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 *       notice, this list of conditions and the following disclaimer in the
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 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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 */
using System;
using System.Collections.Generic;
using System.Text;

using OMV = OpenMetaverse;
using OpenSim.Framework;
using OpenSim.Region.Physics.Manager;

namespace OpenSim.Region.Physics.BulletSPlugin
{
// Class to wrap all objects.
// The rest of BulletSim doesn't need to keep checking for avatars or prims
// unless the difference is significant.
public abstract class BSPhysObject : PhysicsActor
{
    protected void BaseInitialize(BSScene parentScene, uint localID, string name, string typeName)
    {
        PhysicsScene = parentScene;
        LocalID = localID;
        PhysObjectName = name;
        TypeName = typeName;

        Linkset = new BSLinkset(PhysicsScene, this);

        CollisionCollection = new CollisionEventUpdate();
        SubscribedEventsMs = 0;
        CollidingStep = 0;
        CollidingGroundStep = 0;
    }

    public BSScene PhysicsScene { get; protected set; }
    // public override uint LocalID { get; set; } // Use the LocalID definition in PhysicsActor
    public string PhysObjectName { get; protected set; }
    public string TypeName { get; protected set; }

    public BSLinkset Linkset { get; set; }

    // Return the object mass without calculating it or having side effects
    public abstract float MassRaw { get; }

    // Reference to the physical body (btCollisionObject) of this object
    public BulletBody BSBody;
    // Reference to the physical shape (btCollisionShape) of this object
    public BulletShape BSShape;

    // Stop all physical motion.
    public abstract void ZeroMotion();

    // Step the vehicle simulation for this object. A NOOP if the vehicle was not configured.
    public virtual void StepVehicle(float timeStep) { }

    // Update the physical location and motion of the object. Called with data from Bullet.
    public abstract void UpdateProperties(EntityProperties entprop);

    // Tell the object to clean up.
    public abstract void Destroy();

    #region Collisions

    // Requested number of milliseconds between collision events. Zero means disabled.
    protected int SubscribedEventsMs { get; set; }
    // Given subscription, the time that a collision may be passed up
    protected int NextCollisionOkTime { get; set; }
    // The simulation step that last had a collision
    protected long CollidingStep { get; set; }
    // The simulation step that last had a collision with the ground
    protected long CollidingGroundStep { get; set; }
    // The collision flags we think are set in Bullet
    protected CollisionFlags CurrentCollisionFlags { get; set; }

    // The collisions that have been collected this tick
    protected CollisionEventUpdate CollisionCollection;

    // The simulation step is telling this object about a collision.
    // Return 'true' if a collision was processed and should be sent up.
    // Called at taint time from within the Step() function
    public virtual bool Collide(uint collidingWith, BSPhysObject collidee, 
                    OMV.Vector3 contactPoint, OMV.Vector3 contactNormal, float pentrationDepth)
    {
        bool ret = false;

        // The following lines make IsColliding() and IsCollidingGround() work
        CollidingStep = PhysicsScene.SimulationStep;
        if (collidingWith <= PhysicsScene.TerrainManager.HighestTerrainID)
        {
            CollidingGroundStep = PhysicsScene.SimulationStep;
        }

        // prims in the same linkset cannot collide with each other
        if (collidee != null && (this.Linkset.LinksetID == collidee.Linkset.LinksetID))
        {
            return ret;
        }

        // if someone has subscribed for collision events....
        if (SubscribedEvents()) {
            CollisionCollection.AddCollider(collidingWith, new ContactPoint(contactPoint, contactNormal, pentrationDepth));
            DetailLog("{0},{1}.Collison.AddCollider,call,with={2},point={3},normal={4},depth={5}",
                            LocalID, TypeName, collidingWith, contactPoint, contactNormal, pentrationDepth);
            ret = true;
        }
        return ret;
    }

    // Routine to send the collected collisions into the simulator.
    // Also handles removal of this from the collection of objects with collisions if
    //      there are no collisions from this object. Mechanism is create one last
    //      collision event to make collision_end work.
    // Called at taint time from within the Step() function thus no locking problems
    //      with CollisionCollection and ObjectsWithNoMoreCollisions.
    public virtual void SendCollisions()
    {
        // throttle the collisions to the number of milliseconds specified in the subscription
        int nowTime = PhysicsScene.SimulationNowTime;
        if (nowTime >= NextCollisionOkTime)
        {
            NextCollisionOkTime = nowTime + SubscribedEventsMs;

            // We are called if we previously had collisions. If there are no collisions
            //   this time, send up one last empty event so OpenSim can sense collision end.
            if (CollisionCollection.Count == 0)
                PhysicsScene.ObjectsWithNoMoreCollisions.Add(this);

            DetailLog("{0},{1}.SendCollisionUpdate,call,numCollisions={2}", LocalID, TypeName, CollisionCollection.Count);
            base.SendCollisionUpdate(CollisionCollection);

            // The collisionCollection structure is passed around in the simulator.
            // Make sure we don't have a handle to that one and that a new one is used for next time.
            CollisionCollection = new CollisionEventUpdate();
        }
    }

    // Subscribe for collision events.
    // Parameter is the millisecond rate the caller wishes collision events to occur.
    public override void SubscribeEvents(int ms) {
        DetailLog("{0},BSScene.SubscribeEvents,subscribing,ms={1}", BSScene.DetailLogZero, ms);
        SubscribedEventsMs = ms;
        if (ms > 0)
        {
            // make sure first collision happens
            NextCollisionOkTime = Util.EnvironmentTickCountSubtract(SubscribedEventsMs);

            PhysicsScene.TaintedObject(TypeName+".SubscribeEvents", delegate()
            {
                CurrentCollisionFlags = BulletSimAPI.AddToCollisionFlags2(BSBody.ptr, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
            });
        }
        else
        {
            // Subscribing for zero or less is the same as unsubscribing
            UnSubscribeEvents();
        }
    }
    public override void UnSubscribeEvents() { 
        DetailLog("{0},BSScene.UnSubscribeEvents,unsubscribing", BSScene.DetailLogZero);
        SubscribedEventsMs = 0;
        PhysicsScene.TaintedObject(TypeName+".UnSubscribeEvents", delegate()
        {
            CurrentCollisionFlags = BulletSimAPI.RemoveFromCollisionFlags2(BSBody.ptr, CollisionFlags.BS_SUBSCRIBE_COLLISION_EVENTS);
        });
    }
    // Return 'true' if the simulator wants collision events
    public override bool SubscribedEvents() { 
        return (SubscribedEventsMs > 0);
    }

    #endregion // Collisions

    // High performance detailed logging routine used by the physical objects.
    protected void DetailLog(string msg, params Object[] args)
    {
        PhysicsScene.PhysicsLogging.Write(msg, args);
    }
}
}