feat: game lobby service

lobby/internal/service/declineinvite/service.go

@@ -0,0 +1,154 @@
+// Package declineinvite implements the `lobby.invite.decline` message type.
+// It transitions the invite from created to declined when the actor is the
+// invitee. Per `lobby/README.md` §Invite Lifecycle, no notification is
+// published in v1.
+package declineinvite
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"galaxy/lobby/internal/domain/common"
+	"galaxy/lobby/internal/domain/invite"
+	"galaxy/lobby/internal/logging"
+	"galaxy/lobby/internal/ports"
+	"galaxy/lobby/internal/service/shared"
+	"galaxy/lobby/internal/telemetry"
+)
+
+// Service executes the private-game invite decline use case.
+type Service struct {
+	invites   ports.InviteStore
+	clock     func() time.Time
+	logger    *slog.Logger
+	telemetry *telemetry.Runtime
+}
+
+// Dependencies groups the collaborators used by Service.
+type Dependencies struct {
+	// Invites loads the target invite and applies the
+	// created → declined transition.
+	Invites ports.InviteStore
+
+	// Clock supplies the wall-clock used for DecidedAt.
+	Clock func() time.Time
+
+	// Logger records structured service-level events.
+	Logger *slog.Logger
+
+	// Telemetry records the `lobby.invite.outcomes` counter on each
+	// successful decline. Optional; nil disables metric emission.
+	Telemetry *telemetry.Runtime
+}
+
+// NewService constructs one Service with deps.
+func NewService(deps Dependencies) (*Service, error) {
+	if deps.Invites == nil {
+		return nil, errors.New("new decline invite service: nil invite store")
+	}
+	clock := deps.Clock
+	if clock == nil {
+		clock = time.Now
+	}
+	logger := deps.Logger
+	if logger == nil {
+		logger = slog.Default()
+	}
+	return &Service{
+		invites:   deps.Invites,
+		clock:     clock,
+		logger:    logger.With("service", "lobby.declineinvite"),
+		telemetry: deps.Telemetry,
+	}, nil
+}
+
+// Input stores the arguments required to decline one invite.
+type Input struct {
+	// Actor identifies the caller. Must be the invitee.
+	Actor shared.Actor
+
+	// GameID identifies the game referenced by the request path; it must
+	// match the loaded invite's GameID.
+	GameID common.GameID
+
+	// InviteID identifies the target invite.
+	InviteID common.InviteID
+}
+
+// Handle authorizes the invitee, validates the invite state, transitions the
+// invite to declined, and returns the updated record.
+func (service *Service) Handle(ctx context.Context, input Input) (invite.Invite, error) {
+	if service == nil {
+		return invite.Invite{}, errors.New("decline invite: nil service")
+	}
+	if ctx == nil {
+		return invite.Invite{}, errors.New("decline invite: nil context")
+	}
+	if err := input.Actor.Validate(); err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: actor: %w", err)
+	}
+	if !input.Actor.IsUser() {
+		return invite.Invite{}, fmt.Errorf(
+			"%w: only the invited user may decline an invite",
+			shared.ErrForbidden,
+		)
+	}
+	if err := input.GameID.Validate(); err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: %w", err)
+	}
+	if err := input.InviteID.Validate(); err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: %w", err)
+	}
+
+	inv, err := service.invites.Get(ctx, input.InviteID)
+	if err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: %w", err)
+	}
+	if inv.GameID != input.GameID {
+		return invite.Invite{}, fmt.Errorf(
+			"decline invite: invite %q does not belong to game %q: %w",
+			inv.InviteID, input.GameID, invite.ErrNotFound,
+		)
+	}
+	if inv.InviteeUserID != input.Actor.UserID {
+		return invite.Invite{}, fmt.Errorf(
+			"%w: invite is addressed to a different user",
+			shared.ErrForbidden,
+		)
+	}
+	if inv.Status != invite.StatusCreated {
+		return invite.Invite{}, fmt.Errorf(
+			"decline invite: status %q is not %q: %w",
+			inv.Status, invite.StatusCreated, invite.ErrConflict,
+		)
+	}
+
+	now := service.clock().UTC()
+	if err := service.invites.UpdateStatus(ctx, ports.UpdateInviteStatusInput{
+		InviteID:     inv.InviteID,
+		ExpectedFrom: invite.StatusCreated,
+		To:           invite.StatusDeclined,
+		At:           now,
+	}); err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: %w", err)
+	}
+
+	declined, err := service.invites.Get(ctx, inv.InviteID)
+	if err != nil {
+		return invite.Invite{}, fmt.Errorf("decline invite: %w", err)
+	}
+
+	service.telemetry.RecordInviteOutcome(ctx, "declined")
+
+	logArgs := []any{
+		"game_id", declined.GameID.String(),
+		"invite_id", declined.InviteID.String(),
+		"user_id", declined.InviteeUserID,
+	}
+	logArgs = append(logArgs, logging.ContextAttrs(ctx)...)
+	service.logger.InfoContext(ctx, "invite declined", logArgs...)
+	return declined, nil
+}