package utils

import (
	"bytes"
	"dlt645-server/errors"
	"time"
)

// bytes切割
func BytesSplit(data []byte, limit int) [][]byte {
	var chunk []byte
	chunks := make([][]byte, 0, len(data)/limit+1)
	for len(data) >= limit {
		chunk, data = data[:limit], data[limit:]
		chunks = append(chunks, chunk)
	}
	if len(data) > 0 {
		chunks = append(chunks, data[:len(data)])
	}
	return chunks
}

// bytes转字符串
func BytesToString(data []byte) string {
	n := bytes.IndexByte(data, 0)
	if n == -1 {
		return string(data)
	}
	return string(data[:n])
}

// 字符串转BCD
func StringToBCD(s string, size ...int) []byte {
	if (len(s) & 1) != 0 {
		s = "0" + s
	}

	data := []byte(s)
	bcd := make([]byte, len(s)/2)
	for i := 0; i < len(bcd); i++ {
		high := data[i*2] - '0'
		low := data[i*2+1] - '0'
		bcd[i] = (high << 4) | low
	}

	if len(size) == 0 {
		return bcd
	}

	ret := make([]byte, size[0])
	if size[0] < len(bcd) {
		copy(ret, bcd)
	} else {
		copy(ret[len(ret)-len(bcd):], bcd)
	}
	return ret
}

// BCD转字符串
func BcdToString(data []byte, ignorePadding ...bool) string {
	for {
		if len(data) == 0 {
			return ""
		}
		if data[0] != 0 {
			break
		}
		data = data[1:]
	}

	buf := make([]byte, 0, len(data)*2)
	for i := 0; i < len(data); i++ {
		buf = append(buf, data[i]&0xf0>>4+'0')
		buf = append(buf, data[i]&0x0f+'0')
	}

	if len(ignorePadding) == 0 || !ignorePadding[0] {
		for idx := range buf {
			if buf[idx] != '0' {
				return string(buf[idx:])
			}
		}
	}
	return string(buf)
}

// 转为BCD时间
func ToBCDTime(t time.Time) []byte {
	t = time.Unix(t.Unix(), 0)
	s := t.Format("20060102150405")[2:]
	return StringToBCD(s, 6)
}

// 转为time.Time
func FromBCDTime(bcd []byte) (time.Time, error) {
	if len(bcd) != 6 {
		return time.Time{}, errors.ErrInvalidBCDTime
	}
	t, err := time.ParseInLocation(
		"20060102150405", "20"+BcdToString(bcd), time.Local)
	if err != nil {
		return time.Time{}, err
	}
	return t, nil
}