import { randomUUID } from "node:crypto";
import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
import { desc, eq, inArray, devices, deviceEvents as deviceEventsTable, type Db } from "@parking/db";
import { deviceEvents } from "../device-events.js";
import { requirePermission } from "../auth.js";
import { verifyDigest } from "../digest-auth.js";
import type { LaneStatus } from "../lane-status.js";
import type { AnprBridge } from "../anpr-entry.js";

// Hikvision "Alarm Server" event PUSH ingress. The newer-firmware cameras (Event →
// Smart/VCA with "Detection Target: Human/Vehicle", Notify Surveillance Center, Alarm
// Settings → Alarm Server) HTTP-POST an EventNotificationAlert to a URL we host every
// time the chosen target is detected. This is the same machine-call pattern as the
// Dingtian Input Link push (routes/devices.ts): source-IP guarded, NOT behind the SPA
// cookie/CSRF.
//
// DISCOVERY-FIRST. Hik's push format varies by model/firmware (event XML, or multipart
// with an attached JPEG, or — on some ANPR units — an <ANPR>/<plateNumber> block). So
// this endpoint is deliberately PERMISSIVE: it accepts ANY content-type as raw bytes,
// records the verbatim body as a `kind:"alarm"` device_event, and best-effort extracts a
// summary (eventType / target / plate). The goal of this first cut is to SEE exactly what
// a given camera sends — inspect via GET /api/events or the logs — before we wire it into
// the read bus / a snapshot trigger. It never opens a barrier (a plate read is advisory,
// never the sole reason; see wiki/concepts/append-only-event-chain.md).
//
// See wiki/entities/lpr-camera.md, wiki/concepts/device-input-flow.md.

interface HikDeviceConfig {
  host?: string;
  alarmPushEnabled?: boolean | string | number;
  pushUser?: string;
  pushPassword?: string;
  /** Skip the source-IP guard for this device's pushes. The source IP is the primary
   *  LAN guard, but it's UNRELIABLE in some environments — notably WSL mirrored mode,
   *  which rewrites an inbound packet's source to the host's OWN address, so the camera's
   *  real IP never survives and a strict check rejects every push. When pushUser/
   *  pushPassword (Digest) are set, that auth is the real guard and source-IP adds little;
   *  this flag lets a deployment opt out. The signed ledger remains the anti-fraud truth. */
  skipSourceIpCheck?: boolean | string | number;
}

/** Coerce a device-config flag to a boolean. The config is loosely-typed JSON from the
 *  setup form, which has historically stored a checkbox as the STRING "true" (a form-
 *  serialization quirk) — so accept true / "true" / 1 / "1" / "yes" / "on", reject the
 *  rest. Being lenient here means a stray "true" never silently disables a real feature. */
function isOn(v: unknown): boolean {
  if (v === true) return true;
  if (typeof v === "number") return v === 1;
  if (typeof v === "string") return /^(1|true|yes|on)$/i.test(v.trim());
  return false;
}

/** A best-effort summary pulled out of the raw push body (XML or JSON), for the device
 *  event detail + the log line. Absent fields just mean "not found in this firmware's
 *  payload" — the raw body is always stored so nothing is lost. */
interface AlarmSummary {
  eventType?: string;
  /** `active` (target entered the region) | `inactive` (target left). The edge that
   *  drives lane busy/free — see [[lpr-camera]] / hikvision-alarm.ts. */
  eventState?: string;
  target?: string;
  plate?: string;
  dateTime?: string;
  channelId?: string;
}

function clientIp(req: FastifyRequest): string {
  return req.ip.replace(/^::ffff:/, "");
}

/** First capture group of `re` in `s`, trimmed, or undefined. */
function pick(s: string, re: RegExp): string | undefined {
  const m = re.exec(s);
  return m?.[1]?.trim() || undefined;
}

/**
 * Best-effort summary extraction. Hikvision event XML uses tags like <eventType>,
 * <dateTime>, <channelID>; smart/ANPR events add target/plate tags whose exact names
 * vary by firmware (<detectionTarget>, <targetType>, <plateNumber>, <licensePlate>).
 * We probe several spellings; whatever doesn't match is simply absent. JSON bodies are
 * scanned for the same keys.
 */
function summarize(body: string): AlarmSummary {
  return {
    eventType: pick(body, /<eventType>([^<]+)<\/eventType>/i) ?? pick(body, /"eventType"\s*:\s*"([^"]+)"/i),
    eventState: pick(body, /<eventState>([^<]+)<\/eventState>/i) ?? pick(body, /"eventState"\s*:\s*"([^"]+)"/i),
    target:
      pick(body, /<(?:detectionTarget|targetType|objectType)>([^<]+)<\//i) ??
      pick(body, /"(?:detectionTarget|targetType|objectType)"\s*:\s*"([^"]+)"/i),
    plate:
      pick(body, /<(?:plateNumber|licensePlate|plateNo)>([^<]+)<\//i) ??
      pick(body, /"(?:plateNumber|licensePlate|plateNo)"\s*:\s*"([^"]+)"/i),
    dateTime: pick(body, /<dateTime>([^<]+)<\/dateTime>/i),
    channelId: pick(body, /<channelID>([^<]+)<\/channelID>/i) ?? pick(body, /<channelId>([^<]+)<\/channelId>/i),
  };
}

