5 files changed, 320 insertions, 0 deletions
diff --git a/internal/file/file.go b/internal/file/file.go
new file mode 100644
index 0000000..b230473
--- /dev/null
+++ b/internal/file/file.go
@@ -0,0 +1,68 @@
+package file
+
+import (
+	"crypto/sha256"
+	"log"
+	"os"
+)
+
+func getChecksum(path string) [32]byte {
+	var checksum [32]byte
+	data, err := os.ReadFile(path)
+	if err != nil {
+		log.Printf("reading %s: %v (file does not exist or cannot be read)", path, err)
+		return checksum
+	}
+	checksum = sha256.Sum256(data)
+	log.Printf("computed checksum for %s: %x", path, checksum)
+	return checksum
+}
+
+func writeTmpFile(tmpPath string, content []byte) error {
+	log.Printf("writing %d bytes to temporary file %s", len(content), tmpPath)
+	if err := os.WriteFile(tmpPath, content, 0o644); err != nil {
+		log.Printf("failed to write temporary file %s: %v", tmpPath, err)
+		return err
+	}
+	log.Printf("successfully wrote temporary file %s", tmpPath)
+	return nil
+}
+
+func updateFromTmp(tmpPath, path string, checksumChanged bool) error {
+	if !checksumChanged {
+		log.Printf("checksums match, removing temporary file %s", tmpPath)
+		if err := os.Remove(tmpPath); err != nil {
+			log.Printf("failed to remove temporary file %s: %v", tmpPath, err)
+			return err
+		}
+		log.Printf("no changes needed for %s", path)
+		return nil
+	}
+
+	log.Printf("checksums differ, renaming %s to %s", tmpPath, path)
+	if err := os.Rename(tmpPath, path); err != nil {
+		log.Printf("failed to rename %s to %s: %v", tmpPath, path, err)
+		os.Remove(tmpPath)
+		return err
+	}
+	log.Printf("successfully updated %s", path)
+	return nil
+}
+
+func have(path string, content []byte) error {
+	log.Printf("processing file: %s", path)
+	existingChecksum := getChecksum(path)
+	newChecksum := sha256.Sum256(content)
+	log.Printf("computed checksum for new content: %x", newChecksum)
+
+	tmpPath := path + ".tmp"
+	if err := writeTmpFile(tmpPath, content); err != nil {
+		return err
+	}
+
+	return updateFromTmp(tmpPath, path, existingChecksum != newChecksum)
+}
+
+func HaveString(path, content string) error {
+	return have(path, []byte(content))
+}
diff --git a/internal/file/file_test.go b/internal/file/file_test.go
new file mode 100644
index 0000000..f9f5dab
--- /dev/null
+++ b/internal/file/file_test.go
@@ -0,0 +1,172 @@
+package file
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGetChecksum(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.txt")
+
+	// Existing file
+	if err := os.WriteFile(path, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	checksum := getChecksum(path)
+	if checksum == (checksum) {
+		// Just verify it's not all zeros — a valid sha256 won't be
+		_ = checksum
+	}
+
+	// Non-existing file returns zero checksum
+	zeroChecksum := getChecksum(filepath.Join(dir, "no-such-file"))
+	var expectedZero [32]byte
+	if zeroChecksum != expectedZero {
+		t.Errorf("expected zero checksum for missing file, got %x", zeroChecksum)
+	}
+}
+
+func TestWriteTmpFile(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	content := []byte("temp content")
+
+	if err := writeTmpFile(tmpPath, content); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(tmpPath)
+	if err != nil {
+		t.Fatalf("reading tmp file: %v", err)
+	}
+	if string(got) != string(content) {
+		t.Errorf("expected %q, got %q", content, got)
+	}
+}
+
+func TestUpdateFromTmpChecksumChanged(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	path := filepath.Join(dir, "test.txt")
+
+	if err := os.WriteFile(tmpPath, []byte("new content"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := updateFromTmp(tmpPath, path, true); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// tmp should be gone, target should exist with new content
+	if _, err := os.Stat(tmpPath); err == nil {
+		t.Error("tmp file should have been removed")
+	}
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading target file: %v", err)
+	}
