// Package userlifecycle implements the cascade worker that reacts to
// `user.lifecycle.permanent_blocked` and `user.lifecycle.deleted` events
// from the User Service stream. The worker registers itself as a handler
// on a ports.UserLifecycleConsumer (typically the Redis adapter) and
// settles every Lobby artefact tied to the affected user:
//
//  1. Race Name Directory: release every registered, reservation, and
//     pending_registration binding via RND.ReleaseAllByUser.
//  2. Memberships: every active membership transitions to `blocked`. For
//     each affected private game, publish a `lobby.membership.blocked`
//     intent to the owner.
//  3. Applications: every `submitted` application transitions to
//     `rejected`.
//  4. Invites: every `created` invite where the user is invitee or
//     inviter transitions to `revoked`.
//  5. Owned games: every owner-side game (status != cancelled/finished)
//     transitions to `cancelled` via the `external_block` trigger. For
//     in-flight games (`starting`, `running`, `paused`), publish a
//     stop-job to Runtime Manager before the status transition.
//
// All store mutations are CAS-protected; replays detect the post-state
// via *.ErrConflict / *.ErrInvalidTransition and short-circuit without
// raising errors. Any non-conflict error returns to the consumer so the
// stream offset is held and the next iteration retries.
package userlifecycle

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

	"galaxy/lobby/internal/domain/application"
	"galaxy/lobby/internal/domain/common"
	"galaxy/lobby/internal/domain/game"
	"galaxy/lobby/internal/domain/invite"
	"galaxy/lobby/internal/domain/membership"
	"galaxy/lobby/internal/logging"
	"galaxy/lobby/internal/ports"
	"galaxy/lobby/internal/telemetry"
	"galaxy/notificationintent"
)

// inflightGameStatuses lists the statuses for which a stop-job to
// Runtime Manager must be published before the cascade transitions the
// game to `cancelled`.
var inflightGameStatuses = map[game.Status]struct{}{
	game.StatusStarting: {},
	game.StatusRunning:  {},
	game.StatusPaused:   {},
}

// Dependencies groups the collaborators consumed by Worker.
type Dependencies struct {
	// Directory exposes the Race Name Directory cascade entry point.
	Directory ports.RaceNameDirectory

	// Memberships persists the active → blocked transition for every
	// membership held by the affected user.
	Memberships ports.MembershipStore

	// Applications persists the submitted → rejected transition for every
	// application authored by the affected user.
	Applications ports.ApplicationStore

	// Invites persists the created → revoked transition for every invite
	// the affected user is invitee or inviter on.
	Invites ports.InviteStore

	// Games owns the cascade-cancel transition for games owned by the
	// affected user.
	Games ports.GameStore

	// RuntimeManager publishes stop-jobs for in-flight cancelled games.
	RuntimeManager ports.RuntimeManager

	// Intents publishes `lobby.membership.blocked` notifications to
	// private-game owners whose roster lost the affected member.
	Intents ports.IntentPublisher

	// Clock supplies the wall-clock used for status transition
	// timestamps. Defaults to time.Now when nil.
	Clock func() time.Time

	// Logger receives structured worker-level events. Defaults to
	// slog.Default when nil.
	Logger *slog.Logger

	// Telemetry records the
	// `lobby.user_lifecycle.cascade_releases`,
	// `lobby.membership.changes`, and `lobby.game.transitions`
	// counters per processed event. Optional; nil disables metric
	// emission.
	Telemetry *telemetry.Runtime
}

// Worker executes the cascade triggered by one user-lifecycle event.
type Worker struct {
	directory      ports.RaceNameDirectory
	memberships    ports.MembershipStore
	applications   ports.ApplicationStore
	invites        ports.InviteStore
	games          ports.GameStore
	runtimeManager ports.RuntimeManager
	intents        ports.IntentPublisher
	clock          func() time.Time
	logger         *slog.Logger
	telemetry      *telemetry.Runtime
}