export async function hikvisionAlarmRoutes(
  app: FastifyInstance,
  db: Db,
  laneStatus?: LaneStatus,
  anprBridge?: AnprBridge,
): Promise<void> {
  // Accept ANY content-type as a raw Buffer (the camera may POST application/xml,
  // multipart/form-data with a JPEG, or text). Fastify's default JSON parser would 415
  // or empty these — we want the bytes verbatim. Scoped to THIS app instance via a
  // wildcard parser; a 10 MB cap covers an event + an attached frame.
  app.addContentTypeParser("*", { parseAs: "buffer", bodyLimit: 10 * 1024 * 1024 }, (_req, body, done) => {
    done(null, body);
  });

  /** Record EVERY push (accepted or rejected) as a device_event so the read endpoint /
   *  DB always shows that SOMETHING arrived — the key fix: a rejected push used to log a
   *  warning and vanish, so "no event" was ambiguous (never sent? or sent + rejected?). */
  function record(args: {
    deviceId: string;
    method: string;
    accepted: boolean;
    reason?: string;
    ip: string;
    contentType: string;
    raw: Buffer;
    summary: AlarmSummary;
  }): void {
    try {
      db.insert(deviceEventsTable)
        .values({
          id: randomUUID(),
          deviceId: args.deviceId,
          category: "camera",
          kind: args.accepted ? "alarm" : "alarm-rejected",
          detail: {
            source: "hikvision-alarm-server",
            accepted: args.accepted,
            method: args.method,
            ...(args.reason ? { reason: args.reason } : {}),
            ip: args.ip,
            contentType: args.contentType,
            bytes: args.raw.length,
            ...args.summary,
            // Readable head verbatim (the XML part); truncated to keep the row small.
            rawHead: args.raw.toString("utf8").slice(0, 8000),
          },
          occurredAt: new Date().toISOString(),
        })
        .run();
    } catch (err) {
      app.log.error(`hik-alarm device-event insert failed: ${(err as Error).message}`);
    }
  }

  const handle = async (req: FastifyRequest<{ Params: { deviceId: string } }>, reply: FastifyReply) => {
    const { deviceId } = req.params;
    const method = req.method;
    const row = await db.select().from(devices).where(eq(devices.id, deviceId)).get();
    const cfg = row?.config as HikDeviceConfig | undefined;
    const ip = clientIp(req);
    const contentType = String(req.headers["content-type"] ?? "");
    const raw: Buffer = Buffer.isBuffer(req.body) ? (req.body as Buffer) : Buffer.from("");
    const summary = summarize(raw.toString("utf8"));
    // Log EVERY hit immediately (method + ip + size), before any guard — so even a probe
    // that gets rejected is visible in the dev log the instant it arrives.
    app.log.info(`[hik-alarm:${deviceId}] HIT ${method} from ${ip} (${contentType || "no-ct"} ${raw.length}B)`);

    // Guard: must be a known hikvision device with alarm-push enabled, posting from its
    // configured host IP. Source-IP is the primary guard on the LAN (like the Dingtian).
    // On rejection we STILL record it (with the precise reason) so a push that reached us
    // never silently disappears — that's what makes "is it coming?" answerable.
    // The source-IP check is skipped when the device opts out (skipSourceIpCheck) — needed
    // where the network rewrites the inbound source IP (e.g. WSL mirrored mode rewrites it
    // to the host's own address), so a strict match can never pass. Digest auth (when set)
    // and the signed ledger remain the real guards. See HikDeviceConfig.skipSourceIpCheck.
    const skipIp = isOn(cfg?.skipSourceIpCheck);
    let reason: string | null = null;
    if (!row || !cfg) reason = "unknown device id";
    else if (row.driverId !== "hikvision") reason = `device is ${row.driverId}, not hikvision`;
    else if (!isOn(cfg.alarmPushEnabled)) reason = "alarm push not enabled on this device (tick it in Setup)";
    else if (!cfg.host) reason = "device has no host IP configured";
    else if (!skipIp && ip !== cfg.host) reason = `source IP ${ip} != device host ${cfg.host} (set skipSourceIpCheck if the network rewrites it, e.g. WSL)`;

    if (reason) {
      app.log.warn(`[hik-alarm:${deviceId}] REJECTED ${method} from ${ip} (${contentType} ${raw.length}B): ${reason}`);
      record({ deviceId, method, accepted: false, reason, ip, contentType, raw, summary });
      return reply.code(404).send({ error: "not found", reason });
    }

