Fix excess divider mess in message display.

Also the title is visible.

.gitignore

@@ -21,3 +21,5 @@
 # Go workspace file
 go.work
 
+# Visual studio Code exclusions
+.vscode/settings.json

README.md

@@ -2,6 +2,8 @@
 
 Basic engine for NationStates-like "make decisions on issues" simulation games. Very incomplete.
 
+[![Go Reference](https://pkg.go.dev/badge/git.chromaticdragon.app/kistaro/CardSimEngine.svg)](https://pkg.go.dev/git.chromaticdragon.app/kistaro/CardSimEngine)
+
 ## General turn model
 
 1. Player has a hand of cards. Each card has one or more actions available.

cardsim/card.go

@@ -5,9 +5,8 @@ package cardsim
 type Card[C StatsCollection] interface {
 	// Title is the short name of the card displayed in the hand
 	// and at the top of the card output. It receives the current
-	// player as an argument. If it returns an error that is not
-	// a warning, the game crashes.
-	Title(p *Player[C]) (Message, error)
+	// player as an argument.
+	Title(p *Player[C]) Message
 
 	// Urgent reports whether the card is considered urgent. If
 	// the player has any urgent cards in hand, they cannot choose to act
@@ -50,8 +49,12 @@ type CardOption[C StatsCollection] interface {
 	// a warning, the game crashes.
 	//
 	// After an option is enacted, the card is deleted. If a card should be
-	// repeatable, Enact must return it to the deck (on every option).
+	// repeatable, Enact must return it to the deck (on every option) or
+	// the card needs to reinsert itself with its Then function.
 	Enact(p *Player[C]) (Message, error)
+
+	// Enabled returns whether this option can curently be enacted.
+	Enabled(p *Player[C]) bool
 }
 
 // A BasicCard is a Card with fixed title, text, options, and optional
@@ -61,37 +64,45 @@ type BasicCard[C StatsCollection] struct {
 	IsUrgent    bool
 	CardText    Message
 	CardOptions []CardOption[C]
-	AfterOption func(p *Player[C], option CardOption[C]) error
+	// AfterOption is given the card itself as its first argument.
+	AfterOption func(c Card[C], p *Player[C], option CardOption[C]) error
 }
 
-func (b *BasicCard[C]) Title(p *Player[C]) (Message, error) {
-	return b.CardTitle, nil
+// Title implements Card.
+func (b *BasicCard[C]) Title(_ *Player[C]) Message {
+	return b.CardTitle
 }
 
+// Urgent implements Card.
 func (b *BasicCard[C]) Urgent(_ *Player[C]) bool {
 	return b.IsUrgent
 }
 
-func (b *BasicCard[C]) EventText(p *Player[C]) (Message, error) {
+// EventText implements Card.
+func (b *BasicCard[C]) EventText(_ *Player[C]) (Message, error) {
 	return b.CardText, nil
 }
 
+// Options implements Card.
 func (b *BasicCard[C]) Options(_ *Player[C]) ([]CardOption[C], error) {
 	return b.CardOptions, nil
 }
 
+// Then implements Card.
 func (b *BasicCard[C]) Then(p *Player[C], option CardOption[C]) error {
 	if b.AfterOption == nil {
 		return nil
 	}
-	return b.AfterOption(p, option)
+	return b.AfterOption(b, p, option)
 }
 
-func (b *BasicCard[C]) Drawn(p *Player[C]) bool {
+// Drawn implements Card.
+func (b *BasicCard[C]) Drawn(_ *Player[C]) bool {
 	return true
 }
 
 // A BasicOption is a CardOption with fixed text, effects, and output.
+// It's always enabled.
 type BasicOption[C StatsCollection] struct {
 	Text   Message
 	Effect func(*Player[C]) error
@@ -108,6 +119,11 @@ func (b *BasicOption[C]) Enact(p *Player[C]) (Message, error) {
 	return b.Output, b.Effect(p)
 }
 
+// Enabled implements CardOption.
+func (b *BasicOption[C]) Enabled(p *Player[C]) bool {
+	return true
+}
+
 // OptionFunc attaches a fixed prompt to an Enact-like function. Unlike
 // BasicOption, the enactment function provided to OptionFunc returns
 // the text that should be output as a result of the action, so it is
@@ -121,10 +137,17 @@ type optionFunc[C StatsCollection] struct {
 	f    func(*Player[C]) (Message, error)
 }
 
+// OptionText implements CardOption.
 func (o *optionFunc[C]) OptionText(p *Player[C]) (Message, error) {
 	return o.text, nil
 }
 
+// Enact implements CardOption.
 func (o *optionFunc[C]) Enact(p *Player[C]) (Message, error) {
 	return o.f(p)
 }
+
+// Enabled implements CardOption.
+func (o *optionFunc[C]) Enabled(p *Player[C]) bool {
+	return true
+}

cardsim/errors.go

@@ -52,6 +52,15 @@ func Warningf(f string, args ...any) *Warning {
 	return &Warning{fmt.Errorf(f, args...)}
 }
 
+// IsSeriousError returns whether e is a non-warning error. If e is nil, this
+// returns false.
+func IsSeriousError(e error) bool {
+	if e == nil {
+		return false
+	}
+	return !errors.Is(e, AnyWarning)
+}
+
 // A Failure is an error that is definitely not a Warning. If a Warning is
 // wrapped in a Failure, it stops being a Warning.
 type Failure struct {
@@ -144,8 +153,11 @@ func (f Failure) As(target any) bool {
 //   - Otherwise, it returns an error that combines all the errors it collected.
 //     The aggregated error is a Warning if and only if all collected errors
 //     were also warnings.
+//
+// An ErrorCollector's Errs should not be written by anything other than Add,
+// or HasFailure may get out of sync.
 type ErrorCollector struct {
-	errs       []error
+	Errs       []error
 	hasFailure bool
 }
 
@@ -157,12 +169,12 @@ func (ec *ErrorCollector) Add(e error) {
 	if !errors.Is(e, AnyWarning) {
 		ec.hasFailure = true
 	}
-	ec.errs = append(ec.errs, e)
+	ec.Errs = append(ec.Errs, e)
 }
 
 // IsEmpty reports whether ec has zero accumulated errors/warnings.
 func (ec *ErrorCollector) IsEmpty() bool {
-	return len(ec.errs) == 0
+	return len(ec.Errs) == 0
 }
 
 // HasFailure reports whether ec has at least one non-warning error.
@@ -181,16 +193,16 @@ func (ec *ErrorCollector) HasFailure() bool {
 // errors.Is does not erroneously represent a failure as a warning because it
 // contains a warning as a subcomponent.
 func (ec *ErrorCollector) Emit() error {
-	if len(ec.errs) == 0 {
+	if len(ec.Errs) == 0 {
 		return nil
 	}
-	if len(ec.errs) == 1 {
-		return ec.errs[0]
+	if len(ec.Errs) == 1 {
+		return ec.Errs[0]
 	}
 	if ec.HasFailure() {
-		return aggregateFailure(ec.errs)
+		return aggregateFailure(ec.Errs)
 	}
-	return &aggregateError{ec.errs} // all these are recognizable warnings
+	return &aggregateError{ec.Errs} // all these are recognizable warnings
 }
 
