import { BadRequestException, Injectable, Logger, NotFoundException, ServiceUnavailableException } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { Prisma } from '@prisma/client';
import { createHash } from 'node:crypto';
import { PrismaService } from '../prisma/prisma.service';
import { compareMountpoints, FILESYSTEM_LABELS, FILESYSTEM_SELECTOR, FILESYSTEM_USAGE_PERCENT, filesystemIdentity } from './filesystem-metrics';
import type {
  InfrastructureAlert,
  InfrastructureMetricPoint,
  InfrastructureMonitoringOverview,
  InfrastructureMonitoringRange,
  InfrastructureServiceStatus,
  InfrastructureServiceMetricGroup,
} from './infrastructure-monitoring.contracts';

type PrometheusSample = [number, string];
type PrometheusSeries = {
  metric: Record<string, string>;
  value?: PrometheusSample;
  values?: PrometheusSample[];
};
type PrometheusQueryResponse = {
  status: 'success' | 'error';
  data?: { result?: PrometheusSeries[] };
  error?: string;
};
type PrometheusAlertResponse = {
  status: 'success' | 'error';
  data?: {
    alerts?: Array<{
      labels?: Record<string, string>;
      annotations?: Record<string, string>;
      state?: string;
      activeAt?: string;
      value?: string;
    }>;
  };
};

const RANGE_CONFIG: Record<InfrastructureMonitoringRange, { seconds: number; step: number }> = {
  '1h': { seconds: 60 * 60, step: 60 },
  '24h': { seconds: 24 * 60 * 60, step: 300 },
  '7d': { seconds: 7 * 24 * 60 * 60, step: 1800 },
};

const QUERIES = {
  cpuUsagePercent: '100 - (avg by (instance) (rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100)',
  memoryUsagePercent: '(1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) * 100',
  memoryTotalBytes: 'node_memory_MemTotal_bytes',
  memoryAvailableBytes: 'node_memory_MemAvailable_bytes',
  diskUsagePercent: FILESYSTEM_USAGE_PERCENT,
  diskTotalBytes: `node_filesystem_size_bytes${FILESYSTEM_SELECTOR}`,
  diskAvailableBytes: `min by (${FILESYSTEM_LABELS}) (node_filesystem_avail_bytes${FILESYSTEM_SELECTOR})`,
  networkReceiveBytesPerSecond: 'sum(rate(node_network_receive_bytes_total{device!~"lo"}[5m]))',
  networkTransmitBytesPerSecond: 'sum(rate(node_network_transmit_bytes_total{device!~"lo"}[5m]))',
  load1: 'node_load1',
  uptimeSeconds: 'time() - node_boot_time_seconds',
  lastSampleAt: 'max(timestamp(node_uname_info))',
  // PromQL字符串本身需要两个反斜杠才能把正则的“\.”传给RE2；TypeScript字面量因此需要写四个。
  services: 'max by (name) (node_systemd_unit_state{name=~"cmpp-api\\\\.service|cmpp-gateway\\\\.service|postgresql\\\\.service|redis(-server)?\\\\.service|cmpp-minio\\\\.service|nginx\\\\.service",state="active"})',
} as const;

const SERVICE_DEFINITIONS = [
  { key: 'api', name: 'API服务', units: ['cmpp-api.service'] },
  { key: 'gateway', name: 'Gateway服务', units: ['cmpp-gateway.service'] },
  { key: 'postgresql', name: 'PostgreSQL', units: ['postgresql.service'] },
  { key: 'redis', name: 'Redis', units: ['redis.service', 'redis-server.service'] },
  { key: 'minio', name: 'MinIO', units: ['cmpp-minio.service'] },
  { key: 'nginx', name: 'Nginx', units: ['nginx.service'] },
] as const;

