package utils

import (
	"encoding/binary"
	"log"
	"math"
	"os"
	"unsafe"
)

func ReadByteFromFile(file *os.File, size int32) []byte {
	tmp := make([]byte, size)
	file.Read(tmp)
	return tmp
}

func CheckError(e error) {
	if e != nil {
		log.Panic(e)
	}
}

/*
github.com/32bitkid/bitreader

	func ReadBitsWithFirstBitCheckFromFile(file *os.File) (byteArr []byte, err error) {
		arr := make([]byte, 4)
		reader := bitreader.NewReader(file)
		n := 0
		state, err := reader.Read1()
		if err != nil || state == true {
			return nil, fmt.Errorf("ERR or VAL in BIT CHECK")
		}
		n += 1
		if n == 0 {
			val, err := reader.Read32(32)
			if err != nil {
				return nil, fmt.Errorf("ERR or VAL in BIT CHECK")
			}
			binary.LittleEndian.PutUint32(arr, val)
		}
		return arr, nil
	}
*/
func IntFromBytes(byteArr []byte) uint32 {
	int := binary.LittleEndian.Uint32(byteArr)
	return int
}

func FloatFromBytes(byteArr []byte) float32 {
	bits := binary.LittleEndian.Uint32(byteArr)
	float := math.Float32frombits(bits)
	return float
}

func FloatArrFromBytes(byteArr []byte) []float32 {
	if len(byteArr) == 0 {
		return nil
	}

	l := len(byteArr) / 4
	ptr := unsafe.Pointer(&byteArr[0])
	// It is important to keep in mind that the Go garbage collector
	// will not interact with this data, and that if src if freed,
	// the behavior of any Go code using the slice is nondeterministic.
	// Reference: https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
	return (*[1 << 26]float32)((*[1 << 26]float32)(ptr))[:l:l]
}