From 2bb75e9cca1d02d34f9eec25177cc8a3c93b18d8 Mon Sep 17 00:00:00 2001
From: Fabian Burth <fabian.burth@sap.com>
Date: Wed, 29 May 2024 10:12:25 +0200
Subject: [PATCH] documentation and bugfix in GetPackageNameForFunc

---
 pkg/utils/package.go | 47 ++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/pkg/utils/package.go b/pkg/utils/package.go
index 7f84c6b6f9..fa9671849b 100644
--- a/pkg/utils/package.go
+++ b/pkg/utils/package.go
@@ -2,41 +2,49 @@ package utils
 
 import (
 	"fmt"
+	"reflect"
+	"runtime"
+	"strings"
+
 	"github.com/mandelsoft/filepath/pkg/filepath"
 	"github.com/mandelsoft/goutils/general"
 	"github.com/mandelsoft/vfs/pkg/osfs"
 	"github.com/mandelsoft/vfs/pkg/vfs"
 	"golang.org/x/mod/modfile"
-	"reflect"
-	"runtime"
-	"strings"
 )
 
+const GO_MOD = "go.mod"
+
+// GetRelativePathToProjectRoot calculates the relative path to a go projects root directory.
+// It therefore assumes that the project root is the directory containing the go.mod file.
+// The optional parameter i determines how many directories the function will step up through, attempting to find a
+// go.mod file. If it cannot find a directory with a go.mod file within i iterations, the function throws an error.
 func GetRelativePathToProjectRoot(i ...int) (string, error) {
 	iterations := general.OptionalDefaulted(20, i...)
 
 	path := "."
 	for count := 0; count < iterations; count++ {
-		if ok, err := vfs.FileExists(osfs.OsFs, filepath.Join(path, "go.mod")); err != nil || ok {
+		if ok, err := vfs.FileExists(osfs.OsFs, filepath.Join(path, GO_MOD)); err != nil || ok {
 			if err != nil {
-				return "", fmt.Errorf("failed to check if go.mod exists: %v", err)
+				return "", fmt.Errorf("failed to check if %s exists: %w", GO_MOD, err)
 			}
 			return path, nil
 		}
 		if count == iterations {
-			return "", fmt.Errorf("could not find go.mod (within %d steps)", iterations)
+			return "", fmt.Errorf("could not find %s (within %d steps)", GO_MOD, iterations)
 		}
 		path = filepath.Join(path, "..")
 	}
 	return "", nil
 }
 
+// GetModuleName returns a go modules module name by finding and parsing the go.mod file.
 func GetModuleName() (string, error) {
 	pathToRoot, err := GetRelativePathToProjectRoot()
 	if err != nil {
 		return "", err
 	}
-	pathToGoMod := filepath.Join(pathToRoot, "go.mod")
+	pathToGoMod := filepath.Join(pathToRoot, GO_MOD)
 	// Read the content of the go.mod file
 	data, err := vfs.ReadFile(osfs.OsFs, pathToGoMod)
 	if err != nil {
@@ -44,18 +52,29 @@ func GetModuleName() (string, error) {
 	}
 
 	// Parse the go.mod file
-	modFile, err := modfile.Parse("go.mod", data, nil)
+	modFile, err := modfile.Parse(GO_MOD, data, nil)
 	if err != nil {
-		return "", fmt.Errorf("error parsing go.mod file: %w", err)
+		return "", fmt.Errorf("error parsing %s file: %w", GO_MOD, err)
 	}
 
 	// Print the module path
 	return modFile.Module.Mod.Path, nil
 }
 
-func GetPackageNameForFunc(i interface{}) (string, error) {
+func GetPackageNameForFunc(i ...interface{}) (string, error) {
+	// if no function is passed, assume the package name should be determined for the caller of this function
+	pc, _, _, ok := runtime.Caller(1)
+	if !ok {
+		panic("unable to find caller")
+	}
+
 	// Get the function's pointer
-	ptr := reflect.ValueOf(i).Pointer()
+	var ptr uintptr
+	if len(i) > 0 {
+		ptr = reflect.ValueOf(general.Optional(i...)).Pointer()
+	} else {
+		ptr = pc
+	}
 	// Retrieve the function's runtime information
 	funcForPC := runtime.FuncForPC(ptr)
 	if funcForPC == nil {
@@ -68,10 +87,12 @@ func GetPackageNameForFunc(i interface{}) (string, error) {
 	// Assuming the format: "package/path.functionName"
 	lastSlashIndex := strings.LastIndex(fullFuncName, "/")
 	if lastSlashIndex == -1 {
-		return "", fmt.Errorf("could not determine package name")
+		panic("unable to find package name")
 	}
 
-	packagePath := fullFuncName[:lastSlashIndex]
+	funcIndex := strings.Index(fullFuncName[lastSlashIndex:], ".")
+	packagePath := fullFuncName[:lastSlashIndex+funcIndex]
+
 	return packagePath, nil
 }