fix: add missing template functions (#724)

* fix: adding missing template functions

* refactor: simplify function

Co-authored-by: Yash Bhardwaj <imyashbhardwaj@gmail.com>

internal/compiler/engine.go

@@ -26,9 +26,7 @@ type Engine struct {
 func NewEngine() *Engine {
 	baseTemplate := template.
 		New("optimus_template_engine").
-		Funcs(map[string]any{
-			"Date": dateFn,
-		})
+		Funcs(OptimusFuncMap())
 
 	return &Engine{
 		baseTemplate: baseTemplate,
@@ -65,11 +63,3 @@ func (e *Engine) CompileString(input string, context map[string]any) (string, er
 	}
 	return strings.TrimSpace(buf.String()), nil
 }
-
-func dateFn(timeStr string) (string, error) {
-	t, err := time.Parse(ISOTimeFormat, timeStr)
-	if err != nil {
-		return "", err
-	}
-	return t.Format(ISODateFormat), nil
-}

internal/compiler/template_func.go

@@ -0,0 +1,95 @@
+package compiler
+
+import (
+	"strconv"
+	"strings"
+	"text/template"
+	"time"
+)
+
+func OptimusFuncMap() template.FuncMap {
+	return map[string]any{
+		"Date":        Date,
+		"replace":     Replace,
+		"trunc":       Trunc,
+		"date":        date,
+		"date_modify": dateModify,
+		"toDate":      toDate,
+		"unixEpoch":   unixEpoch,
+		"list":        list,
+		"join":        join,
+	}
+}
+
+func Date(timeStr string) (string, error) {
+	t, err := time.Parse(ISOTimeFormat, timeStr)
+	if err != nil {
+		return "", err
+	}
+	return t.Format(ISODateFormat), nil
+}
+
+func Replace(old, newStr, name string) string {
+	return strings.ReplaceAll(name, old, newStr)
+}
+
+func Trunc(c int, s string) string {
+	if c >= 0 && len(s) > c {
+		return s[:c]
+	}
+	return s
+}
+
+func date(fmt string, date interface{}) string {
+	return dateInZone(fmt, date, "Local")
+}
+
+func dateInZone(fmt string, date interface{}, zone string) string {
+	var t time.Time
+	switch date := date.(type) {
+	default:
+		t = time.Now()
+	case time.Time:
+		t = date
+	case *time.Time:
+		t = *date
+	case int64:
+		t = time.Unix(date, 0)
+	case int:
+		t = time.Unix(int64(date), 0)
+	case int32:
+		t = time.Unix(int64(date), 0)
+	}
+
+	loc, err := time.LoadLocation(zone)
+	if err != nil {
+		loc, _ = time.LoadLocation("UTC")
+	}
+
+	return t.In(loc).Format(fmt)
+}
+
+func dateModify(fmt string, date time.Time) time.Time {
+	d, err := time.ParseDuration(fmt)
+	if err != nil {
+		return date
+	}
+	return date.Add(d)
+}
+
+func toDate(fmt, str string) time.Time {
+	t, _ := time.ParseInLocation(fmt, str, time.Local)
+	return t
+}
+
+func unixEpoch(date time.Time) string {
+	return strconv.FormatInt(date.Unix(), 10) //nolint
+}
+
+func list(v ...string) []string {
+	return v
+}
+
+func join(sep string, v []string) string {
+	return strings.Join(v, sep)
+}