package ports

import (
	"context"
	"fmt"
	"strings"
	"time"

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

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

	// Get returns the record identified by inviteID. It returns
	// invite.ErrNotFound when no record exists.
	Get(ctx context.Context, inviteID common.InviteID) (invite.Invite, error)

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

	// GetByUser returns every invite addressed to inviteeUserID. The
	// order is adapter-defined; callers may reorder as needed.
	GetByUser(ctx context.Context, inviteeUserID string) ([]invite.Invite, error)

	// GetByInviter returns every invite created by inviterUserID. The
	// order is adapter-defined; callers may reorder as needed. The
	// secondary index is maintained alongside the per-game and per-user
	// indexes; cascade-release callers read it without touching
	// the per-game listings.
	GetByInviter(ctx context.Context, inviterUserID string) ([]invite.Invite, error)

	// UpdateStatus applies one status transition in a compare-and-swap
	// fashion. The adapter must first call invite.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, set DecidedAt to input.At, and apply
	// input.RaceName when transitioning to redeemed. input.RaceName must
	// be non-empty when To is redeemed and empty otherwise.
	UpdateStatus(ctx context.Context, input UpdateInviteStatusInput) error
}

// UpdateInviteStatusInput stores the arguments required to apply one
// status transition through an InviteStore.
type UpdateInviteStatusInput struct {
	// InviteID identifies the record to mutate.
	InviteID common.InviteID

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

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

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

	// RaceName carries the invitee's confirmed in-game name. It is
	// required when To is redeemed and must be empty otherwise.
	RaceName string
}

// Validate reports whether input contains a structurally valid status
// transition request.
func (input UpdateInviteStatusInput) Validate() error {
	if err := input.InviteID.Validate(); err != nil {
		return fmt.Errorf("update invite status: invite id: %w", err)
	}
	if !input.ExpectedFrom.IsKnown() {
		return fmt.Errorf(
			"update invite status: expected from status %q is unsupported",
			input.ExpectedFrom,
		)
	}
	if !input.To.IsKnown() {
		return fmt.Errorf(
			"update invite status: to status %q is unsupported",
			input.To,
		)
	}
	if input.At.IsZero() {
		return fmt.Errorf("update invite status: at must not be zero")
	}
	if input.To == invite.StatusRedeemed {
		if strings.TrimSpace(input.RaceName) == "" {
			return fmt.Errorf(
				"update invite status: race name must not be empty when redeeming",
			)
		}
	} else if input.RaceName != "" {
		return fmt.Errorf(
			"update invite status: race name must be empty when transitioning to %q",
			input.To,
		)
	}
	return nil
}