concept G22LeftArrowScript > ConceptWithChangeListeners {
  settableWithVar S description;
  
  // the script (last "saved" version)
  settableWithVar S text;
  
  // the latest code that has been cleared to auto-run (if any)
  settableWithVar ClearForAutoRun<S> clearedForAutoRun;

  // text currently being modified in an editor (or null)
  // Note that "" doesn't count as null.
  settableWithVar S editingText;
  
  @Override void _doneLoading2() {
    //print("_doneLoading " + this);
    cMigrateField(this, "code", "text");
  }
  
  S myType() { ret dropPrefix("G22", shortClassName(this)); }
  
  toString { ret or2(description, myType() + " " + id); }
  
  void initEditingText {
    editingText(unnull(or(editingText, text))); 
  }
  
  S stableText() { ret text; }
  
  void completeEdit aka save() {
    S t = editingText;
    if (t != null) {
      setTextWithHistory(t);
      editingText(null);
    }
  }
  
  void setTextWithHistory(S text) {
    if (eq(this.text, text)) ret;
    text(text);
    saveTextToHistory();
  }
  
  S textForEditing() {
    initEditingText();
    ret editingText;
  }
  
  File historyFile() {
    ret fileInConceptsDir("History/" + shortDynName(this) + id + ".history");
  }
  
  void saveTextToHistory() {
    saveFieldToHistory("text", text);
  }
  
  void saveFieldToHistory(S field, S value) {
    File historyFile = assertNotNull(+historyFile());
    S contents = value == null ? "empty" : " (" + nLines(value) + ", " + nChars(value) + "):\n" +
      indentx(value) + "\n" +
      "\n";
    appendToTextFile(historyFile,
      "\n===\n" +
      "Concept ID: " + id + "\n" +
      "Date: " + dateWithMSUTC() + "\n" +
      firstToUpper(field) + contents +
      "===" + "\n");
  }
  
  bool isSaved() { ret text != null; }
  bool isEditing() { ret editingText != null; }
  bool isClearForAutoRun() { ret clearedForAutoRun != null; }
  
  S codeForAutoRun() { ret getVar(clearedForAutoRun()); }
}