package types

import (
	"bufio"
	"encoding/binary"
	"errors"
)

func DecodeBits(r *bufio.Reader) ([8]bool, error) {
	bitflags, err := r.ReadByte()
	if err != nil {
		return [8]bool{}, err
	}

	var res [8]bool
	for i := range res {
		res[i] = (bitflags>>i)&1 == 1
	}
	return res, nil
}

func DecodeUint16(r *bufio.Reader) (uint16, error) {
	buf := make([]byte, 2)
	_, err := r.Read(buf)
	if err != nil {
		return 0, err
	}
	return binary.BigEndian.Uint16(buf), nil
}

func DecodeUint32(r *bufio.Reader) (uint32, error) {
	buf := make([]byte, 4)
	_, err := r.Read(buf)
	if err != nil {
		return 0, err
	}
	return binary.BigEndian.Uint32(buf), nil
}

func DecodeDataWithVarIntLen(r *bufio.Reader) ([]byte, error) {
	len, err := DecodeVariableByteInt(r)
	if err != nil {
		return []byte{}, err
	}
	buffer := make([]byte, len)
	_, err = r.Read(buffer)
	return buffer, err
}

func DecodeBinaryData(r *bufio.Reader) ([]byte, error) {
	len, err := DecodeUint16(r)
	if err != nil {
		return []byte{}, err
	}
	buffer := make([]byte, len)
	_, err = r.Read(buffer)
	return buffer, err
}

func DecodeUTF8String(r *bufio.Reader) (string, error) {
	binary, err := DecodeBinaryData(r)
	return string(binary[:]), err
}

func DecodeVariableByteInt(r *bufio.Reader) (value uint32, err error) {
	multiplier := uint32(1)
	value = 0

	for {
		encodedByte, err := r.ReadByte()
		if err != nil {
			return value, err
		}
		value += uint32((encodedByte & 127)) * multiplier
		if multiplier > 128*128*128 {
			return value, errors.New("Malformed Variable Byte Integer")
		}
		multiplier *= 128

		if encodedByte&128 == 0 {
			break
		}
	}
	return value, nil
}