#include <stdio.h>
#include <stdlib.h>

#include "spglib.h"

static void example_spg_get_symmetry(void);
static void example_spg_get_symmetry_with_collinear_spin(void);
static void example_spg_get_multiplicity(void);
static void example_spg_find_primitive_BCC(void);
static void example_spg_find_primitive_corundum(void);
static void example_spg_standardize_cell_BCC(void);
static void example_spg_standardize_cell_BCC_prim(void);
static void example_spg_standardize_cell_corundum(void);
static void example_spg_get_international(void);
static void example_spg_get_schoenflies(void);
static void example_spg_get_spacegroup_type(void);
static void example_spg_get_magnetic_spacegroup_type(void);
static void example_spg_get_symmetry_from_database(void);
static void example_spg_refine_cell_BCC(void);
static void example_spg_get_dataset(void);
static void example_layer_spg_get_dataset(void);
static void example_spg_get_ir_reciprocal_mesh(void);
static void example_spg_get_error_message(void);
static void show_spg_dataset(double lattice[3][3], double const origin_shift[3],
                             double position[][3], int const num_atom,
                             int const types[]);
static void show_layer_spg_dataset(double lattice[3][3],
                                   double const origin_shift[3],
                                   double position[][3], int const num_atom,
                                   int const types[], int const aperiodic_axis,
                                   double const symprec);
static void show_cell(double lattice[3][3], double position[][3],
                      int const types[], int const num_atom);
static void sub_spg_standardize_cell(double lattice[3][3], double position[][3],
                                     int types[], int const num_atom,
                                     double const symprec,
                                     int const to_primitive,
                                     int const no_idealize);

// Windows C compilers do not accept variable length array. Need to use a macro
#define max_size -1

int main(int argc, char *argv[]) {
    example_spg_find_primitive_BCC();
    example_spg_find_primitive_corundum();
    example_spg_standardize_cell_BCC();
    example_spg_standardize_cell_BCC_prim();
    example_spg_standardize_cell_corundum();
    example_spg_get_multiplicity();
    example_spg_get_symmetry();
    example_spg_get_symmetry_with_collinear_spin();
    example_spg_get_international();
    example_spg_get_schoenflies();
    example_spg_get_spacegroup_type();
    example_spg_get_magnetic_spacegroup_type();
    example_spg_get_symmetry_from_database();
    example_spg_refine_cell_BCC();
    example_spg_get_dataset();
    example_layer_spg_get_dataset();
    example_spg_get_ir_reciprocal_mesh();
    example_spg_get_error_message();

    return 0;
}

static void example_spg_find_primitive_BCC(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 4}};
    double position[][3] = {{0, 0, 0}, {0.5, 0.5, 0.5}};
    int types[] = {1, 1};
    int num_atom = 2;
    double symprec = 1e-5;

    /* lattice, position, and types are overwritten. */
    printf(
        "*** Example of spg_find_primitive (BCC unitcell --> primitive) "
        "***:\n");
    int num_primitive_atom =
        spg_find_primitive(lattice, position, types, num_atom, symprec);
    if (num_primitive_atom == 0) {
        printf("Primitive cell was not found.\n");
    } else {
        show_cell(lattice, position, types, num_primitive_atom);
    }
}

