import { randomUUID } from "node:crypto";
import { devices, deviceEvents as deviceEventsTable, eq, type Db } from "@parking/db";
import type { FastifyBaseLogger } from "fastify";
import type { DeviceReadEvent, ReadOutcome } from "./device-events.js";
import type { ExitFlow } from "./exit-flow.js";
import { validateTicketCode } from "./entry-flow.js";
import type { SubscriptionFlow } from "./subscription-flow.js";
import { relayForDevice } from "./device-resolve.js";

// Routes a credential read (ticket scan / plate / card) to the right flow. A read
// can mean a subscription entry/exit OR a transient exit, so we dispatch by WHAT the
// credential is (decision 2026-06-15):
//   - matches a subscription (card/QR/bound plate) → SUBSCRIPTION flow,
//   - else → transient EXIT flow (open ticket session → exit, else reject+log).
//
// The reader is BOUND to a controller relay (config.controllerId + relay), so a read
// resolves to exactly the barrier it sits at, and the direction is inherited from
// that relay (see entry-exit-points.md). The resolved relay is handed to the flow so
// it opens that exact barrier. An "entry" reader drives the entry side, an "exit"
// reader the exit side; "both" defers to the flow's own inference (subscription:
// session state; transient: exit).
//
// STRUCTURAL FILTER (2026-07-04, operator-requested). The DT-008's scan engine
// false-decodes sunlight stripe patterns into short garbage codes (phantom reads —
// see wiki/entities/dingtian-dt008-reader.md), and each one was reaching the exit
// flow and signing an exit.refused.noSession anomaly: red "who is trying to exit?"
// rows for NOBODY, training the operator to ignore the feed (alarm fatigue is the
// adversary's friend). So a reader value that matched nothing AND cannot possibly be
// a credential we issued is dropped to UNSIGNED telemetry (device_events, still
// auditable) instead of the signed ledger. "Possibly ours" stays deliberately wide —
// any of these still reaches the flows and signs the normal refusal anomaly:
//   - a Luhn-valid ticket shape (validateTicketCode — a forged/expired ticket is a
//     real probe),
//   - our issued-code prefixes (SUB- / SUBSESS-),
//   - ANY read on a CONFIRMED RF channel (a physically present card, enrolled or
//     not, is a real event — RF is never sun noise),
//   - plates (different population; never shape-filtered here).

export class ReadDispatcher {
  readonly #db: Db;
  readonly #exit: ExitFlow;
  readonly #subscription: SubscriptionFlow;
  readonly #logger: FastifyBaseLogger;

  constructor(db: Db, exit: ExitFlow, subscription: SubscriptionFlow, logger: FastifyBaseLogger) {
    this.#db = db;
    this.#exit = exit;
    this.#subscription = subscription;
    this.#logger = logger;
  }

  async dispatch(e: DeviceReadEvent): Promise<ReadOutcome> {
    const reader = this.#db.select().from(devices).where(eq(devices.id, e.deviceId)).get();
    if (!reader || !reader.enabled) {
      return { accepted: false, reason: "read from unknown/disabled device" };
    }
    const resolved = relayForDevice(this.#db, reader);
    if (!resolved) {
      return { accepted: false, reason: "reader not bound to a barrier (no relay to open)" };
    }

    const sub = this.#subscription.match(e);
    if (sub) {
      return this.#subscription.run(resolved, e, sub);
    }

    // Matched nothing — if the value can't even BE one of ours, it's scanner noise
    // (phantom optical decode): refuse with unsigned telemetry, keep the signed feed
    // for events that involve an actual credential or an actual card.
    if ((e.kind === "qr" || e.kind === "card" || e.kind === "ticket") && !plausibleCredential(e)) {
      this.#recordUnrecognized(e);
      this.#logger.info(`read filtered (not a credential shape): '${e.value}' from ${e.deviceId}${e.channel ? ` ch=${e.channel}` : ""}`);
      return {
        accepted: false,
        direction: resolved.direction === "entry" ? "entry" : "exit",
        reason: "unrecognized code (no credential shape — telemetry only)",
      };
    }

    // Not a subscription → transient ticket exit. An ENTRY reader can't produce a
    // transient exit (transient entry is the button flow, not a reader), so reject+log
    // rather than treat an entry scan as an exit.
    if (resolved.direction === "entry") {
      return { accepted: false, direction: "entry", reason: "entry reader: no transient entry via reader" };
    }
    return this.#exit.handleAt(resolved, e);
  }

  /** Unsigned telemetry for a filtered read — auditable in device_events, out of the
   *  signed feed. Mirrors the entry flow's suppressed-press pattern. */
  #recordUnrecognized(e: DeviceReadEvent): void {
    try {
      this.#db
        .insert(deviceEventsTable)
        .values({
          id: randomUUID(),
          deviceId: e.deviceId,
          category: "reader",
          kind: "read",
          detail: {
            unrecognizedRead: true,
            value: e.value,
            readKind: e.kind,
            ...(e.channel ? { channel: e.channel } : {}),
            reason: "no credential shape (phantom decode / garbage scan)",
          },
          occurredAt: e.at,
        })
        .run();
    } catch (err) {
      this.#logger.error(`unrecognized-read telemetry insert failed: ${(err as Error).message}`);
    }
  }
}

/** Could this reader value possibly be a credential WE issued (or a real card)?
 *  Deliberately WIDE — only shapes that can't be anything of ours are filtered. */
function plausibleCredential(e: DeviceReadEvent): boolean {
  if (e.channel === "rf") return true; // a physically present card — never sun noise
  if (validateTicketCode(e.value)) return true; // ticket shape (10–14 digits + Luhn)
  if (/^SUB(SESS)?-/.test(e.value)) return true; // our subscription QR / window-slip ids
  return false;
}