/**
 * Fleet Prometheus Metrics
 * - /metrics 엔드포인트에 Prometheus text format으로 노출
 * - 디바이스/커맨드/배포/알림 통계
 */

import { query, queryOne } from "../database/db";

export class FleetMetricsService {
  /**
   * Prometheus text format 메트릭 생성
   */
  static async generate(): Promise<string> {
    const lines: string[] = [];

    // 디바이스 상태
    const devices = await query<any>(
      `SELECT
         is_online,
         company_code,
         COUNT(*) as n
       FROM fleet_devices
       GROUP BY is_online, company_code`,
    );
    lines.push("# HELP fleet_devices_total 디바이스 총 개수");
    lines.push("# TYPE fleet_devices_total gauge");
    for (const d of devices) {
      const online = d.is_online ? "true" : "false";
      lines.push(
        `fleet_devices_total{online="${online}",company_code="${d.company_code || "unknown"}"} ${d.n}`,
      );
    }

    // 최근 1시간 heartbeat
    const hbStats = await queryOne<any>(
      `SELECT
         AVG(cpu_percent) as avg_cpu,
         AVG(memory_percent) as avg_memory,
         AVG(disk_percent) as avg_disk,
         COUNT(*) as hb_count
       FROM fleet_heartbeats
       WHERE received_at > NOW() - INTERVAL '1 hour'`,
    );
    lines.push("# HELP fleet_cpu_percent_avg 최근 1시간 평균 CPU (%)");
    lines.push("# TYPE fleet_cpu_percent_avg gauge");
    lines.push(`fleet_cpu_percent_avg ${hbStats?.avg_cpu || 0}`);
    lines.push("# HELP fleet_memory_percent_avg 최근 1시간 평균 메모리 (%)");
    lines.push("# TYPE fleet_memory_percent_avg gauge");
    lines.push(`fleet_memory_percent_avg ${hbStats?.avg_memory || 0}`);
    lines.push("# HELP fleet_heartbeat_count 최근 1시간 heartbeat 수");
    lines.push("# TYPE fleet_heartbeat_count counter");
    lines.push(`fleet_heartbeat_count ${hbStats?.hb_count || 0}`);

    // 커맨드
    const cmds = await query<any>(
      `SELECT status, COUNT(*) as n FROM fleet_commands
       WHERE issued_at > NOW() - INTERVAL '24 hours'
       GROUP BY status`,
    );
    lines.push("# HELP fleet_commands_total 최근 24시간 커맨드 (상태별)");
    lines.push("# TYPE fleet_commands_total counter");
    for (const c of cmds) {
      lines.push(`fleet_commands_total{status="${c.status}"} ${c.n}`);
    }

    // 알림
    const alerts = await query<any>(
      `SELECT severity, status, COUNT(*) as n FROM fleet_alerts
       GROUP BY severity, status`,
    );
    lines.push("# HELP fleet_alerts_total 알림 (심각도/상태별)");
    lines.push("# TYPE fleet_alerts_total gauge");
    for (const a of alerts) {
      lines.push(
        `fleet_alerts_total{severity="${a.severity}",status="${a.status}"} ${a.n}`,
      );
    }

    // 배포
    const deploys = await query<any>(
      `SELECT status, COUNT(*) as n FROM fleet_deployments
       WHERE created_at > NOW() - INTERVAL '7 days'
       GROUP BY status`,
    );
    lines.push("# HELP fleet_deployments_total 최근 7일 배포 (상태별)");
    lines.push("# TYPE fleet_deployments_total counter");
    for (const d of deploys) {
      lines.push(`fleet_deployments_total{status="${d.status}"} ${d.n}`);
    }

    // PLC 연결 상태
    const plcs = await query<any>(
      `SELECT status, COUNT(*) as n FROM fleet_plc_connections GROUP BY status`,
    );
    lines.push("# HELP fleet_plc_connections_total PLC 연결 (상태별)");
    lines.push("# TYPE fleet_plc_connections_total gauge");
    for (const p of plcs) {
      lines.push(`fleet_plc_connections_total{status="${p.status}"} ${p.n}`);
    }

    // 실시간 데이터 수집
    const edgeData = await queryOne<any>(
      `SELECT
         COUNT(*) as records_1h,
         COUNT(DISTINCT device_id) as active_devices,
         COUNT(DISTINCT tag_name) as unique_tags
       FROM fleet_edge_raw_data
       WHERE time > NOW() - INTERVAL '1 hour'`,
    );
    lines.push("# HELP fleet_edge_records_1h 최근 1시간 수집 레코드");
    lines.push("# TYPE fleet_edge_records_1h counter");
    lines.push(`fleet_edge_records_1h ${edgeData?.records_1h || 0}`);
    lines.push("# HELP fleet_edge_active_devices 최근 1시간 활성 디바이스");
    lines.push("# TYPE fleet_edge_active_devices gauge");
    lines.push(`fleet_edge_active_devices ${edgeData?.active_devices || 0}`);

    return lines.join("\n") + "\n";
  }
}