using System;
using System.Collections.Generic;
using System.Threading;
using ExtensionLoader;
using OpenMetaverse;
using OpenMetaverse.Packets;

namespace Simian
{
    public class PeriscopeMovement
    {
        const int UPDATE_ITERATION = 100; //rate in milliseconds to send ObjectUpdate
        const bool ENVIRONMENT_SOUNDS = true; //collision sounds, splashing, etc
        const float GRAVITY = 9.8f; //meters/sec
        const float WALK_SPEED = 3f; //meters/sec
        const float RUN_SPEED = 5f; //meters/sec
        const float FLY_SPEED = 10f; //meters/sec
        const float FALL_DELAY = 0.33f; //seconds before starting animation
        const float FALL_FORGIVENESS = 0.25f; //fall buffer in meters
        const float JUMP_IMPULSE_VERTICAL = 8.5f; //boost amount in meters/sec
        const float JUMP_IMPULSE_HORIZONTAL = 10f; //boost amount in meters/sec (no clue why this is so high) 
        const float INITIAL_HOVER_IMPULSE = 2f; //boost amount in meters/sec
        const float PREJUMP_DELAY = 0.25f; //seconds before actually jumping
        const float AVATAR_TERMINAL_VELOCITY = 54f; //~120mph

        static readonly UUID BIG_SPLASH_SOUND = new UUID("486475b9-1460-4969-871e-fad973b38015");

        const float SQRT_TWO = 1.41421356f;

        ISceneProvider scene;
        Periscope periscope;
        Timer updateTimer;
        long lastTick;

        public int LastTick
        {
            get { return (int)Interlocked.Read(ref lastTick); }
            set { Interlocked.Exchange(ref lastTick, value); }
        }

        public PeriscopeMovement(ISceneProvider scene, Periscope periscope)
        {
            this.scene = scene;
            this.periscope = periscope;

            scene.UDP.RegisterPacketCallback(PacketType.AgentUpdate, AgentUpdateHandler);
            scene.UDP.RegisterPacketCallback(PacketType.SetAlwaysRun, SetAlwaysRunHandler);

            updateTimer = new Timer(new TimerCallback(UpdateTimer_Elapsed));
            LastTick = Environment.TickCount;
            updateTimer.Change(UPDATE_ITERATION, UPDATE_ITERATION);
        }

        public void Stop()
        {
            if (updateTimer != null)
            {
                updateTimer.Dispose();
                updateTimer = null;
            }
        }

        void UpdateTimer_Elapsed(object sender)
        {
            int tick = Environment.TickCount;
            float seconds = (float)((tick - LastTick) / 1000f);
            LastTick = tick;

            scene.ForEachAgent(
                delegate(Agent agent)
                {
                    // Don't handle movement for the master agent or foreign agents
                    if (agent != periscope.MasterAgent && agent.SessionID != UUID.Zero)
                    {
                        bool animsChanged = false;

                        // Create forward and left vectors from the current avatar rotation
                        Matrix4 rotMatrix = Matrix4.CreateFromQuaternion(agent.Avatar.Prim.Rotation);
                        Vector3 fwd = Vector3.Transform(Vector3.UnitX, rotMatrix);
                        Vector3 left = Vector3.Transform(Vector3.UnitY, rotMatrix);

                        // Check control flags
                        bool heldForward = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_AT_POS) == AgentManager.ControlFlags.AGENT_CONTROL_AT_POS;
                        bool heldBack = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_AT_NEG) == AgentManager.ControlFlags.AGENT_CONTROL_AT_NEG;
                        bool heldLeft = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_LEFT_POS) == AgentManager.ControlFlags.AGENT_CONTROL_LEFT_POS;
                        bool heldRight = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_LEFT_NEG) == AgentManager.ControlFlags.AGENT_CONTROL_LEFT_NEG;
                        //bool heldTurnLeft = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_TURN_LEFT) == AgentManager.ControlFlags.AGENT_CONTROL_TURN_LEFT;
                        //bool heldTurnRight = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_TURN_RIGHT) == AgentManager.ControlFlags.AGENT_CONTROL_TURN_RIGHT;
                        bool heldUp = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_UP_POS) == AgentManager.ControlFlags.AGENT_CONTROL_UP_POS;
                        bool heldDown = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_UP_NEG) == AgentManager.ControlFlags.AGENT_CONTROL_UP_NEG;
                        bool flying = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_FLY) == AgentManager.ControlFlags.AGENT_CONTROL_FLY;
                        //bool mouselook = (agent.ControlFlags & AgentManager.ControlFlags.AGENT_CONTROL_MOUSELOOK) == AgentManager.ControlFlags.AGENT_CONTROL_MOUSELOOK;

                        // direction in which the avatar is trying to move
                        Vector3 move = Vector3.Zero;
                        if (heldForward) { move.X += fwd.X; move.Y += fwd.Y; }
                        if (heldBack) { move.X -= fwd.X; move.Y -= fwd.Y; }
                        if (heldLeft) { move.X += left.X; move.Y += left.Y; }
                        if (heldRight) { move.X -= left.X; move.Y -= left.Y; }
                        if (heldUp) { move.Z += 1; }
                        if (heldDown) { move.Z -= 1; }

