// Package policysvc implements the trusted sanction and limit command use
// cases owned by User Service.
package policysvc

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

	"galaxy/user/internal/domain/common"
	"galaxy/user/internal/domain/policy"
	"galaxy/user/internal/ports"
	"galaxy/user/internal/service/shared"
	"galaxy/user/internal/telemetry"
)

const adminInternalAPISource = common.Source("admin_internal_api")

// ActorInput stores one transport-facing audit actor payload.
type ActorInput struct {
	// Type stores the machine-readable actor type.
	Type string

	// ID stores the optional stable actor identifier.
	ID string
}

// ApplySanctionInput stores one trusted sanction-apply command request.
type ApplySanctionInput struct {
	// UserID identifies the user whose sanction set must change.
	UserID string

	// SanctionCode stores the sanction that must become active.
	SanctionCode string

	// Scope stores the machine-readable sanction scope.
	Scope string

	// ReasonCode stores the machine-readable mutation reason.
	ReasonCode string

	// Actor stores the audit actor metadata.
	Actor ActorInput

	// AppliedAt stores when the sanction becomes effective.
	AppliedAt string

	// ExpiresAt stores the optional planned sanction expiry.
	ExpiresAt string
}

// RemoveSanctionInput stores one trusted sanction-remove command request.
type RemoveSanctionInput struct {
	// UserID identifies the user whose sanction set must change.
	UserID string

	// SanctionCode stores the sanction that must no longer stay active.
	SanctionCode string

	// ReasonCode stores the machine-readable mutation reason.
	ReasonCode string

	// Actor stores the audit actor metadata.
	Actor ActorInput
}

// SetLimitInput stores one trusted limit-set command request.
type SetLimitInput struct {
	// UserID identifies the user whose limit set must change.
	UserID string

	// LimitCode stores the limit override that must become active.
	LimitCode string

	// Value stores the active numeric override value.
	Value int

	// ReasonCode stores the machine-readable mutation reason.
	ReasonCode string

	// Actor stores the audit actor metadata.
	Actor ActorInput

	// AppliedAt stores when the limit becomes effective.
	AppliedAt string

	// ExpiresAt stores the optional planned limit expiry.
	ExpiresAt string
}

// RemoveLimitInput stores one trusted limit-remove command request.
type RemoveLimitInput struct {
	// UserID identifies the user whose limit set must change.
	UserID string

	// LimitCode stores the limit override that must no longer stay active.
	LimitCode string

	// ReasonCode stores the machine-readable mutation reason.
	ReasonCode string

	// Actor stores the audit actor metadata.
	Actor ActorInput
}

// ActorRefView stores transport-ready audit actor metadata.
type ActorRefView struct {
	// Type stores the machine-readable actor type.
	Type string `json:"type"`

	// ID stores the optional stable actor identifier.
	ID string `json:"id,omitempty"`
}

// ActiveSanctionView stores one transport-ready active sanction.
type ActiveSanctionView struct {
	// SanctionCode stores the active sanction code.
	SanctionCode string `json:"sanction_code"`

	// Scope stores the machine-readable sanction scope.
	Scope string `json:"scope"`

	// ReasonCode stores the machine-readable sanction reason.
	ReasonCode string `json:"reason_code"`

	// Actor stores the audit actor metadata attached to the sanction.
	Actor ActorRefView `json:"actor"`

	// AppliedAt stores when the sanction became active.
	AppliedAt time.Time `json:"applied_at"`

	// ExpiresAt stores the optional planned sanction expiry.
	ExpiresAt *time.Time `json:"expires_at,omitempty"`
}

// ActiveLimitView stores one transport-ready active limit.
type ActiveLimitView struct {
	// LimitCode stores the active limit code.
	LimitCode string `json:"limit_code"`

	// Value stores the active override value.
	Value int `json:"value"`

	// ReasonCode stores the machine-readable limit reason.
	ReasonCode string `json:"reason_code"`

	// Actor stores the audit actor metadata attached to the limit.
	Actor ActorRefView `json:"actor"`

	// AppliedAt stores when the limit became active.
	AppliedAt time.Time `json:"applied_at"`

	// ExpiresAt stores the optional planned limit expiry.
	ExpiresAt *time.Time `json:"expires_at,omitempty"`
}

// SanctionCommandResult stores one trusted sanction-command result.
type SanctionCommandResult struct {
	// UserID identifies the mutated user.
	UserID string `json:"user_id"`

	// ActiveSanctions stores the current active sanctions sorted by code.
	ActiveSanctions []ActiveSanctionView `json:"active_sanctions"`
}

// LimitCommandResult stores one trusted limit-command result.
type LimitCommandResult struct {
	// UserID identifies the mutated user.
	UserID string `json:"user_id"`