const SERVICE_METRIC_DEFINITIONS = [
  { key: 'api', name: 'API服务', metrics: [
    ['requestsPerSecond', '请求速率', 'cmpp:service_api:requests_per_second', 'per_second'],
    ['errorPercent', '5xx错误率', 'cmpp:service_api:error_percent', 'percent'],
    ['latencyP95', 'P95响应', 'cmpp:service_api:latency_p95_seconds', 'seconds'],
    ['eventLoopP99', '事件循环P99', 'cmpp:service_api:event_loop_p99_seconds', 'seconds'],
  ] },
  { key: 'gateway', name: 'Gateway服务', metrics: [
    ['submitsPerSecond', '提交速率', 'cmpp:service_gateway:submits_per_second', 'per_second'],
    ['failurePercent', '提交失败率', 'cmpp:service_gateway:failure_percent', 'percent'],
    ['queuePending', 'Stream pending', 'cmpp:service_gateway:queue_pending', 'count'],
    ['queueOldestSeconds', '最旧pending', 'cmpp:service_gateway:queue_oldest_seconds', 'seconds'],
  ] },
  { key: 'postgresql', name: 'PostgreSQL', metrics: [
    ['connectionPercent', '连接使用率', 'cmpp:service_postgresql:connection_percent', 'percent'],
    ['deadlocks15m', '15分钟死锁', 'cmpp:service_postgresql:deadlocks_15m', 'count'],
  ] },
  { key: 'redis', name: 'Redis', metrics: [
    ['memoryPercent', '内存使用率', 'cmpp:service_redis:memory_percent', 'percent'],
    ['memoryUsedBytes', '已用内存', 'cmpp:service_redis:memory_used_bytes', 'bytes'],
    ['connectedClients', '客户端连接', 'cmpp:service_redis:connected_clients', 'count'],
    ['evictions5m', '5分钟淘汰', 'cmpp:service_redis:evictions_5m', 'count'],
  ] },
  { key: 'minio', name: 'MinIO', metrics: [
    ['capacityPercent', '存储容量使用率', 'cmpp:service_minio:capacity_percent', 'percent'],
    ['usageBytes', '对象数据量', 'cmpp:service_minio:usage_bytes', 'bytes'],
    ['objects', '对象数', 'cmpp:service_minio:objects', 'count'],
    ['drivesOffline', '离线存储盘', 'cmpp:service_minio:drives_offline', 'count'],
  ] },
  { key: 'nginx', name: 'Nginx', metrics: [
    ['connectionsActive', '活跃连接', 'cmpp:service_nginx:connections_active', 'count'],
    ['requestsPerSecond', '请求速率', 'cmpp:service_nginx:requests_per_second', 'per_second'],
  ] },
] as const;

const SERVICE_METRICS_QUERY = '{__name__=~"cmpp:service_.*"}';

function finiteNumber(value: string | number | undefined): number | null {
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : null;
}

function normalizePrometheusUrl(rawValue: unknown) {
  const url = new URL(String(rawValue ?? 'http://127.0.0.1:9090'));
  if (url.protocol !== 'http:' && url.protocol !== 'https:') throw new Error('PROMETHEUS_URL must use HTTP or HTTPS');
  if (url.username || url.password) throw new Error('PROMETHEUS_URL must not contain credentials');
  const privateIpv4 = /^(10\.|192\.168\.|172\.(1[6-9]|2\d|3[01])\.)/.test(url.hostname);
  const loopback = url.hostname === '127.0.0.1' || url.hostname === 'localhost' || url.hostname === '[::1]';
  // Plain HTTP is only safe on loopback or an explicit RFC1918 address; named remote endpoints must use HTTPS.
  if (url.protocol === 'http:' && !loopback && !privateIpv4) throw new Error('Remote PROMETHEUS_URL must use HTTPS');
  return url.toString().replace(/\/$/, '');
}

function vectorValue(response: PrometheusQueryResponse): number | null {
  return finiteNumber(response.data?.result?.[0]?.value?.[1]);
}

