package com.adx.tencent.conversionsync;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.time.Instant;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;

/**
 * 后台补拉任务服务。
 * 用于把 backfill 从同步 HTTP 请求改成异步 job。
 */
public class ConversionBackfillJobService {

    private static final Logger log = LoggerFactory.getLogger(ConversionBackfillJobService.class);

    private final ConversionSyncRunner runner;
    private final ExecutorService executor;
    private final Map<String, JobState> jobs = new ConcurrentHashMap<>();

    public ConversionBackfillJobService(ConversionSyncRunner runner) {
        this.runner = runner;
        this.executor = Executors.newFixedThreadPool(2, r -> {
            Thread t = new Thread(r, "conversion-backfill-job");
            t.setDaemon(true);
            return t;
        });
    }

    public JobHandle submit(List<Integer> offsets) {
        String jobId = UUID.randomUUID().toString().replace("-", "");
        JobState state = new JobState(jobId, "QUEUED", Instant.now(), null, null);
        jobs.put(jobId, state);

        executor.submit(() -> {
            update(jobId, "RUNNING", null, null);
            try {
                ConversionSyncService.SyncResult result = runner.runBackfillForOffsetsParallel(offsets, 3);
                update(jobId, "SUCCEEDED", result, null);
            } catch (Exception e) {
                log.error("[ConversionBackfill] job failed: jobId={}, error={}", jobId, e.getMessage(), e);
                update(jobId, "FAILED", null, e.getMessage());
            }
        });

        return new JobHandle(jobId, state.status(), state.createdAt());
    }

    public JobState getJob(String jobId) {
        return jobs.get(jobId);
    }

    private void update(String jobId, String status, ConversionSyncService.SyncResult result, String error) {
        JobState current = jobs.get(jobId);
        if (current == null) return;
        jobs.put(jobId, new JobState(jobId, status, current.createdAt(), result, error));
    }

    public record JobHandle(String jobId, String status, Instant createdAt) {}

    public record JobState(String jobId, String status, Instant createdAt,
                           ConversionSyncService.SyncResult result, String errorMessage) {}
}