 // An aggregateError is a collection of errors that is itself an error.

cardsim/infopanel.go

@@ -11,7 +11,7 @@ import (
 type InfoPanel[C StatsCollection] interface {
 	// Title returns the title of this InfoPanel, which is also used as the
 	// label presented to the player to access this panel.
-	Title(p *Player[C]) (Message, error)
+	Title(p *Player[C]) Message
 
 	// Info returns the displayable contents of this InfoPanel. A nil Message
 	// in the output is interpreted as a paragraph break.
@@ -44,8 +44,8 @@ func VisibleOrDebug[C StatsCollection](p *Player[C], s Stat) bool {
 }
 
 // Title implements `InfoPanel[C]` by returning b's `Name`.
-func (b *BasicStatsPanel[C]) Title(p *Player[C]) (Message, error) {
-	return b.Name, nil
+func (b *BasicStatsPanel[C]) Title(p *Player[C]) Message {
+	return b.Name
 }
 
 // Info implements `InfoPanel[C]` by dumpiing p.Stats, showing those items for

cardsim/messages.go

@@ -1,6 +1,9 @@
 package cardsim
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 // Message is an opaque interface representing a displayable message.
 // Using an interface here allows for implementation of new message display
@@ -25,3 +28,50 @@ func MsgStr(s string) Message {
 func Msgf(f string, args ...any) Message {
 	return stringMessage(fmt.Sprintf(f, args...))
 }
+
+// A SpecialMessage is a specific, uniquely identifiable message.
+type SpecialMessage struct {
+	msg Message
+}
+
+// String implements Message.
+func (s *SpecialMessage) String() string {
+	if s == nil {
+		return ""
+	}
+	return s.msg.String()
+}
+
+// Messages that various display surfaces or other components may have a special interpretation of
+// and identify specifically. These are largely sentinel values. Nil is a paragraph break.
+var (
+	SectionBreak = &SpecialMessage{MsgStr("      --------------------------------------------------------------------      ")}
+	ChapterBreak = &SpecialMessage{MsgStr("      ====================================================================      ")}
+)
+
+// IsSpecialMessage returns whether a provided Message is a specific SpecialMessage.
+func IsSpecialMessage(m Message, s *SpecialMessage) bool {
+	if m == nil {
+		return s == nil
+	}
+	if s2, ok := m.(*SpecialMessage); ok {
+		return s == s2
+	}
+	return false
+}
+
+// MultiMessage is a sequence of messages treated like one message.
+type MultiMessage []Message
+
+func (m MultiMessage) String() string {
+	s := make([]string, len(m))
+	for i, msg := range m {
+		if msg == nil {
+			s[i] = ""
+			continue
+		}
+		s[i] = msg.String()
+		continue
+	}
+	return strings.Join(s, "\n")
+}

cardsim/player.go

@@ -1,6 +1,21 @@
 package cardsim
 
-import "math/rand"
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+var (
+	ErrUncooperativeCards = errors.New("a milion cards refused to join the hand")
+	ErrInvalidCard        = errors.New("invalid card specified")
+	ErrInvalidChoice      = errors.New("invalid choice specified")
+	ErrNotUrgent          = errors.New("action not urgent when urgent card is available")
+	ErrNoActions          = errors.New("no actions remaining")
+
+	WarningStalemate = errors.New("no actions can be taken")
+)
 
 // Player stores all gameplay state for one player at a specific point in time.
 // Game-specific data is stored in Stats.
@@ -59,7 +74,7 @@ type Player[C StatsCollection] struct {
 	Name string
 
 	// Rand is a source of randomness that other components can use.
-	Rand rand.Rand
+	Rand *rand.Rand
 
 	Deck       *Deck[C]
 	Hand       []Card[C]
@@ -83,7 +98,10 @@ type Player[C StatsCollection] struct {
 	ActionsPerTurn   int
 	ActionsRemaining int
 
-	// PermanentActions are an "extra hand" of cards that are not discarded when used.
+	// PermanentActions are an "extra hand" of cards that are not discarded when
+	// used. An Urgent PermanentAction does not block non-urgent actions and
+	// cards in hand from being used, but it can be used even when an urgent
+	// card is in the hand.
 	PermanentActions []Card[C]
 
 	// InfoPanels lists informational views available to the player. The Prompt
@@ -134,7 +152,331 @@ const (
 	GameStalled
 )
 