function matrixValues(response: PrometheusQueryResponse): InfrastructureMetricPoint[] {
  return (response.data?.result?.[0]?.values ?? []).flatMap(([timestamp, value]) => {
    const parsed = finiteNumber(value);
    return parsed === null ? [] : [{ timestamp: new Date(timestamp * 1000).toISOString(), value: parsed }];
  });
}

function emptyMetrics(): InfrastructureMonitoringOverview['metrics'] {
  return {
    cpuUsagePercent: null,
    memoryUsagePercent: null,
    memoryTotalBytes: null,
    memoryAvailableBytes: null,
    diskUsagePercent: null,
    diskTotalBytes: null,
    diskAvailableBytes: null,
    networkReceiveBytesPerSecond: null,
    networkTransmitBytesPerSecond: null,
    load1: null,
    uptimeSeconds: null,
  };
}

function emptyTrends(): InfrastructureMonitoringOverview['trends'] {
  return {
    cpuUsagePercent: [],
    memoryUsagePercent: [],
    diskUsagePercent: [],
    networkReceiveBytesPerSecond: [],
    networkTransmitBytesPerSecond: [],
  };
}

@Injectable()
export class InfrastructureMonitoringService {
  private readonly logger = new Logger(InfrastructureMonitoringService.name);
  private readonly prometheusUrl: string;
  private readonly queryTimeoutMs: number;

  constructor(config: ConfigService, private readonly prisma: PrismaService) {
    this.prometheusUrl = normalizePrometheusUrl(config.get('PROMETHEUS_URL'));
    this.queryTimeoutMs = Math.min(15_000, Math.max(1_000, Number(config.get('PROMETHEUS_QUERY_TIMEOUT_MS') ?? 5_000)));
  }

  async overview(rawRange?: string, userId?: string): Promise<InfrastructureMonitoringOverview> {
    const range = this.parseRange(rawRange);
    const collectedAt = new Date().toISOString();
    try {
      const [instant, trends, serviceResponse, serviceMetricResponse, alertResponse] = await Promise.all([
        this.loadInstantMetrics(),
        this.loadTrends(range),
        this.query(QUERIES.services),
        this.query(SERVICE_METRICS_QUERY),
        this.getJson<PrometheusAlertResponse>('/api/v1/alerts'),
      ]);
      const services = this.parseServices(serviceResponse);
      const serviceMetrics = this.parseServiceMetrics(serviceMetricResponse);
      const alerts = await this.attachReadState(this.parseAlerts(alertResponse), userId);
      const warningAlerts = alerts.filter((item) => item.severity === 'warning').length;
      const criticalAlerts = alerts.filter((item) => item.severity === 'critical').length;
      const overallStatus = criticalAlerts > 0 ? 'critical' : warningAlerts > 0 ? 'warning' : 'healthy';
      const rootDisk = instant.disks.find((disk) => disk.mountpoints.includes('/'));
      return {
        available: true,
        range,
        collectedAt,
        lastSampleAt: instant.lastSampleAt === null ? null : new Date(instant.lastSampleAt * 1000).toISOString(),
        summary: {
          overallStatus,
          serviceTotal: services.length,
          serviceHealthy: services.filter((item) => item.status === 'healthy').length,
          warningAlerts,
          criticalAlerts,
          activeAlerts: alerts.length,
        },
        metrics: instant.metrics,
        trends: { ...trends.metrics, diskUsagePercent: rootDisk ? trends.disks.get(rootDisk.id) ?? [] : [] },
        disks: instant.disks.map((disk) => ({ ...disk, trend: trends.disks.get(disk.id) ?? [] })),
        services,
        serviceMetrics,
        alerts,
      };
    } catch (error) {
      // 页面必须整体清空陈旧指标，但服务端仍需留下不含PromQL/地址/凭据的根因摘要便于运维诊断。
      this.logger.warn(`Prometheus monitoring overview unavailable: ${error instanceof Error ? error.message : 'unknown error'}`);
      return this.unavailable(range, collectedAt);
    }
  }

