path: root/go/game/action.go

package game

import (
	"errors"
	"fmt"
	"regexp"
	"slices"
	"strings"

	"muhq.space/muhqs-game/go/log"
	"muhq.space/muhqs-game/go/utils"
)

type ActionSpeed int

const (
	slow ActionSpeed = iota
	fast
)

var ActionSpeeds = struct {
	Slow ActionSpeed
	Fast ActionSpeed
}{
	Slow: slow,
	Fast: fast,
}

type (
	ActionCostFunc      func(*LocalState) bool
	ActionResolveFunc   func(*LocalState)
	ActionFuncPrototype func(Action) ActionResolveFunc
)

type Action interface {
	Source() any
	Controller() *Player
	Speed() ActionSpeed
	GameState() *LocalState
	Targets() *Targets
	// Shortcut for the first target
	Target() *Target

	NeedsActionCostChoice() bool
	CheckTargets(*LocalState) error
	// Check if an actions play costs can be payed and if so pays them
	PayCosts(s *LocalState) bool
	// Apply an actions effects to the game state
	resolve(s *LocalState)
	String() string
}

type PassPriority struct{ player *Player }

func (a *PassPriority) Source() any                  { return a.player }
func (a *PassPriority) Controller() *Player          { return a.player }
func (a *PassPriority) Speed() ActionSpeed           { return fast }
func (a *PassPriority) GameState() *LocalState       { return a.player.gameState }
func (*PassPriority) Targets() *Targets              { return nil }
func (*PassPriority) Target() *Target                { return nil }
func (*PassPriority) NeedsActionCostChoice() bool    { return false }
func (*PassPriority) CheckTargets(*LocalState) error { return nil }
func (*PassPriority) PayCosts(*LocalState) bool      { return true }
func (*PassPriority) resolve(*LocalState)            {}
func (*PassPriority) String() string                 { return "pass" }
func NewPassPriority(p *Player) Action               { return &PassPriority{p} }

type TargetSelection struct {
	player  *Player
	targets *Targets
}

func (sel *TargetSelection) Source() any                      { return sel.player }
func (sel *TargetSelection) Controller() *Player              { return sel.player }
func (sel *TargetSelection) Speed() ActionSpeed               { return fast }
func (sel *TargetSelection) GameState() *LocalState           { return sel.player.gameState }
func (sel *TargetSelection) Targets() *Targets                { return sel.targets }
func (sel *TargetSelection) Target() *Target                  { return sel.targets.ts[0] }
func (*TargetSelection) NeedsActionCostChoice() bool          { return false }
func (sel *TargetSelection) CheckTargets(s *LocalState) error { return sel.targets.CheckTargets(s) }
func (*TargetSelection) PayCosts(*LocalState) bool            { return true }
func (*TargetSelection) resolve(*LocalState)                  {}
func (*TargetSelection) String() string                       { return "target selection" }

func newTargetSelection(player *Player, targets *Targets) Action {
	return &TargetSelection{player, targets}
}

func newHandCardSelection(p *Player, min, max int) Action {
	a := &TargetSelection{player: p}
	targetDesc := TargetDesc{"hand card", fmt.Sprintf("%d-%d", min, max)}
	a.targets = newTargets(newTarget(p.gameState, targetDesc, a))
	return a
}

func newAlliedUnitSelection(p *Player, min, max int) Action {
	a := &TargetSelection{player: p}
	targetDesc := TargetDesc{"unit you control", fmt.Sprintf("%d-%d", min, max)}
	a.targets = newTargets(newTarget(p.gameState, targetDesc, a))
	return a
}

func newTileSelection(p *Player, constraint TargetConstraintFunc, min, max int) Action {
	a := &TargetSelection{player: p}
	desc := TargetDesc{"tile", fmt.Sprintf("%d-%d", min, max)}
	a.targets = newTargets(newConstraintTarget(p.gameState, desc, constraint, a))
	return a
}

type FreeDiscardAction struct {
	TargetSelection
}

func NewFreeDiscardAction(p *Player) *FreeDiscardAction {
	a := &FreeDiscardAction{TargetSelection: TargetSelection{player: p}}
	targetDesc := TargetDesc{"hand card", "2"}
	a.targets = newTargets(newTarget(p.gameState, targetDesc, a))
	return a
}