// NewWorker constructs one Worker from deps.
func NewWorker(deps Dependencies) (*Worker, error) {
	switch {
	case deps.Directory == nil:
		return nil, errors.New("new user lifecycle worker: nil race name directory")
	case deps.Memberships == nil:
		return nil, errors.New("new user lifecycle worker: nil membership store")
	case deps.Applications == nil:
		return nil, errors.New("new user lifecycle worker: nil application store")
	case deps.Invites == nil:
		return nil, errors.New("new user lifecycle worker: nil invite store")
	case deps.Games == nil:
		return nil, errors.New("new user lifecycle worker: nil game store")
	case deps.RuntimeManager == nil:
		return nil, errors.New("new user lifecycle worker: nil runtime manager")
	case deps.Intents == nil:
		return nil, errors.New("new user lifecycle worker: nil intent publisher")
	}

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

	return &Worker{
		directory:      deps.Directory,
		memberships:    deps.Memberships,
		applications:   deps.Applications,
		invites:        deps.Invites,
		games:          deps.Games,
		runtimeManager: deps.RuntimeManager,
		intents:        deps.Intents,
		clock:          clock,
		logger:         logger.With("worker", "lobby.userlifecycle"),
		telemetry:      deps.Telemetry,
	}, nil
}

// Handle processes one decoded lifecycle event and runs the full
// cascade. The function returns nil when every per-entity step either
// succeeded or was absorbed as an idempotent replay; non-conflict errors
// abort processing and bubble up so the consumer can retry the entry.
func (worker *Worker) Handle(ctx context.Context, event ports.UserLifecycleEvent) error {
	if worker == nil {
		return errors.New("user lifecycle handle: nil worker")
	}
	if ctx == nil {
		return errors.New("user lifecycle handle: nil context")
	}
	if err := event.Validate(); err != nil {
		// Decode-level guard so an obviously malformed event is rejected
		// at the boundary rather than wandering through the cascade.
		worker.logger.WarnContext(ctx, "drop invalid user lifecycle event",
			"stream_entry_id", event.EntryID,
			"err", err.Error(),
		)
		return nil
	}

	reason := reasonForEvent(event.EventType)
	now := worker.clock().UTC()

	startArgs := []any{
		"stream_entry_id", event.EntryID,
		"lifecycle_event", string(event.EventType),
		"user_id", event.UserID,
	}
	startArgs = append(startArgs, logging.ContextAttrs(ctx)...)
	worker.logger.InfoContext(ctx, "user lifecycle cascade starting", startArgs...)

	worker.telemetry.RecordUserLifecycleCascadeRelease(ctx, string(event.EventType))

	if err := worker.directory.ReleaseAllByUser(ctx, event.UserID); err != nil {
		return fmt.Errorf("user lifecycle handle: release race names: %w", err)
	}

	memberCount, err := worker.cascadeMemberships(ctx, event, reason, now)
	if err != nil {
		return err
	}

	applicationCount, err := worker.cascadeApplications(ctx, event.UserID, now)
	if err != nil {
		return err
	}

	inviteCount, err := worker.cascadeInvites(ctx, event.UserID, now)
	if err != nil {
		return err
	}

	gameCount, err := worker.cascadeOwnedGames(ctx, event.UserID, now)
	if err != nil {
		return err
	}

	completedArgs := []any{
		"stream_entry_id", event.EntryID,
		"lifecycle_event", string(event.EventType),
		"user_id", event.UserID,
		"memberships_blocked", memberCount,
		"applications_rejected", applicationCount,
		"invites_revoked", inviteCount,
		"games_cancelled", gameCount,
	}
	completedArgs = append(completedArgs, logging.ContextAttrs(ctx)...)
	worker.logger.InfoContext(ctx, "user lifecycle cascade completed", completedArgs...)
	return nil
}

func (worker *Worker) cascadeMemberships(
	ctx context.Context,
	event ports.UserLifecycleEvent,
	reason string,
	now time.Time,
) (int, error) {
	records, err := worker.memberships.GetByUser(ctx, event.UserID)
	if err != nil {
		return 0, fmt.Errorf("user lifecycle handle: load memberships: %w", err)
	}