+// InitPlayer returns a mostly-uninitialized Player with the fields
+// that require specific initialization already configured and the
+// provided StatsCollection (if any) already assigned to its Stats.
+// Most fields are not configured and need to be assigned after this.
+//
+// The Player is initialized with an empty deck, empty rule collection,
+// a hand limit of 1, an actions-per-turn limit of 1, and a random
+// number generator seeded with the nanosecond component of the current time.
+// The Deck shares this random number generator.
+func InitPlayer[C StatsCollection](stats C) *Player[C] {
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	return &Player[C]{
+		Stats:          stats,
+		Rand:           r,
+		Deck:           &Deck[C]{rand: r},
+		HandLimit:      1,
+		ActionsPerTurn: 1,
+		Rules:          NewRuleCollection[C](),
+	}
+}
+
 // Over returns whether this state represents a game that is over.
 func (g GameState) Over() bool {
 	return g == GameLost || g == GameWon || g == GameCrashed || g == GameStalled
 }
+
+// ChapterBreak apends a chapter break to p.TemporaryMessages, unless it is
+// empty or the most recent non-nil message is already a chapter break.
+func (p *Player[C]) ChapterBreak() {
+	for i := len(p.TemporaryMessages) - 1; i >= 0; i-- {
+		m := p.TemporaryMessages[i]
+		if IsSpecialMessage(m, ChapterBreak) {
+			return
+		}
+		if p.TemporaryMessages[i] != nil {
+			p.TemporaryMessages = append(p.TemporaryMessages, ChapterBreak)
+			return
+		}
+	}
+	// No non-nil messages -- nothing to do.
+}
+
+// SectionBreak apends a section break to p.TemporaryMessages, unless it is
+// empty or the most recent non-nil message is already a section/chapter break.
+func (p *Player[C]) SectionBreak() {
+	for i := len(p.TemporaryMessages) - 1; i >= 0; i-- {
+		m := p.TemporaryMessages[i]
+		if IsSpecialMessage(m, ChapterBreak) || IsSpecialMessage(m, SectionBreak) {
+			return
+		}
+		if m != nil {
+			p.TemporaryMessages = append(p.TemporaryMessages, SectionBreak)
+			return
+		}
+	}
+	// No non-nil messages -- nothing to do.
+}
+
+// Simulate executes the simulation up to the start of the next turn. If the
+// simulation crashes, the game state becomes GameCrashed. This returns any
+// generated errors; if the debugging mode is 0 or greater, they also become
+// temporary messages for the next turn.
+func (p *Player[C]) Simulate() error {
+	var errs ErrorCollector
+	p.TemporaryMessages = nil
+	p.TemporaryPanels = nil
+	errs.Add(p.Rules.Run(p))
+	errs.Add(p.StartNextTurn())
+
+	if errs.HasFailure() {
+		p.State = GameCrashed
+	}
+
+	if p.DebugLevel > 0 && !errs.IsEmpty() {
+		p.ChapterBreak()
+		p.TemporaryMessages = append(p.TemporaryMessages, Msgf("%d ERRORS AND WARNINGS while simulating turn:", len(errs.Errs)))
+		for i, e := range errs.Errs {
+			yikes := " "
+			if IsSeriousError(e) {
+				yikes = "!"
+			}
+			p.TemporaryMessages = append(p.TemporaryMessages, Msgf("%s[%d]:\t%v", yikes, i, e))
+		}
+	}
+	return errs.Emit()
+}
+
+// StartNextTurn increments the turn counter, resets the action counter,
+// and draws back up to full. If the player cannot take any actions after
+// drawing is complete, the game stalls. (If a drawn card would like to
+// force the player to take no actions for a turn, the best approach is to
+// make that card Urgent and make it reset ActionsRemaining to 0 after it runs.)
+func (p *Player[C]) StartNextTurn() error {
+	var errs ErrorCollector
+	p.TurnNumber++
+	p.ActionsRemaining = p.ActionsPerTurn
+	errs.Add(p.FillHand())
+	if len(p.Hand)+len(p.PermanentActions) == 0 {
+		p.State = GameStalled
+		errs.Add(Warningf("%w: no cards in hand, no permanent actions", WarningStalemate))
+	}
+	if p.ActionsRemaining == 0 {
+		p.State = GameStalled
+		errs.Add(Warningf("%w: 0 actions available in the turn", WarningStalemate))
+	}
+	return errs.Emit()
+}
+
+// Draw draws a card into the hand, informing the card that it has been drawn.
+// If more than a million cards refuse to enter the hand, this crashes with
+// ErrUncooperativeCards. If the deck does not have enough cards, this
+// returns WarningTooFewCards.
+func (p *Player[C]) Draw() error {
+	for attempts := 0; attempts < 1000000; attempts++ {
+		if p.Deck.Len() == 0 {
+			return WarningTooFewCards
+		}
+		c := p.Deck.Draw()
+		if c.Drawn(p) {
+			p.Hand = append(p.Hand, c)
+			return nil
+		}
+	}
+	return ErrUncooperativeCards
+}
+
+// FillHand draws up to the hand limit, informing cards that they have been
+// drawn. If more than a million cards refuse to enter the hand, this crashes
+// with ErrUncooperativeCards. If the deck does not have enough cards, this
+// returns WarningTooFewCards.
+func (p *Player[C]) FillHand() error {
+	var lastErr error
+	for p.Deck.Len() > 0 && len(p.Hand) < p.HandLimit {
+		lastErr = p.Draw()
+		if IsSeriousError(lastErr) {
+			return lastErr
+		}
+	}
+
+	if len(p.Hand) >= p.HandLimit {
+		return nil
+	}
+
+	return WarningTooFewCards
+}
+
+// HasUrgentCards returns whether any cards in the Hand think they are Urgent.
+func (p *Player[C]) HasUrgentCards() bool {
+	for _, c := range p.Hand {
+		if c.Urgent(p) {
+			return true
+		}
+	}
+	return false
+}
+
+// EnactCardUnchecked executes a card choice, removes it from the hand, and
+// decrements the ActionsRemaining. It does not check for conflicting Urgent
+// cards or already being out of actions. If no such card or card choice
+// exists, or the specified choice is not enabled, this returns nil and
+// ErrInvalidCard/ErrInvalidChoice without changing anything. Otherwise, this
+// returns the result of enacting the card. If enacting the card causes a
+// serious error, the State becomes GameCrashed.
+func (p *Player[C]) EnactCardUnchecked(cardIdx, choiceIdx int) (Message, error) {
+	if cardIdx < 0 || cardIdx >= len(p.Hand) {
+		return nil, fmt.Errorf("%w: no card #%d when %d cards in hand", ErrInvalidCard, cardIdx, len(p.Hand))
+	}
+	card := p.Hand[cardIdx]
+	var errs ErrorCollector
+	options, err := card.Options(p)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+		return nil, err
+	}
+	errs.Add(err)
+	if choiceIdx < 0 || choiceIdx > len(options) {
+		errs.Add(fmt.Errorf("%w: no option #%d on card #%d with %d options", ErrInvalidChoice, choiceIdx, cardIdx, len(options)))
+		return nil, errs.Emit()
+	}
+
+	chosen := options[choiceIdx]
+	if !chosen.Enabled(p) {
+		errs.Add(fmt.Errorf("%w: option %d on card %d was not enabled", ErrInvalidChoice, choiceIdx, cardIdx))
+		return nil, errs.Emit()
+	}
+
+	p.Hand = DeleteFrom(p.Hand, cardIdx)
+	p.ActionsRemaining--
+
+	ret, err := options[choiceIdx].Enact(p)
+	errs.Add(err)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+		return ret, errs.Emit()
+	}
+
+	err = card.Then(p, options[choiceIdx])
+	errs.Add(err)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+	}
+	return ret, errs.Emit()
+}
+
+// EnactCard executes a card choice, removes it from the hand, and decrements
+// the ActionsRemaining. If the card is not Urgent but urgent cards are
+// available, or the player is out of actions, this returns ErrNotUrgent or
+// ErrNoActions. Otherwise, this acts like EnactCardUnchecked.
+func (p *Player[C]) EnactCard(cardIdx, choiceIdx int) (Message, error) {
+	if p.ActionsRemaining <= 0 {
+		return nil, ErrNoActions
+	}
+	if cardIdx < 0 || cardIdx >= len(p.Hand) {
+		return nil, fmt.Errorf("%w: no card #%d when %d cards in hand", ErrInvalidCard, cardIdx, len(p.Hand))
+	}
+	if !p.Hand[cardIdx].Urgent(p) && p.HasUrgentCards() {
+		return nil, ErrNotUrgent
+	}
+	return p.EnactCardUnchecked(cardIdx, choiceIdx)
+}
+
+// EnactPermanentActionUnchecked executes a permanently-available action and
+// decrements the ActionsRemaining. It does not check for conflicting Urgent
+// cards or already being out of actions. If no such action or card option
+// exists, or the option is not enabled, this returns nil and ErrInvalidCard
+// or ErrInvalidChoice without changing anything. Otherwise, this returns the
+// result of enacting the permanent action. If enacting the card causes a
+// serious error, the State becomes GameCrashed.
+func (p *Player[C]) EnactPermanentActionUnchecked(actionIdx, choiceIdx int) (Message, error) {
+	if actionIdx < 0 || actionIdx >= len(p.PermanentActions) {
+		return nil, fmt.Errorf("%w: no action #%d when %d permanent actions exist", ErrInvalidCard, actionIdx, len(p.PermanentActions))
+	}
+	card := p.PermanentActions[actionIdx]
+	var errs ErrorCollector
+	options, err := card.Options(p)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+		return nil, err
+	}
+	errs.Add(err)
+	if choiceIdx < 0 || choiceIdx > len(options) {
+		errs.Add(fmt.Errorf("%w: no option #%d on permanent action #%d with %d options", ErrInvalidChoice, choiceIdx, actionIdx, len(options)))
+		return nil, errs.Emit()
+	}
+	chosen := options[choiceIdx]
+	if !chosen.Enabled(p) {
+		errs.Add(fmt.Errorf("%w: option #%d on permanent action #%d is not enabled", ErrInvalidChoice, choiceIdx, actionIdx))
+		return nil, errs.Emit()
+	}
+
+	p.ActionsRemaining--
+
+	ret, err := chosen.Enact(p)
+	errs.Add(err)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+		return ret, errs.Emit()
+	}
+
+	err = card.Then(p, chosen)
+	errs.Add(err)
+	if IsSeriousError(err) {
+		p.State = GameCrashed
+	}
+	return ret, errs.Emit()
+}
+
+// EnactPermanentAction executes a permanently-available card and decrements
+// the ActionsRemaining. If the action is not Urgent but urgent cards are
+// available, or the player is out of actions, this returns ErrNotUrgent or
+// ErrNoActions. Otherwise, this acts like EnactPermanentActionUnchecked.
+func (p *Player[C]) EnactPermanentAction(actionIdx, choiceIdx int) (Message, error) {
+	if p.ActionsRemaining <= 0 {
+		return nil, ErrNoActions
+	}
+	if actionIdx < 0 || actionIdx >= len(p.PermanentActions) {
+		return nil, fmt.Errorf("%w: no action #%d when %d permanent actions available", ErrInvalidCard, actionIdx, len(p.PermanentActions))
+	}
+	if !p.PermanentActions[actionIdx].Urgent(p) && p.HasUrgentCards() {
+		return nil, ErrNotUrgent
+	}
+	return p.EnactPermanentActionUnchecked(actionIdx, choiceIdx)
+}
+
+// ReportError adds an error to the temporary messages, depending on
+// its severity and debug settings:
+//
+//   - If the error is nil, this never does anything.
+//   - If the error is serious, this emits the error if the debug level is
+//     -1 or greater.
+//   - If the error is only a warning, this emits the error if the debug
+//     level is 0 or greater.
+func (p *Player[C]) ReportError(e error) {
+	if e == nil || p.DebugLevel < -1 {
+		return
+	}
+	if p.DebugLevel < 0 && !IsSeriousError(e) {
+		return
+	}
+	p.ChapterBreak()
+	severity := "[Warning]"
+	if IsSeriousError(e) {
+		severity = "[ERROR]"
+	}
+	p.TemporaryMessages = append(p.TemporaryMessages, Msgf("%s: %v", severity, e))
+}
+
+// CanAct returns whether the player has actions theoretically available.
+func (p *Player[C]) CanAct() bool {
+	return p.ActionsRemaining > 0 && (len(p.Hand) > 0 || len(p.PermanentActions) > 0)
+}
+
+// Debug adds a message to the player's temporary messages if their debug level
+// is at least the level specified.
+func (p *Player[C]) Debug(minLevel int, msg Message) {
+	if p.DebugLevel < minLevel || msg == nil {
+		return
+	}
+	p.TemporaryMessages = append(p.TemporaryMessages, msg)
+}
+
+// Emit adds a message to the player's temporary messages.
+func (p *Player[C]) Emit(msg Message) {
+	if msg == nil {
+		return
+	}
+	p.TemporaryMessages = append(p.TemporaryMessages, msg)
+}

