import {
  createRootRouteWithContext,
  createRoute,
  createRouter,
  Link,
  Outlet,
  redirect,
} from "@tanstack/react-router";
import { useState } from "react";
import { useTranslation } from "react-i18next";
import { useQueryClient } from "@tanstack/react-query";
import type { Lang, Permission, SessionUser, Theme } from "./api.js";
import { can, closeShift, logout, openShift, setLanguagePref, setThemePref } from "./api.js";
import { qk, queryClient } from "./lib/query.js";
import { setLanguage } from "./lib/i18n/index.js";
import { applyTheme } from "./lib/theme.js";
import { useLiveFeed } from "./lib/use-live-feed.js";
import { useShift } from "./lib/use-shift.js";
import { DeviceFooter } from "./ui/DeviceFooter.js";
import { StatusDot } from "./ui/StatusDot.js";
import { BoothScreen } from "./BoothScreen.js";
import { SetupWizard } from "./SetupWizard.js";
import { TariffComposer } from "./TariffComposer.js";
import { SubscriptionManager } from "./SubscriptionManager.js";
import { ShiftControl } from "./ShiftControl.js";
import { SiteSettings } from "./SiteSettings.js";
import { UsersManager } from "./UsersManager.js";
import { RolesManager } from "./RolesManager.js";
import { ShiftsHistory } from "./ShiftsHistory.js";
import { LogsViewer } from "./LogsViewer.js";

// Code-based TanStack Router (no file-based codegen — the app is small enough that
// an explicit tree is clearer). The router context carries the signed-in user and
// a setter so route guards can redirect by role. The root renders the terminal
// chrome (nav + user + live status) and opens the booth WebSocket once, app-wide.

export interface RouterContext {
  user: SessionUser | null;
  setUser: (u: SessionUser | null) => void;
}

const rootRoute = createRootRouteWithContext<RouterContext>()({
  component: RootLayout,
});

function NavLink({ to, label }: { to: string; label: string }) {
  return (
    <Link
      to={to}
      className="px-2 py-1 text-[11px] uppercase tracking-wider text-term-muted rounded-term hover:text-term-text [&.active]:text-term-amber [&.active]:bg-term-panel-2"
    >
      {label}
    </Link>
  );
}

/** A tab inside the Setup layout. `exact` (activeOptions) so the Devices tab at
 *  `/setup` doesn't stay highlighted on the child tabs. */
function SetupTab({ to, label, exact = false }: { to: string; label: string; exact?: boolean }) {
  return (
    <Link
      to={to}
      activeOptions={{ exact }}
      className="border-b-2 border-transparent px-3 py-2 text-[12px] uppercase tracking-wider text-term-muted hover:text-term-text [&.active]:border-term-amber [&.active]:text-term-amber"
    >
      {label}
    </Link>
  );
}

/** Setup layout — the config hub. Renders a permission-gated tab bar and the active
 *  tab's screen via <Outlet>. Each tab is a child route (its own URL + guard), so
 *  deep links and the back button work and a denied tab redirects to the booth. */
function SetupLayout() {
  const { user } = rootRoute.useRouteContext();
  const { t } = useTranslation();
  const show = (perm: Permission) => can(user, perm);
  return (
    <div className="mx-auto max-w-4xl">
      <nav className="mb-4 flex flex-wrap items-center gap-1 border-b border-term-border">
        {show("site:update") && <SetupTab to="/setup" label={t("nav.devices")} exact />}
        {show("tariff:read") && <SetupTab to="/setup/tariff" label={t("nav.tariff")} />}
        {show("subscription:read") && <SetupTab to="/setup/subscriptions" label={t("nav.subscriptions")} />}
        {show("site:read") && <SetupTab to="/setup/site" label={t("nav.site")} />}
        {show("user:read") && <SetupTab to="/setup/users" label={t("nav.users")} />}
        {show("role:read") && <SetupTab to="/setup/roles" label={t("nav.roles")} />}
        {show("shift:read") && <SetupTab to="/setup/shifts" label={t("nav.shifts")} />}
        {show("log:read") && <SetupTab to="/setup/logs" label={t("nav.logs")} />}
      </nav>
      <Outlet />
    </div>
  );
}

