add config loader

go.mod

@@ -0,0 +1,5 @@
+module gitea.meta-tech.academy/go/config-loader
+
+go 1.20
+
+require gopkg.in/yaml.v3 v3.0.1

go.sum

@@ -0,0 +1,3 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

loader.go

@@ -0,0 +1,110 @@
+package config
+
+import (
+	"os"
+	"reflect"
+	"regexp"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Cfg interface {
+	GetVar() []VarConfig
+}
+
+type VarConfig struct {
+	Name  string `yaml:"name"`
+	Value string `yaml:"value"`
+}
+
+type ConfigLoader struct {
+	Var    []VarConfig
+	Config interface{}
+	varDef *VarPattern
+	refstr []*reflect.Value
+}
+
+func LoadConfig(path string, out Cfg, varPattern *VarPattern) {
+	cl := &ConfigLoader{varDef: varPattern, refstr: []*reflect.Value{}}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		panic(err)
+	}
+	if err = yaml.Unmarshal(data, out); err != nil {
+		panic(err)
+	}
+	cl.Var = out.GetVar()
+	cl.Config = out
+	cl.parse()
+	cl.refstr = []*reflect.Value{}
+	// cl.setConfigPtr(outi)
+}
+
+func (cl *ConfigLoader) findVarName(match string) string {
+	re := regexp.MustCompile(cl.varDef.getPatternCaptureName())
+	parts := re.FindStringSubmatch(match)
+	if len(parts) > 0 {
+		match = parts[1]
+	}
+	return match
+}
+
+func (cl *ConfigLoader) findVarValue(v string) string {
+	names := strings.SplitN(v, ".", 2)
+	if names[0] == "var" {
+		for _, varConfig := range cl.Var {
+			if varConfig.Name == names[1] {
+				v = varConfig.Value
+			}
+		}
+	}
+	return v
+}
+
+func (cl *ConfigLoader) findStringRef(ref reflect.Value) {
+	switch ref.Kind() {
+	case reflect.Ptr, reflect.Interface:
+		cl.findStringRef(ref.Elem())
+	case reflect.Struct:
+		for i := 0; i < ref.NumField(); i++ {
+			refc := ref.Field(i)
+			cl.findStringRef(refc)
+		}
+	case reflect.Slice:
+		if !ref.IsNil() {
+			for i := 0; i < ref.Len(); i++ {
+				refc := ref.Index(i)
+				cl.findStringRef(refc)
+			}
+		}
+	case reflect.String:
+		if ref.Len() > 0 {
+			cl.refstr = append(cl.refstr, &ref)
+		}
+	}
+}
+
+func (cl *ConfigLoader) parse() {
+	var name string
+	var tmp string
+	var parts []string
+	var re2 *regexp.Regexp
+
+	cl.findStringRef(reflect.ValueOf(&cl))
+
+	re := regexp.MustCompile(cl.varDef.getPatternVar())
+	for _, ref := range cl.refstr {
+		tmp = ref.String()
+		parts = re.FindStringSubmatch(tmp)
+		if len(parts) > 0 {
+			s := strings.SplitAfter(parts[1], cl.varDef.Close)
+			for _, part := range s {
+				name = cl.findVarName(part)
+				re2 = regexp.MustCompile(cl.varDef.getPatternVarName(name))
+				tmp = re2.ReplaceAllString(tmp, cl.findVarValue(name))
+			}
+			ref.SetString(tmp)
+		}
+	}
+}

varpattern.go

@@ -0,0 +1,31 @@
+package config
+
+import (
+	"fmt"
+	"regexp"
+)
+
+type VarPattern struct {
+	Open  string
+	Close string
+}
+
+func (vp *VarPattern) getPatternCaptureName() string {
+	return fmt.Sprintf("%s([^%s]+)%s", regexp.QuoteMeta(vp.Open), regexp.QuoteMeta(string(vp.Close[:1])), regexp.QuoteMeta((vp.Close)))
+}
+
+func (vp *VarPattern) getPatternVar() string {
+	return fmt.Sprintf("(%s.+%s)", regexp.QuoteMeta(vp.Open), regexp.QuoteMeta(vp.Close))
+}
+
+func (vp *VarPattern) getPatternVarName(name string) string {
+	return fmt.Sprintf("%s%s%s", regexp.QuoteMeta(vp.Open), name, regexp.QuoteMeta(vp.Close))
+}
+
+func NewVarPattern(open string, close string) *VarPattern {
+	return &VarPattern{open, close}
+}
+
+func DefaultVarPattern() *VarPattern {
+	return NewVarPattern("{%", "%}")
+}