cardsim/rules.go

@@ -141,7 +141,7 @@ func (r *RuleCollection[C]) performInsert(k *keyedRule[C]) {
 	r.rules[k.id] = k
 
 	s := r.byStep[k.Step()]
-	if s == nil {
+	if len(s) == 0 {
 		r.steps = nil
 	}
 	s = append(s, k.id)
@@ -326,7 +326,7 @@ func (r *RuleCollection[C]) Run(p *Player[C]) error {
 	steps := r.steps
 	if steps == nil {
 		// Step set changed, recalculate.
-		steps := make([]int, 0, len(r.byStep))
+		steps = make([]int, 0, len(r.byStep))
 		for step := range r.byStep {
 			steps = append(steps, step)
 		}
@@ -334,18 +334,21 @@ func (r *RuleCollection[C]) Run(p *Player[C]) error {
 		r.steps = steps
 	}
 
+	p.Debug(2, Msgf("Executing steps: %v", steps))
+
 	var errs ErrorCollector
 	for _, step := range steps {
 		stepRules := r.byStep[step]
-		p.Rand.Shuffle(len(stepRules), func(i, j int) {
-			stepRules[i], stepRules[j] = stepRules[j], stepRules[i]
-		})
+		p.Debug(3, Msgf("Executing step %d; length %d", step, len(stepRules)))
+		ShuffleAll(stepRules, p.Rand)
 		var remove []RuleID
 		halt := false
 		for _, id := range stepRules {
 			rule := r.rules[id]
+			p.Debug(4, Msgf("Executing rule %x (labeled %q)", id, rule.Label()))
 			err := rule.Enact(p)
 			if err != nil {
+				p.Debug(2, Msgf("Rule %x (%q): error: %v", id, rule.Label(), err))
 				ignore := false
 				if errors.Is(err, ErrDeleteRule) {
 					remove = append(remove, id)
@@ -377,10 +380,14 @@ func (r *RuleCollection[C]) Run(p *Player[C]) error {
 			}
 		}
 		if halt {
-			return errs.Emit()
+			ret := errs.Emit()
+			p.Debug(2, Msgf("Rules stopping early. Result: %v", ret))
+			return ret
 		}
 	}
-	return errs.Emit()
+	ret := errs.Emit()
+	p.Debug(2, Msgf("Rules complete. Result: %v", ret))
+	return ret
 }
 
