//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose: Implements visual effects entities: sprites, beams, bubbles, etc.
//
// $NoKeywords: $
//=============================================================================//

#ifndef ENV_WIND_SHARED_H
#define ENV_WIND_SHARED_H

#include <float.h>
#include "mathlib/vector.h"
#include "tier0/dbg.h"
#include "utllinkedlist.h"
#include "vstdlib/random.h"

//-----------------------------------------------------------------------------
// Forward declarations
//-----------------------------------------------------------------------------
class CSoundPatch;

//-----------------------------------------------------------------------------
// Class used to help store events that occurred over time
//-----------------------------------------------------------------------------
template <class T, class I>
class CTimedEventQueue {
   public:
    // The time passed in here represents the amount of time the queue stores
    CTimedEventQueue(float flMaxTime);

    // Adds an event to the queue, will pop off stale events from the queue
    // NOTE: All events added to the queue must monotonically increase in time!
    I PushEvent(float flTime, const T &data);

    // Grabs the last event that happened before or at the specified time
    I GetEventIndex(float flTime) const;

    // Gets event information
    float GetEventTime(I i) const;
    const T &GetEventData(I i) const;

   private:
    struct QueueEntry_t {
        float m_flTime;
        T m_Data;
    };

    float m_flQueueHeadTime;
    float m_flMaxTime;
    CUtlLinkedList<T, I> m_Queue;
};

//-----------------------------------------------------------------------------
// The time passed in here represents the amount of time the queue stores
//-----------------------------------------------------------------------------
template <class T, class I>
CTimedEventQueue<T, I>::CTimedEventQueue(float flMaxTime)
    : m_flMaxTime(flMaxTime) {
    // The length of time of events in the queue must be reasonable
    Assert(m_flMaxTime > 0.0f);
    m_flQueueHeadTime = -FLT_MAX;
}

//-----------------------------------------------------------------------------
// Adds an event to the queue, will pop off stale events from the queue
//-----------------------------------------------------------------------------
template <class T, class I>
I CTimedEventQueue<T, I>::PushEvent(float flTime, const T &data) {
    Assert(m_flQueueHeadTime <= flTime);
    m_flQueueHeadTime = flTime;

    // First push the event...
    I idx = m_Queue.AddToHead();
    m_Queue[idx].m_flTime = flTime;
    m_Queue[idx].m_Data = data;

    // Then retire stale events...
    I i = m_Queue.Tail();
    while (m_Queue[i].m_flTime < m_flQueueHeadTime - m_flMaxTime) {
        I prev = m_Queue.Prev(i);
        Assert(prev != m_Queue.InvalidIndex());
        m_Queue.Remove(i);
        i = prev;
    }

    return idx;
}

//-----------------------------------------------------------------------------
// Grabs the last event that happened before or at the specified time
//-----------------------------------------------------------------------------
template <class T, class I>
I CTimedEventQueue<T, I>::GetEventIndex(float flTime) const {
    // This checks for a request that fell off the queue
    Assert((flTime >= m_flQueueHeadTime - m_flMaxTime) &&
           (flTime <= m_flQueueHeadTime));

    // Then retire stale events...
    I i = m_Queue.Head();
    while (m_Queue[i].m_flTime > flTime) {
        i = m_Queue.Next(i);
        Assert(i != m_Queue.InvalidIndex());
    }

    return i;
}

//-----------------------------------------------------------------------------
// Gets event information
//-----------------------------------------------------------------------------
template <class T, class I>
inline float CTimedEventQueue<T, I>::GetEventTime(I i) const {
    return m_Queue[i].m_flTime;
}

template <class T, class I>
inline const T &CTimedEventQueue<T, I>::GetEventData(I i) const {
    return m_Queue[i].m_Data;
}

//-----------------------------------------------------------------------------
// Implementation of the class that computes windspeed
//-----------------------------------------------------------------------------
class CEnvWindShared {
   public:
    DECLARE_CLASS_NOBASE(CEnvWindShared);
    DECLARE_EMBEDDED_NETWORKVAR();

    CEnvWindShared();
    ~CEnvWindShared();

    void Init(int iEntIndex, int iRandomSeed, float flTime, int iWindDir,
              float flInitialWindSpeed);

    // Method to update the wind speed
    // Time passed in here is global time, not delta time
    // The function returns the time at which it must be called again
    float WindThink(float flTime);

    // FIXME: These really should be private
    CNetworkVar(float, m_flStartTime);

    CNetworkVar(int, m_iWindSeed);  // random number seed...

    CNetworkVar(int, m_iMinWind);  // the slowest the wind can normally blow
    CNetworkVar(int, m_iMaxWind);  // the fastest the wind can normally blow
    CNetworkVar(int, m_iMinGust);  // the slowest that a gust can be
    CNetworkVar(int, m_iMaxGust);  // the fastest that a gust can be

    CNetworkVar(float, m_flMinGustDelay);  // min time between gusts
    CNetworkVar(float, m_flMaxGustDelay);  // max time between gusts

    CNetworkVar(float, m_flGustDuration);  // max time between gusts

    CNetworkVar(
        int,
        m_iGustDirChange);  // max number of degrees wind dir changes on gusts.
    int m_iszGustSound;     // name of the wind sound to play for gusts.
    int m_iWindDir;         // wind direction (yaw)
    float m_flWindSpeed;    // the wind speed

    CNetworkVar(int, m_iInitialWindDir);
    CNetworkVar(float, m_flInitialWindSpeed);

#ifndef CLIENT_DLL
    COutputEvent m_OnGustStart;
    COutputEvent m_OnGustEnd;
#endif

   private:
    struct WindAveEvent_t {
        float m_flStartWindSpeed;  // the wind speed at the time of the event
        float m_flAveWindSpeed;    // the average wind speed of the event
    };

    struct WindVariationEvent_t {
        float m_flWindAngleVariation;
        float m_flWindSpeedVariation;
    };

    void ComputeWindVariation(float flTime);

    // Updates the wind sound
    void UpdateWindSound(float flTotalWindSpeed);

    float m_flVariationTime;
    float m_flSimTime;       // What's the time I last simulated up to?
    float m_flSwitchTime;    // when do I actually switch from gust to not gust
    float m_flAveWindSpeed;  // the average wind speed
    bool m_bGusting;         // is the wind gusting right now?

    float m_flWindAngleVariation;
    float m_flWindSpeedVariation;

    int m_iEntIndex;

    // Used to generate random numbers
    CUniformRandomStream m_Stream;

    // NOTE: In order to make this algorithm independent of calling frequency
    // I have to decouple the stream used to generate average wind speed
    // and the stream used to generate wind variation since they are
    // simulated using different timesteps
    CUniformRandomStream m_WindVariationStream;

    // Used to generate the wind sound...
    CSoundPatch *m_pWindSound;

    // Event history required for prediction
    CTimedEventQueue<WindAveEvent_t, unsigned short> m_WindAveQueue;
    CTimedEventQueue<WindVariationEvent_t, unsigned short> m_WindVariationQueue;

   private:
    CEnvWindShared(const CEnvWindShared &);  // not defined, not accessible
};

//-----------------------------------------------------------------------------
// Method to sample the windspeed at a particular time
//-----------------------------------------------------------------------------
void GetWindspeedAtTime(float flTime, Vector &vecVelocity);

//-----------------------------------------------------------------------------
// Method to reset windspeed..
//-----------------------------------------------------------------------------
void ResetWindspeed();

#endif  // ENV_WIND_SHARED_H