GLAMOUR_STYLE environment variable support (#69)

glamour.go

@@ -36,6 +36,13 @@ func Render(in string, stylePath string) (string, error) {
 	return string(b), err
 }
 
+// RenderWithEnvironmentConfig initializes a new TermRenderer and renders a
+// markdown with a specific style defined by the GLAMOUR_STYLE environment variable.
+func RenderWithEnvironmentConfig(in string) (string, error) {
+	b, err := RenderBytes([]byte(in), getEnvironmentStyle())
+	return string(b), err
+}
+
 // RenderBytes initializes a new TermRenderer and renders a markdown with a
 // specific style.
 func RenderBytes(in []byte, stylePath string) ([]byte, error) {
@@ -117,6 +124,12 @@ func WithAutoStyle() TermRendererOption {
 	return WithStandardStyle("auto")
 }
 
+// WithEnvironmentConfig sets a TermRenderer's styles based on the
+// GLAMOUR_STYLE environment variable.
+func WithEnvironmentConfig() TermRendererOption {
+	return WithStylePath(getEnvironmentStyle())
+}
+
 // WithStylePath sets a TermRenderer's style from stylePath. stylePath is first
 // interpreted as a filename. If no such file exists, it is re-interpreted as a
 // standard style.
@@ -207,6 +220,15 @@ func (tr *TermRenderer) RenderBytes(in []byte) ([]byte, error) {
 	return buf.Bytes(), err
 }
 
+func getEnvironmentStyle() string {
+	glamourStyle := os.Getenv("GLAMOUR_STYLE")
+	if len(glamourStyle) == 0 {
+		glamourStyle = "auto"
+	}
+
+	return glamourStyle
+}
+
 func getDefaultStyle(style string) (*ansi.StyleConfig, error) {
 	if style == "auto" {
 		if termenv.HasDarkBackground() {