3 files changed, 159 insertions, 1 deletions

diff --git a/go/game/action.go b/go/game/action.go
index fbabb06b..4f433845 100644
--- a/go/game/action.go
+++ b/go/game/action.go
@@ -79,6 +79,29 @@ func (a *ActionBase) CheckTargets(s *State) error {
 	return a.targets.CheckTargets(s)
 }
 
+type TriggeredAction struct {
+	ActionBase
+	event Event
+}
+
+func newTriggeredAction(event Event, source Trigger, resolveFunc ActionResolveFunc,
+	costFunc ActionCostFunc,
+) *TriggeredAction {
+	return &TriggeredAction{
+		ActionBase: ActionBase{
+			source:      source,
+			Card:        source.Card(),
+			resolveFunc: resolveFunc,
+			costFunc:    costFunc,
+		},
+		event: event,
+	}
+}
+
+func (a *TriggeredAction) String() string {
+	return fmt.Sprintf("%v ! %v", a.event, a.source)
+}
+
 type PileDropAction struct {
 	ActionBase
 	pile []Permanent
diff --git a/go/game/state.go b/go/game/state.go
index 49ee0c06..6bb3dbf0 100644
--- a/go/game/state.go
+++ b/go/game/state.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"golang.org/x/exp/slices"
+	"muhq.space/muhqs-game/go/utils"
 )
 
 type State struct {
@@ -24,6 +25,8 @@ type State struct {
 	Rand                 *rand.Rand
 	eotEffects           []effect
 	outstandingEquipment []*Card
+	events               []Event
+	triggers             []Trigger
 }
 
 func NewState() *State {
@@ -96,6 +99,39 @@ func (s *State) Loop() []*Player {
 	return winners
 }
 
+func (s *State) removeTriggers(triggers []Trigger) {
+	for _, t := range triggers {
+		s.triggers = utils.RemoveFromUnorderedSlice(s.triggers, t)
+	}
+}
+
+func (s *State) handleTriggers() {
+	var actions []Action
+	var triggersToRemove []Trigger
+
+	for _, e := range s.events {
+		for _, t := range s.triggers {
+			a, remove := t.trigger(s, e)
+			if a != nil {
+				actions = append(actions, a...)
+			}
+			if remove {
+				triggersToRemove = append(triggersToRemove, t)
+			}
+		}
+	}
+
+	// Reset occured events
+	s.events = nil
+
+	s.removeTriggers(triggersToRemove)
+
+	orderedActions := s.orderTriggeredActions(actions)
+	for _, a := range orderedActions {
+		s.declareAction(a)
+	}
+}
+
 func (s *State) stateBasedActions() {
 	for _, p := range s.Permanents {
 		p.Card().Impl.stateBasedActions(s, p)
@@ -104,6 +140,8 @@ func (s *State) stateBasedActions() {
 			s.destroyPermanent(p)
 		}
 	}
+
+	s.handleTriggers()
 }
 
 func (s *State) IsValidPlay(a *PlayAction) error {
@@ -322,6 +360,11 @@ func (s *State) declareAction(a Action) {
 	s.broadcastNotification(newDeclaredActionNotification(a, err))
 }
 
+func (s *State) orderTriggeredActions(actions []Action) []Action {
+	// TODO: implement ordering
+	return actions
+}
+
 func (s *State) allPassing(skipFirst bool) bool {
 	nPlayers := len(s.Players)
 	i := 0
@@ -600,6 +643,8 @@ func (s *State) endOfTurn() {
 	for _, e := range s.eotEffects {
 		e.end(s)
 	}
+	s.eotEffects = nil
 
-	s.eotEffects = []effect{}
+	s.events = append(s.events, newEotEvent())
+	s.stateBasedActions()
 }
diff --git a/go/game/trigger.go b/go/game/trigger.go
new file mode 100644
index 00000000..39901d71
--- /dev/null
+++ b/go/game/trigger.go
@@ -0,0 +1,90 @@
+package game
+
+import (
+	"fmt"
+	"log"
+)
+
+type eventType int
+
+const (
+	destruction eventType = iota
+	eot
+	sacrifice
+	play
+)
+
+var EventTypes = struct {
+	Destruction eventType
+	Eot         eventType
+	Sacrifice   eventType
+	Play        eventType
+}{
+	Destruction: destruction,
+	Eot:         eot,
+	Play:        play,
+}
+
+func (e eventType) String() string {
+	switch e {
+	case destruction:
+		return "destruction"
+	case eot:
+		return "eot"
+	case sacrifice:
+		return "sacrifice"
+	case play:
+		return "play"
+	}
+
+	log.Panicf("Unknown evenType", e)
+	return ""
+}
+
+type Event struct {
+	eventType eventType
+	sources   []interface{}
+}
+
+func (e Event) String() string {
+	if len(e.sources) == 0 {
+		return e.eventType.String()
+	}
+
+	return fmt.Sprintf("%v:%v", e.sources, e.eventType)
+}
+
+func newEotEvent() Event {
+	return Event{eventType: eot}
+}
+
+type Trigger interface {
+	Card() *Card
+	String() string
+	trigger(*State, Event) ([]Action, bool)
+}
+
+type triggerBase struct {
+	card        *Card
+	condition   func(*State, Event) (bool, bool)
+	resolveFunc ActionResolveFunc
+	costFunc    ActionCostFunc
+	desc        string
+}
+
+func (t *triggerBase) Card() *Card {
+	return t.card
+}
+
+func (t *triggerBase) String() string {
+	return t.desc
+}
+
+func (t *triggerBase) trigger(s *State, e Event) ([]Action, bool) {
+	triggered, remove := t.condition(s, e)
+	if !triggered {
+		return nil, remove
+	}
+
+	return []Action{newTriggeredAction(e, t, t.resolveFunc, t.costFunc)}, remove
+}