/**
 * MQTT Collector - MQTT 토픽 구독으로 태그 값 수집.
 *
 * Python data_collector/collectors/mqtt_collector.py 포팅.
 *
 * 동작:
 *   1) 지정 브로커에 연결, 태그의 address 필드를 topic 으로 구독
 *   2) 메시지 수신 시 topic → 최신 값 캐시
 *   3) readTags() 호출 시 캐시의 최근 값 반환 (pull 방식)
 *
 * 연결 파라미터(protocol_config 예):
 *   {
 *     "broker_url": "mqtt://192.168.1.10:1883",
 *     "username": "user",
 *     "password": "pass",
 *     "client_id": "pipeline-collector",
 *     "qos": 1,
 *     "keepalive_sec": 60
 *   }
 *
 * tag.address 가 MQTT topic 으로 사용됨. payload 는
 *   (1) 순수 숫자/불리언 문자열, 또는
 *   (2) JSON (tag.json_path 로 특정 필드 추출, 미설정이면 전체) 가능.
 */

import mqtt, { MqttClient as MqttLib, IClientOptions } from "mqtt";
import { logger } from "../../../utils/logger";

export interface MqttCollectorTag {
  tagName: string;
  topic: string;
  dataType: string; // "BOOL" | "INT16" | "UINT16" | "INT32" | "UINT32" | "FLOAT32" | "STRING"
  jsonPath?: string; // 점 표기 ("a.b.c"), 생략 시 payload 전체
  scaleFactor?: number;
  offsetValue?: number;
}

export interface MqttCollectorReadResult {
  tagName: string;
  topic: string;
  value: number | string | boolean | null;
  quality: "good" | "bad";
  timestamp: Date;
}

export interface MqttCollectorConfig {
  brokerUrl: string; // "mqtt://host:port" or "mqtts://..."
  username?: string;
  password?: string;
  clientId?: string;
  qos?: 0 | 1 | 2;
  keepaliveSec?: number;
}

interface CacheEntry {
  raw: any;
  at: Date;
}

export class MqttCollectorClient {
  private cfg: MqttCollectorConfig;
  private client: MqttLib | null = null;
  private cache = new Map<string, CacheEntry>();
  private subscribed = new Set<string>();
  private connected = false;

  constructor(cfg: MqttCollectorConfig) {
    this.cfg = cfg;
  }

  async connect(tags: MqttCollectorTag[]): Promise<void> {
    if (this.connected && this.client) {
      // 새 태그 토픽이 있으면 구독
      this.subscribeTopics(tags);
      return;
    }
    const opts: IClientOptions = {
      clientId: this.cfg.clientId || `pipeline-collector-${Date.now()}`,
      username: this.cfg.username,
      password: this.cfg.password,
      keepalive: this.cfg.keepaliveSec ?? 60,
      reconnectPeriod: 5000,
      connectTimeout: 10000,
    };
    return new Promise((resolve, reject) => {
      const c = mqtt.connect(this.cfg.brokerUrl, opts);
      this.client = c;

      const onConnect = () => {
        this.connected = true;
        c.off("error", onError);
        logger.info(`[MQTT-Collector] 연결 성공: ${this.cfg.brokerUrl}`);
        this.subscribeTopics(tags);
        resolve();
      };
      const onError = (err: Error) => {
        this.connected = false;
        c.off("connect", onConnect);
        reject(new Error(`[MQTT-Collector] 연결 실패: ${err.message}`));
      };
      c.once("connect", onConnect);
      c.once("error", onError);

      c.on("message", (topic, payload) => {
        try {
          const str = payload.toString("utf-8");
          let parsed: any = str;
          try {
            parsed = JSON.parse(str);
          } catch {}
          this.cache.set(topic, { raw: parsed, at: new Date() });
        } catch (err) {
          logger.debug(`[MQTT-Collector] 메시지 처리 실패 topic=${topic}: ${(err as Error).message}`);
        }
      });

      c.on("close", () => {
        this.connected = false;
      });
    });
  }

  private subscribeTopics(tags: MqttCollectorTag[]): void {
    if (!this.client) return;
    const qos = this.cfg.qos ?? 0;
    for (const t of tags) {
      if (!t.topic || this.subscribed.has(t.topic)) continue;
      this.client.subscribe(t.topic, { qos }, (err) => {
        if (err) logger.warn(`[MQTT-Collector] 구독 실패 ${t.topic}: ${err.message}`);
        else {
          this.subscribed.add(t.topic);
          logger.debug(`[MQTT-Collector] 구독 성공 topic=${t.topic} qos=${qos}`);
        }
      });
    }
  }

  async disconnect(): Promise<void> {
    return new Promise((resolve) => {
      if (!this.client) {
        this.connected = false;
        return resolve();
      }
      this.client.end(true, {}, () => {
        this.client = null;
        this.connected = false;
        this.cache.clear();
        this.subscribed.clear();
        resolve();
      });
    });
  }

  isConnected(): boolean {
    return this.connected;
  }

  async readTags(tags: MqttCollectorTag[]): Promise<MqttCollectorReadResult[]> {
    const out: MqttCollectorReadResult[] = [];
    const now = new Date();
    for (const t of tags) {
      const cached = this.cache.get(t.topic);
      if (!cached) {
        out.push({ tagName: t.tagName, topic: t.topic, value: null, quality: "bad", timestamp: now });
        continue;
      }
      let raw = cached.raw;
      if (t.jsonPath && typeof raw === "object" && raw !== null) {
        raw = t.jsonPath.split(".").reduce((acc: any, k) => (acc == null ? acc : acc[k]), raw);
      }
      const value = coerce(raw, t.dataType, t.scaleFactor, t.offsetValue);
      out.push({
        tagName: t.tagName,
        topic: t.topic,
        value,
        quality: value === null ? "bad" : "good",
        timestamp: cached.at,
      });
    }
    return out;
  }
}

function coerce(
  raw: any,
  dataType: string,
  scale?: number,
  offset?: number,
): number | string | boolean | null {
  if (raw === null || raw === undefined) return null;
  const t = (dataType || "").toUpperCase();
  try {
    if (t === "BOOL") {
      if (typeof raw === "boolean") return raw;
      if (typeof raw === "number") return raw !== 0;
      const s = String(raw).trim().toLowerCase();
      return s === "true" || s === "1" || s === "on";
    }
    if (t === "STRING") return String(raw);
    let v = Number(raw);
    if (!Number.isFinite(v)) return null;
    if (scale && scale !== 1) v = v * scale;
    if (offset) v = v + offset;
    if (t.startsWith("INT") || t.startsWith("UINT")) return Math.trunc(v);
    return v;
  } catch {
    return null;
  }
}

// ─── pool ─────────────────────────────────────────
const pool = new Map<string, MqttCollectorClient>();
export function getMqttCollectorClient(cfg: MqttCollectorConfig): MqttCollectorClient {
  const key = `${cfg.brokerUrl}@${cfg.clientId || "anon"}`;
  if (!pool.has(key)) pool.set(key, new MqttCollectorClient(cfg));
  return pool.get(key)!;
}
export function closeAllMqttCollectors(): void {
  for (const [, c] of pool) c.disconnect().catch(() => undefined);
  pool.clear();
}