	// ActiveLimits stores the current active limits sorted by code.
	ActiveLimits []ActiveLimitView `json:"active_limits"`
}

type commandSupport struct {
	accounts    ports.UserAccountStore
	sanctions   ports.SanctionStore
	limits      ports.LimitStore
	lifecycle   ports.PolicyLifecycleStore
	clock       ports.Clock
	idGenerator ports.IDGenerator
}

func newCommandSupport(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
) (commandSupport, error) {
	switch {
	case accounts == nil:
		return commandSupport{}, fmt.Errorf("user account store must not be nil")
	case sanctions == nil:
		return commandSupport{}, fmt.Errorf("sanction store must not be nil")
	case limits == nil:
		return commandSupport{}, fmt.Errorf("limit store must not be nil")
	case lifecycle == nil:
		return commandSupport{}, fmt.Errorf("policy lifecycle store must not be nil")
	case clock == nil:
		return commandSupport{}, fmt.Errorf("clock must not be nil")
	case idGenerator == nil:
		return commandSupport{}, fmt.Errorf("id generator must not be nil")
	default:
		return commandSupport{
			accounts:    accounts,
			sanctions:   sanctions,
			limits:      limits,
			lifecycle:   lifecycle,
			clock:       clock,
			idGenerator: idGenerator,
		}, nil
	}
}

func (support commandSupport) ensureUserExists(ctx context.Context, userID common.UserID) error {
	exists, err := support.accounts.ExistsByUserID(ctx, userID)
	switch {
	case err != nil:
		return shared.ServiceUnavailable(err)
	case !exists:
		return shared.SubjectNotFound()
	default:
		return nil
	}
}

func (support commandSupport) loadActiveSanctions(
	ctx context.Context,
	userID common.UserID,
	now time.Time,
) ([]policy.SanctionRecord, error) {
	records, err := support.sanctions.ListByUserID(ctx, userID)
	if err != nil {
		return nil, shared.ServiceUnavailable(err)
	}

	active, err := policy.ActiveSanctionsAt(records, now)
	if err != nil {
		return nil, shared.InternalError(fmt.Errorf("evaluate active sanctions for user %q: %w", userID, err))
	}

	return active, nil
}

func (support commandSupport) loadActiveLimits(
	ctx context.Context,
	userID common.UserID,
	now time.Time,
) ([]policy.LimitRecord, error) {
	records, err := support.limits.ListByUserID(ctx, userID)
	if err != nil {
		return nil, shared.ServiceUnavailable(err)
	}

	active, err := policy.ActiveLimitsAt(records, now)
	if err != nil {
		return nil, shared.InternalError(fmt.Errorf("evaluate active limits for user %q: %w", userID, err))
	}

	return active, nil
}

// ApplySanctionService executes the explicit trusted sanction-apply command.
type ApplySanctionService struct {
	support            commandSupport
	logger             *slog.Logger
	telemetry          *telemetry.Runtime
	publisher          ports.SanctionChangedPublisher
	lifecyclePublisher ports.UserLifecyclePublisher
}

// NewApplySanctionService constructs one sanction-apply use case.
func NewApplySanctionService(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
) (*ApplySanctionService, error) {
	return NewApplySanctionServiceWithObservability(accounts, sanctions, limits, lifecycle, clock, idGenerator, nil, nil, nil, nil)
}

// NewApplySanctionServiceWithObservability constructs one sanction-apply use
// case with optional observability hooks. `lifecyclePublisher` is consulted
// when the newly applied sanction is `SanctionCodePermanentBlock`: one
// `user.lifecycle.permanent_blocked` event is emitted after the commit.
func NewApplySanctionServiceWithObservability(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
	logger *slog.Logger,
	telemetryRuntime *telemetry.Runtime,
	publisher ports.SanctionChangedPublisher,
	lifecyclePublisher ports.UserLifecyclePublisher,
) (*ApplySanctionService, error) {
	support, err := newCommandSupport(accounts, sanctions, limits, lifecycle, clock, idGenerator)
	if err != nil {
		return nil, fmt.Errorf("policy apply sanction service: %w", err)
	}

	return &ApplySanctionService{
		support:            support,
		logger:             logger,
		telemetry:          telemetryRuntime,
		publisher:          publisher,
		lifecyclePublisher: lifecyclePublisher,
	}, nil
}

