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;
  /** Whether this camera may AUTO-OPEN the barrier (entry/exit). Absent ⇒ true (when anpr is
   *  on). Set false to keep recognition but suppress auto-trigger — e.g. the exit camera on a
   *  shared entry/exit lane. */
  readonly anprAutoTrigger?: 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;
}

/** A single alarm fires the INSTANT motion starts — the car is still approaching, so the
 *  first frame often has a small/blurry/absent plate (a low-confidence misread). But the car
 *  then STOPS at the barrier (waiting for it to open) — the same stationary, well-framed
 *  moment the manual test reads at ~100%. So instead of one shot, we POLL fresh frames and
 *  re-run ANPR until one clears the confidence floor, or the window elapses. Poll interval: */
function pollMs(): number {
  const raw = Number(process.env.ANPR_POLL_MS ?? 1000);
  return Number.isFinite(raw) && raw > 0 ? raw : 1000;
}

/** How long to keep polling AFTER THE LAST vehicle push before giving up. SLIDING: each new
 *  push for the camera extends the deadline by this much from now — so a loop started by a
 *  far/early car keeps pulling fresh frames as the REAL car arrives and settles at the
 *  barrier (the loop tracks "whoever is here now", not the car that started it). */
function pollWindowMs(): number {
  const raw = Number(process.env.ANPR_POLL_WINDOW_MS ?? 8000);
  return Number.isFinite(raw) && raw > 0 ? raw : 8000;
}

/** Hard ceiling on a single loop from its START, so a continuously-busy lane (pushes never
 *  stop) can't slide the window forever. The loop ends at min(lastPush + window, start + max). */
function pollMaxMs(): number {
  const raw = Number(process.env.ANPR_POLL_MAX_MS ?? 30_000);
  return Number.isFinite(raw) && raw > 0 ? raw : 30_000;
}

const sleep = (ms: number) => new Promise<void>((r) => setTimeout(r, ms));

/** A plate DeviceReadEvent skeleton (value filled by the caller) — for matching the
 *  subscriber by plate during the poll loop without re-building the whole event. */
function baseRead(row: { driverId: string }, deviceId: string): Omit<DeviceReadEvent, "value"> {
  return { driverId: row.driverId, deviceId, kind: "plate", at: new Date().toISOString() };
}

export class AnprBridge {
  readonly #db: Db;
  readonly #vision: VisionClient | null;
  readonly #subscription: SubscriptionFlow;
  readonly #logger: FastifyBaseLogger;
  readonly #entryMinConfidence: number;
  readonly #debounceMs: number;
  readonly #pollMs: number;
  readonly #pollWindowMs: number;
  readonly #pollMaxMs: 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>();
  /** Cameras with a poll loop already in flight — a re-fired alarm (the camera pushes ~1Hz
   *  while the car sits) must NOT start a second concurrent loop on the same camera. */
  readonly #polling = new Set<string>();
  /** Per-camera SLIDING deadline for the running poll loop. A push that joins a running loop
   *  bumps this forward (lastPush + window, capped at start + max), so the loop keeps pulling
   *  fresh frames while cars keep arriving — tracking whoever settles at the barrier. */
  readonly #pollDeadline = 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();
    this.#pollMs = pollMs();
    this.#pollWindowMs = pollWindowMs();
    this.#pollMaxMs = pollMaxMs();
  }

  /**
   * 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;
      const cfg = row.config as CameraConfig;
      if (cfg?.anpr !== true) return; // recognition opt-in (also gates the evidence/advisory path)
      // Per-camera AUTO-TRIGGER gate. `anpr` keeps recognition (snapshots + plate record) on;
      // this controls whether THIS camera may auto-open the barrier. A shared entry/exit lane
      // sets it false on (e.g.) the exit camera so its back-plate read doesn't phantom-exit the
      // car that just entered. Absent ⇒ true (back-compat: existing anpr cameras still trigger).
      if (cfg.anprAutoTrigger === false) return;

      // Post-success debounce: once we've emitted a read for this camera, ignore the
      // ~1Hz re-fires for #debounceMs (set on success below). A fresh alarm AFTER the
      // window is a new presentation and may start a new poll loop.
      if (this.#debounced(deviceId)) return;
      // One poll loop per camera. A push that arrives while a loop runs JOINs it — and
      // SLIDES the deadline forward (a different car arriving mid-loop keeps the loop alive
      // so it tracks whoever's at the barrier now, instead of giving up on the early car).
      const now = Date.now();
      if (this.#polling.has(deviceId)) {
        const cur = this.#pollDeadline.get(deviceId) ?? now;
        // Slide to lastPush + window, but never past the per-loop hard ceiling (set at start).
        this.#pollDeadline.set(deviceId, Math.max(cur, now + this.#pollWindowMs));
        return;
      }
      this.#polling.add(deviceId);
      // Initial deadline; the hard ceiling (start + max) is enforced in the loop below.
      this.#pollDeadline.set(deviceId, now + this.#pollWindowMs);

      const camera = buildCamera(row);
      if (!camera) {
        this.#polling.delete(deviceId);
        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";

