// Package manualreadytostart implements the `lobby.game.ready_to_start`
// message type. It transitions a game record from `enrollment_open` to
// `ready_to_start` after enforcing admin-or-owner authorization and the
// `approved_count >= min_players` precondition. Side effects (expiring
// every still-created invite and publishing `lobby.invite.expired`) are
// delegated to shared.CloseEnrollment so the auto-close path used by the
// enrollment automation worker stays in sync.
package manualreadytostart

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"time"

	"galaxy/lobby/internal/domain/common"
	"galaxy/lobby/internal/domain/game"
	"galaxy/lobby/internal/logging"
	"galaxy/lobby/internal/ports"
	"galaxy/lobby/internal/service/shared"
	"galaxy/lobby/internal/telemetry"
)

// Service executes the manual ready-to-start use case.
type Service struct {
	games       ports.GameStore
	memberships ports.MembershipStore
	invites     ports.InviteStore
	intents     ports.IntentPublisher
	clock       func() time.Time
	logger      *slog.Logger
	telemetry   *telemetry.Runtime
}

// Dependencies groups the collaborators used by Service.
type Dependencies struct {
	// Games mediates the CAS status transition and the result read.
	Games ports.GameStore

	// Memberships is scanned for active records to evaluate the
	// approved_count >= min_players precondition.
	Memberships ports.MembershipStore

	// Invites is forwarded to shared.CloseEnrollment for the cascading
	// expiry of created invites on close.
	Invites ports.InviteStore

	// Intents publishes lobby.invite.expired notifications produced by
	// the cascading expiry.
	Intents ports.IntentPublisher

	// Clock supplies the wall-clock used for UpdatedAt and downstream
	// notification timestamps. Defaults to time.Now when nil.
	Clock func() time.Time

	// Logger records structured service-level events. Defaults to
	// slog.Default when nil.
	Logger *slog.Logger

	// Telemetry forwards into shared.CloseEnrollment so the
	// `lobby.game.transitions` and `lobby.invite.outcomes` counters
	// are emitted on each manual close. Optional; nil disables metric
	// emission.
	Telemetry *telemetry.Runtime
}

// NewService constructs one Service with deps.
func NewService(deps Dependencies) (*Service, error) {
	if deps.Games == nil {
		return nil, errors.New("new manual ready-to-start service: nil game store")
	}
	if deps.Memberships == nil {
		return nil, errors.New("new manual ready-to-start service: nil membership store")
	}
	if deps.Invites == nil {
		return nil, errors.New("new manual ready-to-start service: nil invite store")
	}
	if deps.Intents == nil {
		return nil, errors.New("new manual ready-to-start service: nil intent publisher")
	}

	clock := deps.Clock
	if clock == nil {
		clock = time.Now
	}
	logger := deps.Logger
	if logger == nil {
		logger = slog.Default()
	}

	return &Service{
		games:       deps.Games,
		memberships: deps.Memberships,
		invites:     deps.Invites,
		intents:     deps.Intents,
		clock:       clock,
		logger:      logger.With("service", "lobby.manualreadytostart"),
		telemetry:   deps.Telemetry,
	}, nil
}

// Input stores the arguments required to manually close enrollment on one
// game.
type Input struct {
	// Actor identifies the caller.
	Actor shared.Actor

	// GameID identifies the target game record.
	GameID common.GameID
}

// Handle authorizes the actor, checks status and roster preconditions,
// performs the enrollment close (transition + invite expiry +
// notifications), and returns the post-transition snapshot.
func (service *Service) Handle(ctx context.Context, input Input) (game.Game, error) {
	if service == nil {
		return game.Game{}, errors.New("manual ready-to-start: nil service")
	}
	if ctx == nil {
		return game.Game{}, errors.New("manual ready-to-start: nil context")
	}
	if err := input.Actor.Validate(); err != nil {
		return game.Game{}, fmt.Errorf("manual ready-to-start: actor: %w", err)
	}
	if err := input.GameID.Validate(); err != nil {
		return game.Game{}, fmt.Errorf("manual ready-to-start: %w", err)
	}

	record, err := service.games.Get(ctx, input.GameID)
	if err != nil {
		return game.Game{}, fmt.Errorf("manual ready-to-start: %w", err)
	}

	if err := authorize(input.Actor, record); err != nil {
		return game.Game{}, err
	}

	if record.Status != game.StatusEnrollmentOpen {
		return game.Game{}, fmt.Errorf(
			"manual ready-to-start: status %q is not enrollment_open: %w",
			record.Status, game.ErrConflict,
		)
	}

	approvedCount, err := shared.CountActiveMemberships(ctx, service.memberships, input.GameID)
	if err != nil {
		return game.Game{}, fmt.Errorf("manual ready-to-start: %w", err)
	}
	if approvedCount < record.MinPlayers {
		return game.Game{}, fmt.Errorf(
			"manual ready-to-start: approved_count %d is below min_players %d: %w",
			approvedCount, record.MinPlayers, game.ErrConflict,
		)
	}

	at := service.clock().UTC()
	updated, err := shared.CloseEnrollment(ctx, shared.CloseEnrollmentDeps{
		Games:     service.games,
		Invites:   service.invites,
		Intents:   service.intents,
		Logger:    service.logger,
		Telemetry: service.telemetry,
	}, input.GameID, game.TriggerManual, at)
	if err != nil {
		return game.Game{}, fmt.Errorf("manual ready-to-start: %w", err)
	}

	logArgs := []any{
		"game_id", updated.GameID.String(),
		"from_status", string(game.StatusEnrollmentOpen),
		"to_status", string(updated.Status),
		"trigger", string(game.TriggerManual),
		"approved_count", approvedCount,
		"actor_kind", string(input.Actor.Kind),
	}
	logArgs = append(logArgs, logging.ContextAttrs(ctx)...)
	service.logger.InfoContext(ctx, "game manually moved to ready_to_start", logArgs...)

	return updated, nil
}

// authorize enforces admin OR private-owner access to the record.
func authorize(actor shared.Actor, record game.Game) error {
	if actor.IsAdmin() {
		return nil
	}
	if record.GameType == game.GameTypePrivate && actor.UserID == record.OwnerUserID {
		return nil
	}
	return fmt.Errorf("%w: actor is not authorized to close enrollment on game %q",
		shared.ErrForbidden, record.GameID.String())
}