// Execute applies one new active sanction when the current state does not
// already contain an active sanction with the same code.
func (service *ApplySanctionService) Execute(ctx context.Context, input ApplySanctionInput) (result SanctionCommandResult, err error) {
	outcome := shared.ErrorCodeInternalError
	userIDString := strings.TrimSpace(input.UserID)
	reasonCodeValue := strings.TrimSpace(input.ReasonCode)
	actorTypeValue := strings.TrimSpace(input.Actor.Type)
	actorIDValue := strings.TrimSpace(input.Actor.ID)
	defer func() {
		if service.telemetry != nil {
			service.telemetry.RecordSanctionMutation(ctx, "apply", outcome)
		}
		shared.LogServiceOutcome(service.logger, ctx, "sanction apply completed", err,
			"use_case", "apply_sanction",
			"command", "apply",
			"outcome", outcome,
			"user_id", userIDString,
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCodeValue,
			"actor_type", actorTypeValue,
			"actor_id", actorIDValue,
		)
	}()

	if ctx == nil {
		outcome = shared.ErrorCodeInvalidRequest
		return SanctionCommandResult{}, shared.InvalidRequest("context must not be nil")
	}

	userID, err := shared.ParseUserID(input.UserID)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	userIDString = userID.String()
	if err := service.support.ensureUserExists(ctx, userID); err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}

	recordID, err := service.support.idGenerator.NewSanctionRecordID()
	if err != nil {
		outcome = shared.ErrorCodeServiceUnavailable
		return SanctionCommandResult{}, shared.ServiceUnavailable(err)
	}
	record, now, err := buildSanctionRecord(recordID, userID, input, service.support.clock.Now().UTC())
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	reasonCodeValue = record.ReasonCode.String()
	actorTypeValue = record.Actor.Type.String()
	actorIDValue = record.Actor.ID.String()

	if err := service.support.lifecycle.ApplySanction(ctx, ports.ApplySanctionInput{
		NewRecord: record,
	}); err != nil {
		switch {
		case errors.Is(err, ports.ErrConflict):
			outcome = shared.ErrorCodeConflict
			return SanctionCommandResult{}, shared.Conflict()
		default:
			outcome = shared.ErrorCodeServiceUnavailable
			return SanctionCommandResult{}, shared.ServiceUnavailable(err)
		}
	}

	active, err := service.support.loadActiveSanctions(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	outcome = "success"
	result = SanctionCommandResult{
		UserID:          userID.String(),
		ActiveSanctions: sanctionViews(active),
	}
	publishSanctionChanged(ctx, service.publisher, service.telemetry, service.logger, "apply_sanction", ports.SanctionChangedOperationApplied, record)
	if record.SanctionCode == policy.SanctionCodePermanentBlock {
		publishUserLifecyclePermanentBlocked(ctx, service.lifecyclePublisher, service.telemetry, service.logger, record)
	}

	return result, nil
}

// RemoveSanctionService executes the explicit trusted sanction-remove
// command.
type RemoveSanctionService struct {
	support   commandSupport
	logger    *slog.Logger
	telemetry *telemetry.Runtime
	publisher ports.SanctionChangedPublisher
}

// NewRemoveSanctionService constructs one sanction-remove use case.
func NewRemoveSanctionService(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
) (*RemoveSanctionService, error) {
	return NewRemoveSanctionServiceWithObservability(accounts, sanctions, limits, lifecycle, clock, idGenerator, nil, nil, nil)
}

// NewRemoveSanctionServiceWithObservability constructs one sanction-remove use
// case with optional observability hooks.
func NewRemoveSanctionServiceWithObservability(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
	logger *slog.Logger,
	telemetryRuntime *telemetry.Runtime,
	publisher ports.SanctionChangedPublisher,
) (*RemoveSanctionService, error) {
	support, err := newCommandSupport(accounts, sanctions, limits, lifecycle, clock, idGenerator)
	if err != nil {
		return nil, fmt.Errorf("policy remove sanction service: %w", err)
	}

	return &RemoveSanctionService{
		support:   support,
		logger:    logger,
		telemetry: telemetryRuntime,
		publisher: publisher,
	}, nil
}

// Execute removes the current active sanction of input.SanctionCode. When no
// active sanction exists, the command succeeds without changing state.
func (service *RemoveSanctionService) Execute(ctx context.Context, input RemoveSanctionInput) (result SanctionCommandResult, err error) {
	outcome := shared.ErrorCodeInternalError
	userIDString := strings.TrimSpace(input.UserID)
	reasonCodeValue := strings.TrimSpace(input.ReasonCode)
	actorTypeValue := strings.TrimSpace(input.Actor.Type)
	actorIDValue := strings.TrimSpace(input.Actor.ID)
	defer func() {
		if service.telemetry != nil {
			service.telemetry.RecordSanctionMutation(ctx, "remove", outcome)
		}
		shared.LogServiceOutcome(service.logger, ctx, "sanction remove completed", err,
			"use_case", "remove_sanction",
			"command", "remove",
			"outcome", outcome,
			"user_id", userIDString,
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCodeValue,
			"actor_type", actorTypeValue,
			"actor_id", actorIDValue,
		)
	}()

	if ctx == nil {
		outcome = shared.ErrorCodeInvalidRequest
		return SanctionCommandResult{}, shared.InvalidRequest("context must not be nil")
	}

	userID, err := shared.ParseUserID(input.UserID)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	userIDString = userID.String()
	if err := service.support.ensureUserExists(ctx, userID); err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}

