java.md

Java Example

Korean | English

Note: This English text was translated and edited with LLM assistance. If anything reads awkwardly, please check the Korean version or open an issue.

Problem

The service method performs validation, lookup, permission checks, state changes, notification, and events in one place, increasing regression risk on changes.

Before

public Result suspendAccount(Input input) {
    long started = System.currentTimeMillis();
    Parsed parsed = parseInput(input);
    if (!parsed.ok()) {
        audit.log("invalid_input");
        return Result.fail("invalid_input");
    }

    User actor = userRepo.find(parsed.actorId());
    Account account = accountRepo.find(parsed.accountId());
    if (actor == null || account == null) {
        audit.log("lookup_failed");
        return Result.fail("resource_not_found");
    }
    if (account.isDeleted()) {
        return Result.fail("resource_not_found");
    }

    boolean canSuspend = permission.canSuspend(actor, account);
    if (!canSuspend) {
        audit.log("forbidden", actor.id(), account.id());
        return Result.fail("forbidden");
    }

    if (account.status() == AccountStatus.SUSPENDED) {
        metrics.increment("already_suspended");
        return Result.fail("already_suspended");
    }

    if (parsed.force()) {
        audit.log("suspend_forced", actor.id(), account.id());
    }

    accountRepo.updateStatus(account.id(), AccountStatus.SUSPENDED);
    accountRepo.touchUpdatedAt(account.id());
    if (parsed.clearSessions()) {
        sessionRepo.revokeAll(account.userId());
    }

    if (parsed.notifyOwner()) {
        try {
            notifier.send(account.ownerEmail(), "account_suspended");
            if (parsed.notifyActor()) {
                notifier.send(actor.email(), "suspend_done");
            }
        } catch (Exception e) {
            audit.log("notify_failed", account.id());
        }
    }

    try {
        eventBus.publish("account.suspended", account.id(), actor.id());
    } catch (Exception e) {
        audit.log("event_publish_failed", account.id());
    }
    metrics.increment("account_suspended");
    metrics.timing("suspend_account_ms", System.currentTimeMillis() - started);

    return Result.ok(account.id());
}

After (Applied with structure-first)

public Result suspendAccount(Input input) {
    var req = parseSuspendRequest(input);
    if (req.isFail()) return Result.fail("invalid_input");

    var ctx = loadSuspendContext(req.value());
    if (ctx.isFail()) return Result.fail(ctx.reason());

    var decision = decideSuspend(ctx.value());
    if (decision.isFail()) return Result.fail(decision.reason());

    var saved = persistSuspend(decision.value());
    notifySuspend(saved, req.value());
    publishSuspended(saved.accountId(), saved.actorId());
    recordSuspendMetrics(saved.startedAt());

    return Result.ok(saved.accountId());
}

DecisionResult decideSuspend(SuspendContext ctx) {
    if (!ctx.permission().canSuspend()) return DecisionResult.fail("forbidden");
    if (ctx.account().status() == AccountStatus.SUSPENDED) return DecisionResult.fail("already_suspended");
    if (ctx.account().isDeleted()) return DecisionResult.fail("resource_not_found");
    return DecisionResult.ok(new SuspendDecision(ctx.account().id(), ctx.actor().id(), ctx.request().clearSessions()));
}

Interpretation

• Primary Flow: parse -> load -> decide -> persist -> notify -> publish -> metrics
• Boundary(I/O): loadSuspendContext, persistSuspend, notifySuspend, publishSuspended, recordSuspendMetrics
• Atom(domain): decideSuspend
• Readability impact: the service method keeps only flow orchestration while policy decisions are fixed by the decideSuspend contract.