// 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[];
};

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 DeviceConfig = Record<string, string | number | boolean>;

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 AssignBody {
  lane: number;
  category: DeviceCategory;
  driverId: string;
  config: DeviceConfig;
}

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