  async notificationSummary(userId?: string) {
    try {
      const alerts = await this.attachReadState(this.parseAlerts(await this.getJson<PrometheusAlertResponse>('/api/v1/alerts')), userId);
      const unreadAlerts = alerts.filter((item) => !item.acknowledged);
      return { count: unreadAlerts.length, criticalCount: unreadAlerts.filter((item) => item.severity === 'critical').length };
    } catch (error) {
      this.logger.warn(`Prometheus notification summary unavailable: ${error instanceof Error ? error.message : 'unknown error'}`);
      throw new ServiceUnavailableException('Prometheus活动告警当前不可用');
    }
  }

  async markAlertRead(fingerprint: string, rawActiveAt: unknown, userId: string) {
    if (!/^[a-f0-9]{24}$/.test(fingerprint)) throw new BadRequestException('告警指纹无效');
    const activeAt = new Date(String(rawActiveAt ?? ''));
    if (!Number.isFinite(activeAt.getTime())) throw new BadRequestException('告警开始时间无效');
    const activeAlerts = this.parseAlerts(await this.getJson<PrometheusAlertResponse>('/api/v1/alerts'));
    const current = activeAlerts.find((item) => item.fingerprint === fingerprint && Date.parse(item.startedAt) === activeAt.getTime());
    if (!current) throw new NotFoundException('该次活动告警已结束或已重新触发，请刷新后重试');
    const readAt = new Date();
    const log = () => this.prisma.operationLog.create({
      data: { userId, action: 'monitoring.alert_marked_read', resource: 'infrastructure_alert', resourceId: fingerprint, detail: { activeAt: activeAt.toISOString(), alertName: current.name, severity: current.severity } },
    });
    let read;
    try {
      [read] = await this.prisma.$transaction([
        this.prisma.infrastructureAlertRead.create({ data: { fingerprint, activeAt, userId, readAt } }),
        log(),
      ]);
    } catch (error) {
      if (!(error instanceof Prisma.PrismaClientKnownRequestError) || error.code !== 'P2002') throw error;
      const existing = await this.prisma.infrastructureAlertRead.findUniqueOrThrow({ where: { fingerprint_userId: { fingerprint, userId } } });
      // 同一次触发重复点击不更新readAt也不重复写日志；activeAt变化才代表同指纹的新触发周期。
      if (existing.activeAt.getTime() === activeAt.getTime()) read = existing;
      else [read] = await this.prisma.$transaction([
        this.prisma.infrastructureAlertRead.update({ where: { fingerprint_userId: { fingerprint, userId } }, data: { activeAt, readAt } }),
        log(),
      ]);
    }
    return { fingerprint, activeAt: read.activeAt.toISOString(), acknowledged: true, acknowledgedAt: read.readAt.toISOString() };
  }

  private parseRange(value?: string): InfrastructureMonitoringRange {
    const range = value || '24h';
    if (!(range in RANGE_CONFIG)) throw new BadRequestException('监控时间范围只支持1h、24h或7d');
    return range as InfrastructureMonitoringRange;
  }

