package ports

import (
	"context"
	"fmt"
	"time"

	"galaxy/lobby/internal/domain/common"
	"galaxy/lobby/internal/domain/membership"
)

// MembershipStore stores membership records and their secondary indexes.
// Adapters are responsible for maintaining the per-game set and per-user
// set together with the record.
type MembershipStore interface {
	// Save persists a new active membership record. Save rejects records
	// whose status is not active and is create-only: re-saving an
	// existing membership id returns membership.ErrConflict.
	Save(ctx context.Context, record membership.Membership) error

	// Get returns the record identified by membershipID. It returns
	// membership.ErrNotFound when no record exists.
	Get(ctx context.Context, membershipID common.MembershipID) (membership.Membership, error)

	// GetByGame returns every membership attached to gameID. The order
	// is adapter-defined; callers may reorder as needed.
	GetByGame(ctx context.Context, gameID common.GameID) ([]membership.Membership, error)

	// GetByUser returns every membership held by userID. The order is
	// adapter-defined; callers may reorder as needed.
	GetByUser(ctx context.Context, userID string) ([]membership.Membership, error)

	// UpdateStatus applies one status transition in a compare-and-swap
	// fashion. The adapter must first call membership.Transition to
	// reject invalid pairs without touching the store; on success it
	// must verify that the current status equals input.ExpectedFrom,
	// update the primary record, and set RemovedAt to input.At when
	// transitioning out of active.
	UpdateStatus(ctx context.Context, input UpdateMembershipStatusInput) error

	// Delete removes the membership record identified by membershipID
	// from the primary store and from the per-game and per-user
	// secondary index sets in one operation. Delete is the pre-start
	// path of removemember; the post-start path uses
	// UpdateStatus(active → removed). Delete returns
	// membership.ErrNotFound when no record exists for the id.
	Delete(ctx context.Context, membershipID common.MembershipID) error
}

// UpdateMembershipStatusInput stores the arguments required to apply one
// status transition through a MembershipStore.
type UpdateMembershipStatusInput struct {
	// MembershipID identifies the record to mutate.
	MembershipID common.MembershipID

	// ExpectedFrom stores the status the caller believes the record
	// currently has. A mismatch results in membership.ErrConflict.
	ExpectedFrom membership.Status

	// To stores the destination status.
	To membership.Status

	// At stores the wall-clock used for RemovedAt.
	At time.Time
}

// Validate reports whether input contains a structurally valid status
// transition request.
func (input UpdateMembershipStatusInput) Validate() error {
	if err := input.MembershipID.Validate(); err != nil {
		return fmt.Errorf("update membership status: membership id: %w", err)
	}
	if !input.ExpectedFrom.IsKnown() {
		return fmt.Errorf(
			"update membership status: expected from status %q is unsupported",
			input.ExpectedFrom,
		)
	}
	if !input.To.IsKnown() {
		return fmt.Errorf(
			"update membership status: to status %q is unsupported",
			input.To,
		)
	}
	if input.At.IsZero() {
		return fmt.Errorf("update membership status: at must not be zero")
	}
	return nil
}