3 files changed, 82 insertions, 42 deletions
diff --git a/internal/file/content.go b/internal/file/content.go
new file mode 100644
index 0000000..2bb787d
--- /dev/null
+++ b/internal/file/content.go
@@ -0,0 +1,52 @@
+package file
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+	"text/template"
+)
+
+func resolveContent(param, targetPath string) ([]byte, error) {
+	var content []byte
+	var err error
+
+	if strings.HasPrefix(param, "source://") {
+		sourcePath := strings.TrimPrefix(param, "source://")
+		content, err = os.ReadFile(sourcePath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read source file %s: %w", sourcePath, err)
+		}
+	} else {
+		content = []byte(param)
+	}
+
+	if strings.HasSuffix(targetPath, ".tmpl") || (strings.HasPrefix(param, "source://") && strings.HasSuffix(strings.TrimPrefix(param, "source://"), ".tmpl")) {
+		return applyTemplate(content, param)
+	}
+
+	return content, nil
+}
+
+func applyTemplate(content []byte, param string) ([]byte, error) {
+	data := make(map[string]string)
+	for _, env := range os.Environ() {
+		pair := strings.SplitN(env, "=", 2)
+		if len(pair) == 2 {
+			data[pair[0]] = pair[1]
+		}
+	}
+	data["Param"] = param
+
+	tmpl, err := template.New("resource").Parse(string(content))
+	if err != nil {
+		return nil, fmt.Errorf("template parse error: %w", err)
+	}
+
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, data); err != nil {
+		return nil, fmt.Errorf("template execute error: %w", err)
+	}
+	return buf.Bytes(), nil
+}
diff --git a/internal/file/file.go b/internal/file/file.go
index ee759e0..aed7b13 100644
--- a/internal/file/file.go
+++ b/internal/file/file.go
@@ -8,9 +8,15 @@ import (
 	"codeberg.org/snonux/gonf/internal/resource"
 )
 
-func HaveString(path, content string) error {
+func Have(path, param string) error {
 	_ = resource.Register("File", path)
-	return have(path, []byte(content))
+
+	content, err := resolveContent(param, path)
+	if err != nil {
+		log.Fatalf("failed to resolve content for %s: %v", path, err)
+	}
+
+	return have(path, content)
 }
 
 func getChecksum(path string) [32]byte {
diff --git a/internal/file/file_test.go b/internal/file/file_test.go
index f9f5dab..e41d7dc 100644
--- a/internal/file/file_test.go
+++ b/internal/file/file_test.go
@@ -3,6 +3,7 @@ package file
 import (
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 )
 
@@ -10,17 +11,14 @@ 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
+	if checksum == [32]byte{} {
+		t.Error("expected non-zero checksum")
 	}
 
-	// Non-existing file returns zero checksum
 	zeroChecksum := getChecksum(filepath.Join(dir, "no-such-file"))
 	var expectedZero [32]byte
 	if zeroChecksum != expectedZero {
@@ -59,7 +57,6 @@ func TestUpdateFromTmpChecksumChanged(t *testing.T) {
 		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")
 	}
@@ -88,7 +85,6 @@ func TestUpdateFromTmpChecksumUnchanged(t *testing.T) {
 		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")
 	}
@@ -105,7 +101,7 @@ func TestHaveStringCreateNewFile(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "new.txt")
 
-	if err := HaveString(path, "hello world"); err != nil {
+	if err := Have(path, "hello world"); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 
@@ -116,57 +112,43 @@ func TestHaveStringCreateNewFile(t *testing.T) {
 	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) {
+func TestHaveSourceFile(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)
-	}
+	sourcePath := filepath.Join("..", "..", "assets", "testfiles", "test.txt")
+	targetPath := filepath.Join(dir, "target.txt")
 
-	if err := HaveString(path, "new"); err != nil {
+	if err := Have(targetPath, "source://"+sourcePath); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 
-	got, err := os.ReadFile(path)
+	got, err := os.ReadFile(targetPath)
 	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")
+	expected, _ := os.ReadFile(sourcePath)
+	if string(got) != string(expected) {
+		t.Errorf("expected %q, got %q", string(expected), string(got))
 	}
 }
 
-func TestHaveStringNoChange(t *testing.T) {
+func TestHaveTemplateFile(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)
-	}
+	sourcePath := filepath.Join("..", "..", "assets", "testfiles", "test.tmpl")
+	targetPath := filepath.Join(dir, "target.conf")
 
-	if err := HaveString(path, content); err != nil {
+	if err := Have(targetPath, "source://"+sourcePath); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 
-	got, err := os.ReadFile(path)
+	got, err := os.ReadFile(targetPath)
 	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")
+
+	expectedParam := "source://" + sourcePath
+	if !strings.Contains(string(got), expectedParam) {
+		t.Errorf("expected content to contain Param %q, got %q", expectedParam, string(got))
 	}
-}
-\ No newline at end of file
+}