                        // is the avatar trying to move?
                        bool moving = move != Vector3.Zero;
                        bool jumping = agent.TickJump != 0;

                        // 2-dimensional speed multipler
                        float speed = seconds * (flying ? FLY_SPEED : agent.Running && !jumping ? RUN_SPEED : WALK_SPEED);
                        if ((heldForward || heldBack) && (heldLeft || heldRight))
                            speed /= SQRT_TWO;

                        Vector3 agentPosition = agent.Avatar.GetSimulatorPosition();
                        float oldFloor = scene.GetTerrainHeightAt(agentPosition.X, agentPosition.Y);

                        agentPosition += (move * speed);
                        float newFloor = scene.GetTerrainHeightAt(agentPosition.X, agentPosition.Y);

                        if (!flying && newFloor != oldFloor)
                            speed /= (1 + (SQRT_TWO * Math.Abs(newFloor - oldFloor)));

                        // least possible distance from avatar to the ground
                        // TODO: calculate to get rid of "bot squat"
                        float lowerLimit = newFloor + agent.Avatar.Prim.Scale.Z / 2;

                        // Z acceleration resulting from gravity
                        float gravity = 0f;

                        float waterChestHeight = scene.WaterHeight - (agent.Avatar.Prim.Scale.Z * .33f);

                        if (flying)
                        {
                            agent.TickFall = 0;
                            agent.TickJump = 0;

                            //velocity falloff while flying
                            agent.Avatar.Prim.Velocity.X *= 0.66f;
                            agent.Avatar.Prim.Velocity.Y *= 0.66f;
                            agent.Avatar.Prim.Velocity.Z *= 0.33f;

                            if (agent.Avatar.Prim.Position.Z == lowerLimit)
                                agent.Avatar.Prim.Velocity.Z += INITIAL_HOVER_IMPULSE;

                            if (move.X != 0 || move.Y != 0)
                            { //flying horizontally
                                if (scene.Avatars.SetDefaultAnimation(agent, Animations.FLY))
                                    animsChanged = true;
                            }
                            else if (move.Z > 0)
                            { //flying straight up
                                if (scene.Avatars.SetDefaultAnimation(agent, Animations.HOVER_UP))
                                    animsChanged = true;
                            }
                            else if (move.Z < 0)
                            { //flying straight down
                                if (scene.Avatars.SetDefaultAnimation(agent, Animations.HOVER_DOWN))
                                    animsChanged = true;
                            }
                            else
                            { //hovering in the air
                                if (scene.Avatars.SetDefaultAnimation(agent, Animations.HOVER))
                                    animsChanged = true;
                            }
                        }
                        else if (agent.Avatar.Prim.Position.Z > lowerLimit + FALL_FORGIVENESS || agent.Avatar.Prim.Position.Z <= waterChestHeight)
                        { //falling, floating, or landing from a jump

                            if (agent.Avatar.Prim.Position.Z > scene.WaterHeight)
                            { //above water

                                move = Vector3.Zero; //override controls while drifting
                                agent.Avatar.Prim.Velocity *= 0.95f; //keep most of our inertia

                                float fallElapsed = (float)(Environment.TickCount - agent.TickFall) / 1000f;

                                if (agent.TickFall == 0 || (fallElapsed > FALL_DELAY && agent.Avatar.Prim.Velocity.Z >= 0f))
                                { //just started falling
                                    agent.TickFall = Environment.TickCount;
                                }
                                else
                                {
                                    gravity = GRAVITY * fallElapsed * seconds; //normal gravity

                                    if (!jumping)
                                    { //falling
                                        if (fallElapsed > FALL_DELAY)
                                        { //falling long enough to trigger the animation
                                            if (scene.Avatars.SetDefaultAnimation(agent, Animations.FALLDOWN))
                                                animsChanged = true;
                                        }
                                    }
                                }
                            }
                        }
                        else
                        { //on the ground

                            agent.TickFall = 0;

                            //friction
                            agent.Avatar.Prim.Acceleration *= 0.2f;
                            agent.Avatar.Prim.Velocity *= 0.2f;

                            agent.Avatar.Prim.Position.Z = lowerLimit;

                            if (move.Z > 0)
                            { //jumping
                                if (!jumping)
                                { //begin prejump
                                    move.Z = 0; //override Z control
                                    if (scene.Avatars.SetDefaultAnimation(agent, Animations.PRE_JUMP))
                                        animsChanged = true;

                                    agent.TickJump = Environment.TickCount;
                                }
                                else if (Environment.TickCount - agent.TickJump > PREJUMP_DELAY * 1000)
                                { //start actual jump

                                    if (agent.TickJump == -1)
                                    {
                                        //already jumping! end current jump
                                        agent.TickJump = 0;
                                        return;
                                    }

