package main

import (
    "bytes"

    "github.com/celestiaorg/rsmt2d"
)

func main() {
    // Size of each share, in bytes
    bufferSize := 64
    // Init new codec
    codec := rsmt2d.NewLeoRSFF8Codec()

    ones := bytes.Repeat([]byte{1}, bufferSize)
    twos := bytes.Repeat([]byte{2}, bufferSize)
    threes := bytes.Repeat([]byte{3}, bufferSize)
    fours := bytes.Repeat([]byte{4}, bufferSize)

    // Compute parity shares
    eds, err := rsmt2d.ComputeExtendedDataSquare(
        [][]byte{
            ones, twos,
            threes, fours,
        },
        codec,
        rsmt2d.NewDefaultTree,
    )
    if err != nil {
        // ComputeExtendedDataSquare failed
    }

    // Save all shares in flattened form.
    flattened := make([][]byte, 0, eds.Width()*eds.Width())
    for i := uint(0); i < eds.Width(); i++ {
        flattened = append(flattened, eds.Row(i)...)
    }

    // Delete some shares, just enough so that repairing is possible.
    flattened[0], flattened[2], flattened[3] = nil, nil, nil
    flattened[4], flattened[5], flattened[6], flattened[7] = nil, nil, nil, nil
    flattened[8], flattened[9], flattened[10] = nil, nil, nil
    flattened[12], flattened[13] = nil, nil

    // Repair square.
    repaired, err := rsmt2d.RepairExtendedDataSquare(
        eds.RowRoots(),
        eds.ColRoots(),
        flattened,
        codec,
        rsmt2d.NewDefaultTree,
    )
    if err != nil {
        // err contains information to construct a fraud proof
        // See extendeddatacrossword_test.go
    }
    _ = repaired
}