// Encode returns a EAN 8 or EAN 13 barcode for the given code
func Encode(code string) (barcode.Barcode, error) {
var checkSum int
if len(code) == 7 || len(code) == 12 {
code += string(calcCheckNum(code))
checkSum = utils.RuneToInt(calcCheckNum(code))
} else if len(code) == 8 || len(code) == 13 {
check := code[0 : len(code)-1]
check += string(calcCheckNum(check))
if check != code {
return nil, errors.New("checksum missmatch")
}
checkSum = utils.RuneToInt(rune(code[len(code)-1]))
}
if len(code) == 8 {
result := encodeEAN8(code)
if result != nil {
return utils.New1DCode("EAN 8", code, result, checkSum), nil
}
} else if len(code) == 13 {
result := encodeEAN13(code)
if result != nil {
return utils.New1DCode("EAN 13", code, result, checkSum), nil
}
}
return nil, errors.New("invalid ean code data")
}
func calcCheckNum(code string) rune {
x3 := len(code) == 7
sum := 0
for _, r := range code {
curNum := utils.RuneToInt(r)
if curNum < 0 || curNum > 9 {
return 'B'
}
if x3 {
curNum = curNum * 3
}
x3 = !x3
sum += curNum
}
return utils.IntToRune((10 - (sum % 10)) % 10)
}
// AddCheckSum calculates the correct check-digit and appends it to the given content.
func AddCheckSum(content string) (string, error) {
if content == "" {
return "", errors.New("content is empty")
}
even := len(content)%2 == 1
sum := 0
for _, r := range content {
if _, ok := encodingTable[r]; ok {
value := utils.RuneToInt(r)
if even {
sum += value * 3
} else {
sum += value
}
even = !even
} else {
return "", fmt.Errorf("can not encode \"%s\"", content)
}
}
return content + string(utils.IntToRune(sum%10)), nil
}