static void example_spg_find_primitive_corundum(void) {
    double lattice[3][3] = {{4.8076344022756095, -2.4038172011378047, 0},
                            {0, 4.1635335244786962, 0},
                            {0, 0, 13.1172699198127543}};
    double position[][3] = {
        {0.0000000000000000, 0.0000000000000000, 0.3521850942289043},
        {0.6666666666666643, 0.3333333333333357, 0.6855184275622400},
        {0.3333333333333357, 0.6666666666666643, 0.0188517608955686},
        {0.0000000000000000, 0.0000000000000000, 0.6478149057711028},
        {0.6666666666666643, 0.3333333333333357, 0.9811482391044314},
        {0.3333333333333357, 0.6666666666666643, 0.3144815724377600},
        {0.0000000000000000, 0.0000000000000000, 0.1478149057710957},
        {0.6666666666666643, 0.3333333333333357, 0.4811482391044314},
        {0.3333333333333357, 0.6666666666666643, 0.8144815724377600},
        {0.0000000000000000, 0.0000000000000000, 0.8521850942288972},
        {0.6666666666666643, 0.3333333333333357, 0.1855184275622400},
        {0.3333333333333357, 0.6666666666666643, 0.5188517608955686},
        {0.3061673906454899, 0.0000000000000000, 0.2500000000000000},
        {0.9728340573121541, 0.3333333333333357, 0.5833333333333357},
        {0.6395007239788255, 0.6666666666666643, 0.9166666666666643},
        {0.6938326093545102, 0.0000000000000000, 0.7500000000000000},
        {0.3604992760211744, 0.3333333333333357, 0.0833333333333357},
        {0.0271659426878458, 0.6666666666666643, 0.4166666666666643},
        {0.0000000000000000, 0.3061673906454899, 0.2500000000000000},
        {0.6666666666666643, 0.6395007239788255, 0.5833333333333357},
        {0.3333333333333357, 0.9728340573121541, 0.9166666666666643},
        {0.0000000000000000, 0.6938326093545102, 0.7500000000000000},
        {0.6666666666666643, 0.0271659426878458, 0.0833333333333357},
        {0.3333333333333357, 0.3604992760211744, 0.4166666666666643},
        {0.6938326093545102, 0.6938326093545102, 0.2500000000000000},
        {0.3604992760211744, 0.0271659426878458, 0.5833333333333357},
        {0.0271659426878458, 0.3604992760211744, 0.9166666666666643},
        {0.3061673906454899, 0.3061673906454899, 0.7500000000000000},
        {0.9728340573121541, 0.6395007239788255, 0.0833333333333357},
        {0.6395007239788255, 0.9728340573121541, 0.4166666666666643},
    };
    int types[30];
    int num_atom = 30;
    double symprec = 1e-5;

    for (int i = 0; i < 12; i++) {
        types[i] = 1;
    }
    for (int i = 12; i < 30; i++) {
        types[i] = 2;
    }

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_find_primitive (Corundum) ***:\n");
    int num_primitive_atom =
        spg_find_primitive(lattice, position, types, num_atom, symprec);
    if (num_primitive_atom == 0) {
        printf("Primitive cell was not found.\n");
    } else {
        show_cell(lattice, position, types, num_primitive_atom);
    }
}

static void example_spg_refine_cell_BCC(void) {
    double lattice[3][3] = {{0, 2, 2}, {2, 0, 2}, {2, 2, 0}};

    /* 4 times larger memory space must be prepared. */
    double position[4][3];
    int types[4];

    int num_atom = 1;
    double symprec = 1e-5;

    position[0][0] = 0;
    position[0][1] = 0;
    position[0][2] = 0;
    types[0] = 1;

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_refine_cell ***:\n");
    int num_atom_bravais =
        spg_refine_cell(lattice, position, types, num_atom, symprec);
    show_cell(lattice, position, types, num_atom_bravais);
}

static void example_spg_standardize_cell_BCC(void) {
    double lattice[3][3] = {{3.97, 0, 0}, {0, 4.03, 0}, {0, 0, 4.0}};
    double position[][3] = {{0.002, 0, 0}, {0.5, 0.5001, 0.5}};
    int types[] = {1, 1};
    int num_atom = 2;
    double symprec = 1e-1;

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_standardize_cell (BCC unitcell) ***:\n");
    printf("------------------------------------------------------\n");
    for (int j = 0; j < 2; j++) {
        for (int k = 0; k < 2; k++) {
            sub_spg_standardize_cell(lattice, position, types, num_atom,
                                     symprec, j, k);
            printf("------------------------------------------------------\n");
        }
    }
}

static void example_spg_standardize_cell_BCC_prim(void) {
    double lattice[3][3] = {{-2.01, 2, 2}, {2, -2.02, 2}, {2, 2, -2.03}};
    double position[][3] = {
        {0.002, 0, 0},
    };
    int types[] = {1};
    int num_atom = 1;
    double symprec = 1e-1;

