A big progress

A big progress

pkg/chart/patches/patches.go

@@ -0,0 +1,72 @@
+package patches
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+
+	"github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v2"
+)
+
+type Patch struct {
+	Name    string
+	Targets []string
+	Before  string
+	After   string
+}
+
+type Patches []*Patch
+
+func NewPatchFromFile(filePath string) (*Patch, error){
+	var patch Patch
+	logrus.Infof("reading a new patch file: %s", filePath)
+	patchFile, err := os.ReadFile(filePath)
+	if err != nil {
+		return nil, err 
+	}
+
+	if err := yaml.Unmarshal(patchFile, &patch); err != nil {
+		return nil, err
+	}
+	return &patch, nil
+}
+
+func(p *Patch) Apply(chartDir string) error {
+	logrus.Infof("Applying patch: %s", p.Name)
+	if len(p.Before) > 0 {
+		beforeCompiled, err := regexp.Compile(p.Before)
+		if err != nil {
+			return err
+		}
+
+		for _, target := range p.Targets {
+			fullTarget := fmt.Sprintf("%s/%s", chartDir, target)
+			file, err := os.ReadFile(fullTarget)
+			if err != nil {
+				return err
+			}
+			newfile := beforeCompiled.ReplaceAll(file, []byte(p.After))
+			err = os.WriteFile(fullTarget, newfile, os.ModePerm)
+			if err != nil {
+				return err
+			}	
+		}
+	} else {
+		for _, target := range p.Targets {
+			fullTarget := fmt.Sprintf("%s/%s", chartDir, target)
+    	f, err := os.OpenFile(fullTarget, os.O_APPEND|os.O_CREATE|os.O_WRONLY, os.ModePerm)
+	    if err != nil {
+	        return err
+	    }
+			defer f.Close()
+	    if _, err := f.Write([]byte(p.After + "\n")); err != nil {
+				return err
+	    }
+	    if err := f.Close(); err != nil {
+        return err
+  	  }
+		}
+	}
+	return nil
+}