(ns closh.zero.util
  (:require [clojure.data :refer [diff]]
            [closh.zero.platform.process :refer [shx setenv getenv unsetenv]]
            [closh.zero.pipeline :refer [process-value]]
            #?(:clj [clojure.data.json :as json])
            #?@(:cljs [[fs] [tmp]])))

(def ignore-env-vars #{"_" "OLDPWD" "PWD" "SHELLOPTS" "SHLVL"})

(defn with-tempfile [cb]
  #?(:cljs
     (let [file (tmp/fileSync)
           f (.-name file)
           result (cb f)]
       (.removeCallback file)
       result)
     :clj
     (let [file (java.io.File/createTempFile "closh-tmp-" ".txt")
           f (.getAbsolutePath file)
           result (cb f)]
       (.delete file)
       result)))

(defn spawn-shell
  [shell exp]
  (process-value (shx shell ["-c" exp])))

(defn setenv-diff
  [before after]
  (let [var-diff (diff before after)
        removed (remove #(ignore-env-vars (first %)) (first var-diff))
        changed (remove #(ignore-env-vars (first %)) (second var-diff))]
    (doseq [[k _] removed] (unsetenv k))
    (doseq [[k v] changed] (setenv k v))))

(defn source-shell
  "Spawns a shell interpreter and executes `exp`. If it executes successfully,
  any exported variables are then saved into the closh environment"
  ([exp] (source-shell "bash" exp))
  ([shell exp]
   (with-tempfile
     (fn [temp-file]
       (let [before (getenv)
             result (spawn-shell shell (str exp "&& (node -p 'JSON.stringify(process.env)') >" temp-file))]
         (if (= (:code result) 0)
           (let [after #?(:cljs (js->clj (js/JSON.parse (fs/readFileSync temp-file "utf8")))
                          :clj (json/read-str (slurp temp-file)))
                 stdout (:stdout result)]
             (setenv-diff before after)
             (when-not (= stdout "") stdout))
           (println "Error while executing" shell "command:" exp "\n" (:stderr result))))))))

#?(:clj
   (defn thread-stop [^Thread thread]
     (.stop thread)))