// Thin API client for the operator/admin UI.
//
// Auth is cookie-based: the JWT lives in an HttpOnly cookie the browser sends
// automatically (credentials: 'include'). For mutations we echo the readable
// CSRF cookie back in the X-CSRF-Token header (double-submit). See
// wiki/entities/local-jwt-auth.md.

const CSRF_COOKIE = "parking_csrf";
const CSRF_HEADER = "X-CSRF-Token";

function readCookie(name: string): string | null {
  const m = document.cookie.match(new RegExp(`(?:^|; )${name}=([^;]*)`));
  return m ? decodeURIComponent(m[1]!) : null;
}

/** fetch wrapper: sends cookies, adds CSRF header on mutations, parses errors. */
export async function apiFetch<T>(path: string, init: RequestInit = {}): Promise<T> {
  const method = (init.method ?? "GET").toUpperCase();
  const headers = new Headers(init.headers);
  if (init.body && !headers.has("content-type")) {
    headers.set("content-type", "application/json");
  }
  if (method !== "GET" && method !== "HEAD") {
    const csrf = readCookie(CSRF_COOKIE);
    if (csrf) headers.set(CSRF_HEADER, csrf);
  }
  const res = await fetch(path, { ...init, headers, credentials: "include" });
  if (!res.ok) {
    const msg = (await res.json().catch(() => ({}))) as { error?: string };
    throw new ApiError(msg.error ?? `${path}: ${res.status}`, res.status);
  }
  if (res.status === 204) return undefined as T;
  return res.json() as Promise<T>;
}

export class ApiError extends Error {
  constructor(
    message: string,
    readonly status: number,
  ) {
    super(message);
  }
}

// --- Auth -----------------------------------------------------------------

export type Role = "admin" | "operator" | "cashier" | "readonly";
export interface SessionUser {
  id: string;
  username: string;
  role: Role;
}

export function login(username: string, password: string): Promise<SessionUser> {
  return apiFetch<SessionUser>("/api/auth/login", {
    method: "POST",
    body: JSON.stringify({ username, password }),
  });
}

export function logout(): Promise<{ ok: boolean }> {
  return apiFetch("/api/auth/logout", { method: "POST" });
}

/** Returns the current user, or null if not authenticated. */
export async function fetchMe(): Promise<SessionUser | null> {
  try {
    return await apiFetch<SessionUser>("/api/auth/me");
  } catch (e) {
    if (e instanceof ApiError && (e.status === 401 || e.status === 403)) return null;
    throw e;
  }
}

// --- Device setup ---------------------------------------------------------

export interface ConfigField {
  key: string;
  label: string;
  type: "string" | "number" | "boolean" | "host" | "port" | "secret" | "select";
  required: boolean;
  default?: string | number | boolean;
  options?: { value: string; label: string }[];
  help?: string;
}

export interface CatalogEntry {
  id: string;
  label: string;
  description: string;
  transports: string[];
  configFields: ConfigField[];
}

export type DeviceCategory = "access" | "reader" | "camera" | "printer";
export type Catalog = Record<DeviceCategory, CatalogEntry[]> & {
  /** Driver ids that support LAN discovery. */
  discoverable: string[];
  /** Driver ids that push to the backend (need a backend IP at assign time). */
  pushCapable: string[];
};

export function fetchCatalog(): Promise<Catalog> {
  return apiFetch<Catalog>("/api/setup/catalog");
}

export interface DiscoveredDevice {
  id: string;
  label: string;
  config: Record<string, string | number | boolean>;
  info?: Record<string, string>;
  health: { status: string; detail?: string };
}

/** Scan the LAN for devices a driver can discover. Admin-only. */
export async function discoverDevices(driverId: string): Promise<DiscoveredDevice[]> {
  const body = await apiFetch<{ devices: DiscoveredDevice[] }>(
    `/api/setup/discover/${driverId}`,
  );
  return body.devices;
}

export type ConfigValue =
  | string
  | number
  | boolean
  | null
  | ConfigValue[]
  | { [k: string]: ConfigValue };
export type DeviceConfig = Record<string, ConfigValue>;

/** Direction a barrier/relay (or a device bound to it) serves. */
export type Direction = "entry" | "exit" | "both";

/** One relay on an access controller: which barrier it opens, in which direction,
 *  and (optionally) the input terminal its entry button is wired to. */
export interface RelaySpec {
  relay: number;
  direction: Direction;
  /** Input terminal of the entry button that fires this relay (transient entry). */
  button?: number;
}

export interface TestResult {
  health: { status: string; detail?: string };
  preconditions: {
    ok: boolean;
    issues: { key: string; message: string; fixable: boolean }[];
  };
}

/** Test a device config (reachability + preconditions) without saving. */
export function testDevice(driverId: string, config: DeviceConfig): Promise<TestResult> {
  return apiFetch<TestResult>("/api/setup/test", {
    method: "POST",
    body: JSON.stringify({ driverId, config }),
  });
}

export interface BackendIpCandidate {
  ip: string;
  iface: string;
  onDeviceSubnet: boolean;
}