                                    if (scene.Avatars.SetDefaultAnimation(agent, Animations.JUMP))
                                        animsChanged = true;

                                    agent.Avatar.Prim.Velocity.X += agent.Avatar.Prim.Acceleration.X * JUMP_IMPULSE_HORIZONTAL;
                                    agent.Avatar.Prim.Velocity.Y += agent.Avatar.Prim.Acceleration.Y * JUMP_IMPULSE_HORIZONTAL;
                                    agent.Avatar.Prim.Velocity.Z = JUMP_IMPULSE_VERTICAL * seconds;

                                    agent.TickJump = -1; //flag that we are currently jumping
                                }
                                else
                                {
                                    move.Z = 0; //override Z control
                                }
                            }
                            else
                            { //not jumping

                                agent.TickJump = 0;

                                if (move.X != 0 || move.Y != 0)
                                { //not walking

                                    if (move.Z < 0)
                                    { //crouchwalking
                                        if (scene.Avatars.SetDefaultAnimation(agent, Animations.CROUCHWALK))
                                            animsChanged = true;
                                    }
                                    else if (agent.Running)
                                    { //running
                                        if (scene.Avatars.SetDefaultAnimation(agent, Animations.RUN))
                                            animsChanged = true;
                                    }
                                    else
                                    { //walking
                                        if (scene.Avatars.SetDefaultAnimation(agent, Animations.WALK))
                                            animsChanged = true;
                                    }
                                }
                                else
                                { //walking
                                    if (move.Z < 0)
                                    { //crouching
                                        if (scene.Avatars.SetDefaultAnimation(agent, Animations.CROUCH))
                                            animsChanged = true;
                                    }
                                    else
                                    { //standing
                                        if (scene.Avatars.SetDefaultAnimation(agent, Animations.STAND))
                                            animsChanged = true;
                                    }
                                }
                            }
                        }

                        if (animsChanged)
                            scene.Avatars.SendAnimations(agent);

                        float maxVel = AVATAR_TERMINAL_VELOCITY * seconds;

                        // static acceleration when any control is held, otherwise none
                        if (moving)
                        {
                            agent.Avatar.Prim.Acceleration = move * speed;
                            if (agent.Avatar.Prim.Acceleration.Z < -maxVel)
                                agent.Avatar.Prim.Acceleration.Z = -maxVel;
                            else if (agent.Avatar.Prim.Acceleration.Z > maxVel)
                                agent.Avatar.Prim.Acceleration.Z = maxVel;
                        }
                        else
                        {
                            agent.Avatar.Prim.Acceleration = Vector3.Zero;
                        }

                        agent.Avatar.Prim.Velocity += agent.Avatar.Prim.Acceleration - new Vector3(0f, 0f, gravity);
                        if (agent.Avatar.Prim.Velocity.Z < -maxVel)
                            agent.Avatar.Prim.Velocity.Z = -maxVel;
                        else if (agent.Avatar.Prim.Velocity.Z > maxVel)
                            agent.Avatar.Prim.Velocity.Z = maxVel;

                        agent.Avatar.Prim.Position += agent.Avatar.Prim.Velocity;

                        if (agent.Avatar.Prim.Position.X < 0) agent.Avatar.Prim.Position.X = 0f;
                        else if (agent.Avatar.Prim.Position.X > 255) agent.Avatar.Prim.Position.X = 255f;

                        if (agent.Avatar.Prim.Position.Y < 0) agent.Avatar.Prim.Position.Y = 0f;
                        else if (agent.Avatar.Prim.Position.Y > 255) agent.Avatar.Prim.Position.Y = 255f;

                        if (agent.Avatar.Prim.Position.Z < lowerLimit) agent.Avatar.Prim.Position.Z = lowerLimit;
                    }
                }
            );
        }

        void AgentUpdateHandler(Packet packet, Agent agent)
        {
            AgentUpdatePacket update = (AgentUpdatePacket)packet;

            // Don't use the local physics to update the master agent
            if (agent != periscope.MasterAgent)
            {
                agent.Avatar.Prim.Rotation = update.AgentData.BodyRotation;
                agent.ControlFlags = (AgentManager.ControlFlags)update.AgentData.ControlFlags;
                agent.State = (AgentState)update.AgentData.State;
                agent.HideTitle = update.AgentData.Flags != 0;
            }

            SimulationObject obj;
            if (scene.TryGetObject(update.AgentData.AgentID, out obj))
            {
                obj.Prim.Rotation = update.AgentData.BodyRotation;
                scene.ObjectAddOrUpdate(this, obj, obj.Prim.OwnerID, 0, PrimFlags.None, UpdateFlags.Rotation);
            }
        }

        void SetAlwaysRunHandler(Packet packet, Agent agent)
        {
            SetAlwaysRunPacket run = (SetAlwaysRunPacket)packet;

            agent.Running = run.AgentData.AlwaysRun;
        }
    }
}