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#ifndef SAPLINGS_H

#define SAPLINGS_H

#include "grid.h"

#include "snag.h"

struct SaplingTree {

    SaplingTree() { clear(); }

    short unsigned int age;  // number of consectuive years the sapling suffers from dire conditions

    short unsigned int species_index; // index of the species within the resource-unit-species container

    unsigned char stress_years; // (upper 16bits) + age of sapling (lower 16 bits)

    unsigned char flags;

    float height; // height of the sapling in meter

    bool is_occupied() const { return height>0.f; }

    void clear()  {  age=0; species_index=0; stress_years=0; flags=0; height=0.f;  }

    void setSapling(const float h_m, const int age_yrs, const int species_idx) { height=h_m; age=static_cast<short unsigned int>(age_yrs); stress_years=0; species_index=static_cast<short unsigned int>(species_idx); }

};

#define NSAPCELLS 5

struct SaplingCell {

    enum ECellState { CellInvalid=0, CellFree=1, CellFull=2};

    SaplingCell() {

        state=CellInvalid;

    }

    ECellState state;

    SaplingTree saplings[NSAPCELLS];

    void checkState() { if (state==CellInvalid) return;

                        bool free = false;

                        for (int i=0;i<NSAPCELLS;++i) {

                            // locked for all species, if a sapling of one species >1.3m

                            if (saplings[i].height>1.3f) {state = CellFull; return; }

                            // locked, if all slots are occupied.

                            if (!saplings[i].is_occupied())

                                free=true;

                        }

                        state = free? CellFree : CellFull;

                      }

};

class ResourceUnit;

class Saplings;

class SaplingStat

{

public:

    SaplingStat() { clearStatistics(); }

    void clearStatistics();

    // actions

    void addCarbonOfDeadSapling(float dbh) { mDied++; mSumDbhDied+=dbh; }

    // access to statistics

    int newSaplings() const { return mAdded; }

    int diedSaplings() const { return mDied; }

    int livingSaplings() const { return mLiving; } ///< get the number

    int recruitedSaplings() const { return mRecruited; }

    ///  returns the *represented* (Reineke's Law) number of trees (N/ha) and the mean dbh/height (cm/m)

    double livingStemNumber(double &rAvgDbh, double &rAvgHeight, double &rAvgAge) const;

    double averageHeight() const { return mAvgHeight; }

    double averageAge() const { return mAvgAge; }

    double averageDeltaHPot() const { return mAvgDeltaHPot; }

    double averageDeltaHRealized() const { return mAvgHRealized; }

    /// return the number of trees represented by one sapling of the current species and given 'height'

    double representedStemNumber(float height) const;

    // carbon and nitrogen

    const CNPair &carbonLiving() const { return mCarbonLiving; } ///< state of the living

    const CNPair &carbonGain() const { return mCarbonGain; } ///< state of the living

private:

    int mAdded; ///< number of trees added

    int mRecruited; ///< number recruited (i.e. grown out of regeneration layer)

    int mDied; ///< number of trees died

    double mSumDbhDied; ///< running sum of dbh of died trees (used to calculate detritus)

    int mLiving; ///< number of trees (cohorts!!!) currently in the regeneration layer

    double mAvgHeight; ///< average height of saplings (m)

    double mAvgAge; ///< average age of saplings (years)

    double mAvgDeltaHPot; ///< average height increment potential (m)

    double mAvgHRealized; ///< average realized height increment

    CNPair mCarbonLiving;

    CNPair mCarbonGain; ///< net growth (kg / ru) of saplings

    friend class Saplings;

};

class Saplings

{

public:

    Saplings();

    void setup();

    // main functions

    void establishment(const ResourceUnit *ru);

    void saplingGrowth(const ResourceUnit *ru);

    void clearStats() { mAdded=0; mTested=0;}

    int saplingsAdded() const { return mAdded; }

    int pixelTested() const { return mTested; }

    static void setRecruitmentVariation(const double variation) { mRecruitmentVariation = variation; }

    static void updateBrowsingPressure();

private:

    bool growSapling(const ResourceUnit *ru, SaplingTree &tree, int isc, float dom_height, float lif_value);

    Grid<SaplingCell> mGrid;

    int mAdded;

    int mTested;

    static double mRecruitmentVariation;

    static double mBrowsingPressure;

};

#endif // SAPLINGS_H