resident")
                            {
                                if (ssp.Firstname.ToLower() == ts.name)
                                    senseEntity(ssp);
                                return;
                            }
                            if (ssp.Name.Replace(" ", ".").ToLower() == ts.name)
                                senseEntity(ssp);
                        }
                    );
                }

                return sensedEntities;
            }
            else
            {
                m_CmdManager.m_ScriptEngine.World.ForEachRootScenePresence(senseEntity);
            }
            return sensedEntities;
        }

        public Object[] GetSerializationData(UUID itemID)
        {
            List<Object> data = new List<Object>();

            foreach (SensorInfo ts in SenseRepeaters)
            {
                if (ts.itemID == itemID)
                {
                    data.Add(ts.interval);
                    data.Add(ts.name);
                    data.Add(ts.keyID);
                    data.Add(ts.type);
                    data.Add(ts.range);
                    data.Add(ts.arc);
                }
            }

            return data.ToArray();
        }

        public void CreateFromData(uint localID, UUID itemID, UUID objectID,
                                   Object[] data)
        {
            SceneObjectPart part =
                m_CmdManager.m_ScriptEngine.World.GetSceneObjectPart(
                    objectID);

            if (part == null)
                return;

            int idx = 0;

            while (idx < data.Length)
            {
                SensorInfo ts = new SensorInfo();

                ts.localID = localID;
                ts.itemID = itemID;

                ts.interval = (double)data[idx];
                ts.name = (string)data[idx+1];
                ts.keyID = (UUID)data[idx+2];
                ts.type = (int)data[idx+3];
                ts.range = (double)data[idx+4];
                ts.arc = (double)data[idx+5];
                ts.host = part;

                ts.next =
                    DateTime.Now.ToUniversalTime().AddSeconds(ts.interval);

                AddSenseRepeater(ts);
                
                idx += 6;
            }
        }

        public List<SensorInfo> GetSensorInfo()
        {
            List<SensorInfo> retList = new List<SensorInfo>();

            lock (SenseRepeatListLock)
            {
                foreach (SensorInfo i in SenseRepeaters)
                    retList.Add(i.Clone());
            }

            return retList;
        }           
    }
}