mixmaker/backend/internal/domain/series_fsm.go

package domain

import (
	"fmt"
	"slices"
	"time"
)

type SeriesPhase string

const (
	CoinTossPending SeriesPhase = "CoinTossPending"
	MapBanPhase     SeriesPhase = "MapBan"
	MapPickPhase    SeriesPhase = "MapPick"
	HeroBanPhase    SeriesPhase = "HeroBan"
	PlayingPhase    SeriesPhase = "Playing"
	SeriesComplete  SeriesPhase = "Completed"
)

type SeriesAction struct {
	Kind           string    `json:"kind"`
	Summary        string    `json:"summary"`
	TeamID         string    `json:"teamId,omitempty"`
	ActorAccountID string    `json:"actorAccountId"`
	At             time.Time `json:"at"`
}

type SeriesMap struct {
	Number   int           `json:"number"`
	Name     string        `json:"name"`
	HeroBans []DraftAction `json:"heroBans"`
	Result   *MapResult    `json:"result,omitempty"`
}

func NewSeries(id, eventID, tournamentID string, teams [2]string, rules Ruleset) (*Series, error) {
	if id == "" || eventID == "" || teams[0] == "" || teams[1] == "" || teams[0] == teams[1] {
		return nil, fmt.Errorf("%w: invalid series", ErrInvalid)
	}
	if err := rules.Validate(); err != nil {
		return nil, err
	}
	return &Series{
		ID: id, EventID: eventID, TournamentID: tournamentID,
		TeamAID: teams[0], TeamBID: teams[1], BestOf: rules.BestOf,
		RulesetID: rules.ID, Phase: CoinTossPending,
		SeriesBans: map[string][]string{},
	}, nil
}

func (s *Series) Toss(seed, actor string, now time.Time, rules Ruleset) error {
	if s.Phase != CoinTossPending {
		return fmt.Errorf("%w: coin toss is unavailable", ErrConflict)
	}
	toss, err := TossCoin(s.TeamAID, s.TeamBID, seed, now)
	if err != nil {
		return err
	}
	s.CoinToss = &toss
	first := toss.WinnerTeamID
	if rules.InitialMapBanner == 1 {
		first = s.otherTeam(first)
	}
	draft, err := NewMapDraft(s.availablePool(rules, 0), first, [2]string{s.TeamAID, s.TeamBID})
	if err != nil {
		return err
	}
	s.MapDraft, s.Phase = draft, MapBanPhase
	s.Version++
	s.Audit = append(s.Audit, SeriesAction{Kind: "coin_toss", Summary: "Coin toss won by " + toss.WinnerTeamID, TeamID: toss.WinnerTeamID, ActorAccountID: actor, At: now})
	return nil
}

func (s *Series) BanMap(teamID, name, actor string, now time.Time, rules Ruleset) error {
	if s.Phase != MapBanPhase || s.MapDraft == nil {
		return fmt.Errorf("%w: map ban is unavailable", ErrConflict)
	}
	if err := s.MapDraft.Ban(teamID, name, actor, now); err != nil {
		return err
	}
	s.Version++
	s.Audit = append(s.Audit, SeriesAction{Kind: "map_ban", Summary: name + " banned", TeamID: teamID, ActorAccountID: actor, At: now})
	selected, complete := s.MapDraft.Selected()
	if !complete {
		return nil
	}
	return s.startHeroDraft(selected, actor, now, rules)
}

func (s *Series) PickMap(teamID, name, actor string, now time.Time, rules Ruleset) error {
	if s.Phase != MapPickPhase {
		return fmt.Errorf("%w: map pick is unavailable", ErrConflict)
	}
	if teamID != s.NextMapPickerID {
		return fmt.Errorf("%w: only the previous map loser can pick", ErrConflict)
	}
	if !slices.Contains(s.AvailableMaps, name) {
		return fmt.Errorf("%w: map unavailable", ErrInvalid)
	}
	s.Version++
	s.Audit = append(s.Audit, SeriesAction{Kind: "map_selected", Summary: name + " picked", TeamID: teamID, ActorAccountID: actor, At: now})
	return s.startHeroDraft(name, actor, now, rules)
}

