/**
 * Fleet Deployment Service - 실제 배포 엔진
 * - 릴리즈를 선택한 디바이스에 배포
 * - 롤아웃 전략: immediate, canary, rolling
 * - 각 디바이스별 deploy 커맨드 발행 (MQTT)
 * - 응답 받아 성공/실패 집계
 */

import { query, queryOne } from "../database/db";
import { logger } from "../utils/logger";
import { FleetCommandService } from "./fleetCommandService";

export type DeploymentStatus =
  | "pending"     // 생성됨, 아직 실행 전
  | "running"     // 진행 중
  | "paused"      // 일시정지 (실패율 초과)
  | "completed"   // 완료
  | "failed"      // 실패
  | "cancelled"   // 취소됨
  | "rolled_back";

export interface FleetDeployment {
  id?: number;
  release_id: number;
  target_type: "all" | "company" | "group" | "device_list";
  target_value?: string;        // company_code, group name, or device ids (csv)
  rollout_strategy: "immediate" | "canary" | "rolling";
  rollout_percentage?: number;
  batch_size?: number;
  max_failures?: number;
  pause_on_failure?: boolean;
  description?: string;
  scheduled_at?: Date;
  status?: DeploymentStatus;
}

export class FleetDeploymentService {
  static async list(filter: { status?: string; release_id?: number } = {}) {
    const wheres: string[] = [];
    const params: any[] = [];
    let idx = 1;

    if (filter.status) { wheres.push(`d.status = $${idx++}`); params.push(filter.status); }
    if (filter.release_id) { wheres.push(`d.release_id = $${idx++}`); params.push(filter.release_id); }

    const where = wheres.length ? `WHERE ${wheres.join(" AND ")}` : "";
    return await query<any>(
      `SELECT d.*,
        r.version as release_version, r.backend_image, r.frontend_image, r.agent_image
       FROM fleet_deployments d
       LEFT JOIN fleet_releases r ON d.release_id = r.id
       ${where}
       ORDER BY d.created_at DESC LIMIT 100`,
      params,
    );
  }

  static async get(id: number) {
    return await queryOne<any>(
      `SELECT d.*, r.version as release_version, r.backend_image, r.frontend_image, r.agent_image
       FROM fleet_deployments d
       LEFT JOIN fleet_releases r ON d.release_id = r.id
       WHERE d.id = $1`,
      [id],
    );
  }

  static async getStatus(deploymentId: number) {
    return await query<any>(
      `SELECT ds.*, d.device_name, d.company_code
       FROM fleet_deployment_status ds
       LEFT JOIN fleet_devices d ON ds.device_id = d.device_id
       WHERE ds.deployment_id = $1
       ORDER BY ds.device_id`,
      [deploymentId],
    );
  }

  static async create(data: FleetDeployment & { created_by?: string }): Promise<any> {
    if (!data.release_id || !data.target_type) {
      throw new Error("release_id, target_type 필수");
    }

    // 대상 디바이스 선정
    const deviceIds = await this.resolveTargetDevices(data.target_type, data.target_value);
    if (deviceIds.length === 0) throw new Error("대상 디바이스가 없습니다.");

    const deploy = await query<any>(
      `INSERT INTO fleet_deployments
        (release_id, target_type, target_value, rollout_strategy, rollout_percentage,
         batch_size, max_failures, pause_on_failure, description, scheduled_at,
         status, total_devices, created_by)
       VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,'pending',$11,$12)
       RETURNING *`,
      [
        data.release_id,
        data.target_type,
        data.target_value || null,
        data.rollout_strategy || "rolling",
        data.rollout_percentage || 100,
        data.batch_size || 10,
        data.max_failures || 3,
        data.pause_on_failure !== false,
        data.description || null,
        data.scheduled_at || null,
        deviceIds.length,
        data.created_by || null,
      ],
    );

    // 각 대상 디바이스별 status 레코드 생성
    for (const did of deviceIds) {
      await query(
        `INSERT INTO fleet_deployment_status (deployment_id, device_id, status)
         VALUES ($1, $2, 'pending')`,
        [deploy[0].id, did],
      );
    }

    logger.info(`[Fleet Deploy] 생성: id=${deploy[0].id}, 대상 ${deviceIds.length}개`);
    return { ...deploy[0], device_count: deviceIds.length };
  }

  /**
   * 배포 대상 디바이스 목록 해석
   */
  static async resolveTargetDevices(
    targetType: string,
    targetValue?: string | null,
  ): Promise<string[]> {
    if (targetType === "all") {
      const r = await query<any>(
        `SELECT device_id FROM fleet_devices WHERE is_online = TRUE`,
      );
      return r.map((x: any) => x.device_id);
    }
    if (targetType === "company" && targetValue) {
      const r = await query<any>(
        `SELECT device_id FROM fleet_devices WHERE company_code = $1 AND is_online = TRUE`,
        [targetValue],
      );
      return r.map((x: any) => x.device_id);
    }
    if (targetType === "group" && targetValue) {
      const r = await query<any>(
        `SELECT device_id FROM fleet_devices WHERE device_group = $1 AND is_online = TRUE`,
        [targetValue],
      );
      return r.map((x: any) => x.device_id);
    }
    if (targetType === "device_list" && targetValue) {
      return targetValue.split(",").map((s) => s.trim()).filter(Boolean);
    }
    return [];
  }