	blocked := 0
	for _, record := range records {
		if record.Status != membership.StatusActive {
			continue
		}

		updateErr := worker.memberships.UpdateStatus(ctx, ports.UpdateMembershipStatusInput{
			MembershipID: record.MembershipID,
			ExpectedFrom: membership.StatusActive,
			To:           membership.StatusBlocked,
			At:           now,
		})
		switch {
		case updateErr == nil:
			blocked++
			worker.telemetry.RecordMembershipChange(ctx, "external_block")
			worker.publishMembershipBlocked(ctx, event, record, reason, now)
		case errors.Is(updateErr, membership.ErrConflict),
			errors.Is(updateErr, membership.ErrInvalidTransition),
			errors.Is(updateErr, membership.ErrNotFound):
			worker.logger.InfoContext(ctx, "membership cascade absorbed",
				"membership_id", record.MembershipID.String(),
				"user_id", record.UserID,
				"err", updateErr.Error(),
			)
		default:
			return blocked, fmt.Errorf("user lifecycle handle: block membership %s: %w",
				record.MembershipID, updateErr)
		}
	}
	return blocked, nil
}

func (worker *Worker) publishMembershipBlocked(
	ctx context.Context,
	event ports.UserLifecycleEvent,
	record membership.Membership,
	reason string,
	now time.Time,
) {
	gameRecord, err := worker.games.Get(ctx, record.GameID)
	if err != nil {
		worker.logger.WarnContext(ctx, "load game for membership.blocked intent",
			"membership_id", record.MembershipID.String(),
			"game_id", record.GameID.String(),
			"err", err.Error(),
		)
		return
	}
	// Intent target is the private-game owner. Public games and self-owned
	// memberships do not produce a notification.
	if gameRecord.GameType != game.GameTypePrivate {
		return
	}
	if gameRecord.OwnerUserID == "" || gameRecord.OwnerUserID == record.UserID {
		return
	}

	intent, err := notificationintent.NewLobbyMembershipBlockedIntent(
		notificationintent.Metadata{
			IdempotencyKey: "lobby.membership.blocked:" + record.MembershipID.String() + ":" + event.EntryID,
			OccurredAt:     now,
			TraceID:        event.TraceID,
		},
		gameRecord.OwnerUserID,
		notificationintent.LobbyMembershipBlockedPayload{
			GameID:             gameRecord.GameID.String(),
			GameName:           gameRecord.GameName,
			MembershipUserID:   record.UserID,
			MembershipUserName: record.RaceName,
			Reason:             reason,
		},
	)
	if err != nil {
		worker.logger.WarnContext(ctx, "build membership.blocked intent",
			"membership_id", record.MembershipID.String(),
			"err", err.Error(),
		)
		return
	}
	if _, err := worker.intents.Publish(ctx, intent); err != nil {
		worker.logger.WarnContext(ctx, "publish membership.blocked intent",
			"membership_id", record.MembershipID.String(),
			"owner_user_id", gameRecord.OwnerUserID,
			"err", err.Error(),
		)
	}
}

func (worker *Worker) cascadeApplications(
	ctx context.Context,
	userID string,
	now time.Time,
) (int, error) {
	records, err := worker.applications.GetByUser(ctx, userID)
	if err != nil {
		return 0, fmt.Errorf("user lifecycle handle: load applications: %w", err)
	}

	rejected := 0
	for _, record := range records {
		if record.Status != application.StatusSubmitted {
			continue
		}

		updateErr := worker.applications.UpdateStatus(ctx, ports.UpdateApplicationStatusInput{
			ApplicationID: record.ApplicationID,
			ExpectedFrom:  application.StatusSubmitted,
			To:            application.StatusRejected,
			At:            now,
		})
		switch {
		case updateErr == nil:
			rejected++
		case errors.Is(updateErr, application.ErrConflict),
			errors.Is(updateErr, application.ErrInvalidTransition),
			errors.Is(updateErr, application.ErrNotFound):
			worker.logger.InfoContext(ctx, "application cascade absorbed",
				"application_id", record.ApplicationID.String(),
				"err", updateErr.Error(),
			)
		default:
			return rejected, fmt.Errorf("user lifecycle handle: reject application %s: %w",
				record.ApplicationID, updateErr)
		}
	}
	return rejected, nil
}

