concept G22Text > ConceptWithChangeListeners {
  settableWithVar S description;
  
  // the script (last "saved" version)
  settableWithVar S text;
  
  // text currently being modified in an editor (or null)
  // Note that "" doesn't count as null.
  settableWithVar S editingText;
  
  // When imported from another project
  settableWithVar S importNote;
  
  S myType() { ret dropPrefix("G22", shortClassName(this)); }
  
  toString {
    ret colonCombine(myType() + id, description);
  }
  
  void initEditingText {
    editingText(unnull(or(editingText, text))); 
  }
  
  void receiveEditingText(S text) {
    //printVars_shorten("receiveEditingText", +text);
    editingText(text);
  }
  
  S stableText() { ret text; }
  S latestText() { ret or(editingText, text); }
  
  void completeEdit aka save() {
    S t = editingText;
    //printVars_shorten("completeEdit", +t);
    if (t != null) {
      setTextWithHistory(t);
      //printVars_shorten("completeEdit", +editingText);
    }
  }
  
  void setTextWithHistory(S text) {
    if (eq(this.text, text)) ret;
    text(text);
    saveTextToHistory();
  }
  
  void discardEdit {
    S text = editedText();
    if (text == null) ret;
    saveFieldToHistory("discardingEdit", text);
    editingText(null);
  }
  
  S textForEditing() {
    initEditingText();
    ret editingText;
  }
  
  File historyFile() {
    ret fileInConceptsDir("History/" + shortDynName(this) + id + ".history");
  }
  
  void saveTextToHistory() {
    saveFieldToHistory(+text);
  }
  
  void saveFieldToHistory(S field, S value) {
    File historyFile = historyFile();
    if (historyFile == null) ret;
    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 editedText() != null; }

  S editedText() { ret eq(editingText, text) ? null : editingText; }

  G22Utils g22utils() {
    ret assertNotNull(g22utils := main g22utils(_concepts()));
  }
  
  Set<S> allTexts() {
    ret asSet(llNonNulls(text(), editedText());
  }
}

Began life as a copy of #1034255