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_standardize_cell (BCC primitive) ***:\n");
    printf("------------------------------------------------------\n");
    for (int j = 0; j < 2; j++) {
        for (int k = 0; k < 2; k++) {
            sub_spg_standardize_cell(lattice, position, types, num_atom,
                                     symprec, j, k);
            printf("------------------------------------------------------\n");
        }
    }
}

static void example_spg_standardize_cell_corundum(void) {
    double lattice[3][3] = {{4.8076344022756095, -2.4038172011378047, 0},
                            {0, 4.1635335244786962, 0},
                            {0, 0, 13.1172699198127543}};
    double position[][3] = {
        {0.0000000000000000, 0.0000000000000000, 0.3521850942289043},
        {0.6666666666666643, 0.3333333333333357, 0.6855184275622400},
        {0.3333333333333357, 0.6666666666666643, 0.0188517608955686},
        {0.0000000000000000, 0.0000000000000000, 0.6478149057711028},
        {0.6666666666666643, 0.3333333333333357, 0.9811482391044314},
        {0.3333333333333357, 0.6666666666666643, 0.3144815724377600},
        {0.0000000000000000, 0.0000000000000000, 0.1478149057710957},
        {0.6666666666666643, 0.3333333333333357, 0.4811482391044314},
        {0.3333333333333357, 0.6666666666666643, 0.8144815724377600},
        {0.0000000000000000, 0.0000000000000000, 0.8521850942288972},
        {0.6666666666666643, 0.3333333333333357, 0.1855184275622400},
        {0.3333333333333357, 0.6666666666666643, 0.5188517608955686},
        {0.3061673906454899, 0.0000000000000000, 0.2500000000000000},
        {0.9728340573121541, 0.3333333333333357, 0.5833333333333357},
        {0.6395007239788255, 0.6666666666666643, 0.9166666666666643},
        {0.6938326093545102, 0.0000000000000000, 0.7500000000000000},
        {0.3604992760211744, 0.3333333333333357, 0.0833333333333357},
        {0.0271659426878458, 0.6666666666666643, 0.4166666666666643},
        {0.0000000000000000, 0.3061673906454899, 0.2500000000000000},
        {0.6666666666666643, 0.6395007239788255, 0.5833333333333357},
        {0.3333333333333357, 0.9728340573121541, 0.9166666666666643},
        {0.0000000000000000, 0.6938326093545102, 0.7500000000000000},
        {0.6666666666666643, 0.0271659426878458, 0.0833333333333357},
        {0.3333333333333357, 0.3604992760211744, 0.4166666666666643},
        {0.6938326093545102, 0.6938326093545102, 0.2500000000000000},
        {0.3604992760211744, 0.0271659426878458, 0.5833333333333357},
        {0.0271659426878458, 0.3604992760211744, 0.9166666666666643},
        {0.3061673906454899, 0.3061673906454899, 0.7500000000000000},
        {0.9728340573121541, 0.6395007239788255, 0.0833333333333357},
        {0.6395007239788255, 0.9728340573121541, 0.4166666666666643},
    };
    int types[30];
    int num_atom = 30;
    double symprec = 1e-5;

    for (int i = 0; i < 12; i++) {
        types[i] = 1;
    }
    for (int i = 12; i < 30; i++) {
        types[i] = 2;
    }

