import { randomUUID } from "node:crypto";
import { devices, deviceEvents as deviceEventsTable, eq, siteConfig, type Db, type DeviceRow } from "@parking/db";
import type { FastifyBaseLogger } from "fastify";
import { deviceEvents, type DeviceReadEvent } from "./device-events.js";
import { directionOf, type FlowDirection } from "./device-resolve.js";
import { buildCamera } from "./snapshot.js";
import type { SubscriptionFlow } from "./subscription-flow.js";
import type { VisionClient } from "./vision-client.js";

// The ANPR "bridge": a subscriber's plate, read from the lane camera, admits them through
// the SAME gated SubscriptionFlow a QR/card scan uses. It is the one missing wire between
// the camera's vehicle PUSH (hikvision-alarm.ts) and the read bus — NOT a new service.
//
// On a `vehicle`/`active` event from an OPT-IN camera (config.anpr === true), the bridge:
//   pull a fresh snapshot → vision.analyze → entry confidence floor → debounce → MATCH the
//   plate to a subscription → emit a DeviceReadEvent{kind:"plate"} ONLY if it matched.
// The existing onRead → ReadDispatcher then re-matches and runs the gated SubscriptionFlow
// (active / window / blocklist / car-count), which signs the entry/exit and opens the relay.
//
// INVARIANTS (see wiki/concepts/lane-presence-and-anpr-entry.md §2, append-only-event-chain.md):
//   - Advisory, never sole authority: the bridge only emitRead()s — the signed decision +
//     barrier open stay inside the existing flow. A spoofed printed plate is just another
//     credential through the same gate.
//   - Subscriber-ONLY: it MATCHES before emitting, so a random plate never reaches the
//     transient plate-as-ticket exit flow.
//   - Fail-soft + fire-and-forget: any snapshot/vision error degrades to the card/QR path;
//     never throws into the push handler, never awaited on the camera's 200 response.
//   - Opt-in per camera, and debounced (the camera re-fires ~1Hz while a car sits).

/** Camera config flag opting it into the ANPR bridge (same flag advisory ANPR uses). */
interface CameraConfig {
  readonly anpr?: boolean;
  readonly [k: string]: unknown;
}

/** Stricter-than-advisory confidence floor for a BARRIER-driving plate read. A near-miss
 *  read falls back to the subscriber's card/QR, so we'd rather skip than wrongly admit.
 *  Distinct from vision-client's advisory VISION_MIN_CONFIDENCE. */
function entryMinConfidence(): number {
  const raw = Number(process.env.VISION_ENTRY_MIN_CONFIDENCE ?? 0.85);
  return Number.isFinite(raw) && raw > 0 ? raw : 0.85;
}

/** Same plate/camera within this window = ONE credential presentation. The camera re-fires
 *  ~1Hz while a car is present; emitting every second would drive repeat entries (a fleet
 *  sub opens a 2nd occurrence) or exit spam. Required for correctness, not CPU. */
function debounceMs(): number {
  const raw = Number(process.env.ANPR_DEBOUNCE_MS ?? 12_000);
  return Number.isFinite(raw) && raw > 0 ? raw : 12_000;
}

export class AnprBridge {
  readonly #db: Db;
  readonly #vision: VisionClient | null;
  readonly #subscription: SubscriptionFlow;
  readonly #logger: FastifyBaseLogger;
  readonly #entryMinConfidence: number;
  readonly #debounceMs: number;
  /** Last-fire timestamps, keyed by deviceId (camera-level, pre-snapshot) AND by
   *  `deviceId:plate` (post-match) — both gated against #debounceMs. */
  readonly #lastFire = new Map<string, number>();

  constructor(db: Db, vision: VisionClient | null, subscription: SubscriptionFlow, logger: FastifyBaseLogger) {
    this.#db = db;
    this.#vision = vision;
    this.#subscription = subscription;
    this.#logger = logger;
    this.#entryMinConfidence = entryMinConfidence();
    this.#debounceMs = debounceMs();
  }