func (a *FreeDiscardAction) PayCosts(s *LocalState) bool {
	if a.targets.CheckTargets(s) != nil {
		return false
	}
	cards := utils.InterfaceSliceToTypedSlice[*Card](a.Target().Selection())
	a.player.discardCards(cards)
	return true
}

func (*FreeDiscardAction) CheckTargets(*LocalState) error { return nil }

func (a *FreeDiscardAction) resolve(*LocalState) {
	a.player.gainResource(1)
}

func (a *FreeDiscardAction) String() string {
	if a.Target().RequireSelection() {
		return fmt.Sprintf("%s discard two", a.player.Name)
	}

	sel := utils.InterfaceSliceToTypedSlice[*Card](a.Target().Selection())
	return fmt.Sprintf("%s discard [%s,%s]", a.player.Name, sel[0].Name, sel[1].Name)
}

type DraftPick struct {
	player *Player
	pick   *Card
	pack   PileOfCards
}

func (pick *DraftPick) Source() any                      { return pick.player }
func (pick *DraftPick) Controller() *Player              { return pick.player }
func (pick *DraftPick) Speed() ActionSpeed               { return fast }
func (pick *DraftPick) GameState() *LocalState           { return pick.player.gameState }
func (pick *DraftPick) Targets() *Targets                { return nil }
func (pick *DraftPick) Target() *Target                  { return nil }
func (*DraftPick) NeedsActionCostChoice() bool           { return false }
func (pick *DraftPick) CheckTargets(s *LocalState) error { return nil }
func (*DraftPick) PayCosts(*LocalState) bool             { return true }
func (pick *DraftPick) resolve(*LocalState)              { pick.pack.MoveCard(pick.pick, pick.player.Deck) }
func (*DraftPick) String() string                        { return "draft pick" }
func (pick *DraftPick) Pack() PileOfCards {
	return pick.pack
}

func (pick *DraftPick) Pick() *Card {
	return pick.pick
}

func NewDraftPick(p *Player, pack PileOfCards, card *Card) Action {
	return &DraftPick{player: p, pack: pack, pick: card}
}

func newRandomDraftPick(p *Player, n PlayerNotification) Action {
	pack := n.Context.(PileOfCards)
	return NewDraftPick(p, pack, pack.RandomCard())
}

type ActionBase struct {
	source      any
	Card        *Card
	targets     *Targets
	resolveFunc ActionResolveFunc
	costFunc    ActionCostFunc
}

func (a *ActionBase) Source() any { return a.source }
func (a *ActionBase) Controller() *Player {
	switch t := a.source.(type) {
	case *Player:
		return t
	case Permanent:
		return t.Controller()
	default:
		log.Panicf("Unhandled source type %v", t)
		return nil
	}
}
func (a *ActionBase) Speed() ActionSpeed     { return slow }
func (a *ActionBase) GameState() *LocalState { return a.Controller().gameState }
func (a *ActionBase) resolve(s *LocalState)  { a.resolveFunc(s) }
func (a *ActionBase) PayCosts(s *LocalState) bool {
	if a.costFunc != nil {
		return a.costFunc(s)
	}
	return true
}
func (a *ActionBase) Targets() *Targets { return a.targets }
func (a *ActionBase) Target() *Target   { return a.targets.ts[0] }
func (a *ActionBase) CheckTargets(s *LocalState) error {
	if a.targets == nil {
		return nil
	}
	return a.targets.CheckTargets(s)
}

type TriggeredAction struct {
	ActionBase
	event Event
}

func newTriggeredAction(event Event, trigger Trigger, resolveFunc ActionResolveFunc,
	costFunc ActionCostFunc,
) *TriggeredAction {
	return &TriggeredAction{
		ActionBase: ActionBase{
			source:      trigger.Source(),
			Card:        trigger.Card(),
			resolveFunc: resolveFunc,
			costFunc:    costFunc,
		},
		event: event,
	}
}

func (*TriggeredAction) Speed() ActionSpeed { return fast }

func (a *TriggeredAction) String() string {
	return fmt.Sprintf("%v ! %v", a.event, a.source)
}

