Function ReplaceFileExt

internal/system/file.go:26–36

ReplaceExt replaces the extension of `fp` with `ext` if the extension of `fp` is in `formats`. This is used in places where we need to normalize file extensions (e.g., `foo.mdx` -> `foo.md`) in order to respect format associations.

(fp string, formats map[string]string)

// This is used in places where we need to normalize file extensions (e.g.,
// `foo.mdx` -> `foo.md`) in order to respect format associations.
func ReplaceFileExt(fp string, formats map[string]string) string {
	var ext string

	old := filepath.Ext(fp)
	if normed, found := formats[strings.Trim(old, ".")]; found {
		ext = "." + normed
		fp = fp[0:len(fp)-len(old)] + ext
	}

	return fp
}