 func (r *RuleCollection[C]) applyDelayedUpdates() {

cardsim/terminalui.go

@@ -0,0 +1,528 @@
+package cardsim
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func RunSimpleTerminalUI[C StatsCollection](p *Player[C]) error {
+
+	err := p.StartNextTurn()
+	if p.DebugLevel < 1 && IsSeriousError(err) {
+		return err
+	}
+	p.ReportError(err)
+
+	for {
+		for p.CanAct() {
+			isCard, cardIdx, choiceIdx, err := pickNextAction(p)
+			p.ReportError(err)
+			if IsSeriousError(err) {
+				if p.DebugLevel < 1 {
+					return err
+				}
+				continue
+			}
+			var msg Message
+			if isCard {
+				msg, err = p.EnactCard(cardIdx, choiceIdx)
+			} else {
+				msg, err = p.EnactPermanentAction(cardIdx, choiceIdx)
+			}
+			p.ReportError(err)
+			if IsSeriousError(err) {
+				if p.DebugLevel < 1 {
+					return err
+				}
+				continue
+			}
+			display(msg)
+			wait()
+		}
+
+		// Allow player to review state before continuing simulation.
+		// Errors from review mode are reported *after* the simulation
+		// step because the first thing Simulate does is throw out old
+		// messages -- like these errors.
+		reviewErr := review(p)
+		if p.DebugLevel < 1 && IsSeriousError(err) {
+			return reviewErr
+		}
+		err = p.Simulate()
+		if p.DebugLevel < 1 && IsSeriousError(err) {
+			return err
+		}
+		// Simulation errors are already in messages; now add the review error.
+		p.ReportError(reviewErr)
+
+		if p.DebugLevel < 1 && p.State.Over() {
+			return nil
+		}
+	}
+	// loop forever until the game ends or the player quits
+}
+
+func display(m Message) {
+	if m == nil {
+		return
+	}
+	fmt.Println(m.String())
+}
+
+func wait() {
+	fmt.Println()
+	fmt.Println("<press ENTER to continue>")
+	fmt.Scanln()
+}
+
+func displayMainMenu[C StatsCollection](p *Player[C]) (actionsOffset, handOffset, max int) {
+	cls()
+	needsDivider := displayMessageSection(p)
+	if needsDivider {
+		divider()
+	}
+	displayOnePanel(p, p.Prompt)
+	divider()
+	actionsOffset = displayStatsMenu(p)
+	if actionsOffset > 0 {
+		divider()
+	}
+	handOffset = displayPermanentActionsMenu(p, actionsOffset)
+	if handOffset > actionsOffset {
+		fmt.Println()
+	}
+	max = displayHandMenu(p, handOffset)
+	return // uses named return values
+}
+
+func pickNextAction[C StatsCollection](p *Player[C]) (isCard bool, cardIdx int, choiceIdx int, err error) {
+	for {
+		actionsOffset, handOffset, max := displayMainMenu(p)
+
+		divider()
+		fmt.Printf("%d actions remaining.\n", p.ActionsRemaining)
+		fmt.Printf("Show just (M)essages, (I)nfo Panels, (A)ctions, or consider an item (1-%d), or (Q)uit? > ", max)
+		input := getResponse()
+		switch input {
+		// Special cases
+		case "m", "msg", "message", "messages":
+			cls()
+			if displayMessageSection(p) {
+				divider()
+			}
+			displayOnePanel(p, p.Prompt)
+			wait()
+		case "s", "stat", "stats", "i", "info", "p", "panel", "panels", "infopanel", "infopanels":
+			statsMode(p)
+		case "a", "act", "actions":
+			var committed bool
+			isCard, cardIdx, choiceIdx, committed, err = actionsMode(p, true)
+			if committed {
+				return
+			}
+		case "q", "quit", "exit":
+			confirmQuit()
+		default:
+			i, err := strconv.Atoi(input)
+			if err != nil {
+				fmt.Println("Sorry, I don't understand.")
+				wait()
+			} else if i > max {
+				fmt.Println("That's not on this menu. If the menu is too big to read, choose a detail view.")
+				wait()
+			} else if i <= actionsOffset {
+				cls()
+				displayOnePanel(p, p.InfoPanels[i-1])
+				wait()
+			} else if i <= handOffset {
+				i = i - actionsOffset - 1
+				option, promptErr := promptCard(p, p.PermanentActions[i])
+				if option >= 0 || IsSeriousError(promptErr) {
+					return false, i, option, promptErr
+				}
+			} else {
+				i = i - handOffset - 1
+				option, promptErr := promptCard(p, p.Hand[i])
+				if option >= 0 || IsSeriousError(promptErr) {
+					return true, i, option, nil
+				}
+			}
+		}
+	}
+}
+
+func cls() {
+	fmt.Println("\033[H\033[2J")
+}
+
+func getResponse() string {
+	var input string
+	fmt.Scanln(&input)
+	input = strings.TrimSpace(input)
+	input = strings.ToLower(input)
+	return input
+}
+
+func divider() {
+	fmt.Println()
+	fmt.Println(ChapterBreak.String())
+	fmt.Println()
+}
+
+func lightDivider() {
+	fmt.Println()
+	fmt.Println(SectionBreak.String())
+	fmt.Println()
+}
+
+func confirmQuit() {
+	divider()
+	fmt.Println("Are you sure you want to quit? (Y/N) > ")
+	s := getResponse()
+	if s == "y" || s == "yes" {
+		fmt.Println("Bye!")
+		os.Exit(0)
+	}
+}
+
+func displayOnePanel[C StatsCollection](p *Player[C], panel InfoPanel[C]) error {
+	ts := panel.Title(p).String()
+	if len(ts) > 0 {
+		fmt.Println(ts)
+		fmt.Println(strings.Repeat("-", len(ts)))
+		fmt.Println()
+	}
+	m, err := panel.Info(p)
+	if IsSeriousError(err) {
+		return err
+	}
+	display(MultiMessage(m))
+	return err
+}
+
+func displayMessageSection[C StatsCollection](p *Player[C]) bool {
+	if len(p.TemporaryMessages) == 0 {
+		return false
+	}
+	for _, m := range p.TemporaryMessages {
+		if m != nil {
+			display(m)
+		} else {
+			fmt.Println()
+		}
+	}
+	return true
+}
+
+func displayStatsMenu[C StatsCollection](p *Player[C]) int {
+	if len(p.InfoPanels) == 0 {
+		return 0
+	}
+	fmt.Println("Info Panels")
+	fmt.Println("-----------")
+	for i, s := range p.InfoPanels {
+		fmt.Printf("[%2d]: %s\n", i+1, s.Title(p).String())
+	}
+	return len(p.InfoPanels)
+}
+
+func displayPermanentActionsMenu[C StatsCollection](p *Player[C], offset int) int {
+	if len(p.PermanentActions) == 0 {
+		return offset
+	}
+	fmt.Println("Always Available")
+	fmt.Println("----------------")
+	for i, s := range p.PermanentActions {
+		fmt.Printf("[%2d]: %s\n", i+offset+1, s.Title(p))
+	}
+	return offset + len(p.PermanentActions)
+}
+
+func displayHandMenu[C StatsCollection](p *Player[C], offset int) int {
+	if len(p.Hand) == 0 {
+		return offset
+	}
+	fmt.Println("Hand")
+	fmt.Println("----")
+	for i, s := range p.Hand {
+		fmt.Printf("[%2d]: %s\n", i+offset+1, s.Title(p))
+	}
+	return offset + len(p.Hand)
+}
+
+// promptCard asks the player to take an action on a card. Returns the option
+// they chose, or -1 if there was a serious error or they cancelled selection.
+func promptCard[C StatsCollection](p *Player[C], card Card[C]) (optionIdx int, err error) {
+	// Iterate until the player makes a valid choice.
+	for {
+		opts, valid, err := displayCard(p, card, true)
+		if IsSeriousError(err) {
+			return -1, err
+		}
+		fmt.Println()
+		if valid {
+			fmt.Printf("Go (B)ack, (Q)uit, or enact a choice (1 - %d)? > ", len(opts))
+		} else {
+			fmt.Print("Go (B)ack or (Q)uit? > ")
