package game

type Game struct {
	RNG    RNG
	PP     [2]Player
	Shells []bool
	HP     int8
	Round  uint
	Group  uint
	Turn   uint
	Damage int8
	Reveal bool

	// Backing storage for shells.
	ShellArray [8]bool
}

func NewGame() *Game {
	return &Game{
		RNG:    NewRNG(),
		Damage: 1,
	}
}

func (g *Game) StartRound() {
	g.PP[0].StartRound()
	g.PP[1].StartRound()
	g.Round++
}

func (g *Game) StartGroup() {
	items := g.RNG.Intn(4) + 1
	g.HP = int8(g.RNG.Intn(3) + 2)
	g.PP[0].StartGroup(&g.RNG, g.HP, items)
	g.PP[1].StartGroup(&g.RNG, g.HP, items)
	shells := g.RNG.Intn(6) + 2
	for i := 0; i < shells/2; i++ {
		g.ShellArray[i] = true
	}
	for i := shells / 2; i < shells; i++ {
		g.ShellArray[i] = false
	}
	g.Shells = g.ShellArray[:shells]
	ShuffleSlice(&g.RNG, g.Shells)
	g.Group++
	g.Turn = 0
}

// CurrentPlayer gets the index of the current player, either 0 or 1.
func (g *Game) CurrentPlayer() *Player {
	return &g.PP[g.Turn%2]
}

// Opponent returns the player who is not the current player.
func (g *Game) Opponent() *Player {
	return &g.PP[g.Turn%2^1]
}

// Apply uses an item by index for the current player.
func (g *Game) Apply(item int) {
	cur := g.CurrentPlayer()
	if item < 0 || item >= len(cur.Items) {
		return
	}
	if cur.Items[item].Apply(g) {
		cur.Items[item] = ItemNone
	}
}

// PopShell removes a shell from the shotgun.
// This may cause the shotgun to be empty, but does not start the next group
// if so.
func (g *Game) PopShell() bool {
	r := g.Shells[0]
	g.Shells = g.Shells[1:]
	return r
}

// Empty returns whether the shotgun is empty.
func (g *Game) Empty() bool {
	return len(g.Shells) == 0
}

// Winner returns the player who won, or nil if the round is not over.
func (g *Game) Winner() *Player {
	if g.PP[0].HP <= 0 {
		return &g.PP[1]
	}
	if g.PP[1].HP <= 0 {
		return &g.PP[0]
	}
	return nil
}

// Shoot fires the shotgun, at the opponent if self is false and at the current
// player if self is true. Afterward, the round may be over, or the shotgun may
// be empty.
func (g *Game) Shoot(self bool) {
	target := g.Opponent()
	if self {
		target = g.CurrentPlayer()
	}
	live := g.PopShell()
	if live {
		target.HP -= g.Damage
		g.Turn++
	} else if !self {
		g.Turn++
	}
}