  /**
   * A camera reported a vehicle. If the camera opts into ANPR, pull a snapshot, read the
   * plate, and — only if it matches a subscription — emit a plate read onto the bus.
   * Fire-and-forget; fail-soft. Never throws (the push handler must always 200).
   */
  async onVehicleDetected(deviceId: string): Promise<void> {
    try {
      if (!this.#vision?.enabled) return; // no recognizer configured
      // Admin master switch (read LIVE so toggling in Site Settings takes effect with no
      // restart). Gates ONLY this barrier-driving bridge — advisory snapshot-ANPR and lane
      // busy/free are unaffected. Absent/unreadable config ⇒ enabled (the default).
      const site = this.#db.select().from(siteConfig).where(eq(siteConfig.id, 1)).get();
      if (site && site.anprEntryEnabled === false) return;
      const row = this.#db.select().from(devices).where(eq(devices.id, deviceId)).get();
      if (!row || !row.enabled || row.category !== "camera") return;
      if ((row.config as CameraConfig)?.anpr !== true) return; // opt-in only

      // Camera-level debounce (pre-snapshot): a car re-firing ~1Hz must not pull a
      // snapshot + analyze every second.
      if (this.#debounced(deviceId)) return;
      this.#stamp(deviceId);

      const camera = buildCamera(row);
      if (!camera) {
        this.#logger.warn(`anpr-bridge: camera ${deviceId} config won't build`);
        return;
      }

      // "both" collapses to entry purely for the capture hint (it doesn't pick the lane —
      // the gated flow infers the verb from the camera's bound relay direction).
      const direction: FlowDirection = directionOf(this.#db, row) === "exit" ? "exit" : "entry";
      const shot = await camera.captureSnapshot({ direction });
      const result = await this.#vision.analyze(shot.bytes, shot.contentType);
      if (!result || !result.plate) return; // nothing read

      // Entry floor — stricter than the advisory floor (analyze() still returns the plate
      // object with its confidence even when its own lowConfidence flag is set).
      if (result.plate.confidence < this.#entryMinConfidence) {
        this.#logger.info(
          `anpr-bridge: plate '${result.plate.text}' below entry floor ` +
            `(${result.plate.confidence.toFixed(3)} < ${this.#entryMinConfidence}) — ignored`,
        );
        return;
      }

      const plate = result.plate.text.trim().toUpperCase();
      if (!plate) return;

      const e: DeviceReadEvent = {
        driverId: row.driverId,
        deviceId,
        value: plate,
        kind: "plate",
        at: new Date().toISOString(),
      };

      // MATCH BEFORE EMIT — subscriber-only. A non-subscriber plate records advisory
      // telemetry and stops; it must NEVER reach the transient plate-as-ticket exit flow.
      const match = this.#subscription.match(e);
      if (!match) {
        this.#recordSkip(deviceId, plate, result.plate.confidence);
        return;
      }

      // Plate-level debounce — belt-and-suspenders against a gap that slips the
      // camera-level gate re-emitting the SAME plate.
      const plateKey = `${deviceId}:${plate}`;
      if (this.#debounced(plateKey)) return;
      this.#stamp(plateKey);

      this.#logger.info(
        `anpr-bridge: subscriber plate '${plate}' (${result.plate.confidence.toFixed(3)}) → read bus`,
      );
      deviceEvents.emitRead(e); // → onRead → ReadDispatcher → gated SubscriptionFlow
    } catch (err) {
      // Fail-soft: an ANPR failure degrades to the subscriber's card/QR, never strands the lane.
      this.#logger.warn(`anpr-bridge failed (${deviceId}): ${(err as Error).message}`);
    }
  }

  #debounced(key: string): boolean {
    const last = this.#lastFire.get(key);
    return last != null && Date.now() - last < this.#debounceMs;
  }

  #stamp(key: string): void {
    this.#lastFire.set(key, Date.now());
  }

  /** Advisory telemetry: a plate was read at the lane but matched no subscription. Not a
   *  read on the bus — just a breadcrumb so the operator can see ANPR is working. */
  #recordSkip(deviceId: string, plate: string, confidence: number): void {
    this.#logger.info(`anpr-bridge: plate '${plate}' matched no subscription — skipped`);
    try {
      this.#db
        .insert(deviceEventsTable)
        .values({
          id: randomUUID(),
          deviceId,
          category: "camera",
          kind: "anpr-skip",
          detail: { plate, confidence, source: "anpr-bridge", reason: "no subscription match" },
          occurredAt: new Date().toISOString(),
        })
        .run();
    } catch (err) {
      this.#logger.error(`anpr-bridge skip-record insert failed: ${(err as Error).message}`);
    }
  }
}

// DeviceRow is re-exported for the test's seed typing convenience.
export type { DeviceRow };