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_standardize_cell (Corundum) ***:\n");
    printf("------------------------------------------------------\n");
    for (int j = 0; j < 2; j++) {
        for (int k = 0; k < 2; k++) {
            sub_spg_standardize_cell(lattice, position, types, num_atom,
                                     symprec, j, k);
            printf("------------------------------------------------------\n");
        }
    }
}

static void example_spg_get_international(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 3}};
    double position[][3] = {
        {0, 0, 0},     {0.5, 0.5, 0.5}, {0.3, 0.3, 0},
        {0.7, 0.7, 0}, {0.2, 0.8, 0.5}, {0.8, 0.2, 0.5},
    };
    int types[] = {1, 1, 2, 2, 2, 2};
    int num_atom = 6;
    char symbol[21];

    int num_spg =
        spg_get_international(symbol, lattice, position, types, num_atom, 1e-5);
    printf("*** Example of spg_get_international ***:\n");
    if (num_spg > 0) {
        printf("%s (%d)\n", symbol, num_spg);
    } else {
        printf("Space group could not be found.\n");
    }
}

static void example_spg_get_schoenflies(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 3}};
    double position[][3] = {
        {0, 0, 0},     {0.5, 0.5, 0.5}, {0.3, 0.3, 0},
        {0.7, 0.7, 0}, {0.2, 0.8, 0.5}, {0.8, 0.2, 0.5},
    };
    int types[] = {1, 1, 2, 2, 2, 2};
    int num_atom = 6;
    char symbol[7];

    spg_get_schoenflies(symbol, lattice, position, types, num_atom, 1e-5);
    printf("*** Example of spg_get_schoenflies ***:\n");
    printf("Schoenflies: %s\n", symbol);
}

static void example_spg_get_spacegroup_type(void) {
    SpglibSpacegroupType spgtype;
    spgtype = spg_get_spacegroup_type(446);

    printf("*** Example of spg_get_spacegroup_type ***:\n");
    printf("Number:        %d\n", spgtype.number);
    printf("Schoenflies:   %s\n", spgtype.schoenflies);
    printf("International: %s\n", spgtype.international);
    printf("International: %s\n", spgtype.international_full);
    printf("International: %s\n", spgtype.international_short);
    printf("Hall symbol:   %s\n", spgtype.hall_symbol);
}

static void example_spg_get_magnetic_spacegroup_type(void) {
    SpglibMagneticSpacegroupType msgtype;
    msgtype = spg_get_magnetic_spacegroup_type(1279);

    printf("*** Example of spg_get_magnetic_spacegroup_type ***:\n");
    printf("UNI Number:    %d\n", msgtype.uni_number);
    printf("Litvin Number: %d\n", msgtype.litvin_number);
    printf("BNS Number:    %s\n", msgtype.bns_number);
    printf("OG Number:     %s\n", msgtype.og_number);
    printf("Number:        %d\n", msgtype.number);
    printf("Type:          %d\n", msgtype.type);
}

static void example_spg_get_symmetry_from_database(void) {
    int rotations[192][3][3];
    double translations[192][3];

    int size = spg_get_symmetry_from_database(rotations, translations, 460);

    printf("*** Example of spg_get_symmetry_from_database ***:\n");
    for (int i = 0; i < size; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", rotations[i][j][0], rotations[i][j][1],
                   rotations[i][j][2]);
        }
        printf("%f %f %f\n", translations[i][0], translations[i][1],
               translations[i][2]);
    }
}

static void example_spg_get_multiplicity(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 4}};
    double position[][3] = {{0, 0, 0}, {0.5, 0.5, 0.5}};
    int types[] = {1, 2};
    int num_atom = 2;

    int size = spg_get_multiplicity(lattice, position, types, num_atom, 1e-5);

    printf("*** Example of spg_get_multiplicity ***:\n");
    printf("Number of symmetry operations: %d\n", size);
}

