import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.Gauge;
import io.micrometer.core.instrument.MeterRegistry;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.HashOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

import java.util.Map;

@Service
public class StatusDelayMonitorService {

    private static final String HASH_NAME = "registros_pendentes";
    private static final long LIMITE_ATRASO_MS = 3_600_000; // 1 hora

    private final Counter atrasoCounter;
    private final HashOperations<String, String, String> hashOps;

    @Autowired
    public StatusDelayMonitorService(RedisTemplate<String, String> redisTemplate, MeterRegistry meterRegistry) {
        this.hashOps = redisTemplate.opsForHash();

        this.atrasoCounter = Counter.builder("registro.atrasos")
                .description("Eventos que excederam tempo máximo aguardando status B")
                .register(meterRegistry);

        // Gauge que retorna o tamanho diretamente do Redis, sem variável intermediária
        Gauge.builder("registros.pendentes", this, s -> s.getPendentesCount())
                .description("Quantidade de registros pendentes em tempo real aguardando status B")
                .register(meterRegistry);
    }

    // 1. Registrar chegada com status A
    public void onStatusA(String registroId) {
        hashOps.put(HASH_NAME, registroId, String.valueOf(System.currentTimeMillis()));
    }

    // 2. Remover ao chegar status B
    public void onStatusB(String registroId) {
        hashOps.delete(HASH_NAME, registroId);
    }

    // 3. Verificação periódica de atrasos
    @Scheduled(fixedRate = 60_000)
    public void verificarAtrasos() {
        long now = System.currentTimeMillis();
        Map<String, String> registros = hashOps.entries(HASH_NAME);
        for (Map.Entry<String, String> entry : registros.entrySet()) {
            String id = entry.getKey();
            long timestamp = Long.parseLong(entry.getValue());
            if ((now - timestamp) > LIMITE_ATRASO_MS) {
                // Esta métrica será utilizada pelo sistema de monitoramento para disparar alarmes de atraso.
                atrasoCounter.increment();
                // Opcional: hashOps.delete(HASH_NAME, id);
            }
        }
    }

    // Micrometer chama este método para atualizar a Gauge
    public int getPendentesCount() {
        return (int) hashOps.size(HASH_NAME);
    }
}