  private async loadInstantMetrics() {
    const keys = Object.keys(emptyMetrics()) as Array<keyof InfrastructureMonitoringOverview['metrics']>;
    const responses = await Promise.all([...keys.map((key) => this.query(QUERIES[key])), this.query(QUERIES.lastSampleAt)]);
    const metrics = emptyMetrics();
    keys.forEach((key, index) => { if (!key.startsWith('disk')) metrics[key] = vectorValue(responses[index]); });
    const diskSamples = (key: keyof typeof metrics) => responses[keys.indexOf(key)].data?.result ?? [];
    const usage = new Map(diskSamples('diskUsagePercent').map((item) => [filesystemIdentity(item.metric), finiteNumber(item.value?.[1])]));
    const available = new Map(diskSamples('diskAvailableBytes').map((item) => [filesystemIdentity(item.metric), finiteNumber(item.value?.[1])]));
    const groups = new Map<string, PrometheusSeries[]>();
    for (const item of diskSamples('diskTotalBytes')) {
      if (!item.metric.device || !item.metric.mountpoint || (finiteNumber(item.value?.[1]) ?? 0) <= 0) continue;
      const id = filesystemIdentity(item.metric);
      const group = groups.get(id) ?? [];
      group.push(item);
      groups.set(id, group);
    }
    const disks = [...groups].map(([id, items]) => {
      const mountpoints = [...new Set(items.map((item) => item.metric.mountpoint))].sort(compareMountpoints);
      const metric = items[0].metric;
      return {
        id, instance: metric.instance ?? '', device: metric.device, filesystem: metric.fstype ?? '',
        mountpoint: mountpoints[0], mountpoints,
        // Never sum aliases. Max/min also tolerate slight sampling differences.
        totalBytes: Math.max(...items.map((item) => finiteNumber(item.value?.[1])!)),
        availableBytes: available.get(id) ?? null, usagePercent: usage.get(id) ?? null,
      };
    })
      .sort((left, right) => left.instance.localeCompare(right.instance) || (left.mountpoint === '/' ? -1 : right.mountpoint === '/' ? 1 : left.mountpoint.localeCompare(right.mountpoint)));
    const rootDisk = disks.find((disk) => disk.mountpoints.includes('/'));
    metrics.diskUsagePercent = rootDisk?.usagePercent ?? null;
    metrics.diskTotalBytes = rootDisk?.totalBytes ?? null;
    metrics.diskAvailableBytes = rootDisk?.availableBytes ?? null;
    return { metrics, disks, lastSampleAt: vectorValue(responses[responses.length - 1]) };
  }

  private async loadTrends(range: InfrastructureMonitoringRange) {
    const config = RANGE_CONFIG[range];
    const end = Math.floor(Date.now() / 1000);
    const start = end - config.seconds;
    const keys = Object.keys(emptyTrends()) as Array<keyof InfrastructureMonitoringOverview['trends']>;
    const responses = await Promise.all(keys.map((key) => this.queryRange(QUERIES[key], start, end, config.step)));
    return {
      metrics: Object.fromEntries(keys.map((key, index) => [key, key === 'diskUsagePercent' ? [] : matrixValues(responses[index])])) as InfrastructureMonitoringOverview['trends'],
      disks: new Map((responses[keys.indexOf('diskUsagePercent')].data?.result ?? []).map((item) => [
        filesystemIdentity(item.metric), matrixValues({ status: 'success', data: { result: [item] } }),
      ])),
    };
  }

  private parseServices(response: PrometheusQueryResponse): InfrastructureServiceStatus[] {
    const values = new Map<string, number>();
    for (const item of response.data?.result ?? []) {
      if (item.metric.name) values.set(item.metric.name, vectorValue({ status: 'success', data: { result: [item] } }) ?? 0);
    }
    return SERVICE_DEFINITIONS.map((definition) => {
      const present = definition.units.filter((unit) => values.has(unit));
      const status = present.length === 0 ? 'unknown' : present.some((unit) => (values.get(unit) ?? 0) >= 1) ? 'healthy' : 'unhealthy';
      return { key: definition.key, name: definition.name, unit: present[0] ?? definition.units[0], status };
    });
  }

  private parseAlerts(response: PrometheusAlertResponse): InfrastructureAlert[] {
    return (response.data?.alerts ?? [])
      .filter((item) => item.state === 'firing' || item.state === 'pending')
      .map<InfrastructureAlert>((item) => {
        const labels = item.labels ?? {};
        const annotations = item.annotations ?? {};
        const severity: InfrastructureAlert['severity'] = labels.severity === 'critical' ? 'critical' : labels.severity === 'warning' ? 'warning' : 'info';
        const identity = JSON.stringify(Object.entries(labels).sort(([left], [right]) => left.localeCompare(right)));
        return {
          fingerprint: createHash('sha256').update(identity).digest('hex').slice(0, 24),
          name: labels.alertname || '未命名告警',
          severity,
          status: item.state || 'unknown',
          startedAt: item.activeAt || new Date().toISOString(),
          summary: annotations.summary || annotations.description || labels.alertname || '监控告警',
          description: annotations.description,
          currentValue: annotations.currentValue || item.value,
          threshold: annotations.threshold,
          service: labels.service,
          instance: labels.instance,
          acknowledged: false,
        };
      })
      .sort((left, right) => {
        const priority: Record<InfrastructureAlert['severity'], number> = { critical: 0, warning: 1, info: 2 };
        return priority[left.severity] - priority[right.severity] || Date.parse(left.startedAt) - Date.parse(right.startedAt);
      });
  }