// Wrapper action to pass all triggered actions through the PlayerControl
type DeclareTriggeredActionsAction struct {
	actions []*TriggeredAction
}

func (sel *DeclareTriggeredActionsAction) Source() any                      { return nil }
func (sel *DeclareTriggeredActionsAction) Controller() *Player              { return nil }
func (sel *DeclareTriggeredActionsAction) Speed() ActionSpeed               { return fast }
func (sel *DeclareTriggeredActionsAction) GameState() *LocalState           { return nil }
func (sel *DeclareTriggeredActionsAction) Targets() *Targets                { return nil }
func (sel *DeclareTriggeredActionsAction) Target() *Target                  { return nil }
func (*DeclareTriggeredActionsAction) NeedsActionCostChoice() bool          { return false }
func (sel *DeclareTriggeredActionsAction) CheckTargets(s *LocalState) error { return nil }
func (*DeclareTriggeredActionsAction) PayCosts(*LocalState) bool            { return true }
func (*DeclareTriggeredActionsAction) resolve(*LocalState)                  {}
func (*DeclareTriggeredActionsAction) String() string                       { return "declared triggered actions" }

func NewDeclareTriggeredActionsAction(t []*TriggeredAction) *DeclareTriggeredActionsAction {
	return &DeclareTriggeredActionsAction{t}
}

type PileDropAction struct {
	ActionBase
	pile []Permanent
	tile *Tile
}

func (a *PileDropAction) String() string {
	perm := a.source.(Permanent)
	controller := perm.Controller()
	if a.targets.RequireSelection() {
		return fmt.Sprintf("%s drop %v", controller.Name, a.tile)
	}

	s := fmt.Sprintf("%s drop [", controller.Name)
	for i, t := range a.targets.ts {
		s = fmt.Sprintf("%s %v@%v,", s, a.pile[i], t.sel[0])
	}
	return s[:len(s)-1] + " ]"
}

func (*PileDropAction) Speed() ActionSpeed        { return fast }
func (*PileDropAction) PayCosts(*LocalState) bool { return true }

func newPileDropAction(perm Permanent, tile *Tile, pile []Permanent) *PileDropAction {
	a := &PileDropAction{
		ActionBase{
			source: perm,
		},
		pile,
		tile,
	}

	a.resolveFunc = func(s *LocalState) {
		for i, p := range pile {
			p.onDrop(p)
			p.setContainingPerm(nil)
			enterTileOrPile(p, a.targets.ts[i].sel[0].(*Tile))
		}

		perm.clearPile()
	}

	a.targets = newPileDropTargets(perm.Controller().gameState, a)
	return a
}

type PlayAction struct {
	ActionBase
	ChoosenVariadicCost int
}

var (
	permanentPlayActionTarget = TargetDesc{"available spawn tile", "1"}
	equipmentPlayActionTarget = TargetDesc{"available spawn tile", "?"}
)

func NewPlayActionCostFunc(a *PlayAction, cost int) ActionCostFunc {
	player := a.source.(*Player)
	s := player.gameState
	card := a.Card

	return func(*LocalState) bool {
		if player.Resource < cost {
			return false
		}
		if additionalCosts := getCardImplementation(card).additionalPlayCosts(a); additionalCosts != nil {
			if !additionalCosts(s) {
				return false
			}
		}
		player.Resource -= cost
		player.Hand.RemoveCard(card)
		return true
	}
}