func (s *Series) startHeroDraft(selected, actor string, now time.Time, rules Ruleset) error {
	s.CurrentMap = selected
	first := s.otherTeam(s.CoinToss.WinnerTeamID)
	if rules.InitialHeroBanner == 0 {
		first = s.CoinToss.WinnerTeamID
	}
	draft, err := NewHeroDraft(rules.Heroes, [2]string{s.TeamAID, s.TeamBID}, first, rules.HeroBansPerTeam, s.SeriesBans)
	if err != nil {
		return err
	}
	s.HeroDraft, s.Phase = draft, HeroBanPhase
	s.NextMapPickerID, s.AvailableMaps = "", nil
	s.Maps = append(s.Maps, SeriesMap{Number: len(s.Maps) + 1, Name: selected})
	if len(s.Audit) == 0 || s.Audit[len(s.Audit)-1].Kind != "map_selected" {
		s.Audit = append(s.Audit, SeriesAction{Kind: "map_selected", Summary: selected + " selected", ActorAccountID: actor, At: now})
	}
	return nil
}

func (s *Series) BanHero(teamID, hero, actor string, now time.Time) error {
	if s.Phase != HeroBanPhase || s.HeroDraft == nil {
		return fmt.Errorf("%w: hero ban is unavailable", ErrConflict)
	}
	if err := s.HeroDraft.Ban(teamID, hero, actor, now); err != nil {
		return err
	}
	s.Version++
	s.Maps[len(s.Maps)-1].HeroBans = slices.Clone(s.HeroDraft.CurrentBans)
	s.Audit = append(s.Audit, SeriesAction{Kind: "hero_ban", Summary: hero + " banned", TeamID: teamID, ActorAccountID: actor, At: now})
	if s.HeroDraft.Complete() {
		s.SeriesBans = s.HeroDraft.SeriesBans
		s.Phase = PlayingPhase
	}
	return nil
}

func (s *Series) RecordCurrentMap(outcome MapOutcome, actor string, now time.Time, rules Ruleset) error {
	if s.Phase != PlayingPhase || s.CurrentMap == "" {
		return fmt.Errorf("%w: map result is unavailable", ErrConflict)
	}
	result := MapResult{MapName: s.CurrentMap, Outcome: outcome, ActorAccountID: actor, RecordedAt: now}
	if err := s.RecordResult(result); err != nil {
		return err
	}
	s.PlayedMaps = append(s.PlayedMaps, s.CurrentMap)
	s.Maps[len(s.Maps)-1].Result = &result
	s.Audit = append(s.Audit, SeriesAction{Kind: "result", Summary: s.CurrentMap + ": " + string(outcome), ActorAccountID: actor, At: now})
	if s.WinnerTeamID != "" {
		s.Phase = SeriesComplete
		return nil
	}
	poolIndex := len(s.Maps)
	if poolIndex >= len(rules.MapPools) {
		poolIndex = len(rules.MapPools) - 1
	}
	switch outcome {
	case TeamAWin:
		s.NextMapPickerID = s.TeamBID
	case TeamBWin:
		s.NextMapPickerID = s.TeamAID
	default:
		// A draw has no loser, so the initial coin-toss loser receives the pick.
		s.NextMapPickerID = s.otherTeam(s.CoinToss.WinnerTeamID)
	}
	s.AvailableMaps = s.availablePool(rules, poolIndex)
	if len(s.AvailableMaps) == 0 {
		return fmt.Errorf("%w: no unplayed maps remain in pool", ErrInvalid)
	}
	s.MapDraft, s.HeroDraft, s.CurrentMap, s.Phase = nil, nil, "", MapPickPhase
	return nil
}

func (s Series) availablePool(rules Ruleset, index int) []string {
	pool := slices.Clone(rules.MapPools[index])
	return slices.DeleteFunc(pool, func(name string) bool { return slices.Contains(s.PlayedMaps, name) })
}

func (s Series) otherTeam(teamID string) string {
	if teamID == s.TeamAID {
		return s.TeamBID
	}
	return s.TeamAID
}