draft/pod.go

package draft

import "errors"

// Errors that can happen during draft
var (
	ErrNotInPack     = errors.New("card picked not in pack")
	ErrNoPacksLeft   = errors.New("no packs left to open")
	ErrNoPendingPack = errors.New("no packs received from other players")
)

// PodDirection is the direction packs are passed between players
type PodDirection string

// All rotations
var (
	PRClockwise     PodDirection = "left"
	PRAnticlockwise PodDirection = "right"
)

// Pod is a group of players drafting packs/cubes
type Pod struct {
	Players   []*Player
	Direction PodDirection

	ReadyNextPick chan bool
	ReadyNextPack chan bool
}

// Player is a single player partecipating in a pod
type Player struct {
	// Packs and picks
	CurrentPack Pack
	Packs       []Pack
	Picks       []Card

	// Nearby players
	left  *Player
	right *Player

	// Pod the player is in
	pod *Pod

	// Channels for passing stuff around
	newpack chan Pack
}

// MakePod creates a pod with a specified number of players and a given set of packs
func MakePod(playerCount int, provider PackProvider) *Pod {
	// Make player list
	players := make([]*Player, playerCount)

	// Make pod
	pod := &Pod{
		Players:       players,
		Direction:     PRAnticlockwise,
		ReadyNextPick: make(chan bool, 1),
		ReadyNextPack: make(chan bool, 1),
	}

	// Fill players
	for i := range players {
		players[i] = &Player{
			Packs:   provider(),
			Picks:   []Card{},
			pod:     pod,
			newpack: make(chan Pack, playerCount-1),
		}
	}
	// Second loop to fill nearby players
	for i := range players {
		if i > 0 {
			players[i].left = players[i-1]
		} else {
			players[i].left = players[playerCount-1]
		}
		players[i].right = players[(i+1)%playerCount]
	}

	return pod
}

// OpenPacks opens the next pack of each player
func (p *Pod) OpenPacks() error {
	for _, p := range p.Players {
		err := p.OpenPack()
		if err != nil {
			return err
		}
	}
	p.flipDirection()
	return nil
}

// NextPacks makes player exchange packs for the next pick
func (p *Pod) NextPacks() error {
	for _, p := range p.Players {
		err := p.NextPack()
		if err != nil {
			return err
		}
	}
	return nil
}

func (p *Pod) flipDirection() {
	if p.Direction == PRClockwise {
		p.Direction = PRAnticlockwise
	} else {
		p.Direction = PRClockwise
	}
}

func (p *Pod) checkPicks() {
	for _, player := range p.Players {
		if len(player.newpack) < 1 {
			// Someone still hasn't passed a pack but has cards
			return
		}
	}

	// Everyone has new packs to draft
	p.ReadyNextPick <- true
}

func (p *Pod) checkEndPack() {
	for _, player := range p.Players {
		if len(player.CurrentPack) != 0 {
			// Someone still has cards to draft
			return
		}
	}

	// Everyone needs to open their next pack
	p.ReadyNextPack <- true
}

// OpenPack opens the next pack the player has
func (p *Player) OpenPack() error {
	if len(p.Packs) < 1 {
		return ErrNoPacksLeft
	}
	p.CurrentPack, p.Packs = p.Packs[0], p.Packs[1:]
	return nil
}

// NextPack picks the next pack passed from other players
func (p *Player) NextPack() error {
	if len(p.newpack) < 1 {
		return ErrNoPendingPack
	}
	p.CurrentPack = <-p.newpack
	return nil
}

// Pick specified what card a player has picked and gives the pack to the next player
func (p *Player) Pick(pick Card) error {
	// Check that pack contains specified card
	id := -1
	for i, card := range p.CurrentPack {
		if pick.ID == card.ID {
			id = i
			break
		}
	}
	if id < 0 {
		return ErrNotInPack
	}
	// Take card from pack and put it into the picks
	p.Picks = append(p.Picks, p.CurrentPack[id])
	// Remove pick from pack using slice tricks
	p.CurrentPack[id] = p.CurrentPack[len(p.CurrentPack)-1]
	p.CurrentPack = p.CurrentPack[:len(p.CurrentPack)-1]

	// Out of cards! Check if everyone else is as well
	if len(p.CurrentPack) == 0 {
		p.pod.checkEndPack()
		return nil
	}

	// Send pack to next player
	if p.pod.Direction == PRClockwise {
		p.left.newpack <- p.CurrentPack
	} else {
		p.right.newpack <- p.CurrentPack
	}

	p.pod.checkPicks()

	return nil
}