	sanctionCode, err := parseSanctionCode(input.SanctionCode)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	reasonCode, err := shared.ParseReasonCode(input.ReasonCode)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	reasonCodeValue = reasonCode.String()
	actor, err := parseActor(input.Actor)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	actorTypeValue = actor.Type.String()
	actorIDValue = actor.ID.String()

	now := service.support.clock.Now().UTC()
	active, err := service.support.loadActiveSanctions(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}

	current, ok := findActiveSanction(active, sanctionCode)
	if !ok {
		outcome = "success"
		return SanctionCommandResult{
			UserID:          userID.String(),
			ActiveSanctions: sanctionViews(active),
		}, nil
	}

	updated := current
	updated.RemovedAt = &now
	updated.RemovedBy = actor
	updated.RemovedReasonCode = reasonCode

	if err := service.support.lifecycle.RemoveSanction(ctx, ports.RemoveSanctionInput{
		ExpectedActiveRecord: current,
		UpdatedRecord:        updated,
	}); err != nil {
		switch {
		case errors.Is(err, ports.ErrConflict):
			active, loadErr := service.support.loadActiveSanctions(ctx, userID, now)
			if loadErr != nil {
				outcome = shared.MetricOutcome(loadErr)
				return SanctionCommandResult{}, loadErr
			}
			next, ok := findActiveSanction(active, sanctionCode)
			if !ok {
				outcome = "success"
				return SanctionCommandResult{
					UserID:          userID.String(),
					ActiveSanctions: sanctionViews(active),
				}, nil
			}
			if next.RecordID != current.RecordID {
				outcome = shared.ErrorCodeConflict
				return SanctionCommandResult{}, shared.Conflict()
			}
			outcome = shared.ErrorCodeConflict
			return SanctionCommandResult{}, shared.Conflict()
		default:
			outcome = shared.ErrorCodeServiceUnavailable
			return SanctionCommandResult{}, shared.ServiceUnavailable(err)
		}
	}

	active, err = service.support.loadActiveSanctions(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return SanctionCommandResult{}, err
	}
	outcome = "success"
	result = SanctionCommandResult{
		UserID:          userID.String(),
		ActiveSanctions: sanctionViews(active),
	}
	publishSanctionChanged(ctx, service.publisher, service.telemetry, service.logger, "remove_sanction", ports.SanctionChangedOperationRemoved, updated)

	return result, nil
}

// SetLimitService executes the explicit trusted limit-set command.
type SetLimitService struct {
	support   commandSupport
	logger    *slog.Logger
	telemetry *telemetry.Runtime
	publisher ports.LimitChangedPublisher
}

// NewSetLimitService constructs one limit-set use case.
func NewSetLimitService(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
) (*SetLimitService, error) {
	return NewSetLimitServiceWithObservability(accounts, sanctions, limits, lifecycle, clock, idGenerator, nil, nil, nil)
}

// NewSetLimitServiceWithObservability constructs one limit-set use case with
// optional observability hooks.
func NewSetLimitServiceWithObservability(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
	logger *slog.Logger,
	telemetryRuntime *telemetry.Runtime,
	publisher ports.LimitChangedPublisher,
) (*SetLimitService, error) {
	support, err := newCommandSupport(accounts, sanctions, limits, lifecycle, clock, idGenerator)
	if err != nil {
		return nil, fmt.Errorf("policy set limit service: %w", err)
	}

	return &SetLimitService{
		support:   support,
		logger:    logger,
		telemetry: telemetryRuntime,
		publisher: publisher,
	}, nil
}

// Execute creates one new active limit or replaces the current active limit of
// the same code.
func (service *SetLimitService) Execute(ctx context.Context, input SetLimitInput) (result LimitCommandResult, err error) {
	outcome := shared.ErrorCodeInternalError
	userIDString := strings.TrimSpace(input.UserID)
	reasonCodeValue := strings.TrimSpace(input.ReasonCode)
	actorTypeValue := strings.TrimSpace(input.Actor.Type)
	actorIDValue := strings.TrimSpace(input.Actor.ID)
	defer func() {
		if service.telemetry != nil {
			service.telemetry.RecordLimitMutation(ctx, "set", outcome)
		}
		shared.LogServiceOutcome(service.logger, ctx, "limit set completed", err,
			"use_case", "set_limit",
			"command", "set",
			"outcome", outcome,
			"user_id", userIDString,
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCodeValue,
			"actor_type", actorTypeValue,
			"actor_id", actorIDValue,
		)
	}()

	if ctx == nil {
		outcome = shared.ErrorCodeInvalidRequest
		return LimitCommandResult{}, shared.InvalidRequest("context must not be nil")
	}

	userID, err := shared.ParseUserID(input.UserID)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	userIDString = userID.String()
	if err := service.support.ensureUserExists(ctx, userID); err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}

