//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
// $Revision: $
// $NoKeywords: $
//
// The BSP tree leaf data system
//
//=============================================================================//

#include "tier0/platform.h"

#if !defined(BSPTREEDATA)
#define BSPTREEDATA
#ifdef _WIN32
#pragma once
#endif

//-----------------------------------------------------------------------------
// Forward declarations
//-----------------------------------------------------------------------------

class Vector;
struct Ray_t;

//-----------------------------------------------------------------------------
// Handle to an renderable in the client leaf system
//-----------------------------------------------------------------------------

typedef unsigned short BSPTreeDataHandle_t;

enum { TREEDATA_INVALID_HANDLE = (BSPTreeDataHandle_t)~0 };

//-----------------------------------------------------------------------------
// Interface needed by tree data to do its job
//
// Note that anything that has convex spatial regions with leaves identified
// by indices can implement the ISpatialQuery. All you have to do is to
// implement a class that can answer the 5 questions in the Query interface
// about the spatial subdivision. For example, a K-D tree or a BSP tree could
// implement this interface
//
//-----------------------------------------------------------------------------

abstract_class ISpatialLeafEnumerator {
   public:
    // call back with a leaf and a context
    // The context is completely user defined; it's passed into the enumeration
    // function of ISpatialQuery.
    // This gets called	by the enumeration methods with each leaf
    // that passes the test; return true to continue enumerating,
    // false to stop

    virtual bool EnumerateLeaf(int leaf, int context) = 0;
};

abstract_class ISpatialQuery {
   public:
    // Returns the number of leaves
    virtual int LeafCount() const = 0;

    // Enumerates the leaves along a ray, box, etc.
    virtual bool EnumerateLeavesAtPoint(
        Vector const& pt, ISpatialLeafEnumerator* pEnum, int context) = 0;
    virtual bool EnumerateLeavesInBox(Vector const& mins, Vector const& maxs,
                                      ISpatialLeafEnumerator* pEnum,
                                      int context) = 0;
    virtual bool EnumerateLeavesInSphere(Vector const& center, float radius,
                                         ISpatialLeafEnumerator* pEnum,
                                         int context) = 0;
    virtual bool EnumerateLeavesAlongRay(
        Ray_t const& ray, ISpatialLeafEnumerator* pEnum, int context) = 0;
};

//-----------------------------------------------------------------------------
// Data associated with leaves.
//
// This is a parasitic class that attaches data to the leaves specified by the
// ISpatialQuery sent in to the initialization function. It can't exist without
// a spatial partition of some sort to hold onto.
//-----------------------------------------------------------------------------

abstract_class IBSPTreeDataEnumerator {
   public:
    // call back with a userId and a context
    virtual bool FASTCALL EnumerateElement(int userId, int context) = 0;
};

abstract_class IBSPTreeData {
   public:
    // Add a virtual destructor so that the derived class destructors will
    // be called.
    virtual ~IBSPTreeData() {}

    // Initializes, shuts down
    virtual void Init(ISpatialQuery * pBSPTree) = 0;
    virtual void Shutdown() = 0;

    // Adds and removes data from the leaf lists
    virtual BSPTreeDataHandle_t Insert(int userId, Vector const& mins,
                                       Vector const& maxs) = 0;
    virtual void Remove(BSPTreeDataHandle_t handle) = 0;

    // Call this when a element moves
    virtual void ElementMoved(BSPTreeDataHandle_t handle, Vector const& mins,
                              Vector const& maxs) = 0;

    // Enumerate elements in a particular leaf
    virtual bool EnumerateElementsInLeaf(
        int leaf, IBSPTreeDataEnumerator* pEnum, int context) = 0;

    // Is the element in any leaves at all?
    virtual bool IsElementInTree(BSPTreeDataHandle_t handle) const = 0;

    // NOTE: These methods call through to the functions in the attached
    // ISpatialQuery
    // For convenience, enumerates the leaves along a ray, box, etc.
    virtual bool EnumerateLeavesAtPoint(
        Vector const& pt, ISpatialLeafEnumerator* pEnum, int context) = 0;
    virtual bool EnumerateLeavesInBox(Vector const& mins, Vector const& maxs,
                                      ISpatialLeafEnumerator* pEnum,
                                      int context) = 0;
    virtual bool EnumerateLeavesInSphere(Vector const& center, float radius,
                                         ISpatialLeafEnumerator* pEnum,
                                         int context) = 0;
    virtual bool EnumerateLeavesAlongRay(
        Ray_t const& ray, ISpatialLeafEnumerator* pEnum, int context) = 0;
};

//-----------------------------------------------------------------------------
// Class factory
//-----------------------------------------------------------------------------

IBSPTreeData* CreateBSPTreeData();
void DestroyBSPTreeData(IBSPTreeData* pTreeData);

#endif  // BSPTREEDATA