refactor: more code cleanup and simplification

pkg/generator/templates.go

@@ -0,0 +1,95 @@
+package generator
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+
+	"github.com/OpenCHAMI/configurator/pkg/util"
+	"github.com/nikolalohinski/gonja/v2"
+	"github.com/nikolalohinski/gonja/v2/exec"
+)
+
+type Template struct {
+	Contents []byte `json:"contents"`
+}
+
+func (t *Template) LoadFromFile(path string) error {
+	// skip loading template if path is a directory with no error
+	if isDir, err := util.IsDirectory(path); err == nil && isDir {
+		return nil
+	} else if err != nil {
+		return fmt.Errorf("failed to test if template path is directory: %w", err)
+	}
+
+	// try and read the contents of the file
+	// NOTE: we don't care if this is actually a Jinja template
+	// or not...at least for now.
+	contents, err := os.ReadFile(path)
+	if err != nil {
+		return fmt.Errorf("failed to read file: %v", err)
+	}
+	t.Contents = contents
+	return nil
+}
+
+func (t *Template) IsEmpty() bool {
+	return len(t.Contents) <= 0
+}
+
+// Wrapper function to slightly abstract away some of the nuances with using gonja
+// into a single function call. This function is *mostly* for convenience and
+// simplication. If no paths are supplied, then no templates will be applied and
+// there will be no output.
+//
+// The "FileList" returns a slice of byte arrays in the same order as the argument
+// list supplied, but with the Jinja templating applied.
+func ApplyTemplates(mappings Mappings, templates map[string]Template) (FileMap, error) {
+	var (
+		data    = exec.NewContext(mappings)
+		outputs = FileMap{}
+	)
+
+	for path, template := range templates {
+		// load jinja template from file
+		t, err := gonja.FromBytes(template.Contents)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read template from file: %w", err)
+		}
+
+		// execute/render jinja template
+		b := bytes.Buffer{}
+		if err = t.Execute(&b, data); err != nil {
+			return nil, fmt.Errorf("failed to execute: %w", err)
+		}
+		outputs[path] = b.Bytes()
+	}
+
+	return outputs, nil
+}
+
+// Wrapper function similiar to "ApplyTemplates" but takes file paths as arguments.
+// This function will load templates from a file instead of using file contents.
+func ApplyTemplateFromFiles(mappings Mappings, paths ...string) (FileMap, error) {
+	var (
+		data    = exec.NewContext(mappings)
+		outputs = FileMap{}
+	)
+
+	for _, path := range paths {
+		// load jinja template from file
+		t, err := gonja.FromFile(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read template from file: %w", err)
+		}
+
+		// execute/render jinja template
+		b := bytes.Buffer{}
+		if err = t.Execute(&b, data); err != nil {
+			return nil, fmt.Errorf("failed to execute: %w", err)
+		}
+		outputs[path] = b.Bytes()
+	}
+
+	return outputs, nil
+}