// Someone's name
concept Name {
  S name;
}

// A person (human or computer)
concept Person {}

// link a person to a name
concept Person2Name {
  new Ref<Person> person;
  new Ref<Name> name;
  bool usable = true;
}

// our user
Person > User {}

// myself
Person > Me {}

// A line typed by user or bot
concept Line {
  S text;
  new Ref<Person> author;
  new Ref<LineIdea> idea; // the interpretation we settled on

  *() {}
  *(Person a, S *text) { author.set(a); }
  *(S *text, LineIdea idea) { this.idea.set(idea); }
  *(S *text, Class<? extends LineIdea> idea) { this.idea.set(uniq(idea)); }
}

// A line interpretation
concept LineIdea {}

// Bot error
LineIdea > LError {
  S stackTrace;
  
  *() {}
  *(Throwable e) { stackTrace = getStackTrace(e); change(); }
}

// "test"
LineIdea > LTest {}

// repeating another line
LineIdea > LRepeating {}

// A greeting ("hello X")
LineIdea > LGreet {
  new Ref<Person2Name> name;
  
  *() {}
  *(Person2Name n) { name.set(n); }
}

// base class for questions
LineIdea > LQuestion {}

// "What is your name?"
LQuestion > LWhatsYourName {}

// "I don't understand"
LineIdea > LIDontUnderstand {}

// I have nothing to say
LineIdea > LLalala {}

// "My name is X"
LineIdea > LMyNameIs {
  new Ref<Name> name;
}

// A specific question/answer pair
concept QA_WhatsYourName_MyNameIs {
  new Ref<Line> q;
  new Ref<Line> a;
}

LineIdea > LAskMeSomething {}

// Wrap a bug during processing of user input
LineIdea > LBug {
  S stackTrace;
  
  *() {}
  *(Throwable e) { stackTrace = getStackTrace(e); change(); }
}

// We couldn't interpret a line yet
LineIdea > LUnknown {}

LineIdea > LIDontKnowWhatToAskYou {}

LineIdea > LGreetMe {}

LineIdea > LISee {}

concept Dialog {
  new RefL<Line> lines;
}

static Dialog dialog() { ret unique(Dialog); }
static User user() { ret uniq(User); }
static Me me() { ret uniq(Me); }

static L<Person2Name> usableNames(Person p) {
  ret list(Person2Name, "usable", true, "person", p);
}

Began life as a copy of #1005284