added filenames_map.go generation

languagesByFilename now is a map[string]string

internal/code-generator/generator/filenames.go

@@ -0,0 +1,50 @@
+package generator
+
+import (
+	"bytes"
+	"io"
+	"text/template"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+// Filenames reads from buf and builds filenames_map.go file from filenamesTmplPath.
+func Filenames(data []byte, filenamesTmplPath, filenamesTmplName, commit string) ([]byte, error) {
+	languages := make(map[string]*languageInfo)
+	if err := yaml.Unmarshal(data, &languages); err != nil {
+		return nil, err
+	}
+
+	languagesByFilename := buildFilenameLanguageMap(languages)
+
+	buf := &bytes.Buffer{}
+	if err := executeFilenamesTemplate(buf, languagesByFilename, filenamesTmplPath, filenamesTmplName, commit); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func buildFilenameLanguageMap(languages map[string]*languageInfo) map[string]string {
+	filenameLangMap := make(map[string]string)
+	for lang, langInfo := range languages {
+		for _, filename := range langInfo.Filenames {
+			filenameLangMap[filename] = lang
+		}
+	}
+
+	return filenameLangMap
+}
+
+func executeFilenamesTemplate(out io.Writer, languagesByFilename map[string]string, filenamesTmplPath, filenamesTmpl, commit string) error {
+	fmap := template.FuncMap{
+		"getCommit": func() string { return commit },
+	}
+
+	t := template.Must(template.New(filenamesTmpl).Funcs(fmap).ParseFiles(filenamesTmplPath))
+	if err := t.Execute(out, languagesByFilename); err != nil {
+		return err
+	}
+
+	return nil
+}