static void example_spg_get_symmetry(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 3}};
    double position[][3] = {
        {0, 0, 0},        {0.5, 0.5, 0.25}, {0.3, 0.3, 0},    {0.7, 0.7, 0},
        {0.2, 0.8, 0.25}, {0.8, 0.2, 0.25}, {0, 0, 0.5},      {0.5, 0.5, 0.75},
        {0.3, 0.3, 0.5},  {0.7, 0.7, 0.5},  {0.2, 0.8, 0.75}, {0.8, 0.2, 0.75}};
    int types[] = {1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2};
    int num_atom = 12;
#undef max_size
#define max_size 50
    int rotation[max_size][3][3];
    double translation[max_size][3];

    double origin_shift[3] = {0.1, 0.1, 0};
    for (int i = 0; i < num_atom; i++) {
        for (int j = 0; j < 3; j++) {
            position[i][j] += origin_shift[j];
        }
    }

    printf("*** Example of spg_get_symmetry (Rutile two unit cells) ***:\n");
    int size = spg_get_symmetry(rotation, translation, max_size, lattice,
                                position, types, num_atom, 1e-5);
    for (int i = 0; i < size; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++)
            printf("%2d %2d %2d\n", rotation[i][j][0], rotation[i][j][1],
                   rotation[i][j][2]);
        printf("%f %f %f\n", translation[i][0], translation[i][1],
               translation[i][2]);
    }
}

static void example_spg_get_symmetry_with_collinear_spin(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 4}};
    double position[][3] = {{0, 0, 0}, {0.5, 0.5, 0.5}};
    int types[] = {1, 1};
    int equivalent_atoms[2];
    double spins[2];
    int num_atom = 2;
#undef max_size
#define max_size 300
    int rotation[max_size][3][3];
    double translation[max_size][3];

    printf("*** Example of spg_get_symmetry_with_spin (BCC ferro) ***:\n");
    spins[0] = 1;
    spins[1] = 1;
    int size = spg_get_symmetry_with_collinear_spin(
        rotation, translation, equivalent_atoms, max_size, lattice, position,
        types, spins, num_atom, 1e-5);
    for (int i = 0; i < size; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", rotation[i][j][0], rotation[i][j][1],
                   rotation[i][j][2]);
        }
        printf("%f %f %f\n", translation[i][0], translation[i][1],
               translation[i][2]);
    }

    printf("*** Example of spg_get_symmetry_with_spin (BCC antiferro) ***:\n");
    spins[0] = 1;
    spins[1] = -1;
    size = spg_get_symmetry_with_collinear_spin(
        rotation, translation, equivalent_atoms, max_size, lattice, position,
        types, spins, num_atom, 1e-5);
    for (int i = 0; i < size; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", rotation[i][j][0], rotation[i][j][1],
                   rotation[i][j][2]);
        }
        printf("%f %f %f\n", translation[i][0], translation[i][1],
               translation[i][2]);
    }

    printf(
        "*** Example of spg_get_symmetry_with_spin (BCC broken spin) ***:\n");
    spins[0] = 1;
    spins[1] = 2;
    size = spg_get_symmetry_with_collinear_spin(
        rotation, translation, equivalent_atoms, max_size, lattice, position,
        types, spins, num_atom, 1e-5);
    for (int i = 0; i < size; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", rotation[i][j][0], rotation[i][j][1],
                   rotation[i][j][2]);
        }
        printf("%f %f %f\n", translation[i][0], translation[i][1],
               translation[i][2]);
    }
}

static void example_spg_get_dataset(void) {
    printf("*** Example of spg_get_dataset (Rutile two unit cells) ***:\n");
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 3}};
    double origin_shift[3] = {0.1, 0.1, 0};
    double position[][3] = {
        {0, 0, 0},        {0.5, 0.5, 0.25}, {0.3, 0.3, 0},    {0.7, 0.7, 0},
        {0.2, 0.8, 0.25}, {0.8, 0.2, 0.25}, {0, 0, 0.5},      {0.5, 0.5, 0.75},
        {0.3, 0.3, 0.5},  {0.7, 0.7, 0.5},  {0.2, 0.8, 0.75}, {0.8, 0.2, 0.75}};
    int types[] = {1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2};
    int num_atom = 12;