      // POLL-UNTIL-CONFIDENT. The alarm fires as the car APPROACHES (small/blurry/absent
      // plate → low-confidence misread, e.g. '111'@0.20). But the car then STOPS at the
      // barrier — the stationary, well-framed moment the manual test reads at ~100%. So we
      // pull a FRESH frame every #pollMs and re-run ANPR until one clears the floor, or the
      // #pollWindowMs window elapses (car drove off / non-subscriber). NB: a fresh pull each
      // tick — NOT captureSnapshotShared, whose TTL would re-serve the same bad frame.
      // While polling, watch whether THIS subscriber transacts by another credential
      // (card/QR at the reader). If their open-occurrence count drops mid-poll, the
      // subscriber already exited/entered — the bridge must NOT also emit (it would act on
      // the NEXT open occurrence: a phantom double-exit, worst for a fleet sub). We learn the
      // subscription as soon as a frame reads the bound plate (identity needs no confidence),
      // snapshot the count, then keep polling for a CONFIDENT read; abort if the count moved.
      let result: Awaited<ReturnType<VisionClient["analyze"]>> = null;
      let watchedSubId: string | null = null;
      let baselineOpen = 0;
      // Hard ceiling for THIS loop (start + max); the sliding deadline (bumped by joining
      // pushes) is read from #pollDeadline each tick but never allowed past this cap.
      const hardCap = Date.now() + this.#pollMaxMs;
      let attempts = 0;
      try {
        // DO-while: a detection always analyzes AT LEAST ONE frame, however loaded the
        // host — a plain while could zero-iterate if the window elapsed between setting
        // the deadline and reaching the loop (seen as a CI flake with the tests' 5ms
        // window; on a busy booth it would silently drop a real car's detection). Exit
        // is via the breaks below (confident read, or next tick would pass the deadline).
        do {
          attempts++;
          const shot = await camera.captureSnapshot({ direction });
          const r = await this.#vision.analyze(shot.bytes, shot.contentType);

          // Identify the subscriber from ANY readable plate (even below the barrier floor),
          // and baseline their open count once — so we can detect a credential beating us.
          if (r?.plate?.text) {
            const m0 = this.#subscription.match({ ...baseRead(row, deviceId), value: r.plate.text.trim().toUpperCase() });
            if (m0 && watchedSubId == null) {
              watchedSubId = m0.subscriptionId;
              baselineOpen = this.#subscription.openOccurrenceCount(watchedSubId);
            }
          }
          // A credential (card/QR) closed/opened an occurrence for this subscriber mid-poll →
          // they already transacted; stop polling and do NOT emit.
          if (watchedSubId && this.#subscription.openOccurrenceCount(watchedSubId) !== baselineOpen) {
            this.#logger.info(
              `anpr-bridge: subscriber ${watchedSubId} transacted by another credential mid-poll — aborting ANPR`,
            );
            return;
          }

          if (r?.plate && r.plate.confidence >= this.#entryMinConfidence) {
            result = r;
            break;
          }
          if (r?.plate) {
            this.#logger.info(
              `anpr-bridge: '${r.plate.text}' (${r.plate.confidence.toFixed(3)}) below floor ` +
                `${this.#entryMinConfidence} — re-pulling (attempt ${attempts})`,
            );
          }
          // Stop if the next tick would land past the (possibly slid) deadline or the cap.
          const effDeadline = Math.min(this.#pollDeadline.get(deviceId) ?? 0, hardCap);
          if (Date.now() + this.#pollMs >= effDeadline) break;
          await sleep(this.#pollMs);
        } while (true);
      } finally {
        this.#polling.delete(deviceId);
        this.#pollDeadline.delete(deviceId);
      }

      if (!result || !result.plate) {
        this.#logger.info(
          `anpr-bridge: no confident plate from ${deviceId} after ${attempts} attempt(s) ` +
            `in ${this.#pollWindowMs}ms — gave up`,
        );
        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;
      }

      // Final guard against the credential-mid-poll race: if the subscriber transacted between
      // our baseline and now (e.g. a card scan in the last tick), don't double-act.
      if (watchedSubId === match.subscriptionId && this.#subscription.openOccurrenceCount(match.subscriptionId) !== baselineOpen) {
        this.#logger.info(`anpr-bridge: ${match.subscriptionId} already transacted — skipping ANPR emit`);
        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);
      // Camera-level debounce stamp — now that we've emitted, suppress the camera's ~1Hz
      // re-fires (and any new poll loop) for #debounceMs.
      this.#stamp(deviceId);

      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 };