	recordID, err := service.support.idGenerator.NewLimitRecordID()
	if err != nil {
		outcome = shared.ErrorCodeServiceUnavailable
		return LimitCommandResult{}, shared.ServiceUnavailable(err)
	}
	record, now, err := buildLimitRecord(recordID, userID, input, service.support.clock.Now().UTC())
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	reasonCodeValue = record.ReasonCode.String()
	actorTypeValue = record.Actor.Type.String()
	actorIDValue = record.Actor.ID.String()

	active, err := service.support.loadActiveLimits(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}

	current, ok := findActiveLimit(active, record.LimitCode)
	setInput := ports.SetLimitInput{NewRecord: record}
	if ok {
		if record.AppliedAt.Before(current.AppliedAt) {
			outcome = shared.ErrorCodeInvalidRequest
			return LimitCommandResult{}, shared.InvalidRequest("applied_at must not be before the current active limit applied_at")
		}

		updated := current
		removedAt := record.AppliedAt
		updated.RemovedAt = &removedAt
		updated.RemovedBy = record.Actor
		updated.RemovedReasonCode = record.ReasonCode
		setInput.ExpectedActiveRecord = &current
		setInput.UpdatedActiveRecord = &updated
	}

	if err := service.support.lifecycle.SetLimit(ctx, setInput); err != nil {
		switch {
		case errors.Is(err, ports.ErrConflict):
			outcome = shared.ErrorCodeConflict
			return LimitCommandResult{}, shared.Conflict()
		default:
			outcome = shared.ErrorCodeServiceUnavailable
			return LimitCommandResult{}, shared.ServiceUnavailable(err)
		}
	}

	active, err = service.support.loadActiveLimits(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	outcome = "success"
	result = LimitCommandResult{
		UserID:       userID.String(),
		ActiveLimits: limitViews(active),
	}
	publishLimitChanged(ctx, service.publisher, service.telemetry, service.logger, "set_limit", ports.LimitChangedOperationSet, record)

	return result, nil
}

// RemoveLimitService executes the explicit trusted limit-remove command.
type RemoveLimitService struct {
	support   commandSupport
	logger    *slog.Logger
	telemetry *telemetry.Runtime
	publisher ports.LimitChangedPublisher
}

// NewRemoveLimitService constructs one limit-remove use case.
func NewRemoveLimitService(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
) (*RemoveLimitService, error) {
	return NewRemoveLimitServiceWithObservability(accounts, sanctions, limits, lifecycle, clock, idGenerator, nil, nil, nil)
}

// NewRemoveLimitServiceWithObservability constructs one limit-remove use case
// with optional observability hooks.
func NewRemoveLimitServiceWithObservability(
	accounts ports.UserAccountStore,
	sanctions ports.SanctionStore,
	limits ports.LimitStore,
	lifecycle ports.PolicyLifecycleStore,
	clock ports.Clock,
	idGenerator ports.IDGenerator,
	logger *slog.Logger,
	telemetryRuntime *telemetry.Runtime,
	publisher ports.LimitChangedPublisher,
) (*RemoveLimitService, error) {
	support, err := newCommandSupport(accounts, sanctions, limits, lifecycle, clock, idGenerator)
	if err != nil {
		return nil, fmt.Errorf("policy remove limit service: %w", err)
	}

	return &RemoveLimitService{
		support:   support,
		logger:    logger,
		telemetry: telemetryRuntime,
		publisher: publisher,
	}, nil
}

// Execute removes the current active limit of input.LimitCode. When no active
// limit exists, the command succeeds without changing state.
func (service *RemoveLimitService) Execute(ctx context.Context, input RemoveLimitInput) (result LimitCommandResult, err error) {
	outcome := shared.ErrorCodeInternalError
	userIDString := strings.TrimSpace(input.UserID)
	reasonCodeValue := strings.TrimSpace(input.ReasonCode)
	actorTypeValue := strings.TrimSpace(input.Actor.Type)
	actorIDValue := strings.TrimSpace(input.Actor.ID)
	defer func() {
		if service.telemetry != nil {
			service.telemetry.RecordLimitMutation(ctx, "remove", outcome)
		}
		shared.LogServiceOutcome(service.logger, ctx, "limit remove completed", err,
			"use_case", "remove_limit",
			"command", "remove",
			"outcome", outcome,
			"user_id", userIDString,
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCodeValue,
			"actor_type", actorTypeValue,
			"actor_id", actorIDValue,
		)
	}()

	if ctx == nil {
		outcome = shared.ErrorCodeInvalidRequest
		return LimitCommandResult{}, shared.InvalidRequest("context must not be nil")
	}

	userID, err := shared.ParseUserID(input.UserID)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	userIDString = userID.String()
	if err := service.support.ensureUserExists(ctx, userID); err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}

