package utils

import (
	"bytes"
	"fmt"
)

// Uint24 represents an integer existing out of 3 bytes. It is actually a
// uint32, but is an alias for the sake of clarity.
type Uint24 uint32

// ReadUint24 reads 3 bytes from the buffer passed and combines it into a
// uint24. If there were no 3 bytes to read, an error is returned.
func ReadUint24(b *bytes.Buffer) (Uint24, error) {
	ba, _ := b.ReadByte()
	bb, _ := b.ReadByte()
	bc, err := b.ReadByte()
	if err != nil {
		return 0, fmt.Errorf("error reading uint24: %v", err)
	}
	return Uint24(ba) | (Uint24(bb) << 8) | (Uint24(bc) << 16), nil
}

// WriteUint24 writes a uint24 to the buffer passed as 3 bytes. If not
// successful, an error is returned.
func WriteUint24(b *bytes.Buffer, value Uint24) {
	b.WriteByte(byte(value))
	b.WriteByte(byte(value >> 8))
	b.WriteByte(byte(value >> 16))
}