  /**
   * 배포 시작 (실제 실행)
   * - 전략별 배치 처리
   * - 각 디바이스에 deploy 커맨드 발행 (MQTT)
   * - 실패율 모니터링
   */
  static async start(deploymentId: number, issuedBy?: string): Promise<any> {
    const deploy = await this.get(deploymentId);
    if (!deploy) throw new Error("배포 없음");
    if (deploy.status !== "pending" && deploy.status !== "paused") {
      throw new Error(`현재 상태(${deploy.status})에서 시작 불가`);
    }

    await query(
      `UPDATE fleet_deployments SET status = 'running', started_at = COALESCE(started_at, NOW()) WHERE id = $1`,
      [deploymentId],
    );

    // 대기 중 디바이스 조회
    const pendingDevices = await query<any>(
      `SELECT device_id FROM fleet_deployment_status
       WHERE deployment_id = $1 AND status = 'pending'
       ORDER BY device_id`,
      [deploymentId],
    );

    logger.info(`[Fleet Deploy] 시작: id=${deploymentId}, 대기중 ${pendingDevices.length}개`);

    // 전략별 실행
    const strategy = deploy.rollout_strategy;
    const batchSize = deploy.batch_size || 10;

    // 비동기로 백그라운드 배포 진행
    this.runDeployment(deploymentId, pendingDevices.map((d: any) => d.device_id), strategy, batchSize, issuedBy)
      .catch((e) => {
        logger.error(`[Fleet Deploy] 실행 에러 (id=${deploymentId}):`, e);
      });

    return { deploymentId, status: "running", scheduled: pendingDevices.length };
  }

  /**
   * 실제 배포 루프 (백그라운드)
   */
  private static async runDeployment(
    deploymentId: number,
    deviceIds: string[],
    strategy: string,
    batchSize: number,
    issuedBy?: string,
  ): Promise<void> {
    const deploy = await this.get(deploymentId);
    const release = deploy ? { image: deploy.backend_image, version: deploy.release_version } : {};

    let failures = 0;
    const maxFailures = deploy?.max_failures || 3;
    const pauseOnFail = deploy?.pause_on_failure !== false;

    // 카나리: 첫 1개만 먼저 배포
    const executeOrder: string[][] = [];
    if (strategy === "canary" && deviceIds.length > 1) {
      executeOrder.push([deviceIds[0]]);  // canary
      // 나머지는 배치로
      for (let i = 1; i < deviceIds.length; i += batchSize) {
        executeOrder.push(deviceIds.slice(i, i + batchSize));
      }
    } else if (strategy === "rolling") {
      for (let i = 0; i < deviceIds.length; i += batchSize) {
        executeOrder.push(deviceIds.slice(i, i + batchSize));
      }
    } else {
      // immediate
      executeOrder.push(deviceIds);
    }

    for (const batch of executeOrder) {
      // 취소 체크
      const cur = await this.get(deploymentId);
      if (!cur || cur.status === "cancelled") {
        logger.info(`[Fleet Deploy] 취소 감지: id=${deploymentId}`);
        return;
      }

      await Promise.all(
        batch.map((did) => this.deployToDevice(deploymentId, did, deploy, issuedBy)),
      );

      // 배치 완료 후 실패율 체크
      const failCount = await queryOne<any>(
        `SELECT COUNT(*) as n FROM fleet_deployment_status
         WHERE deployment_id = $1 AND status IN ('failed','timeout')`,
        [deploymentId],
      );
      failures = parseInt(failCount?.n || 0);

      if (pauseOnFail && failures >= maxFailures) {
        await query(
          `UPDATE fleet_deployments SET status = 'paused', completed_at = NULL WHERE id = $1`,
          [deploymentId],
        );
        logger.warn(`[Fleet Deploy] 실패율 초과로 일시정지: id=${deploymentId} (실패 ${failures}개)`);
        return;
      }

      // 카나리: 첫 배치 완료 후 안정성 대기
      if (strategy === "canary" && executeOrder.indexOf(batch) === 0) {
        await new Promise((r) => setTimeout(r, 3000));  // 3초 관찰
      }
    }