    show_spg_dataset(lattice, origin_shift, position, num_atom, types);

    double lattice_2[3][3] = {{3.7332982433264039, -1.8666491216632011, 0},
                              {0, 3.2331311186244847, 0},
                              {0, 0, 6.0979971306362799}};
    double origin_shift_2[3] = {0.1, 0.1, 0};
    double position_2[][3] = {
        {0, 0, 0},
        {1.0 / 3, 2.0 / 3, 0.4126},
        {1.0 / 3, 2.0 / 3, 0.776},
        {2.0 / 3, 1.0 / 3, 0.2542},
    };
    int types_2[] = {1, 2, 3, 3};
    int num_atom_2 = 4;

    show_spg_dataset(lattice_2, origin_shift_2, position_2, num_atom_2,
                     types_2);
}

static void example_layer_spg_get_dataset(void) {
    printf("*** Example of layer_spg_get_dataset ***:\n");

    /* Xene symprec 1e-5: p-1 (Triclinic) */
    /*              1e-4: c112/m (Monoclinic/Oblique). */
    /*              1e-3: cmmm (Orthorhombic). */
    /*              1e-2: p6/mmm (Hexagonal). */
    double lattice[3][3] = {
        {20.0, 0.0, 0.0000}, {0.0, 4.0, -2.0010}, {0.0, 0.0, 3.4641}};
    double origin_shift[3] = {0.3, 0.0, 0.0};
    double position[][3] = {
        {0.000000, 0.0000, 0.0000},
        {0.000001, 0.3334, 0.6667},
    };
    int types[] = {1, 1};
    int num_atom = 2;
    for (double symprec = 1e-5; symprec < 2e-2; symprec *= 10) {
        show_layer_spg_dataset(lattice, origin_shift, position, num_atom, types,
                               0, symprec);
    }

    /* GaN5I2 symprec 1e-4: cm11 (Monoclinic/Rectangular). */
    /*                1e-3: cm2m (Orthorhombic). */
    /*                1e-2: p4/mmm (Tetragonal). */
    double lattice_2[3][3] = {{3.7861136610483701, 0.0, 0.0},
                              {0.0, 3.7861136610483701, 0.0},
                              {0.0, 0.0, 22.2546809901819991}};
    double origin_shift_2[3] = {0.0, 0.0, 0.0};
    double position_2[][3] = {
        {0.0134919406682438, 0.0134919406682438, 0.4999899437563405},
        {0.5136679699653063, 0.0138303351393375, 0.4268265479223690},
        {0.0138303351393375, 0.5136679699653063, 0.4268265479223690},
        {0.5136704479454860, 0.0138304557132967, 0.5731524477251689},
        {0.0138304557132967, 0.5136704479454860, 0.5731524477251689},
        {0.5135072137498097, 0.5135072137498097, 0.4999893856576149},
        {0.0136291019141326, 0.0136291019141326, 0.3467295769718007},
        {0.0136271585836537, 0.0136271585836537, 0.6532704844322105},
    };
    int types_2[] = {1, 1, 1, 1, 1, 2, 3, 3};
    int num_atom_2 = 8;
    for (double symprec = 1e-4; symprec < 2e-2; symprec *= 10) {
        show_layer_spg_dataset(lattice_2, origin_shift_2, position_2,
                               num_atom_2, types_2, 2, symprec);
    }
}

static void example_spg_get_ir_reciprocal_mesh(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 3}};
    double position[][3] = {
        {0, 0, 0},     {0.5, 0.5, 0.5}, {0.3, 0.3, 0},
        {0.7, 0.7, 0}, {0.2, 0.8, 0.5}, {0.8, 0.2, 0.5},
    };
    int types[] = {1, 1, 2, 2, 2, 2};
    int num_atom = 6;
#undef max_size
#define max_size 40
    int mesh[] = {max_size, max_size, max_size};
    int is_shift[] = {1, 1, 1};
    int grid_address[max_size * max_size * max_size][3];
    int grid_mapping_table[max_size * max_size * max_size];

