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// Package code128 can create Code128 barcodes
package code128
import (
"fmt"
"strings"
"unicode/utf8"
"github.com/boombuler/barcode"
"github.com/boombuler/barcode/utils"
)
func strToRunes(str string) []rune {
result := make([]rune, utf8.RuneCountInString(str))
i := 0
for _, r := range str {
result[i] = r
i++
}
return result
}
func shouldUseCTable(nextRunes []rune, curEncoding byte) bool {
requiredDigits := 4
if curEncoding == startCSymbol {
requiredDigits = 2
}
if len(nextRunes) < requiredDigits {
return false
}
for i := 0; i < requiredDigits; i++ {
if i%2 == 0 && nextRunes[i] == FNC1 {
requiredDigits++
if len(nextRunes) < requiredDigits {
return false
}
continue
}
if nextRunes[i] < '0' || nextRunes[i] > '9' {
return false
}
}
return true
}
func getCodeIndexList(content []rune) *utils.BitList {
result := new(utils.BitList)
curEncoding := byte(0)
for i := 0; i < len(content); i++ {
if shouldUseCTable(content[i:], curEncoding) {
if curEncoding != startCSymbol {
if curEncoding == byte(0) {
result.AddByte(startCSymbol)
} else {
result.AddByte(codeCSymbol)
}
curEncoding = startCSymbol
}
if content[i] == FNC1 {
result.AddByte(102)
} else {
idx := (content[i] - '0') * 10
i++
idx = idx + (content[i] - '0')
result.AddByte(byte(idx))
}
} else {
if curEncoding != startBSymbol {
if curEncoding == byte(0) {
result.AddByte(startBSymbol)
} else {
result.AddByte(codeBSymbol)
}
curEncoding = startBSymbol
}
var idx int
switch content[i] {
case FNC1:
idx = 102
break
case FNC2:
idx = 97
break
case FNC3:
idx = 96
break
case FNC4:
idx = 100
break
default:
idx = strings.IndexRune(bTable, content[i])
break
}
if idx < 0 {
return nil
}
result.AddByte(byte(idx))
}
}
return result
}
// Encode creates a Code 128 barcode for the given content
func Encode(content string) (barcode.Barcode, error) {
contentRunes := strToRunes(content)
if len(contentRunes) <= 0 || len(contentRunes) > 80 {
return nil, fmt.Errorf("content length should be between 1 and 80 runes but got %d", len(contentRunes))
}
idxList := getCodeIndexList(contentRunes)
if idxList == nil {
return nil, fmt.Errorf("\"%s\" could not be encoded", content)
}
result := new(utils.BitList)
sum := 0
for i, idx := range idxList.GetBytes() {
if i == 0 {
sum = int(idx)
} else {
sum += i * int(idx)
}
result.AddBit(encodingTable[idx]...)
}
result.AddBit(encodingTable[sum%103]...)
result.AddBit(encodingTable[stopSymbol]...)
return utils.New1DCode("Code 128", content, result, sum%103), nil
}
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