/** SQ/EN toggle. Persists the choice to the user's profile (restored on next login)
 *  and applies it immediately. Updates the router-context user so App re-syncs. */
function LanguageToggle({
  user,
  setUser,
}: {
  user: SessionUser;
  setUser: (u: SessionUser | null) => void;
}) {
  // The ACTIVE language is i18n's own state, not the router-context `user` — the
  // latter is captured at route-resolution time and does NOT re-render when we call
  // setUser, so reading `user.language` here goes stale after the first switch (the
  // highlight froze and the equality guard blocked switching back until a refresh).
  // useTranslation() subscribes to i18n's languageChanged, so this stays live.
  const { i18n } = useTranslation();
  const active = i18n.language as Lang;
  async function pick(lang: Lang) {
    if (lang === active) return;
    setLanguage(lang); // instant UI (fires i18n languageChanged → re-render)
    setUser({ ...user, language: lang }); // keep context eventually-consistent + persisted state
    try {
      await setLanguagePref(lang); // persist
    } catch {
      /* non-fatal — the choice still applies this session */
    }
  }
  return (
    <div className="flex items-center gap-0.5 text-[10px] uppercase tracking-wider">
      {(["sq", "en"] as const).map((l) => (
        <button
          key={l}
          type="button"
          onClick={() => pick(l)}
          className={`rounded-term px-1.5 py-0.5 ${
            active === l ? "bg-term-panel-2 text-term-amber" : "text-term-muted hover:text-term-text"
          }`}
        >
          {l}
        </button>
      ))}
    </div>
  );
}

/** Dark/light theme toggle. Same shape as the language toggle: applies instantly,
 *  persists to the user's profile, and updates the router-context user so App
 *  re-syncs. Restored on the next login from any booth. */
function ThemeToggle({
  user,
  setUser,
}: {
  user: SessionUser;
  setUser: (u: SessionUser | null) => void;
}) {
  const { t } = useTranslation();
  // Local state for the ACTIVE theme — same reason as LanguageToggle: the router
  // context `user` doesn't re-render on setUser, so reading `user.theme` here froze
  // the highlight after one switch and blocked toggling back until a refresh. Seed
  // from the prop; update optimistically on pick. App's effect keeps the DOM in sync
  // with the persisted user on (re)login.
  const [active, setActive] = useState<Theme>(user.theme);
  async function pick(theme: Theme) {
    if (theme === active) return;
    setActive(theme);
    applyTheme(theme); // instant UI
    setUser({ ...user, theme }); // keep context eventually-consistent + persisted state
    try {
      await setThemePref(theme); // persist
    } catch {
      /* non-fatal — the choice still applies this session */
    }
  }
  return (
    <div className="flex items-center gap-0.5 text-[10px] uppercase tracking-wider">
      {(["dark", "light"] as const).map((th) => (
        <button
          key={th}
          type="button"
          onClick={() => pick(th)}
          className={`rounded-term px-1.5 py-0.5 ${
            active === th ? "bg-term-panel-2 text-term-amber" : "text-term-muted hover:text-term-text"
          }`}
        >
          {t(th === "dark" ? "common.themeDark" : "common.themeLight")}
        </button>
      ))}
    </div>
  );
}