func (worker *Worker) cascadeInvites(
	ctx context.Context,
	userID string,
	now time.Time,
) (int, error) {
	addressed, err := worker.invites.GetByUser(ctx, userID)
	if err != nil {
		return 0, fmt.Errorf("user lifecycle handle: load invitee invites: %w", err)
	}
	owned, err := worker.invites.GetByInviter(ctx, userID)
	if err != nil {
		return 0, fmt.Errorf("user lifecycle handle: load inviter invites: %w", err)
	}

	visited := make(map[common.InviteID]struct{}, len(addressed)+len(owned))
	revoked := 0
	for _, record := range append(append([]invite.Invite(nil), addressed...), owned...) {
		if _, seen := visited[record.InviteID]; seen {
			continue
		}
		visited[record.InviteID] = struct{}{}
		if record.Status != invite.StatusCreated {
			continue
		}

		updateErr := worker.invites.UpdateStatus(ctx, ports.UpdateInviteStatusInput{
			InviteID:     record.InviteID,
			ExpectedFrom: invite.StatusCreated,
			To:           invite.StatusRevoked,
			At:           now,
		})
		switch {
		case updateErr == nil:
			revoked++
		case errors.Is(updateErr, invite.ErrConflict),
			errors.Is(updateErr, invite.ErrInvalidTransition),
			errors.Is(updateErr, invite.ErrNotFound):
			worker.logger.InfoContext(ctx, "invite cascade absorbed",
				"invite_id", record.InviteID.String(),
				"err", updateErr.Error(),
			)
		default:
			return revoked, fmt.Errorf("user lifecycle handle: revoke invite %s: %w",
				record.InviteID, updateErr)
		}
	}
	return revoked, nil
}

func (worker *Worker) cascadeOwnedGames(
	ctx context.Context,
	userID string,
	now time.Time,
) (int, error) {
	records, err := worker.games.GetByOwner(ctx, userID)
	if err != nil {
		return 0, fmt.Errorf("user lifecycle handle: load owned games: %w", err)
	}

	cancelled := 0
	for _, record := range records {
		if record.Status.IsTerminal() {
			continue
		}

		if _, inflight := inflightGameStatuses[record.Status]; inflight {
			if err := worker.runtimeManager.PublishStopJob(ctx, record.GameID.String()); err != nil {
				return cancelled, fmt.Errorf("user lifecycle handle: publish stop job for %s: %w",
					record.GameID, err)
			}
		}

		updateErr := worker.games.UpdateStatus(ctx, ports.UpdateStatusInput{
			GameID:       record.GameID,
			ExpectedFrom: record.Status,
			To:           game.StatusCancelled,
			Trigger:      game.TriggerExternalBlock,
			At:           now,
		})
		switch {
		case updateErr == nil:
			cancelled++
			worker.telemetry.RecordGameTransition(ctx,
				string(record.Status),
				string(game.StatusCancelled),
				string(game.TriggerExternalBlock),
			)
		case errors.Is(updateErr, game.ErrConflict),
			errors.Is(updateErr, game.ErrInvalidTransition),
			errors.Is(updateErr, game.ErrNotFound):
			worker.logger.InfoContext(ctx, "game cascade absorbed",
				"game_id", record.GameID.String(),
				"current_status", string(record.Status),
				"err", updateErr.Error(),
			)
		default:
			return cancelled, fmt.Errorf("user lifecycle handle: cancel game %s: %w",
				record.GameID, updateErr)
		}
	}
	return cancelled, nil
}

func reasonForEvent(eventType ports.UserLifecycleEventType) string {
	switch eventType {
	case ports.UserLifecycleEventTypePermanentBlocked:
		return "permanent_blocked"
	case ports.UserLifecycleEventTypeDeleted:
		return "deleted"
	default:
		return string(eventType)
	}
}