+		}
+		read := getResponse()
+		switch read {
+		case "b", "back":
+			return -1, err
+		case "q", "quit":
+			confirmQuit()
+		default:
+			i, convErr := strconv.Atoi(read)
+			if convErr != nil {
+				fmt.Println("Sorry, I don't understand.")
+				wait()
+			} else if !valid {
+				fmt.Println("You can't enact anything here.")
+				wait()
+			} else if i <= 0 || i > len(opts) {
+				fmt.Println("That's not one of the options.")
+				wait()
+			} else if !opts[i-1].Enabled(p) {
+				fmt.Println("That option is not available to you right now.")
+				wait()
+			} else {
+				return i - 1, err
+			}
+		}
+		// Invalid selection made -- loop to prompt again.
+	}
+}
+
+func displayCard[C StatsCollection](p *Player[C], card Card[C], canAct bool) ([]CardOption[C], bool, error) {
+	cls()
+	t := card.Title(p).String()
+	urgent := card.Urgent(p)
+	if urgent {
+		t = "[URGENT!] " + t
+	}
+	fmt.Println(t)
+	fmt.Println(strings.Repeat("-", len(t)))
+	fmt.Println()
+	event, err := card.EventText(p)
+	if IsSeriousError(err) {
+		return nil, false, err
+	}
+	var errs ErrorCollector
+	errs.Add(err)
+	fmt.Println(event.String())
+	fmt.Println()
+	fmt.Println(SectionBreak.String())
+	fmt.Println()
+	if !urgent && p.HasUrgentCards() {
+		fmt.Println("<You have more urgent matters to attend to! You cannot act on this right now.>")
+		fmt.Println()
+		canAct = false
+	}
+	opts, optErr := card.Options(p)
+	errs.Add(optErr)
+	if IsSeriousError(optErr) {
+		return nil, false, errs.Emit()
+	}
+	valid := false
+	for i, opt := range opts {
+		pfx := "[xx]:"
+		if opt.Enabled(p) {
+			if canAct {
+				pfx = fmt.Sprintf("[%2d]:", i+1)
+				valid = true
+			} else {
+				pfx = "[--]:"
+			}
+		}
+		t, err := opt.OptionText(p)
+		errs.Add(err)
+		if IsSeriousError(err) {
+			return nil, false, errs.Emit()
+		}
+		fmt.Println(pfx, t.String())
+	}
+	return opts, valid, errs.Emit()
+}
+
+func statsMode[C StatsCollection](p *Player[C]) error {
+	var errs ErrorCollector
+	for {
+		cls()
+		n := displayStatsMenu(p)
+		if n <= 0 {
+			fmt.Println("No info panels are available.")
+			wait()
+			return errs.Emit()
+		}
+		fmt.Println()
+		fmt.Printf("Go (B)ack, (Q)uit, or view an info panel (1-%d)? > ", n)
+		s := getResponse()
+		switch s {
+		case "b", "back":
+			return errs.Emit()
+		case "q", "quit":
+			confirmQuit()
+		default:
+			v, err := strconv.Atoi(s)
+			if err != nil {
+				fmt.Println("Sorry, I don't understand.")
+				wait()
+			} else if v <= 0 || v > n {
+				fmt.Println("There's no info panel with that index.")
+			} else {
+				cls()
+				err := displayOnePanel(p, p.InfoPanels[v-1])
+				errs.Add(err)
+				if IsSeriousError(err) {
+					return errs.Emit()
+				}
+				wait()
+			}
+		}
+		// Loop to re-display info panels menu.
+	}
+}
+
+func actionsMode[C StatsCollection](p *Player[C], canAct bool) (isCard bool, cardIdx, choiceIdx int, committed bool, err error) {
+	var errs ErrorCollector
+	for {
+		cls()
+		pOff := displayPermanentActionsMenu(p, 0)
+		if pOff > 0 {
+			fmt.Println()
+		}
+		max := displayHandMenu(p, pOff)
+
+		if max <= 0 {
+			fmt.Println("There are no actions available and no cards in hand.")
+			fmt.Println("That's a problem. The game is stuck.")
+			confirmQuit()
+			errs.Add(WarningStalemate)
+			return false, -1, -1, true, errs.Emit()
+		}
+
+		fmt.Println()
+		if canAct {
+			fmt.Printf("Go (B)ack, (Q)uit, or consider an action (1-%d)? > ", max)
+		} else {
+			fmt.Printf("Go (B)ack, (Q)uit, or view an action (1-%d)? > ", max)
+		}
+		input := getResponse()
+		switch input {
+		case "b", "back":
+			return false, -1, -1, false, errs.Emit()
+		case "q", "quit":
+			confirmQuit()
+		default:
+			v, err := strconv.Atoi(input)
+			if err != nil {
+				fmt.Println("Sorry, I don't understand.")
+				wait()
+			} else if v < 1 || v > max {
+				fmt.Println("That's not a card or action.")
+				wait()
+			} else if v <= pOff {
+				v--
+				if canAct {
+					optIdx, err := promptCard(p, p.PermanentActions[v])
+					errs.Add(err)
+					if optIdx >= 0 || IsSeriousError(err) {
+						return false, v, optIdx, true, errs.Emit()
+					}
+				} else {
+					_, _, err := displayCard(p, p.PermanentActions[v], false)
+					errs.Add(err)
+					if IsSeriousError(err) {
+						return false, -1, -1, true, errs.Emit()
+					}
+					wait()
+				}
+			} else {
+				v = v - pOff - 1
+				if canAct {
+					optIdx, err := promptCard(p, p.Hand[v])
+					errs.Add(err)
+					if optIdx >= 0 || IsSeriousError(err) {
+						return true, v, optIdx, false, errs.Emit()
+					}
+				} else {
+					_, _, err := displayCard(p, p.Hand[v], false)
+					errs.Add(err)
+					if IsSeriousError(err) {
+						return false, -1, -1, false, errs.Emit()
+					}
+					wait()
+				}
+			}
+		}
+		// Re-prompt to get a valid choice.
+	}
+}
+
+func review[C StatsCollection](p *Player[C]) error {
+	var errs ErrorCollector
+	for {
+		actionsOffset, handOffset, max := displayMainMenu(p)
+		divider()
+		fmt.Println("No actions remaining.")
+		fmt.Printf("(C)ontinue, review just (M)essages, (I)nfo Panels, (A)ctions, or an item (1-%d), or (Q)uit? > ", max)
+		input := getResponse()
+		switch input {
+		// Special cases
+		case "m", "msg", "message", "messages":
+			cls()
+			if displayMessageSection(p) {
+				divider()
+			}
+			displayOnePanel(p, p.Prompt)
+			wait()
+		case "s", "stat", "stats", "i", "info", "p", "panel", "panels", "infopanel", "infopanels":
+			err := statsMode(p)
+			errs.Add(err)
+			if IsSeriousError(err) {
+				return errs.Emit()
+			}
+		case "a", "act", "actions":
+			_, _, _, _, err := actionsMode(p, false)
+			errs.Add(err)
+			if IsSeriousError(err) {
+				return errs.Emit()
+			}
+		case "q", "quit", "exit":
+			confirmQuit()
+		case "c", "continue", "ok":
+			return errs.Emit()
+		default:
+			i, err := strconv.Atoi(input)
+			if err != nil {
+				fmt.Println("Sorry, I don't understand.")
+				wait()
+			} else if i <= 0 || i > max {
+				fmt.Println("That's not on this menu. If the menu is too big to read, choose a detail view.")
+				wait()
+			} else if i <= actionsOffset {
+				cls()
+				displayOnePanel(p, p.InfoPanels[i-1])
+				wait()
+			} else if i <= handOffset {
+				i = i - actionsOffset - 1
+				_, _, err := displayCard(p, p.PermanentActions[i], false)
+				errs.Add(err)
+				if IsSeriousError(err) {
+					return errs.Emit()
+				}
+				wait()
+			} else {
+				i = i - handOffset - 1
+				_, _, err := displayCard(p, p.Hand[i], false)
+				errs.Add(err)
+				if IsSeriousError(err) {
+					return errs.Emit()
+				}
+				wait()
+			}
+		}
+	}
+}

