import { BadRequestException, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import { createHash } from 'node:crypto';
import { PrismaService } from '../prisma/prisma.service';
import type { InfrastructureAlert } from './infrastructure-monitoring.contracts';

export async function retainAlerts(prisma: PrismaService, alerts: InfrastructureAlert[], observedAt: Date) {
  await prisma.$transaction(async (tx) => {
    // Serialize snapshots across API processes; timestamps reject late HTTP results.
    await tx.$executeRaw`SELECT pg_advisory_xact_lock(160916, 1)`;
    const previous = await tx.infrastructureAlertCollection.findUnique({ where: { id: 'prometheus' } });
    if (previous && previous.observedAt >= observedAt) return;
    // Read durable work directly: application releases do not install Prometheus rules.
    // Keep one occurrence identity until the condition really recovers, even after manual clear.
    const reviewCount = await tx.smsAttemptCompletionWork.count({ where: { state: 'needs_review' } });
    const oldest = await tx.smsCompletionEvent.findFirst({
      where: { processedAt: null, work: { state: { in: ['pending', 'processing', 'retry_wait'] } } },
      orderBy: { createdAt: 'asc' },
      select: { createdAt: true },
    });
    const age = oldest ? Math.max(0, (observedAt.getTime() - oldest.createdAt.getTime()) / 1000) : 0;
    alerts = [...alerts];
    for (const condition of [
      {
        name: 'SmsCompletionNeedsReview',
        active: reviewCount > 0,
        severity: 'critical' as const,
        summary: '短信收尾工作需要人工排查',
        value: String(reviewCount),
        threshold: '0',
      },
      {
        name: 'SmsCompletionBacklog',
        active: age > 300,
        severity: 'warning' as const,
        summary: '短信收尾工作等待超过5分钟',
        value: `${Math.floor(age)}秒`,
        threshold: '300秒',
      },
    ]) {
      if (!condition.active) continue;
      const fingerprint = createHash('sha256').update(`durable:${condition.name}`).digest('hex').slice(0, 24);
      const occurrence = await tx.infrastructureAlertEvent.findFirst({
        where: { fingerprint, recoveredAt: null },
        orderBy: { activeAt: 'desc' },
      });
      alerts.push({
        fingerprint,
        name: condition.name,
        severity: condition.severity,
        status: 'firing',
        startedAt: (occurrence?.activeAt ?? observedAt).toISOString(),
        summary: condition.summary,
        currentValue: condition.value,
        threshold: condition.threshold,
        service: '短信收尾',
        acknowledged: false,
      });
    }
    await tx.infrastructureAlertCollection.upsert({
      where: { id: 'prometheus' },
      create: { id: 'prometheus', observedAt },
      update: { observedAt },
    });
    for (const alert of alerts) {
      const activeAt = new Date(alert.startedAt);
      const payload = JSON.parse(JSON.stringify(alert)) as Prisma.InputJsonValue;
      await tx.infrastructureAlertEvent.createMany({
        data: [{ fingerprint: alert.fingerprint, activeAt, payload, lastObservedAt: observedAt }],
        skipDuplicates: true,
      });
      await tx.infrastructureAlertEvent.updateMany({
        where: { fingerprint: alert.fingerprint, activeAt, lastObservedAt: { lte: observedAt } },
        data: { payload, lastObservedAt: observedAt, recoveredAt: null },
      });
    }
    await tx.infrastructureAlertEvent.updateMany({
      where: {
        recoveredAt: null,
        lastObservedAt: { lt: observedAt },
        ...(alerts.length
          ? {
              NOT: {
                OR: alerts.map((alert) => ({ fingerprint: alert.fingerprint, activeAt: new Date(alert.startedAt) })),
              },
            }
          : {}),
      },
      data: { recoveredAt: observedAt },
    });
  });
  return retainedAlerts(prisma);
}

export async function retainedAlerts(prisma: PrismaService): Promise<InfrastructureAlert[]> {
  const records = await prisma.infrastructureAlertEvent.findMany({
    where: { clearedAt: null },
    orderBy: [{ activeAt: 'desc' }, { id: 'asc' }],
  });
  return records.map((record) => ({
    ...(record.payload as unknown as InfrastructureAlert),
    ...(record.recoveredAt ? { status: 'resolved' } : {}),
    acknowledged: false,
  }));
}

export async function clearRetainedAlert(
  prisma: PrismaService,
  fingerprint: string,
  rawActiveAt: unknown,
  userId: string,
) {
  const activeAt = new Date(String(rawActiveAt ?? ''));
  if (!/^[a-f0-9]{24}$/.test(fingerprint) || !Number.isFinite(activeAt.getTime()))
    throw new BadRequestException('告警标识无效');
  return prisma.$transaction(async (tx) => {
    const record = await tx.infrastructureAlertEvent.findUnique({
      where: { fingerprint_activeAt: { fingerprint, activeAt } },
    });
    if (!record) throw new NotFoundException('告警记录不存在');
    const clearedAt = new Date();
    const result = await tx.infrastructureAlertEvent.updateMany({
      where: { id: record.id, clearedAt: null },
      data: { clearedAt, clearedBy: userId },
    });
    if (result.count)
      await tx.operationLog.create({
        data: {
          userId,
          action: 'monitoring.alert_cleared',
          resource: 'infrastructure_alert',
          resourceId: record.id,
          detail: { fingerprint, activeAt: activeAt.toISOString() },
        },
      });
    return {
      fingerprint,
      activeAt: activeAt.toISOString(),
      cleared: true,
      clearedAt: (record.clearedAt ?? clearedAt).toISOString(),
    };
  });
}