lel.cljs

(def confidence-threshold 90)
(def target-charset "UTF-8")

(defn open-file [path]
  (let [content (.readFileSync fs path)]
    (either/right {:path path :content content})))

(defn detect-charset [file-descriptor]
  (m/mlet [{:keys [content]} file-descriptor]
    (let [charset (.detectCharset charsetDetector content)]
      (m/fmap #(merge % {:charset (.toString charset)
                         :confidence (.-confidence charset)})
              file-descriptor))))

(defn is-confident? [file-descriptor]
  (m/mlet [{:keys [path confidence]} file-descriptor]
    (if (> confidence confidence-threshold)
      file-descriptor
      (either/left {:error (str "The charset confidence of " path " is " confidence
                                ", which is below the threshold of " confidence-threshold ".")}))))

(defn convert-to-utf8 [file-descriptor]
  (m/mlet [{:keys [content charset]} file-descriptor]
    (if (not= target-charset charset)
      (let [converted-content (cr (.decode iconv content charset))]
            (m/fmap #(merge % {:converted-content converted-content
                               :converted? true})
                    file-descriptor))
      file-descriptor)))

(defn print-error [{:keys [error]}]
  (println "There was an error: " error))

(defn write-file! [{:keys [path decoded-content]}]
  (println "I would write the converted file out here: " path))

(defn clean-file! [path]
  (either/branch
    (-> path
        open-file
        detect-charset
        is-confident?
        convert-to-utf8)
    print-error
    write-file!))