package main

import (
	"fmt"
	"gonum.org/v1/hdf5"
	"math/rand"
	"time"
)


// generate an array of random numbers in range
func randomFloat64(low float64, high float64, size int) []float64 {
	res := make([]float64, size)
	for i := range res {
		res[i] = low + rand.Float64() * (high - low)
	}
	return res
}


// write image data to HDF5 file
func writeImageData(fileName string, image []float64, height int, width int) {
	// create a new HDF5 file
	file, err := hdf5.CreateFile(fileName, hdf5.F_ACC_TRUNC)
	if err != nil {
		panic(err)
	}
	defer file.Close()

	// create a Dataspace of size 'len(image)'
	dims := []uint{uint(len(image))}
	space, err := hdf5.CreateSimpleDataspace(dims, nil)
	if err != nil {
		panic("Failed to create image Dataspace")
	}

	// create a Datatype from the image type
	dtype, err := hdf5.NewDatatypeFromValue(image[0])
	if err != nil {
		panic("Failed to create dtype")
	}

	// create the Dataset itself
	dataset, err := file.CreateDataset("data", dtype, space)

	// write the image data to the dataset
	err = dataset.Write(&image)
	if err != nil {
		panic("Failed to write image data")
	}

	scalar, err := hdf5.CreateDataspace(hdf5.S_SCALAR)
	if err != nil {
		panic("Failed to create scalar dataspace")
	}

	var timestamp = time.Now().UnixNano() / 1000000000  // time in seconds

	heightAttr, err := dataset.CreateAttribute("height", hdf5.T_NATIVE_UINT32, scalar)
	heightAttr.Write(&height, hdf5.T_NATIVE_UINT32)
	heightAttr.Close()

	widthAttr, err := dataset.CreateAttribute("width", hdf5.T_NATIVE_UINT32, scalar)
	widthAttr.Write(&width, hdf5.T_NATIVE_UINT32)
	widthAttr.Close()

	timeAttr, err := dataset.CreateAttribute("timestamp", hdf5.T_NATIVE_FLOAT, scalar)
	timeAttr.Write(&timestamp, hdf5.T_NATIVE_FLOAT)
	timeAttr.Close()

	// close dataset & file
	dataset.Close()
	file.Close()

}


func main(){
	height := 10
	width := 10
	arr := randomFloat64(0.0, 1.0, height * width)
	writeImageData("alt.h5", arr, height, width)
	fmt.Println(arr)
}