	limitCode, err := parseLimitCode(input.LimitCode)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	reasonCode, err := shared.ParseReasonCode(input.ReasonCode)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	reasonCodeValue = reasonCode.String()
	actor, err := parseActor(input.Actor)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	actorTypeValue = actor.Type.String()
	actorIDValue = actor.ID.String()

	now := service.support.clock.Now().UTC()
	active, err := service.support.loadActiveLimits(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}

	current, ok := findActiveLimit(active, limitCode)
	if !ok {
		outcome = "success"
		return LimitCommandResult{
			UserID:       userID.String(),
			ActiveLimits: limitViews(active),
		}, nil
	}

	updated := current
	updated.RemovedAt = &now
	updated.RemovedBy = actor
	updated.RemovedReasonCode = reasonCode

	if err := service.support.lifecycle.RemoveLimit(ctx, ports.RemoveLimitInput{
		ExpectedActiveRecord: current,
		UpdatedRecord:        updated,
	}); err != nil {
		switch {
		case errors.Is(err, ports.ErrConflict):
			active, loadErr := service.support.loadActiveLimits(ctx, userID, now)
			if loadErr != nil {
				outcome = shared.MetricOutcome(loadErr)
				return LimitCommandResult{}, loadErr
			}
			next, ok := findActiveLimit(active, limitCode)
			if !ok {
				outcome = "success"
				return LimitCommandResult{
					UserID:       userID.String(),
					ActiveLimits: limitViews(active),
				}, nil
			}
			if next.RecordID != current.RecordID {
				outcome = shared.ErrorCodeConflict
				return LimitCommandResult{}, shared.Conflict()
			}
			outcome = shared.ErrorCodeConflict
			return LimitCommandResult{}, shared.Conflict()
		default:
			outcome = shared.ErrorCodeServiceUnavailable
			return LimitCommandResult{}, shared.ServiceUnavailable(err)
		}
	}

	active, err = service.support.loadActiveLimits(ctx, userID, now)
	if err != nil {
		outcome = shared.MetricOutcome(err)
		return LimitCommandResult{}, err
	}
	outcome = "success"
	result = LimitCommandResult{
		UserID:       userID.String(),
		ActiveLimits: limitViews(active),
	}
	publishLimitChanged(ctx, service.publisher, service.telemetry, service.logger, "remove_limit", ports.LimitChangedOperationRemoved, updated)

	return result, nil
}

func buildSanctionRecord(
	recordID policy.SanctionRecordID,
	userID common.UserID,
	input ApplySanctionInput,
	now time.Time,
) (policy.SanctionRecord, time.Time, error) {
	sanctionCode, err := parseSanctionCode(input.SanctionCode)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}
	scope, err := parseScope(input.Scope)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}
	reasonCode, err := shared.ParseReasonCode(input.ReasonCode)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}
	actor, err := parseActor(input.Actor)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}
	appliedAt, err := parseTimestamp("applied_at", input.AppliedAt)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}
	expiresAt, err := parseOptionalTimestamp("expires_at", input.ExpiresAt)
	if err != nil {
		return policy.SanctionRecord{}, time.Time{}, err
	}

	record := policy.SanctionRecord{
		RecordID:     recordID,
		UserID:       userID,
		SanctionCode: sanctionCode,
		Scope:        scope,
		ReasonCode:   reasonCode,
		Actor:        actor,
		AppliedAt:    appliedAt,
		ExpiresAt:    expiresAt,
	}
	if err := record.ValidateAt(now); err != nil {
		return policy.SanctionRecord{}, time.Time{}, shared.InvalidRequest(err.Error())
	}
	if !record.IsActiveAt(now) {
		return policy.SanctionRecord{}, time.Time{}, shared.InvalidRequest("expires_at must be in the future relative to current service time")
	}

	return record, now, nil
}

func buildLimitRecord(
	recordID policy.LimitRecordID,
	userID common.UserID,
	input SetLimitInput,
	now time.Time,
) (policy.LimitRecord, time.Time, error) {
	limitCode, err := parseLimitCode(input.LimitCode)
	if err != nil {
		return policy.LimitRecord{}, time.Time{}, err
	}
	reasonCode, err := shared.ParseReasonCode(input.ReasonCode)
	if err != nil {
		return policy.LimitRecord{}, time.Time{}, err
	}
	actor, err := parseActor(input.Actor)
	if err != nil {
		return policy.LimitRecord{}, time.Time{}, err
	}
	appliedAt, err := parseTimestamp("applied_at", input.AppliedAt)
	if err != nil {
		return policy.LimitRecord{}, time.Time{}, err
	}
	expiresAt, err := parseOptionalTimestamp("expires_at", input.ExpiresAt)
	if err != nil {
		return policy.LimitRecord{}, time.Time{}, err
	}

