add template functions

img.go

@@ -24,7 +24,13 @@ import (
 
 	"github.com/kenshaw/escpos"
 )
-import "log"
+import (
+	"log"
+	"strconv"
+
+	"golang.org/x/text/language"
+	"golang.org/x/text/message"
+)
 
 const (
 	defalutFontSize    = 18.0
@@ -102,8 +108,13 @@ func GenImg(width int, outputPath, payload, tmpl string) string {
 	return r
 }
 
+var funcMap = template.FuncMap{
+	"formatNumber": FormatNumber,
+	"div":          Div,
+}
+
 func renderTemplate(tmp string, data map[string]interface{}) (string, error) {
-	tmpl, err := template.New("mytemplate").Parse(tmp)
+	tmpl, err := template.New("mytemplate").Funcs(funcMap).Parse(tmp)
 	if err != nil {
 		return "", err
 	}
@@ -431,3 +442,66 @@ func nodeHeight(n *html.Node, dc *gg.Context, canvasWidth int, xPadding, yPaddin
 	}
 	return y
 }
+
+type RealNumber interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 |
+		~float32 | ~float64
+}
+
+func FormatNumber(precision int, b any) string {
+	return GenericFormatNumber(precision, convertToFloat64(b))
+}
+
+func GenericFormatNumber[T RealNumber](precision int, v T) string {
+	pEnglish := message.NewPrinter(language.English)
+
+	n := float64(v)
+	s := fmt.Sprintf("%.*f", precision, n)
+
+	parts := strings.Split(s, ".")
+	intPart := parts[0]
+	i, err := strconv.Atoi(intPart)
+	if err != nil {
+		return ""
+	}
+	out := pEnglish.Sprintf("%d", i)
+
+	if len(parts) > 1 {
+		return out + "." + parts[1]
+	}
+	return out
+}
+
+func Div(a, b any) float64 {
+	return GenericDiv(convertToFloat64(a), convertToFloat64(b))
+}
+
+func GenericDiv[T RealNumber](a, b T) float64 {
+	floatB := float64(b)
+	if floatB == 0 {
+		return 0
+	}
+	return float64(a) / floatB
+}
+
+func convertToFloat64(v any) float64 {
+	switch t := v.(type) {
+	case float64:
+		return t
+	case float32:
+		return float64(t)
+	case int:
+		return float64(t)
+	case int64:
+		return float64(t)
+	case int32:
+		return float64(t)
+	case uint:
+		return float64(t)
+	case uint64:
+		return float64(t)
+	default:
+		return 0
+	}
+}