    printf(
        "*** Example of spg_get_ir_reciprocal_mesh of Rutile structure ***:\n");

    int num_ir = spg_get_ir_reciprocal_mesh(grid_address, grid_mapping_table,
                                            mesh, is_shift, 1, lattice,
                                            position, types, num_atom, 1e-5);

    printf("Number of irreducible k-points of Rutile with\n");
    printf("40x40x40 Monkhorst-Pack mesh is %d (4200).\n", num_ir);
}

static void example_spg_get_error_message(void) {
    double lattice[3][3] = {{4, 0, 0}, {0, 4, 0}, {0, 0, 4}};
    double position[][3] = {{0, 0, 0}, {0.5, 0.5, 0.5}, {0.5, 0.5, 0.5}};
    int types[] = {1, 1, 1};
    int num_atom = 3;
    double symprec = 1e-5;
    SpglibError error;

    /* lattice, position, and types are overwritten. */
    printf("*** Example of spg_get_error_message ***:\n");
    int num_primitive_atom =
        spg_find_primitive(lattice, position, types, num_atom, symprec);
    if (num_primitive_atom == 0) {
        printf("Primitive cell was not found.\n");
        error = spg_get_error_code();
        printf("%s\n", spg_get_error_message(error));
    }
}

static void show_spg_dataset(double lattice[3][3], double const origin_shift[3],
                             double position[][3], int const num_atom,
                             int const types[]) {
    SpglibDataset *dataset;
    char ptsymbol[6];
    int pt_trans_mat[3][3];

    char const *wl = "abcdefghijklmnopqrstuvwxyz";

    for (int i = 0; i < num_atom; i++) {
        for (int j = 0; j < 3; j++) {
            position[i][j] += origin_shift[j];
        }
    }

    dataset = spg_get_dataset(lattice, position, types, num_atom, 1e-5);

    printf("International: %s (%d)\n", dataset->international_symbol,
           dataset->spacegroup_number);
    printf("Hall symbol:   %s\n", dataset->hall_symbol);
    spg_get_pointgroup(ptsymbol, pt_trans_mat, dataset->rotations,
                       dataset->n_operations);
    printf("Point group:   %s\n", ptsymbol);
    printf("Transformation matrix:\n");
    for (int i = 0; i < 3; i++) {
        printf("%f %f %f\n", dataset->transformation_matrix[i][0],
               dataset->transformation_matrix[i][1],
               dataset->transformation_matrix[i][2]);
    }
    printf("Wyckoff letters:\n");
    for (int i = 0; i < dataset->n_atoms; i++) {
        printf("%c ", wl[dataset->wyckoffs[i]]);
    }
    printf("\n");
    printf("Equivalent atoms:\n");
    for (int i = 0; i < dataset->n_atoms; i++) {
        printf("%d ", dataset->equivalent_atoms[i]);
    }
    printf("\n");

    for (int i = 0; i < dataset->n_operations; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", dataset->rotations[i][j][0],
                   dataset->rotations[i][j][1], dataset->rotations[i][j][2]);
        }
        printf("%f %f %f\n", dataset->translations[i][0],
               dataset->translations[i][1], dataset->translations[i][2]);
    }

    spg_free_dataset(dataset);
}

static void show_layer_spg_dataset(double lattice[3][3],
                                   double const origin_shift[3],
                                   double position[][3], int const num_atom,
                                   int const types[], int const aperiodic_axis,
                                   double const symprec) {
    SpglibDataset *dataset;
    char ptsymbol[6];
    int pt_trans_mat[3][3];

    char const *wl = "abcdefghijklmnopqrstuvwxyz";

    for (int i = 0; i < num_atom; i++) {
        for (int j = 0; j < 3; j++) {
            position[i][j] += origin_shift[j];
        }
    }