	record := policy.LimitRecord{
		RecordID:   recordID,
		UserID:     userID,
		LimitCode:  limitCode,
		Value:      input.Value,
		ReasonCode: reasonCode,
		Actor:      actor,
		AppliedAt:  appliedAt,
		ExpiresAt:  expiresAt,
	}
	if err := record.ValidateAt(now); err != nil {
		return policy.LimitRecord{}, time.Time{}, shared.InvalidRequest(err.Error())
	}
	if !record.IsActiveAt(now) {
		return policy.LimitRecord{}, time.Time{}, shared.InvalidRequest("expires_at must be in the future relative to current service time")
	}

	return record, now, nil
}

func parseSanctionCode(value string) (policy.SanctionCode, error) {
	code := policy.SanctionCode(shared.NormalizeString(value))
	if !code.IsKnown() {
		return "", shared.InvalidRequest("sanction_code is unsupported")
	}

	return code, nil
}

func parseLimitCode(value string) (policy.LimitCode, error) {
	code := policy.LimitCode(shared.NormalizeString(value))
	if !code.IsSupported() {
		return "", shared.InvalidRequest("limit_code is unsupported")
	}

	return code, nil
}

func parseScope(value string) (common.Scope, error) {
	scope := common.Scope(shared.NormalizeString(value))
	if err := scope.Validate(); err != nil {
		return "", shared.InvalidRequest(err.Error())
	}

	return scope, nil
}

func parseActor(input ActorInput) (common.ActorRef, error) {
	ref := common.ActorRef{
		Type: common.ActorType(shared.NormalizeString(input.Type)),
		ID:   common.ActorID(shared.NormalizeString(input.ID)),
	}
	if err := ref.Validate(); err != nil {
		if ref.Type.IsZero() {
			return common.ActorRef{}, shared.InvalidRequest("actor.type must not be empty")
		}
		return common.ActorRef{}, shared.InvalidRequest(err.Error())
	}

	return ref, nil
}

func parseTimestamp(fieldName string, value string) (time.Time, error) {
	trimmed := shared.NormalizeString(value)
	if trimmed == "" {
		return time.Time{}, shared.InvalidRequest(fieldName + " must not be empty")
	}

	parsed, err := time.Parse(time.RFC3339Nano, trimmed)
	if err != nil {
		return time.Time{}, shared.InvalidRequest(fieldName + " must be a valid RFC 3339 timestamp")
	}

	return parsed.UTC(), nil
}

func parseOptionalTimestamp(fieldName string, value string) (*time.Time, error) {
	trimmed := shared.NormalizeString(value)
	if trimmed == "" {
		return nil, nil
	}

	parsed, err := parseTimestamp(fieldName, trimmed)
	if err != nil {
		return nil, err
	}

	return &parsed, nil
}

func findActiveSanction(
	records []policy.SanctionRecord,
	code policy.SanctionCode,
) (policy.SanctionRecord, bool) {
	for _, record := range records {
		if record.SanctionCode == code {
			return record, true
		}
	}

	return policy.SanctionRecord{}, false
}

func findActiveLimit(
	records []policy.LimitRecord,
	code policy.LimitCode,
) (policy.LimitRecord, bool) {
	for _, record := range records {
		if record.LimitCode == code {
			return record, true
		}
	}

	return policy.LimitRecord{}, false
}

func sanctionViews(records []policy.SanctionRecord) []ActiveSanctionView {
	views := make([]ActiveSanctionView, 0, len(records))
	for _, record := range records {
		views = append(views, ActiveSanctionView{
			SanctionCode: string(record.SanctionCode),
			Scope:        record.Scope.String(),
			ReasonCode:   record.ReasonCode.String(),
			Actor:        actorRefView(record.Actor),
			AppliedAt:    record.AppliedAt.UTC(),
			ExpiresAt:    cloneOptionalTime(record.ExpiresAt),
		})
	}

	return views
}

func limitViews(records []policy.LimitRecord) []ActiveLimitView {
	views := make([]ActiveLimitView, 0, len(records))
	for _, record := range records {
		views = append(views, ActiveLimitView{
			LimitCode:  string(record.LimitCode),
			Value:      record.Value,
			ReasonCode: record.ReasonCode.String(),
			Actor:      actorRefView(record.Actor),
			AppliedAt:  record.AppliedAt.UTC(),
			ExpiresAt:  cloneOptionalTime(record.ExpiresAt),
		})
	}

	return views
}

func actorRefView(ref common.ActorRef) ActorRefView {
	return ActorRefView{
		Type: ref.Type.String(),
		ID:   ref.ID.String(),
	}
}

func cloneOptionalTime(value *time.Time) *time.Time {
	if value == nil {
		return nil
	}

	cloned := value.UTC()
	return &cloned
}

func publishSanctionChanged(
	ctx context.Context,
	publisher ports.SanctionChangedPublisher,
	telemetryRuntime *telemetry.Runtime,
	logger *slog.Logger,
	useCase string,
	operation ports.SanctionChangedOperation,
	record policy.SanctionRecord,
) {
	if publisher == nil {
		return
	}

