package erasure_coding

import (
	"io"
	"os"

	"github.com/klauspost/reedsolomon"
)

const (
	DataShardsCount             = 10
	ParityShardsCount           = 4
	ErasureCodingLargeBlockSize = 1024 * 1024 * 1024 // 1GB
	ErasureCodingSmallBlockSize = 1024 * 1024        // 1MB
)

func encodeData(file *os.File, enc reedsolomon.Encoder, startOffset, blockSize int64, buffers [][]byte) error {

	// read data into buffers
	for i := 0; i < DataShardsCount; i++ {
		n, err := file.ReadAt(buffers[i], startOffset+blockSize*int64(i))
		if err != nil {
			if err != io.EOF {
				return err
			}
		}
		if n < len(buffers[i]) {
			for t := len(buffers[i]) - 1; t >= n; t-- {
				buffers[i][t] = 0
			}
		}
	}

	err := enc.Encode(buffers)
	if err != nil {
		return err
	}

	return nil
}