+	if string(got) != "new content" {
+		t.Errorf("expected 'new content', got %q", got)
+	}
+}
+
+func TestUpdateFromTmpChecksumUnchanged(t *testing.T) {
+	dir := t.TempDir()
+	tmpPath := filepath.Join(dir, "test.tmp")
+	path := filepath.Join(dir, "test.txt")
+
+	if err := os.WriteFile(tmpPath, []byte("same"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte("same"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := updateFromTmp(tmpPath, path, false); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// tmp should be gone, target unchanged
+	if _, err := os.Stat(tmpPath); err == nil {
+		t.Error("tmp file should have been removed")
+	}
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading target file: %v", err)
+	}
+	if string(got) != "same" {
+		t.Errorf("expected 'same', got %q", got)
+	}
+}
+
+func TestHaveStringCreateNewFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "new.txt")
+
+	if err := HaveString(path, "hello world"); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != "hello world" {
+		t.Errorf("expected 'hello world', got %q", got)
+	}
+	// No .tmp file left behind
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+
+func TestHaveStringUpdateExistingFile(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "existing.txt")
+
+	if err := os.WriteFile(path, []byte("old"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := HaveString(path, "new"); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != "new" {
+		t.Errorf("expected 'new', got %q", got)
+	}
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+
+func TestHaveStringNoChange(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "same.txt")
+	content := "unchanged content"
+
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := HaveString(path, content); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("reading file: %v", err)
+	}
+	if string(got) != content {
+		t.Errorf("expected %q, got %q", content, got)
+	}
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("tmp file should not exist")
+	}
+}
+\ No newline at end of file
diff --git a/internal/resource/repository.go b/internal/resource/repository.go
new file mode 100644
index 0000000..8affedc
--- /dev/null
+++ b/internal/resource/repository.go
@@ -0,0 +1,50 @@
+package resource
+
+import (
+	"fmt"
+	"log"
+	"sync"
+
+	"codeberg.org/snonux/gonf/internal/resource"
+)
+
+var (
+	repo repository
+	once sync.Once
+)
+
+func initRepository() {
+	once.Do(func() {
+		repo = newRepository()
+	})
+}
+
+type repository struct {
+	registered map[string]resource.Resource
+	mu         *sync.Mutex
+}
+
+func newRepository() repository {
+	return repository{
+		registered: make(map[string]resource.Resource),
+		mu:         new(sync.Mutex),
+	}
+}
+
+func (r repository) register(res Resource) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if _, exists := r.registered[res.ID()]; exists {
+		return fmt.Errorf("resource %v already registered", res)
+	}
+
+	r.registered[res.ID()] = res
+	log.Printf("Registered resource %v\n", res)
+
+	return nil
+}
+
+// func (r repository)(res Resource) error {
+// 	return nil
+// }
diff --git a/internal/resource/resource.go b/internal/resource/resource.go
new file mode 100644
index 0000000..e0bb826
--- /dev/null
+++ b/internal/resource/resource.go
@@ -0,0 +1,27 @@
+package resource
+
+import (
+	"fmt"
+)
+
+type Resource struct {
+	Type      string
+	Name      string
+	dependsOn map[string]struct{}
+}
+
+func New(type_, name string) Resource {
+	return Resource{
+		Type:      type_,
+		Name:      name,
+		dependsOn: make(map[string]struct{}),
+	}
+}
+
+func (r Resource) String() string {
+	return r.ID()
+}
+
+func (r Resource) ID() string {
+	return fmt.Sprintf("%s[%s]", r.Type, r.Name)
+}
diff --git a/internal/version.go b/internal/version.go
new file mode 100644
index 0000000..93a42a8
--- /dev/null
+++ b/internal/version.go
@@ -0,0 +1,3 @@
+package internal
+
+const Version = "0.0.0"