	reasonCode := record.ReasonCode
	actor := record.Actor
	if operation == ports.SanctionChangedOperationRemoved {
		reasonCode = record.RemovedReasonCode
		actor = record.RemovedBy
	}

	event := ports.SanctionChangedEvent{
		UserID:       record.UserID,
		OccurredAt:   sanctionOccurredAt(record),
		Source:       adminInternalAPISource,
		Operation:    operation,
		SanctionCode: record.SanctionCode,
		Scope:        record.Scope,
		ReasonCode:   reasonCode,
		Actor:        actor,
		AppliedAt:    record.AppliedAt,
		ExpiresAt:    record.ExpiresAt,
		RemovedAt:    record.RemovedAt,
	}
	if err := publisher.PublishSanctionChanged(ctx, event); err != nil {
		if telemetryRuntime != nil {
			telemetryRuntime.RecordEventPublicationFailure(ctx, ports.SanctionChangedEventType)
		}
		shared.LogEventPublicationFailure(logger, ctx, ports.SanctionChangedEventType, err,
			"use_case", useCase,
			"user_id", record.UserID.String(),
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCode.String(),
			"actor_type", actor.Type.String(),
			"actor_id", actor.ID.String(),
		)
	}
}

func publishUserLifecyclePermanentBlocked(
	ctx context.Context,
	publisher ports.UserLifecyclePublisher,
	telemetryRuntime *telemetry.Runtime,
	logger *slog.Logger,
	record policy.SanctionRecord,
) {
	if publisher == nil {
		return
	}

	event := ports.UserLifecycleEvent{
		EventType:  ports.UserLifecyclePermanentBlockedEventType,
		UserID:     record.UserID,
		OccurredAt: record.AppliedAt.UTC(),
		Source:     adminInternalAPISource,
		Actor:      record.Actor,
		ReasonCode: record.ReasonCode,
	}
	if err := publisher.PublishUserLifecycleEvent(ctx, event); err != nil {
		if telemetryRuntime != nil {
			telemetryRuntime.RecordEventPublicationFailure(ctx, string(ports.UserLifecyclePermanentBlockedEventType))
		}
		shared.LogEventPublicationFailure(logger, ctx, string(ports.UserLifecyclePermanentBlockedEventType), err,
			"use_case", "apply_sanction",
			"user_id", record.UserID.String(),
			"source", adminInternalAPISource.String(),
			"reason_code", record.ReasonCode.String(),
			"actor_type", record.Actor.Type.String(),
			"actor_id", record.Actor.ID.String(),
		)
	}
}

func publishLimitChanged(
	ctx context.Context,
	publisher ports.LimitChangedPublisher,
	telemetryRuntime *telemetry.Runtime,
	logger *slog.Logger,
	useCase string,
	operation ports.LimitChangedOperation,
	record policy.LimitRecord,
) {
	if publisher == nil {
		return
	}

	reasonCode := record.ReasonCode
	actor := record.Actor
	if operation == ports.LimitChangedOperationRemoved {
		reasonCode = record.RemovedReasonCode
		actor = record.RemovedBy
	}

	value := record.Value
	event := ports.LimitChangedEvent{
		UserID:     record.UserID,
		OccurredAt: limitOccurredAt(record),
		Source:     adminInternalAPISource,
		Operation:  operation,
		LimitCode:  record.LimitCode,
		ReasonCode: reasonCode,
		Actor:      actor,
		AppliedAt:  record.AppliedAt,
		ExpiresAt:  record.ExpiresAt,
		RemovedAt:  record.RemovedAt,
	}
	if operation == ports.LimitChangedOperationSet || record.RemovedAt == nil {
		event.Value = &value
	}
	if err := publisher.PublishLimitChanged(ctx, event); err != nil {
		if telemetryRuntime != nil {
			telemetryRuntime.RecordEventPublicationFailure(ctx, ports.LimitChangedEventType)
		}
		shared.LogEventPublicationFailure(logger, ctx, ports.LimitChangedEventType, err,
			"use_case", useCase,
			"user_id", record.UserID.String(),
			"source", adminInternalAPISource.String(),
			"reason_code", reasonCode.String(),
			"actor_type", actor.Type.String(),
			"actor_id", actor.ID.String(),
		)
	}
}

func sanctionOccurredAt(record policy.SanctionRecord) time.Time {
	if record.RemovedAt != nil {
		return record.RemovedAt.UTC()
	}

	return record.AppliedAt.UTC()
}

func limitOccurredAt(record policy.LimitRecord) time.Time {
	if record.RemovedAt != nil {
		return record.RemovedAt.UTC()
	}

	return record.AppliedAt.UTC()
}