#include "hdf5.h"
#include <string>
#include <vector>
#include <algorithm>
#include <stdexcept>
struct double3 {double x,y,z;
};


void h5_write(const std::string file_name, const int step_num, const int N, const double t, const double *m, const double3 *x, const double3 *v, const double *pot, const double3 *acc, const double3 *jrk, const int write_mode=0, const bool use_double_precision=true)
{
    bool write_pot = (write_mode   )%2;
    bool write_acc = (write_mode>>1)%2;
    bool write_jrk = (write_mode>>2)%2;

    hid_t file_id, group_id, attribute_id, dataset_id, dataspace_id;
    hsize_t dims[2] = {(hsize_t)N, 3};

    hid_t h5_float_type;
    if (use_double_precision) h5_float_type = H5T_IEEE_F64LE;
    else h5_float_type = H5T_IEEE_F32LE;

    file_id = H5Fcreate(file_name.c_str(), H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
    char group_name[32];
    sprintf(group_name, "/Step#%d", step_num);
    group_id = H5Gcreate2(file_id, group_name, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
    dataspace_id = H5Screate(H5S_SCALAR);
    attribute_id = H5Acreate2 (group_id, "Time", H5T_IEEE_F64LE, dataspace_id, H5P_DEFAULT, H5P_DEFAULT);
    H5Awrite(attribute_id, H5T_NATIVE_DOUBLE, &t);
    H5Sclose(dataspace_id);

    auto write_dataset = [&](const char dataset_name[], int ndims, double *data) {
        hid_t dataspace_id = H5Screate_simple(ndims, dims, NULL);
        char dataset_path[32];
        sprintf(dataset_path, "%s/%s", group_name, dataset_name);
        hid_t dataset_id = H5Dcreate2(file_id, dataset_path, h5_float_type, dataspace_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
        H5Dwrite(dataset_id, H5T_NATIVE_DOUBLE, H5S_ALL, H5S_ALL, H5P_DEFAULT, data);
        H5Dclose(dataset_id);
        H5Sclose(dataspace_id);
    };

    write_dataset("MASS", 1, (double*)m);
    write_dataset("X",    2, (double*)x);
    write_dataset("V",    2, (double*)v);
    if (write_pot) write_dataset("POT", 1, (double*)pot);
    if (write_acc) write_dataset("ACC", 2, (double*)acc);
    if (write_jrk) write_dataset("JRK", 2, (double*)jrk);

    H5Gclose(group_id);
    H5Fclose(file_id);
}


void h5_read(const std::string file_name, int *step_num, int *N, double *t, double m[], double3 x[], double3 v[])
{
    // Open file and root group; count number of top level objects
    hid_t file_id = H5Fopen(file_name.c_str(), H5F_ACC_RDONLY, H5P_DEFAULT);
    hid_t group_id = H5Gopen2(file_id, "/", H5P_DEFAULT);
    H5G_info_t object_info;
    H5Gget_info(group_id, &object_info);
    // Iterate over objects and add the number of each "step" group into a vector
    std::vector<int> step_num_arr;
    for (int i=0; i<object_info.nlinks; i++) {
        char name_cstr[256];
        H5Gget_objname_by_idx(group_id, i, name_cstr, 256);
        std::string name(name_cstr);
        if (name.substr(0, 5) == "Step#") step_num_arr.push_back(std::stoi(name.substr(5, std::string::npos)));
    }
    // Find the highest step in the file
    *step_num = *max_element(step_num_arr.begin(), step_num_arr.end());