// _newPlayAction returns a new PlayAction controlled by the player for a certain card.
// It is important that the returned PlayAction has no cost function yet.
func _newPlayAction(p *Player, c *Card) *PlayAction {
	a := &PlayAction{
		ActionBase{
			source: p,
			Card:   c,
		},
		-1,
	}

	s := p.gameState
	if c.IsPermanent() {
		if c.Type == CardTypes.Equipment {
			a.targets = newTargets(newTarget(s, equipmentPlayActionTarget, a))
		} else {
			a.targets = newTargets(newTarget(s, permanentPlayActionTarget, a))
		}
	} else if targetDesc := c.Impl.playTargets(); targetDesc != INVALID_TARGET_DESC {
		a.targets = newTargets(newTarget(s, targetDesc, a))
	} else {
		a.targets = newTargets()
	}

	a.resolveFunc = func(s *LocalState) {
		s.resolvePlay(a)
	}

	return a
}

func newPlayActionWithCostFunc(p *Player, c *Card, costFunc ActionCostFunc) *PlayAction {
	a := _newPlayAction(p, c)
	a.costFunc = costFunc
	return a
}

func NewPlayAction(p *Player, c *Card) *PlayAction {
	a := _newPlayAction(p, c)

	s := p.gameState
	if a.costFunc == nil {
		a.costFunc = NewPlayActionCostFunc(a, c.PlayCosts.Costs(s))
	}

	return a
}

func NewPlayActionVariadicCosts(p *Player, c *Card, variadicCosts int) *PlayAction {
	a := _newPlayAction(p, c)
	a.costFunc = NewPlayActionCostFunc(a, c.PlayCosts.Costs(p.gameState, variadicCosts))
	a.ChoosenVariadicCost = variadicCosts
	return a
}

func (a *PlayAction) Speed() ActionSpeed {
	if a.Card.IsPermanent() {
		return slow
	}
	return fast
}

func (a *PlayAction) String() string {
	p := a.source.(*Player)
	if a.targets.RequireSelection() {
		return fmt.Sprintf(" %s play %s", p.Name, a.Card.Name)
	}

	if a.Card.Type == CardTypes.Equipment && len(a.Target().sel) == 0 {
		return fmt.Sprintf("%s play %s@next unit", p.Name, a.Card.Name)
	}

	return fmt.Sprintf("%s play %s@%v", p.Name, a.Card.Name, a.targets)
}

type MoveAction struct {
	ActionBase
}

var moveActionTargetDesc = TargetDesc{"available tile", "1"}

func targetTile(t *Target) *Tile {
	if tile, ok := t.sel[0].(*Tile); ok {
		return tile
	}

	return t.sel[0].(*Unit).Tile()
}

func NewMoveAction(u *Unit) *MoveAction {
	a := &MoveAction{
		ActionBase{
			source: u,
			Card:   u.Card(),
		},
	}

	a.targets = newTargets(newTarget(u.Controller().gameState, moveActionTargetDesc, a))

	a.resolveFunc = func(s *LocalState) {
		t := targetTile(a.Target())
		movePermanent(u, t)
	}

	a.costFunc = genMoveActionCost(u)

	return a
}

func (a *MoveAction) String() string {
	u := a.source.(*Unit)
	if a.targets.RequireSelection() {
		return fmt.Sprintf("move %s", u.Movement.String())
	}

	t := targetTile(a.Target())
	return fmt.Sprintf("%v -> %v", u, t.Position)
}

type StreetAction struct {
	ActionBase
}

var streetActionTargetDesc = TargetDesc{"available connected street tile", "1"}

func NewStreetAction(u *Unit) *StreetAction {
	a := &StreetAction{
		ActionBase{
			source: u,
			Card:   u.Card(),
		},
	}

	a.targets = newTargets(newTarget(u.Controller().gameState, streetActionTargetDesc, a))

	a.resolveFunc = func(s *LocalState) {
		t := targetTile(a.Target())
		movePermanent(u, t)
	}

	a.costFunc = func(*LocalState) bool {
		ok := u.AvailStreetActions > 0 && u.Tile() != nil && u.Tile().Type == TileTypes.Street
		if ok {
			u.AvailStreetActions = u.AvailStreetActions - 1
		}
		return ok
	}

	return a
}

func (a *StreetAction) String() string {
	u := a.source.(*Unit)
	if a.targets.RequireSelection() {
		return fmt.Sprintf("street %s", u.Movement.String())
	}

