class _RandomAgent extends Agent {
  _RandomAgent(this.name, this.random);

  final String name;
  final Random random;

  Decision decide(List<Round> history, GameConfiguration configuration) {
    return random.nextBool() ? Decision.cooperate : Decision.defect;
  }
}

class _GrimTriggerAgent extends Agent {
  _GrimTriggerAgent(this.name);

  final String name;

  Decision decide(List<Round> history, GameConfiguration configuration) {
    if (history.any((Round round) => round.partner == Decision.defect)) {
      return Decision.defect;
    }
    return Decision.cooperate;
  }
}

class _TitForTatAgent extends Agent {
  _TitForTatAgent(this.name);

  final String name;

  Decision decide(List<Round> history, GameConfiguration configuration) {
    if (history.isEmpty) {
      return Decision.cooperate;
    }
    switch (history.last.partner) {
      case Decision.cooperate: return Decision.cooperate;
      case Decision.defect: return Decision.defect;
    }
  }
}