    // 최종 집계
    const stats = await queryOne<any>(
      `SELECT
         COUNT(*) FILTER (WHERE status = 'success') as success,
         COUNT(*) FILTER (WHERE status IN ('failed','timeout')) as failed,
         COUNT(*) as total
       FROM fleet_deployment_status WHERE deployment_id = $1`,
      [deploymentId],
    );

    const finalStatus =
      parseInt(stats.failed) > 0
        ? (parseInt(stats.success) > 0 ? "completed" : "failed")
        : "completed";

    await query(
      `UPDATE fleet_deployments
       SET status = $2, completed_at = NOW(),
           success_count = $3, failed_count = $4
       WHERE id = $1`,
      [deploymentId, finalStatus, parseInt(stats.success), parseInt(stats.failed)],
    );

    logger.info(
      `[Fleet Deploy] 완료: id=${deploymentId} 성공 ${stats.success} / 실패 ${stats.failed} / 총 ${stats.total}`,
    );
  }

  /**
   * 개별 디바이스 배포 (MQTT 커맨드)
   */
  private static async deployToDevice(
    deploymentId: number,
    deviceId: string,
    deploy: any,
    issuedBy?: string,
  ): Promise<void> {
    try {
      await query(
        `UPDATE fleet_deployment_status
         SET status = 'running', started_at = NOW()
         WHERE deployment_id = $1 AND device_id = $2`,
        [deploymentId, deviceId],
      );

      // MQTT로 deploy 커맨드 발행
      const cmd = await FleetCommandService.issueCommand(
        deviceId,
        "deploy",
        {
          deployment_id: deploymentId,
          release_id: deploy.release_id,
          backend_image: deploy.backend_image,
          frontend_image: deploy.frontend_image,
          agent_image: deploy.agent_image,
          version: deploy.release_version,
        },
        issuedBy,
        600, // 10분 타임아웃
      );

      // 응답 대기 (폴링) - 60초
      for (let i = 0; i < 60; i++) {
        await new Promise((r) => setTimeout(r, 1000));
        const cs = await queryOne<any>(
          `SELECT status FROM fleet_commands WHERE id = $1`,
          [cmd.id],
        );
        if (["success", "failed", "timeout"].includes(cs?.status)) {
          await query(
            `UPDATE fleet_deployment_status
             SET status = $3, completed_at = NOW()
             WHERE deployment_id = $1 AND device_id = $2`,
            [deploymentId, deviceId, cs.status],
          );
          return;
        }
      }

      // 타임아웃
      await query(
        `UPDATE fleet_deployment_status
         SET status = 'timeout', completed_at = NOW(), error_message = '응답 타임아웃'
         WHERE deployment_id = $1 AND device_id = $2`,
        [deploymentId, deviceId],
      );
    } catch (e: any) {
      await query(
        `UPDATE fleet_deployment_status
         SET status = 'failed', completed_at = NOW(), error_message = $3
         WHERE deployment_id = $1 AND device_id = $2`,
        [deploymentId, deviceId, e.message],
      );
    }
  }

  static async cancel(deploymentId: number) {
    await query(
      `UPDATE fleet_deployments SET status = 'cancelled', completed_at = NOW() WHERE id = $1`,
      [deploymentId],
    );
    await query(
      `UPDATE fleet_deployment_status
       SET status = 'cancelled', completed_at = NOW()
       WHERE deployment_id = $1 AND status IN ('pending','running')`,
      [deploymentId],
    );
    return { success: true };
  }

  /**
   * 롤백: 해당 배포의 이전 버전으로 복원
   */
  static async rollback(deploymentId: number, issuedBy?: string) {
    const deploy = await this.get(deploymentId);
    if (!deploy) throw new Error("배포 없음");
    if (!["completed", "failed", "paused"].includes(deploy.status)) {
      throw new Error(`현재 상태(${deploy.status})에서 롤백 불가`);
    }

    // 이전 completed 배포 찾기 (같은 target)
    const previous = await queryOne<any>(
      `SELECT d.*, r.backend_image, r.frontend_image, r.agent_image, r.version as release_version
       FROM fleet_deployments d
       LEFT JOIN fleet_releases r ON d.release_id = r.id
       WHERE d.id < $1
         AND d.target_type = $2
         AND d.target_value IS NOT DISTINCT FROM $3
         AND d.status = 'completed'
       ORDER BY d.id DESC LIMIT 1`,
      [deploymentId, deploy.target_type, deploy.target_value],
    );

    if (!previous) throw new Error("롤백할 이전 배포 없음");

    const rollbackDeploy = await this.create({
      release_id: previous.release_id,
      target_type: deploy.target_type,
      target_value: deploy.target_value,
      rollout_strategy: "immediate",
      rollout_percentage: 100,
      description: `롤백: #${deploymentId} → #${previous.id} (${previous.release_version})`,
      created_by: issuedBy,
    } as any);

    await this.start(rollbackDeploy.id, issuedBy);

    await query(
      `UPDATE fleet_deployments SET status = 'rolled_back' WHERE id = $1`,
      [deploymentId],
    );

    return { deploymentId: rollbackDeploy.id, originalId: deploymentId, previousReleaseId: previous.release_id };
  }
}