	t := targetTile(a.Target())
	return fmt.Sprintf("%v s-s> %v", u, t.Position)
}

func genBaseActionCost(u *Unit, attack, move int) ActionCostFunc {
	return func(*LocalState) bool {
		if u.AvailAttackActions < attack || u.AvailMoveActions < move {
			return false
		}
		u.AvailAttackActions -= attack
		u.AvailMoveActions -= move
		return true
	}
}

func genAttackActionCost(u *Unit) ActionCostFunc {
	return genBaseActionCost(u, 1, 0)
}

func genMoveActionCost(u *Unit) ActionCostFunc {
	return genBaseActionCost(u, 0, 1)
}

func genFullActionCost(u *Unit) ActionCostFunc {
	return func(*LocalState) bool {
		if u.AvailAttackActions < 1 || u.AvailMoveActions < 1 {
			return false
		}
		u.AvailAttackActions = 0
		u.AvailMoveActions = 0
		return true
	}
}

type EquipAction struct {
	ActionBase
	equipment *Equipment
}

func NewEquipAction(u *Unit, e *Equipment) *EquipAction {
	a := &EquipAction{
		ActionBase{
			source: u,
			Card:   u.Card(),
		},
		e,
	}

	a.resolveFunc = func(s *LocalState) {
		u.equip(e)
	}

	return a
}

func (a *EquipAction) String() string {
	u := a.source.(*Unit)
	return fmt.Sprintf("%v equip %v", u, a.equipment)
}

type AttackAction struct {
	ActionBase
}

var attackActionTargetDesc = TargetDesc{"attackable enemy permanent", "1"}

func NewAttackAction(u *Unit) *AttackAction {
	a := &AttackAction{ActionBase{
		source: u,
		Card:   u.Card(),
	}}

	a.targets = newTargets(newTarget(u.Controller().gameState, attackActionTargetDesc, a))

	a.resolveFunc = func(s *LocalState) {
		s.attack(u, a.Target().sel[0].(Permanent))
	}

	a.costFunc = genAttackActionCost(u)

	return a
}

func (a *AttackAction) String() string {
	u := a.source.(*Unit)
	if a.targets.RequireSelection() {
		return fmt.Sprintf("attack %v", u.Attack)
	}

	target := a.Target().sel[0].(Permanent)
	return fmt.Sprintf("%v x %v", u, target.Tile().Position)
}

type ArtifactSwitchAction struct {
	ActionBase
	Artifact Permanent
}

func newArtifactSwitchAction(u *Unit, artifact Permanent) *ArtifactSwitchAction {
	a := &ArtifactSwitchAction{
		ActionBase{
			source: u,
			Card:   u.Card(),
		},
		artifact,
	}

	a.resolveFunc = func(s *LocalState) {
		s.switchPermanents(a.Source().(*Unit), a.Artifact)
	}

	a.costFunc = genMoveActionCost(u)

	return a
}

func (a *ArtifactSwitchAction) String() string {
	return fmt.Sprintf("%v <-> %v", a.Source().(*Unit), a.Artifact)
}

type ArtifactMoveAction struct {
	ActionBase
	Artifact Permanent
}

func newArtifactMoveAction(u *Unit, artifact Permanent) *ArtifactMoveAction {
	a := &ArtifactMoveAction{
		ActionBase{
			source: u,
			Card:   u.Card(),
		},
		artifact,
	}

	a.targets = newArtifactMoveTargets(u.Controller().gameState, a)

	a.resolveFunc = func(s *LocalState) {
		tile := targetTile(a.Targets().ts[0])
		movePermanent(u, tile)

		tile = targetTile(a.Targets().ts[1])
		movePermanent(artifact, tile)
	}

	a.costFunc = genFullActionCost(u)

	return a
}

func (a *ArtifactMoveAction) String() string {
	if !a.Targets().HasSelections() {
		return fmt.Sprintf("%v -(%v)>", a.Source().(*Unit), a.Artifact)
	}

	t1 := targetTile(a.Targets().ts[0])
	t2 := targetTile(a.Targets().ts[1])
	return fmt.Sprintf("%v -(%v)> %v,%v", a.Source().(*Unit), a.Artifact, t1, t2)
}

type FullAction struct {
	ActionBase
	Desc string
	tag  string
}

func newFullAction(u *Unit, proto ActionFuncPrototype, desc string) *FullAction {
	a := &FullAction{
		ActionBase: ActionBase{
			source: u,
			Card:   u.Card(),
		},

