server/www/game.js

function Game(modules) {
  var deck = document.getElementById("deck");
  var rest = document.getElementById("rest");
  var status = {
    dom: document.getElementById("status"),
    playing: false,
    step: null,
    month: null,
    played: 0
  };
  var sets = {
    river: {
      card: null,
      dom: document.getElementById("river")
    },
    yourHand: {
      card: null,
      dom: document.getElementById("you").getElementsByClassName("hand")[0]
    },
    theirHand: {
      dom: document.getElementById("them").getElementsByClassName("hand")[0]
    }
  };
  var selected = null;

  modules.messaging.addEventListener(["Game"], function(o) {
    setStatus(o.game);
    setCaptures(o.game);
    [
      ['river', o.game.river, RiverCard],
      ['yourHand', o.game.players[modules.session.getKey()].hand, HandCard]
    ].forEach(function(args) {setCardSet.apply(null, args)});
    setTheirCards(o.game.oyake);
    if(status.step == "Turned") {
      setTurned(o.game.step.contents);
    } else {
      if(status.step == "ToPlay" && o.game.playing == o.game.oyake) {
        rest.className = ["card", "count" + (24 - status.played)].join(' ');
      }
      if(deck.lastChild.id != "rest") {
        deck.removeChild(deck.lastChild);
      }
    }
    if(status.playing && status.step == "Scored") {
      play({koiKoi: confirm(
        "You scored ! Do you want to go on ? Press cancel to just get your points and end current month"
      )});
    }
  });

  function play(move) {
    modules.messaging.send({
      tag: "Play",
      move: move
    });
  }

  function matchingInRiver(card) {
    return modules.fun.mapFilter(
      modules.fun.of(sets.river.card),
      modules.fun.isSet
    )(modules.hanafuda.sameMonth(card).map(modules.fun.proj('name')));
  }

  function setStatus(game) {
    modules.dom.clear(status.dom);
    status.step = game.step.tag;
    if(game.month != status.month) {
      status.month = game.month;
      status.played = 0;
    } else {
      if(status.step == "ToPlay") {
        status.played++;
      }
    }
    status.dom.appendChild(
      modules.dom.make('li', {textContent: "This month's flower is the " + status.month})
    );
    var turn = null;
    status.playing = modules.session.is(game.playing);
    if(status.playing) {
      sets.yourHand.dom.classList.toggle("yourTurn", status.step == "ToPlay");
      turn = "Your turn";
    } else {
      sets.yourHand.dom.classList.remove("yourTurn");
      turn = modules.room.name(game.playing) + " is playing";
    }
    status.dom.appendChild(modules.dom.make('li', {textContent: turn}));
  }

  function setCaptures(game) {
    for(var key in game.players) {
      var elem = document.getElementById(modules.session.is(key) ? "you" : "them");
      elem.getElementsByClassName('score')[0].textContent = game.scores[key] + " pts";
      var byClass = {}
      Object.values(modules.hanafuda.Family).forEach(function(family) {
        byClass[family.class] = elem.getElementsByClassName(family.class)[0];
        modules.dom.clear(byClass[family.class]);
      });
      game.players[key].meld.forEach(function(cardName) {
        var card = new Card(cardName);
        byClass[card.value.family.class].appendChild(card.dom);
      });
    }
  }

  function setCardSet(setName, cardNames, constructor) {
    constructor = constructor || Card;
    var set = sets[setName];
    set.card = {};
    modules.dom.clear(set.dom);
    cardNames.forEach(function(cardName) {
      var card = new constructor(cardName);
      set.card[cardName] = card;
      set.dom.appendChild(card.dom);
    });
  }

  function setTheirCards(oyake) {
    var turnsTheyPlayed = Math.floor(
      (status.played + (modules.session.is(oyake) ? 0 : 1)) / 2
    );
    modules.dom.clear(sets.theirHand.dom);
    for(var i = 0; i < 8 - turnsTheyPlayed; i++) {
      sets.theirHand.dom.appendChild(modules.dom.make('li', {class: "card"}));
    }
  }

  function setTurned(cardName) {
    var card = new Card(cardName);
    card.dom.id = "turned";
    deck.appendChild(card.dom);
    if(status.playing) {
      selected = cardName;
      showCandidates(modules.hanafuda.Card[selected], true);
    }
  }

  function showCandidates(card, yes) {
    matchingInRiver(card).forEach(function(riverCard) {riverCard.setCandidate(yes);});
  }

  function Card(name) {
    this.value = modules.hanafuda.Card[name];
    this.name = name;
    this.dom = modules.dom.make('li', {
      class: [
        "card",
        "value" + modules.hanafuda.getValue(this.value),
        "month" + this.value.flower
      ],
      onClick: this.onClick()
    });
  }

  Card.prototype.onClick = function() {return function() {};};

  function RiverCard() {
    Card.apply(this, arguments);
    this.candidate = false;
  }

  RiverCard.prototype.onClick = function() {
    var card = this;
    return function() {
      if(card.candidate) {
        var withCard = selected;
        selected = null;
        play(
          status.step == 'ToPlay' ? {capture: [withCard, card.name]} : {choose: card.name}
        );
      }
    };
  };

  RiverCard.prototype.setCandidate = function(yes) {
    this.candidate = yes;
    this.dom.classList.toggle("candidate", yes);
  }

  function HandCard() {
    Card.apply(this, arguments);
  }

  HandCard.prototype.onClick = function() {
    if(status.playing && status.step == "ToPlay") {
      var card = this;
      return function() {
        if(selected != undefined) {
          sets.yourHand.card[selected].setSelected(false);
        } else {
          card.play();
        }
      };
    } else {
      return function() {};
    }
  };

  HandCard.prototype.setSelected = function(yes) {
    selected = yes ? this.name : null;
    this.dom.classList.toggle('selected', yes);
    showCandidates(this.value, yes);
  }

  HandCard.prototype.play = function() {
    var matching = matchingInRiver(this.value);
    if(matching.length > 1) {
      this.setSelected(true);
    } else {
      play({play: this.name});
    }
  }
}