    // Optional Digest auth — only when the admin configured push creds (some firmware
    // can't authenticate the Alarm Server call; then we rely on source-IP alone).
    if (cfg!.pushUser && cfg!.pushPassword) {
      if (!verifyDigest(req, reply, { user: cfg!.pushUser, password: cfg!.pushPassword })) {
        record({ deviceId, method, accepted: false, reason: "digest auth failed/challenge", ip, contentType, raw, summary });
        return; // 401 challenge already sent
      }
    }

    // Loud log so the operator can SEE the payload during testing.
    app.log.info(
      `[hik-alarm:${deviceId}] ACCEPTED ${method} ${ip} ${contentType} ${raw.length}B ` +
        `event=${summary.eventType ?? "?"}/${summary.eventState ?? "?"} target=${summary.target ?? "?"} plate=${summary.plate ?? "-"}`,
    );
    record({ deviceId, method, accepted: true, ip, contentType, raw, summary });

    // Lane busy/free: a VEHICLE detection marks the camera's bound lane busy (advisory,
    // for the booth barrier lights). Only on a vehicle target that's `active` — an
    // `inactive` (leave) isn't sent by this camera class, so the lane auto-clears on a
    // timeout in LaneStatus. We filter to vehicle per the booth's "vehicle only" intent.
    const isVehicleActive =
      (summary.target ?? "").toLowerCase() === "vehicle" &&
      (summary.eventState ?? "active").toLowerCase() !== "inactive";
    if (laneStatus && isVehicleActive) {
      laneStatus.vehicleDetected(deviceId);
    }

    // ANPR BRIDGE: on a vehicle detection, if this camera opts into ANPR (config.anpr),
    // pull a snapshot → read the plate → if it matches a SUBSCRIBER, emit a plate read
    // onto the bus, which the existing gated SubscriptionFlow turns into an entry/exit +
    // barrier open. Fire-and-forget — NEVER awaited on the 200 path (the camera must get
    // a prompt ack or it retry-storms), and fail-soft inside the bridge. See anpr-entry.ts.
    if (anprBridge && isVehicleActive) {
      void anprBridge.onVehicleDetected(deviceId);
    }

    // Surface on the in-process bus as a generic breadcrumb so a live listener can show
    // "camera saw a vehicle". NOT a DeviceReadEvent yet — that (plate identity driving
    // entry/exit) is the deliberate next step once we know the real payload.
    deviceEvents.emitInput({ driverId: "hikvision", deviceId, input: 0, edge: "on", at: new Date().toISOString(), source: "push" });

    // 200 so the camera considers the alarm delivered and doesn't retry-storm.
    return reply.code(200).send({ ok: true });
  };

  // Listen for EVERY method on the event path. The camera (and its "Test" button) may
  // probe with GET/HEAD/OPTIONS/PUT, not just POST — and a method we don't register gets
  // Fastify's generic 404, which the camera reads as "service available" while our
  // handler never runs (so nothing is recorded). Registering all methods means ANYTHING
  // that hits this URL reaches `handle` and is captured (the method is logged + stored),
  // so we can finally SEE exactly what the camera sends. See wiki/entities/lpr-camera.md.
  // (HEAD is auto-added by Fastify alongside GET — don't register it explicitly.)
  for (const method of ["POST", "GET", "PUT", "PATCH", "DELETE", "OPTIONS"] as const) {
    app.route({ method, url: "/api/devices/hikvision/:deviceId/event", handler: handle });
  }

  // Read endpoint: the recent alarm pushes (accepted AND rejected), newest first — so you
  // can SEE in the browser whether events are arriving and why any were refused, instead
  // of grepping the dev log or querying SQLite. Gated device:read (admin device view).
  app.get<{ Querystring: { limit?: string } }>(
    "/api/devices/hikvision/alarms",
    { preHandler: requirePermission("device:read") },
    async (req) => {
      const limit = Math.min(Math.max(Number(req.query.limit) || 50, 1), 500);
      const rows = db
        .select()
        .from(deviceEventsTable)
        .where(inArray(deviceEventsTable.kind, ["alarm", "alarm-rejected"]))
        .orderBy(desc(deviceEventsTable.occurredAt))
        .limit(limit)
        .all();
      const alarms = rows.map((r) => {
        const d = (r.detail ?? {}) as Record<string, unknown>;
        return {
          at: r.occurredAt,
          deviceId: r.deviceId,
          accepted: d.accepted === true,
          method: (d.method as string) ?? null,
          reason: (d.reason as string) ?? null,
          ip: (d.ip as string) ?? null,
          contentType: (d.contentType as string) ?? null,
          bytes: (d.bytes as number) ?? 0,
          eventType: (d.eventType as string) ?? null,
          eventState: (d.eventState as string) ?? null,
          target: (d.target as string) ?? null,
          plate: (d.plate as string) ?? null,
          rawHead: (d.rawHead as string) ?? null,
        };
      });
      return { count: alarms.length, alarms };
    },
  );
}