		Desc: desc,
	}

	a.resolveFunc = func(s *LocalState) {
		rf := proto(a)
		rf(s)
	}

	a.costFunc = genFullActionCost(u)
	return a
}

func (a *FullAction) String() string {
	u := a.source.(*Unit)
	if a.targets == nil || a.targets.RequireSelection() {
		return fmt.Sprintf("↻ %s", a.Desc)
	}

	return fmt.Sprintf("%v↻@%v", u, a.targets)
}

type FreeAction struct {
	ActionBase
	Desc string
}

// newControllerCostFunc returns a new cost function checking the controller's resource and decreasing it accordingly.
func newControllerResourceCostFunc(p Permanent, amount int) ActionCostFunc {
	return func(s *LocalState) bool {
		c := p.Controller()
		if c.Resource < amount {
			return false
		}
		c.Resource -= amount
		return true
	}
}

func NewFreeAction(p Permanent, resolveProto ActionFuncPrototype, costFunc ActionCostFunc,
	desc string,
) *FreeAction {
	a := &FreeAction{
		ActionBase{
			source:   p,
			Card:     p.Card(),
			costFunc: costFunc,
		},
		desc,
	}

	a.resolveFunc = func(s *LocalState) {
		rf := resolveProto(a)
		rf(s)
	}

	return a
}

func (a *FreeAction) Speed() ActionSpeed { return fast }

func (a *FreeAction) String() (s string) {
	// Format the source
	switch src := a.source.(type) {
	case *Card:
		s += fmt.Sprintf("%v: %s", a.Controller(), src.Name)
	default:
		s += fmt.Sprintf("%s", src)
	}

	// Format the description and potential targets
	if a.targets == nil || a.targets.RequireSelection() {
		s += fmt.Sprintf(" %s", a.Desc)
	} else {
		s += fmt.Sprintf(" %s@%v", a.Desc, a.targets)
	}

	return
}

var buyActionTargetDesc = TargetDesc{"store card", "?"}

type BuyAction struct{ TargetSelection }

func (a *BuyAction) card() *Card {
	return a.Target().sel[0].(*Card)
}

func (a *BuyAction) CheckTargets(s *LocalState) error {
	err := a.targets.CheckTargets(s)
	if err != nil {
		return err
	}
	return s.isValidBuy(a)
}

func (a *BuyAction) resolve(s *LocalState) {
	c := a.card()
	p := a.Controller()
	if p.Store.Contains(c) {
		p.Store.MoveCard(c, p.DiscardPile)
		// Card from a store on the map
	} else {
		for _, s := range p.AvailableStores() {
			if s.Contains(c) {
				s.MoveCard(c, p.DiscardPile)
				return
			}
		}
	}
}

func (a *BuyAction) PayCosts(s *LocalState) bool {
	cost := a.card().BuyCosts.Costs(s)
	if cost < 0 || cost > a.player.Resource {
		return false
	}

	a.player.Resource -= cost
	return true
}

func (a *BuyAction) String() string {
	if !a.Targets().HasSelections() {
		return fmt.Sprintf("%s buy", a.player.Name)
	}

	return fmt.Sprintf("%s buy %s", a.player.Name, a.card().Name)
}

func newBuyAction(p *Player) *BuyAction {
	a := &BuyAction{TargetSelection{player: p}}
	a.targets = newTargets(newTarget(p.gameState, buyActionTargetDesc, a))
	return a
}

var upkeepActionTargetDesc = TargetDesc{"unit you control", "*"}

type UpkeepAction struct {
	TargetSelection
}

func (a *UpkeepAction) PayCosts(*LocalState) bool {
	costs := 0
	p := a.player
	disbanded := utils.InterfaceSliceToTypedSlice[*Unit](a.Target().sel)

	p.gameState.FilterUnits(func(u *Unit) bool {
		if u.controller == p && !slices.Contains(disbanded, u) {
			costs += u.UpkeepCost()
		}
		return false
	})

	log.Debug("calculated total upkeep costs", "costs", costs)
	if a.player.Resource < costs {
		return false
	}

