//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
// $NoKeywords: $
//=============================================================================//
#ifndef QUERYCACHE_H
#define QUERYCACHE_H
#ifdef _WIN32
#pragma once
#endif

#include "mathlib/vector.h"
#include "tier0/platform.h"

// this system provides several piece of functionality to ai or other systems
// which wish to do traces and other trace-like queries.

// a. By maintaining a set of incrementally updated trace results, it makes it
// simple to have ai code use hyteresis on traces as an optimization method.

// b. By updating the cache entries outside of the entity think functions, the
// update is done in a fully multi-threaded fashion

enum EQueryType_t {
    EQUERY_INVALID = 0,  // an invalid or unused entry
    EQUERY_TRACELINE,
    EQUERY_ENTITY_LOS_CHECK,

};

enum EEntityOffsetMode_t {
    EOFFSET_MODE_WORLDSPACE_CENTER,
    EOFFSET_MODE_EYEPOSITION,
    EOFFSET_MODE_NONE,  // nop
};

#define QCACHE_MAXPNTS \
    3  // maximum number of points/entities
       // involved in a query

struct QueryCacheKey_t {
    EQueryType_t m_Type;
    int m_nNumValidPoints;
    Vector m_Points[QCACHE_MAXPNTS];
    EHANDLE m_pEntities[QCACHE_MAXPNTS];
    EEntityOffsetMode_t m_nOffsetMode[QCACHE_MAXPNTS];
    unsigned int m_nTraceMask;
    unsigned int m_nHashIdx;
    int m_nCollisionGroup;
    ShouldHitFunc_t m_pTraceFilterFunction;

    float m_flMinimumUpdateInterval;

    void ComputeHashIndex(void);

    bool Matches(QueryCacheKey_t const *pNode) const;
};

struct QueryCacheEntry_t {
    QueryCacheEntry_t *m_pNext;
    QueryCacheEntry_t *m_pPrev;
    QueryCacheKey_t m_QueryParams;
    float m_flLastUpdateTime;
    bool m_bUsedSinceUpdated;  // was this cell referenced?
    bool m_bSpeculativelyDone;
    bool m_bResult;  // for queries with a boolean result

    void IssueQuery(void);
};

bool IsLineOfSightBetweenTwoEntitiesClear(
    CBaseEntity *pSrcEntity, EEntityOffsetMode_t nSrcOffsetMode,
    CBaseEntity *pDestEntity, EEntityOffsetMode_t nDestOffsetMode,
    CBaseEntity *pSkipEntity, int nCollisionGroup, unsigned int nTraceMask,
    ShouldHitFunc_t pTraceFilterCallback, float flMinimumUpdateInterval = 0.2);

// call during main loop for threaded update of the query cache
void UpdateQueryCache(void);

// call on level transition or other significant step-functions
void InvalidateQueryCache(void);

#endif  // querycache_h