    dataset = spg_get_layer_dataset(lattice, position, types, num_atom,
                                    aperiodic_axis, symprec);

    printf("International: %s (%d)\n", dataset->international_symbol,
           dataset->spacegroup_number);
    printf("Hall symbol:   %s\n", dataset->hall_symbol);
    spg_get_pointgroup(ptsymbol, pt_trans_mat, dataset->rotations,
                       dataset->n_operations);
    printf("Point group:   %s\n", ptsymbol);
    printf("Transformation matrix:\n");
    for (int i = 0; i < 3; i++) {
        printf("%f %f %f\n", dataset->transformation_matrix[i][0],
               dataset->transformation_matrix[i][1],
               dataset->transformation_matrix[i][2]);
    }
    printf("Wyckoff letters:\n");
    for (int i = 0; i < dataset->n_atoms; i++) {
        printf("%c ", wl[dataset->wyckoffs[i]]);
    }
    printf("\n");
    printf("Equivalent atoms:\n");
    for (int i = 0; i < dataset->n_atoms; i++) {
        printf("%d ", dataset->equivalent_atoms[i]);
    }
    printf("\n");

    for (int i = 0; i < dataset->n_operations; i++) {
        printf("--- %d ---\n", i + 1);
        for (int j = 0; j < 3; j++) {
            printf("%2d %2d %2d\n", dataset->rotations[i][j][0],
                   dataset->rotations[i][j][1], dataset->rotations[i][j][2]);
        }
        printf("%f %f %f\n", dataset->translations[i][0],
               dataset->translations[i][1], dataset->translations[i][2]);
    }

    spg_free_dataset(dataset);
}

static void sub_spg_standardize_cell(double lattice[3][3], double position[][3],
                                     int types[], int const num_atom,
                                     double const symprec,
                                     int const to_primitive,
                                     int const no_idealize) {
    double lat[3][3], (*pos)[3];
    int *typ;

    pos = (double (*)[3])malloc(sizeof(double[3]) * 4 * num_atom);
    typ = (int *)malloc(sizeof(int) * 4 * num_atom);

    for (int i = 0; i < 3; i++) {
        lat[i][0] = lattice[i][0];
        lat[i][1] = lattice[i][1];
        lat[i][2] = lattice[i][2];
    }

    for (int i = 0; i < num_atom; i++) {
        pos[i][0] = position[i][0];
        pos[i][1] = position[i][1];
        pos[i][2] = position[i][2];
        typ[i] = types[i];
    }

    /* lattice, position, and types are overwritten. */
    int num_primitive_atom = spg_standardize_cell(
        lat, pos, typ, num_atom, to_primitive, no_idealize, symprec);
    printf("VASP POSCAR format: ");
    if (to_primitive == 0) {
        printf("to_primitive=0 and ");
    } else {
        printf("to_primitive=1 and ");
    }

    if (no_idealize == 0) {
        printf("no_idealize=0\n");
    } else {
        printf("no_idealize=1\n");
    }
    printf("1.0\n");
    for (int i = 0; i < 3; i++) {
        printf("%f %f %f\n", lat[0][i], lat[1][i], lat[2][i]);
    }
    printf("%d\n", num_primitive_atom);
    printf("Direct\n");
    for (int i = 0; i < num_primitive_atom; i++) {
        printf("%f %f %f\n", pos[i][0], pos[i][1], pos[i][2]);
    }

    free(typ);
    typ = NULL;
    free(pos);
    pos = NULL;
}

static void show_cell(double lattice[3][3], double position[][3],
                      int const types[], int const num_atom) {
    printf("Lattice parameter:\n");
    for (int i = 0; i < 3; i++) {
        printf("%f %f %f\n", lattice[0][i], lattice[1][i], lattice[2][i]);
    }
    printf("Atomic positions:\n");
    for (int i = 0; i < num_atom; i++) {
        printf("%d: %f %f %f\n", types[i], position[i][0], position[i][1],
               position[i][2]);
    }
}