	// Paying the upkeep costs is part of the resolution
	return true
}

func (a *UpkeepAction) resolve(*LocalState) {
	p := a.player
	s := p.gameState
	for _, i := range a.Target().sel {
		u := i.(*Unit)
		s.destroyPermanent(u)
	}

	// Keep and pay for the rest
	for _, u := range s.units {
		if u.Controller() != p {
			continue
		}

		log.Debug("pay for upkeep", "costs", u.UpkeepCost(), "unit", u)
		p.Resource -= u.UpkeepCost()
		u.onUpkeep()
	}
}

func (a *UpkeepAction) String() string {
	return fmt.Sprintf("upkeep disbanding: %v", a.Target().sel)
}

func newUpkeepAction(p *Player) *UpkeepAction {
	a := &UpkeepAction{TargetSelection{player: p}}
	a.targets = newTargets(newTarget(p.gameState, upkeepActionTargetDesc, a))

	return a
}

func (a *ActionBase) NeedsActionCostChoice() bool {
	return a.costFunc == nil
}

func UseMoveAction(a Action) {
	switch a := a.(type) {
	case *EquipAction:
		a.costFunc = genMoveActionCost(a.Source().(*Unit))
	}
}

func UseAttackAction(a Action) {
	switch a := a.(type) {
	case *EquipAction:
		a.costFunc = genAttackActionCost(a.Source().(*Unit))
	}
}

type ConcedeAction struct {
	PassPriority
}

func NewConcedeAction(p *Player) *ConcedeAction {
	return &ConcedeAction{PassPriority{p}}
}

func (a *ConcedeAction) resolve(*LocalState) {
	a.player.concede()
}

func (a *ConcedeAction) String() string {
	return fmt.Sprintf("%s concedes", a.player.Name)
}

// Marshal an action to plain text.
// The format of the action is `SOURCE ACTION CONTEXT`.
// PassPriority: PLAYER pass
// ConcedeAction: PLAYER concede
// DraftPick: PLAYER pick CARD:PACK
func MarshalAction(_a Action) []byte {
	out := []byte{}
	switch a := _a.(type) {
	case *PassPriority:
		out = fmt.Appendf(out, "%s\u00A0pass", a.player.Name)
	case *ConcedeAction:
		out = fmt.Appendf(out, "%s\u00A0concede", a.player.Name)
	case *DraftPick:
		out = fmt.Appendf(out, "%s\u00A0pick\u00A0%s:%s", a.player.Name, a.pick.Path(), a.pack)
	default:
		log.Fatalf("MarshalAction(%s) not implemented\n", a)
	}
	return out
}

var (
	ErrInvalidActionFormat = errors.New("invalid action format")
	ErrUnknownPlayer       = errors.New("unknown player")
)

var ActionRegex = regexp.MustCompile(`^([^\xA0]*)\xA0([^\xA0]*)\xA0?(.*)?$`)

func UnmarshalAction(s State, in []byte) (a Action, err error) {
	m := ActionRegex.FindSubmatch(in)
	if len(m) < 2 || len(m) > 4 {
		return nil, ErrInvalidActionFormat
	}
	_action := string(m[2])
	switch _action {
	case "pick":
		p := s.PlayerByName(string(m[1]))
		if p == nil {
			err = ErrUnknownPlayer
			return
		}
		_p := strings.Split(string(m[3]), ":")
		pick, err := NewCardSafe(_p[0])
		if err != nil {
			return nil, err
		}
		pack := NewPileOfCards()
		err = pack.FromString(_p[1])
		if err != nil {
			return nil, err
		}
		a = NewDraftPick(p, pack, pick)
	case "pass", "concede":
		p := s.PlayerByName(string(m[1]))
		if p == nil {
			err = ErrUnknownPlayer
			return
		}
		if _action == "pass" {
			a = NewPassPriority(p)
		} else {
			a = NewConcedeAction(p)
		}
	}
	return
}