package com.ruoyi.system.service.impl;

import java.io.IOException;
import java.time.Instant;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import jakarta.annotation.PreDestroy;
import org.springframework.stereotype.Service;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
import com.ruoyi.device.bts.BtsDevelopmentSimulator;
import com.ruoyi.device.bts.BtsDevelopmentSimulator.CollectorSnapshot;
import com.ruoyi.device.discovery.DeviceDiscoveryCandidateStore;
import com.ruoyi.device.discovery.DeviceDiscoveryCandidateStore.CabinetCandidate;
import com.ruoyi.device.discovery.DeviceDiscoveryCandidateStore.ChannelCandidate;
import com.ruoyi.device.model.Measurement;
import com.ruoyi.system.domain.TTest;
import com.ruoyi.system.domain.TTestBattery;
import com.ruoyi.system.service.ITestLiveService;
import com.ruoyi.system.service.ITTestService;

/** 将设备最新快照转换为测试视角，并托管 SSE 连接生命周期。 */
@Service
public class TTestLiveServiceImpl implements ITestLiveService
{
    private final ITTestService tests;
    private final DeviceDiscoveryCandidateStore candidates;
    private final BtsDevelopmentSimulator simulator;
    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(2);
    private final ConcurrentMap<String, LiveSource> lastSources = new ConcurrentHashMap<>();

    public TTestLiveServiceImpl(ITTestService tests, DeviceDiscoveryCandidateStore candidates,
            BtsDevelopmentSimulator simulator)
    { this.tests = tests; this.candidates = candidates; this.simulator = simulator; }

    @Override public LiveState current(Long testId)
    {
        TTest test = tests.selectTestById(testId);
        List<CabinetCandidate> cabinets = candidates.snapshot(Instant.now()).cabinets();
        List<LiveSource> sources = new ArrayList<>();
        boolean freezeSnapshots = "PAUSED".equals(test.getReceptionStatus())
                || "ENDED".equals(test.getReceptionStatus());
        for (TTestBattery battery : test.getBatteries() == null ? List.<TTestBattery>of() : test.getBatteries())
        {
            if (battery.getBinding() != null)
                sources.add(snapshotFor(testId, cabinetSource(battery, cabinets), freezeSnapshots));
            if (battery.getCollectorId() != null)
                sources.add(snapshotFor(testId, collectorSource(battery), freezeSnapshots));
        }
        List<Map<String, Object>> exceptions = sources.stream().filter(source -> !"ONLINE".equals(source.deviceStatus())
                && !"WORKING".equals(source.deviceStatus()) && !"PAUSED".equals(source.deviceStatus()))
                .map(source -> Map.<String, Object>of("sourceType", source.sourceType(), "sourceId", source.sourceId(),
                        "batteryNo", source.batteryNo(), "status", source.deviceStatus(), "message", "数据来源当前不可观测"))
                .toList();
        return new LiveState(testId, test.getTestStatus(), test.getReceptionStatus(), Instant.now(), sources, exceptions);
    }

    private LiveSource snapshotFor(Long testId, LiveSource fresh, boolean freeze)
    {
        String key = testId + ":" + fresh.sourceType() + ":" + fresh.sourceId() + ":" + fresh.batteryNo();
        if (freeze) return lastSources.getOrDefault(key, fresh);
        lastSources.put(key, fresh);
        return fresh;
    }

    @Override public SseEmitter stream(Long testId)
    {
        SseEmitter emitter = new SseEmitter(0L);
        try { sendAll(emitter, testId); }
        catch (RuntimeException | IOException exception) { emitter.completeWithError(exception); return emitter; }
        ScheduledFuture<?> future = scheduler.scheduleAtFixedRate(() -> {
            try { sendAll(emitter, testId); }
            catch (RuntimeException | IOException exception) { emitter.completeWithError(exception); }
        }, 3, 3, TimeUnit.SECONDS);
        emitter.onCompletion(() -> future.cancel(false));
        emitter.onTimeout(() -> future.cancel(false));
        emitter.onError(error -> future.cancel(false));
        return emitter;
    }

    private void sendAll(SseEmitter emitter, Long testId) throws IOException
    {
        LiveState state = current(testId);
        emitter.send(SseEmitter.event().name("snapshot").data(state));
        emitter.send(SseEmitter.event().name("device-status").data(state.sources()));
        emitter.send(SseEmitter.event().name("reception-status").data(Map.of("testId", testId, "receptionStatus", state.receptionStatus())));
        emitter.send(SseEmitter.event().name("test-status").data(Map.of("testId", testId, "testStatus", state.testStatus())));
        emitter.send(SseEmitter.event().name("exception").data(state.exceptions()));
        emitter.send(SseEmitter.event().name("heartbeat").data(Map.of("at", state.updatedAt())));
    }

    private LiveSource cabinetSource(TTestBattery battery, List<CabinetCandidate> cabinets)
    {
        var binding = battery.getBinding();
        for (CabinetCandidate cabinet : cabinets) for (ChannelCandidate channel : cabinet.channels())
            if (Objects.equals(channel.identity().devtype(), binding.getDevtype())
                    && Objects.equals(channel.identity().devid(), binding.getDevid())
                    && Objects.equals(channel.identity().subdevid(), binding.getSubdevid())
                    && Objects.equals(channel.identity().chlid(), binding.getChlid()))
                return new LiveSource("CABINET_CHANNEL", binding.getChannelId(), battery.getBatteryNo(),
                        channel.online() ? channel.workStatus().name() : "OFFLINE", snapshot(channel));
        return new LiveSource("CABINET_CHANNEL", binding.getChannelId(), battery.getBatteryNo(), "UNKNOWN", Map.of());
    }

    private Map<String, Object> snapshot(ChannelCandidate channel)
    {
        Map<String, Object> value = new LinkedHashMap<>();
        if (channel.latestSnapshot() == null) return value;
        value.put("source", "检测柜");
        value.put("observedAt", channel.latestSnapshot().receivedAt());
        value.put("measurements", channel.latestSnapshot().measurements().entrySet().stream().map(entry -> {
            Measurement measurement = entry.getValue();
            return Map.of("metricCode", entry.getKey(), "value", measurement.value(), "unit", measurement.unit());
        }).toList());
        value.put("units", channel.latestSnapshot().measurements().values().stream().map(Measurement::unit).distinct().toList());
        return value;
    }

    private LiveSource collectorSource(TTestBattery battery)
    {
        for (CollectorSnapshot collector : simulator.snapshot().collectors()) if (collector.collectorId() == battery.getCollectorId())
        {
            Map<String, Object> value = new LinkedHashMap<>();
            value.put("source", "采集器"); value.put("sampleIntervalMs", collector.sampleIntervalMs());
            value.put("measurements", collector.latestMeasurements());
            value.put("units", collector.latestMeasurements().stream().map(item -> item.unit()).distinct().toList());
            collector.latestMeasurements().stream().map(item -> item.serverReceivedAt()).max(Instant::compareTo)
                    .ifPresent(observedAt -> value.put("observedAt", observedAt));
            return new LiveSource("COLLECTOR", (long) collector.collectorId(), battery.getBatteryNo(),
                    collector.online() ? "ONLINE" : "OFFLINE", value);
        }
        return new LiveSource("COLLECTOR", battery.getCollectorId(), battery.getBatteryNo(), "UNKNOWN", Map.of());
    }

    @PreDestroy void shutdown() { scheduler.shutdownNow(); }
}