#ifndef TURING_GRID_HH
#define TURING_GRID_HH

#include <vector>

class structured_grid
{
public:
    // create a 2d grid
    structured_grid(int x, int y, double h_) :
        dim(2), h(h_) {
        // parallel: parallele Aufteilung berechnen und lokalen Patch bestimmen
        N[0] = x; N[1] = y; N[2] = 0;
    }
    // create a 3d grid
    structured_grid(int x, int y, int z, double h_) :
        dim(3), h(h_) {
        N[0] = x; N[1] = y; N[2] = z;
    }
    // query number of vertices in the grid
    unsigned int size() const {
        return (N[0]+1)*(N[1]+1)*(N[2]+1);
    }
    // query number of vertices in direction d
    unsigned int size(unsigned int d) const {
        return N[d]+1;
    }
    // query number of cells in direction d
    unsigned int cells(unsigned int d) const {
        return N[d];
    }
    // query meshwidth
    double meshwidth() const {
        return h;
    }
    // compute linear ordering based on muti-index
    unsigned int index(unsigned int i[3]) const {
        return (i[0]*size(1)+i[1])*size(2)+i[2];
    }
    // compute multi-index based on linear ordering
    unsigned int index(unsigned int i, unsigned int d) const {
        switch (d) {
            case 0: return (i/(size(1)*size(2)))%size(0);
            case 1: return (i/(size(2)))%size(1);
            case 2: return i%(size(2));
            default: return 0;
        }
    }
    // compute neighbors for a given cell
    std::vector<unsigned int> neighbors(unsigned int i[3]) const {
        std::vector<unsigned int> n(6,0); // allocate space for 6 neighbors
        n.resize(0);
        // tmp copy index
        unsigned int j[3];
        for (unsigned int d=0; d<dim; d++)
            j[d] = i[d];
        // create neighbors
        for (unsigned int d=0; d<dim; d++) {
            // left
            j[d]--;
            if (i[d] > 0)
                n.push_back(index(j));
            j[d]++;
            j[d]++;
            // right
            if (i[d] < N[d])
                n.push_back(index(j));
            j[d]--;
        }
        return n;
    }
private:
    // domain
    const unsigned int dim;
    unsigned int N[3];
    const double h;
};

#endif // TURING_GRID_HH