    // Prepare to read the data sets dimensionality data.
    char dataset_path[256];
    hid_t dataset_id, dataspace_id;
    int ndims;
    hsize_t dims[2];

    sprintf(dataset_path, "/Step#%d/MASS", *step_num);
    dataset_id = H5Dopen2(file_id, dataset_path, H5P_DEFAULT);
    dataspace_id = H5Dget_space(dataset_id);
    ndims = H5Sget_simple_extent_ndims(dataspace_id);
    if (ndims != 1)
        throw std::runtime_error("Dataset MASS in Step#" + std::to_string(*step_num) + " of file " + file_name + " is " + std::to_string(ndims) + "-dimensional (expected 1-dimensional)");
    H5Sget_simple_extent_dims(dataspace_id, dims, NULL);
    H5Dread(dataset_id, H5T_NATIVE_DOUBLE, H5S_ALL, H5S_ALL, H5P_DEFAULT, m);
    *N = dims[0];

    sprintf(dataset_path, "/Step#%d/X", *step_num);
    dataset_id = H5Dopen2(file_id, dataset_path, H5P_DEFAULT);
    dataspace_id = H5Dget_space(dataset_id);
    ndims = H5Sget_simple_extent_ndims(dataspace_id);
    if (ndims != 2) throw std::runtime_error("Dataset X in Step#" + std::to_string(*step_num) + " of file " + file_name + " is " + std::to_string(ndims) + "-dimensional (expected 2-dimensional)");
    H5Sget_simple_extent_dims(dataspace_id, dims, NULL);
    if (dims[0] != *N) throw std::runtime_error("Expected " + std::to_string(*N) + "rows in Dataset X in Step#" + std::to_string(*step_num) + " of file " + file_name + " (based on MASS)");
    if (dims[1] != 3) throw std::runtime_error("Dataset X in Step#" + std::to_string(*step_num) + " of file " + file_name + " has " + std::to_string(dims[1]) + " columns (expected 3 columns)");
    H5Dread(dataset_id, H5T_NATIVE_DOUBLE, H5S_ALL, H5S_ALL, H5P_DEFAULT, (double*)x);

    sprintf(dataset_path, "/Step#%d/V", *step_num);
    dataset_id = H5Dopen2(file_id, dataset_path, H5P_DEFAULT);
    dataspace_id = H5Dget_space(dataset_id);
    ndims = H5Sget_simple_extent_ndims(dataspace_id);
    if (ndims != 2) throw std::runtime_error("Dataset V in Step#" + std::to_string(*step_num) + " of file " + file_name + " is " + std::to_string(ndims) + "-dimensional (expected 2-dimensional)");
    H5Sget_simple_extent_dims(dataspace_id, dims, NULL);
    if (dims[0] != *N) throw std::runtime_error("Expected " + std::to_string(*N) + "rows in Dataset V in Step#" + std::to_string(*step_num) + " of file " + file_name + " (based on MASS)");
    if (dims[1] != 3) throw std::runtime_error("Dataset V in Step#" + std::to_string(*step_num) + " of file " + file_name + " has " + std::to_string(dims[1]) + " columns (expected 3 columns)");
    H5Dread(dataset_id, H5T_NATIVE_DOUBLE, H5S_ALL, H5S_ALL, H5P_DEFAULT, (double*)v);
}


int main()
{
//     double3 aaa;
//     double pot;
    std::string file_name = "new_file.h5";
    int N = 25;
    double3 x[N];
    for (int i=0; i<N; i++) {
        x[i].x=i+0.01;
        x[i].y=i+0.02;
        x[i].z=i+0.03;
    }
    double m[N];
    double3 v[N];
    int step_num;
    double t;
    
    h5_write("123.h5", 17, N, 123.987, (double*)x, x, x, (double*)x, x, x, 7, true);
    h5_read("123.h5", &step_num, &N, &t, m, x, v);
    printf("%d %d %f\n", step_num, N, t);
#error still havent implemented reading the time attribute
    
//     h5_write(file_name, 34, 987.654, N, (double*)x, x, x, (double*)x, x, x, 7);

//     h5_read(file_name, &N, (double*)x, x, x);
//     printf("aaaa %d %d %d\n", ndims, dims[0], dims[1]);
}