go.mod

@@ -1,3 +1,10 @@
-module cardSimEngine
+module git.chromaticdragon.app/kistaro/CardSimEngine
 
 go 1.20
+
+require github.com/kr/pretty v0.3.1
+
+require (
+	github.com/kr/text v0.2.0 // indirect
+	github.com/rogpeppe/go-internal v1.9.0 // indirect
+)

go.sum

@@ -0,0 +1,8 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
+github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=

smoketest/cards.go

@@ -0,0 +1,163 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"git.chromaticdragon.app/kistaro/CardSimEngine/cardsim"
+)
+
+// Type aliases, unlike distinctly named types, are fully substitutable for
+// the original type. This trims off some annoying-to-type things.
+type player = cardsim.Player[*SmokeTestCollection]
+type card = cardsim.Card[*SmokeTestCollection]
+type cardOption = cardsim.CardOption[*SmokeTestCollection]
+
+func makeAdditionCard(amt int) cardsim.Card[*SmokeTestCollection] {
+	c := &cardsim.BasicCard[*SmokeTestCollection]{
+		CardTitle: cardsim.Msgf("Additive %d", amt),
+		CardText:  cardsim.Msgf("You can change the Number by %d.", amt),
+		CardOptions: []cardsim.CardOption[*SmokeTestCollection]{
+			&cardsim.BasicOption[*SmokeTestCollection]{
+				Text: cardsim.Msgf("Add %d", amt),
+				Effect: func(p *player) error {
+					p.Stats.Number.Value += amt
+					return nil
+				},
+				Output: cardsim.MsgStr("Added."),
+			},
+			&cardsim.BasicOption[*SmokeTestCollection]{
+				Text: cardsim.Msgf("Subtract %d", amt),
+				Effect: func(p *player) error {
+					p.Stats.Number.Value -= amt
+					return nil
+				},
+				Output: cardsim.MsgStr("Subtracted."),
+			},
+		},
+		AfterOption: func(c card, p *player, _ cardOption) error {
+			p.Deck.InsertRandomBottom(0.5, c)
+			return nil
+		},
+	}
+	return c
+}
+
+func makeMultiplicationCard(amt int) cardsim.Card[*SmokeTestCollection] {
+	c := &cardsim.BasicCard[*SmokeTestCollection]{
+		CardTitle: cardsim.Msgf("Multiplicative %d", amt),
+		CardText:  cardsim.Msgf("You can multiply or divide the Number by %d, or maybe divide the Number by that.", amt),
+		CardOptions: []cardsim.CardOption[*SmokeTestCollection]{
+			&cardsim.BasicOption[*SmokeTestCollection]{
+				Text: cardsim.Msgf("Multiply by %d", amt),
+				Effect: func(p *player) error {
+					p.Stats.Number.Value *= amt
+					return nil
+				},
+				Output: cardsim.MsgStr("Multiplied."),
+			},
+			&cardsim.BasicOption[*SmokeTestCollection]{
+				Text: cardsim.Msgf("Integer divide by %d", amt),
+				Effect: func(p *player) error {
+					p.Stats.Number.Value /= amt
+					return nil
+				},
+				Output: cardsim.MsgStr("Divided."),
+			},
+			inverseDivision(amt),
+		},
+		AfterOption: func(c card, p *player, _ cardOption) error {
+			p.Deck.InsertRandomBottom(0.5, c)
+			return nil
+		},
+	}
+	return c
+}
+
+type inverseDivision int
+
+func (i inverseDivision) OptionText(p *player) (cardsim.Message, error) {
+	if p.Stats.Number.Value == 0 {
+		return cardsim.MsgStr("You can't divide by zero!"), nil
+	}
+	return cardsim.Msgf("Divide %d by the Number", int(i)), nil
+}
+
+func (i inverseDivision) Enact(p *player) (cardsim.Message, error) {
+	if p.Stats.Number.Value == 0 {
+		return nil, errors.New("you can't divide by zero!")
+	}
+	p.Stats.Number.Value = int(i) / p.Stats.Number.Value
+	return cardsim.MsgStr("Inverse divided."), nil
+}
+
+func (i inverseDivision) Enabled(p *player) bool {
+	return p.Stats.Number.Value != 0
+}
+
+func initDeck(d *cardsim.Deck[*SmokeTestCollection]) {
+	addMe := []int{
+		0, 1, 2, 5, 10, 50, 100, 1000, 2500, 500000, 9876543,
+	}
+	for _, n := range addMe {
+		d.Insert(cardsim.BottomOfDeck, makeAdditionCard(n))
+	}
+
+	multiplyMe := []int{
+		2, 4, 8, 16, 32, 64, 128, 512, 1024, 9999, 84720413,
+	}
+	for _, n := range multiplyMe {
+		d.Insert(cardsim.BottomOfDeck, makeMultiplicationCard(n))
+	}
+	if err := d.Shuffle(); cardsim.IsSeriousError(err) {
+		panic(err)
+	} else if err != nil {
+		fmt.Printf("Error shuffling: %v\n", err)
+	}
+}
+
+func installPermanentActions(pa *[]card) {
+	*pa = []card{
+		&cardsim.BasicCard[*SmokeTestCollection]{
+			CardTitle: cardsim.MsgStr("Reset to 0"),
+			CardText:  cardsim.MsgStr("Resets Number to 0."),
+			CardOptions: []cardOption{
+				&cardsim.BasicOption[*SmokeTestCollection]{
+					Text: cardsim.MsgStr("Reset to 0."),
+					Effect: func(p *player) error {
+						p.Stats.Number.Value = 0
+						return nil
+					},
+					Output: cardsim.MsgStr("Done."),
+				},
+			},
+		},
+		&cardsim.BasicCard[*SmokeTestCollection]{
+			CardTitle: cardsim.MsgStr("Reset to 1000000"),
+			CardText:  cardsim.MsgStr("Resets Number to one million."),
+			CardOptions: []cardOption{
+				&cardsim.BasicOption[*SmokeTestCollection]{
+					Text: cardsim.MsgStr("Reset to 1,000,000"),
+					Effect: func(p *player) error {
+						p.Stats.Number.Value = 1000000
+						return nil
+					},
+					Output: cardsim.MsgStr("Done."),
+				},
+			},
+		},
+		&cardsim.BasicCard[*SmokeTestCollection]{
+			CardTitle: cardsim.MsgStr("Draw a card"),
+			CardText:  cardsim.MsgStr("Draw an extra card."),
+			CardOptions: []cardOption{
+				&cardsim.BasicOption[*SmokeTestCollection]{
+					Text: cardsim.MsgStr("Draw an extra card."),
+					Effect: func(p *player) error {
+						return p.Draw()
+					},
+					Output: cardsim.MsgStr("Drawn. Probably."),
+				},
+			},
+		},
+	}
+}