  private async attachReadState(alerts: InfrastructureAlert[], userId?: string) {
    if (!userId || alerts.length === 0) return alerts;
    const reads = await this.prisma.infrastructureAlertRead.findMany({
      where: { userId, fingerprint: { in: alerts.map((item) => item.fingerprint) } },
      select: { fingerprint: true, activeAt: true, readAt: true },
    });
    const byFingerprint = new Map(reads.map((item) => [item.fingerprint, item]));
    return alerts.map((alert) => {
      const read = byFingerprint.get(alert.fingerprint);
      const acknowledged = Boolean(read && read.activeAt.getTime() === Date.parse(alert.startedAt));
      return { ...alert, acknowledged, acknowledgedAt: acknowledged ? read?.readAt.toISOString() : undefined };
    });
  }

  private parseServiceMetrics(response: PrometheusQueryResponse): InfrastructureServiceMetricGroup[] {
    const values = new Map<string, number>();
    for (const item of response.data?.result ?? []) {
      const metricName = item.metric.__name__;
      const value = vectorValue({ status: 'success', data: { result: [item] } });
      if (metricName && value !== null) values.set(metricName, value);
    }
    return SERVICE_METRIC_DEFINITIONS.map((group) => ({
      key: group.key,
      name: group.name,
      available: group.metrics.some((metric) => values.has(metric[2])),
      metrics: group.metrics.map(([key, label, metricName, unit]) => ({ key, label, value: values.get(metricName) ?? null, unit })),
    }));
  }

  private unavailable(range: InfrastructureMonitoringRange, collectedAt: string): InfrastructureMonitoringOverview {
    const services = SERVICE_DEFINITIONS.map((item) => ({ key: item.key, name: item.name, unit: item.units[0], status: 'unknown' as const }));
    return {
      available: false,
      range,
      collectedAt,
      lastSampleAt: null,
      error: 'Prometheus监控数据当前不可用，请检查采集与服务状态',
      summary: { overallStatus: 'unknown', serviceTotal: services.length, serviceHealthy: 0, warningAlerts: 0, criticalAlerts: 0, activeAlerts: 0 },
      metrics: emptyMetrics(),
      disks: [],
      trends: emptyTrends(),
      services,
      serviceMetrics: SERVICE_METRIC_DEFINITIONS.map((group) => ({ key: group.key, name: group.name, available: false, metrics: [] })),
      alerts: [],
    };
  }

  private query(query: string) {
    return this.getJson<PrometheusQueryResponse>('/api/v1/query', { query });
  }

  private queryRange(query: string, start: number, end: number, step: number) {
    return this.getJson<PrometheusQueryResponse>('/api/v1/query_range', { query, start: String(start), end: String(end), step: String(step) });
  }

  private async getJson<T extends { status: 'success' | 'error'; error?: string }>(path: string, params: Record<string, string> = {}): Promise<T> {
    const url = new URL(`${this.prometheusUrl}${path}`);
    Object.entries(params).forEach(([key, value]) => url.searchParams.set(key, value));
    const response = await fetch(url, { headers: { Accept: 'application/json' }, signal: AbortSignal.timeout(this.queryTimeoutMs) });
    if (!response.ok) throw new Error(`Prometheus HTTP ${response.status}`);
    const result = await response.json() as T;
    if (result.status !== 'success') throw new Error('Prometheus query failed');
    return result;
  }
}