implement model for adrenaline

game/game.go

@@ -36,6 +36,9 @@ type Match struct {
 	// reveal indicates whether the current player has revealed the shell that
 	// will fire next.
 	reveal bool
+	// adrenaline indicates whether the current player has adrenaline in
+	// effect, requiring them to use an opponent's item.
+	adrenaline bool
 	// prev is a pointer to the element of shellArray which was fired last this
 	// game, or nil if none has been.
 	prev *bool
@@ -117,17 +120,22 @@ func (g *Match) Opponent() *playerState {
 // Apply uses an item by index for the current player.
 // If this causes the current game to end (a beer discharges the last shell),
 // returns ErrGameEnded but does not start the next game.
-// Returns ErrWrongTurn if id does not correspond to the current player.
+// Returns ErrWrongTurn if id does not correspond to the current player
+// (with appropriate exception for adrenaline).
 func (g *Match) Apply(id player.ID, item int) error {
-	cur := g.CurrentPlayer()
-	if cur.id != id {
+	p := g.CurrentPlayer()
+	if g.adrenaline {
+		p = g.Opponent()
+	}
+	if p.id != id {
 		return ErrWrongTurn
 	}
-	if item < 0 || item >= len(cur.items) {
+	if item < 0 || item >= len(p.items) {
 		return errors.New("item index out of bounds")
 	}
-	if cur.items[item].apply(g) {
-		cur.items[item] = itemNone
+	if p.items[item].apply(g) {
+		p.items[item] = itemNone
+		g.adrenaline = false
 	}
 	if g.Empty() {
 		return ErrGameEnded
@@ -183,10 +191,11 @@ func (g *Match) MatchWinner() *playerState {
 // player if self is true. Advances the turn if appropriate.
 // Returns ErrRoundEnded if this causes the round to end.
 // Returns ErrGameEnded if this causes the game but not the round to end.
-// Returns ErrWrongTurn if id does not correspond to the current player.
+// Returns ErrWrongTurn if id does not correspond to the current player
+// or if adrenaline is in effect.
 func (g *Match) Shoot(id player.ID, self bool) error {
 	cur := g.CurrentPlayer()
-	if cur.id != id {
+	if cur.id != id || g.adrenaline {
 		return ErrWrongTurn
 	}
 	target := g.Opponent()

game/item.go

@@ -62,8 +62,12 @@ func (i item) apply(g *Match) bool {
 		g.damage = 2
 		return true
 	case itemAdrenaline:
+		if g.adrenaline {
+			// Adrenaline forbids using adrenaline.
+			return false
+		}
 		g.action = actAdrenaline
-		// TODO(zeph): implement
+		g.adrenaline = true
 		return true
 	case itemPhone:
 		g.action = actPhone