smoketest/collection.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"git.chromaticdragon.app/kistaro/CardSimEngine/cardsim"
+)
+
+// SmokeTestCollection is a stats collection for the simple test sim.
+type SmokeTestCollection struct {
+	Number cardsim.Stored[int]
+	Total  cardsim.Stored[int64]
+	Turns  cardsim.Invisible[int]
+
+	Flavor cardsim.Stored[string]
+}
+
+func (c *SmokeTestCollection) Average() float64 {
+	return float64(c.Total.Value) / float64(c.Turns.Value)
+}
+
+func (c *SmokeTestCollection) Stats() []cardsim.Stat {
+	stats := cardsim.ExtractStats(c)
+	stats = append(stats, cardsim.StatFunc("Average", c.Average))
+	cardsim.SortStats(stats)
+	return stats
+}

smoketest/main.go

@@ -0,0 +1,79 @@
+// Binary smoketest runs a very simple cardsim thing.
+package main
+
+import (
+	"fmt"
+
+	"git.chromaticdragon.app/kistaro/CardSimEngine/cardsim"
+
+	"github.com/kr/pretty"
+)
+
+func main() {
+	p := cardsim.InitPlayer(
+		&SmokeTestCollection{
+			Number: cardsim.Stored[int]{
+				Name:  "Number",
+				Value: 0,
+			},
+			Total: cardsim.Stored[int64]{
+				Name:  "Total",
+				Value: 0,
+			},
+			Turns: cardsim.Invisible[int]{
+				Name:  "Turns",
+				Value: 0,
+			},
+			Flavor: cardsim.Stored[string]{
+				Name:  "Flavor",
+				Value: "Lemon",
+			},
+		},
+	)
+	p.Name = "Dave"
+	p.HandLimit = 3
+	p.ActionsPerTurn = 2
+	installRules(p.Rules)
+	initDeck(p.Deck)
+	installPermanentActions(&p.PermanentActions)
+	p.InfoPanels = []cardsim.InfoPanel[*SmokeTestCollection]{
+		&cardsim.BasicStatsPanel[*SmokeTestCollection]{
+			Name:  cardsim.MsgStr("Stats"),
+			Intro: cardsim.MsgStr("Hi! These are the smoke test stats."),
+		},
+		ruledumper{},
+	}
+	p.Prompt = prompt{}
+	p.DebugLevel = 5
+
+	err := cardsim.RunSimpleTerminalUI(p)
+	if err != nil {
+		fmt.Println("Terminated with error:")
+		fmt.Println(err)
+	} else {
+		fmt.Println("Terminated without error.")
+	}
+}
+
+type prompt struct{}
+
+func (prompt) Title(p *cardsim.Player[*SmokeTestCollection]) cardsim.Message {
+	return cardsim.MsgStr("Smoke Test")
+}
+
+func (prompt) Info(p *cardsim.Player[*SmokeTestCollection]) ([]cardsim.Message, error) {
+	return []cardsim.Message{
+		cardsim.MsgStr("Here, have some stuff."),
+		cardsim.Msgf("It's turn %d according to the player and turn %d according to me.", p.TurnNumber, p.Stats.Turns.Value),
+	}, nil
+}
+
+type ruledumper struct{}
+
+func (ruledumper) Title(p *player) cardsim.Message {
+	return cardsim.MsgStr("Rule Dumper")
+}
+
+func (ruledumper) Info(p *player) ([]cardsim.Message, error) {
+	return []cardsim.Message{cardsim.Msgf("%# v", pretty.Formatter(p.Rules))}, nil
+}

smoketest/rules.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"math"
+
+	"git.chromaticdragon.app/kistaro/CardSimEngine/cardsim"
+)
+
+var (
+	updateTotal = cardsim.RuleFunc[*SmokeTestCollection]{
+		Name: "updateTotal",
+		Seq:  1,
+		F: func(p *cardsim.Player[*SmokeTestCollection]) error {
+			p.Stats.Total.Value += int64(p.Stats.Number.Value)
+			return nil
+		},
+	}
+
+	countTurn = cardsim.RuleFunc[*SmokeTestCollection]{
+		Name: "countTurn",
+		Seq:  math.MinInt,
+		F: func(p *cardsim.Player[*SmokeTestCollection]) error {
+			p.Stats.Turns.Value++
+			return nil
+		},
+	}
+)
+
+func installRules(rules *cardsim.RuleCollection[*SmokeTestCollection]) {
+	rules.Insert(&updateTotal)
+	rules.Insert(&countTurn)
+}