/** Local IPs the device could push to (on-subnet first), for the wizard to
 *  pre-fill/override. Matters on multi-NIC hosts. */
export function fetchBackendIps(
  host: string,
): Promise<{ candidates: BackendIpCandidate[]; port: number }> {
  return apiFetch(`/api/setup/backend-ips?host=${encodeURIComponent(host)}`);
}

export interface AssignBody {
  category: DeviceCategory;
  driverId: string;
  // Direction/binding lives in config: access → config.relays=[{relay,direction,button?}];
  // reader/camera → config.controllerId + config.relay.
  config: DeviceConfig;
  /** Backend IP the device should push to (overrides auto-pick). */
  backendIp?: string;
}

/** Save + configure the device (preconditions, push setup), then persist. */
export function assignDevice(body: AssignBody): Promise<AssignResult> {
  return apiFetch("/api/setup/assign", { method: "POST", body: JSON.stringify(body) });
}

/** A persisted device assignment (one per instance; machine-only secrets stripped). */
export interface Assignment {
  id: string;
  category: DeviceCategory;
  driverId: string;
  config: DeviceConfig;
  enabled: boolean;
  createdAt?: string;
}

/** Assign response = the saved assignment plus any residual-risk warnings
 *  (e.g. "string protocol could not be disabled — finish in the device web UI"). */
export interface AssignResult extends Assignment {
  warnings?: string[];
}

export interface SetupState {
  completedAt: string | null;
  assignments: Assignment[];
}

/** Current setup status + all assigned device instances. */
export function fetchState(): Promise<SetupState> {
  return apiFetch<SetupState>("/api/setup/state");
}

/** Remove one assigned device instance by id. */
export function unassignDevice(id: string): Promise<void> {
  return apiFetch(`/api/setup/assign/${id}`, { method: "DELETE" });
}

// --- Tariff composer ------------------------------------------------------

export interface TariffBlock {
  uptoMin: number | null;
  priceMinorPerIncrement: number;
}
export interface TariffStructure {
  gracePeriodEntryMin: number;
  incrementMin: number;
  blocks: TariffBlock[];
  dailyCapMinor: number | null;
  lostTicketMinor: number;
  gracePeriodExitMin: number;
  overstay: "reprice";
}
export interface TariffVersion {
  id: string;
  tariffId: string;
  effectiveFrom: string;
  currency: string;
  structure: TariffStructure;
  createdBy?: string | null;
  createdAt?: string;
}
export interface TariffState {
  tariffId: string;
  active: TariffVersion | null;
  versions: TariffVersion[];
}

export function fetchTariff(): Promise<TariffState> {
  return apiFetch<TariffState>("/api/tariff");
}

/** Publish a new immutable tariff version (becomes the active rate card). */
export function publishTariffVersion(body: {
  currency: string;
  structure: TariffStructure;
  effectiveFrom?: string;
}): Promise<TariffVersion> {
  return apiFetch("/api/tariff/versions", { method: "POST", body: JSON.stringify(body) });
}

// --- Permits --------------------------------------------------------------

export interface PermitCredential {
  kind: "rf" | "qr";
  value: string;
}
export interface Permit {
  id: string;
  holderName: string | null;
  contact: string | null;
  maxConcurrent: number | null;
  validFrom: string | null;
  validTo: string | null;
  status: "active" | "suspended" | "revoked";
  credentials: PermitCredential[];
  plates: string[];
}
export type PermitInput = Omit<Permit, "id" | "status"> & {
  status?: Permit["status"];
};

export function fetchPermits(): Promise<{ permits: Permit[] }> {
  return apiFetch("/api/permits");
}
export function createPermit(body: PermitInput): Promise<Permit> {
  return apiFetch("/api/permits", { method: "POST", body: JSON.stringify(body) });
}
export function updatePermit(id: string, body: PermitInput): Promise<Permit> {
  return apiFetch(`/api/permits/${id}`, { method: "PUT", body: JSON.stringify(body) });
}
export function revokePermit(id: string): Promise<Permit> {
  return apiFetch(`/api/permits/${id}/revoke`, { method: "POST" });
}
export function deletePermit(id: string): Promise<void> {
  return apiFetch(`/api/permits/${id}`, { method: "DELETE" });
}

// --- Shifts ---------------------------------------------------------------

export interface ShiftStatus {
  operator: string;
  open: { startedAt: string } | null;
}
export interface ShiftReport {
  operator: string;
  startedAt: string;
  endedAt: string;
  cashTotalMinor: number;
  cardTotalMinor: number;
  currency: string | null;
  paymentCount: number;
  printed: boolean;
}

export function fetchShift(): Promise<ShiftStatus> {
  return apiFetch("/api/shift/current");
}
export function openShift(): Promise<{ startedAt: string }> {
  return apiFetch("/api/shift/open", { method: "POST" });
}
export function closeShift(): Promise<ShiftReport> {
  return apiFetch("/api/shift/close", { method: "POST" });
}

// --- Site config / occupancy ----------------------------------------------

export interface Occupancy {
  count: number;
  capacity: number | null;
  free: number | null;
  full: boolean;
}

export function fetchOccupancy(): Promise<Occupancy> {
  return apiFetch("/api/occupancy");
}
export function fetchSiteConfig(): Promise<{ capacity: number | null }> {
  return apiFetch("/api/site-config");
}
export function setCapacity(capacity: number | null): Promise<{ capacity: number | null }> {
  return apiFetch("/api/site-config", { method: "PUT", body: JSON.stringify({ capacity }) });
}