/**
 * Header shift control — the site-wide single-open shift expressed as one button:
 *  - no shift open       → "Open shift" (enabled; opens this operator's shift)
 *  - my shift open       → "Close shift" (enabled; signs + prints the Z-report)
 *  - another's shift open → disabled, labelled with who holds it (you can neither
 *    open yours nor close theirs until they hand over).
 * On open/close it invalidates the shift status, the per-shift log, and occupancy.
 */
function ShiftButton() {
  const { t } = useTranslation();
  const qc = useQueryClient();
  const { isOpen, isMine, blockedByOther, heldBy } = useShift();
  const [busy, setBusy] = useState(false);
  const [err, setErr] = useState<string | null>(null);

  async function act(kind: "open" | "close") {
    setBusy(true);
    setErr(null);
    try {
      if (kind === "open") await openShift();
      else await closeShift();
      // The shift boundary moves: refresh status, the per-shift log window, drawer.
      void qc.invalidateQueries({ queryKey: qk.shift });
      void qc.invalidateQueries({ queryKey: qk.events });
      void qc.invalidateQueries({ queryKey: qk.occupancy });
    } catch (e) {
      setErr((e as Error).message);
    } finally {
      setBusy(false);
    }
  }

  // Disabled when another operator holds the shift (can't open or close).
  const label = blockedByOther
    ? t("shift.headerHeldByShort", { operator: heldBy ?? "?" })
    : isMine
      ? t("shift.headerClose")
      : t("shift.headerOpen");
  const tone = blockedByOther
    ? "border-term-border text-term-muted opacity-60 cursor-not-allowed"
    : isMine
      ? "border-term-red text-term-red hover:bg-term-red/10"
      : "border-term-green text-term-green hover:bg-term-green/10";

  return (
    <div className="flex items-center gap-1">
      <button
        type="button"
        disabled={busy || blockedByOther}
        title={blockedByOther ? t("shift.headerHeldBy", { operator: heldBy ?? "?" }) : undefined}
        onClick={() => act(isMine ? "close" : "open")}
        className={`rounded-term border px-2 py-0.5 text-[11px] font-semibold uppercase tracking-wider ${tone}`}
      >
        {busy ? t("shift.opening") : label}
      </button>
      {!isOpen && (
        <span className="text-[10px] uppercase tracking-wider text-term-amber">{t("shift.headerNoShift")}</span>
      )}
      {err && <span className="text-[10px] text-term-red">{err}</span>}
    </div>
  );
}

function RootLayout() {
  const { user, setUser } = rootRoute.useRouteContext();
  const { t } = useTranslation();
  // One app-wide WebSocket for the live feed (booth + any live widget).
  useLiveFeed();
  // Nav is gated by PERMISSION, not role — a tab shows iff the user's role grants
  // the permission its screen needs (the route guards enforce the same server-side).
  const show = (perm: Permission) => can(user, perm);

  return (
    <div className="flex h-screen flex-col bg-term-bg text-term-text">
      <header className="flex items-center gap-4 border-b border-term-border bg-term-panel px-4 py-2">
        <span className="text-sm font-bold uppercase tracking-widest text-term-amber">▮ Parking</span>
        <nav className="flex items-center gap-1">
          <NavLink to="/booth" label={t("nav.booth")} />
          <NavLink to="/shift" label={t("nav.shift")} />
          {/* One Setup entry — its tabs hold devices/tariff/subscriptions/site/users/
              roles/shifts. Shown if the user can reach ANY of those screens (an
              operator with only shift:read still gets in, landing on Shifts). */}
          {(show("site:update") ||
            show("tariff:read") ||
            show("subscription:read") ||
            show("site:read") ||
            show("user:read") ||
            show("role:read") ||
            show("shift:read")) && <NavLink to="/setup" label={t("nav.setup")} />}
        </nav>
        <div className="ml-auto flex items-center gap-3">
          {user && <ShiftButton />}
          {user && <LanguageToggle user={user} setUser={setUser} />}
          {user && <ThemeToggle user={user} setUser={setUser} />}
          <StatusDot />
          <span className="text-[11px] text-term-muted">
            {user?.username} · {user?.roleName}
          </span>
          <button
            type="button"
            className="btn btn-ghost btn-sm"
            onClick={async () => {
              await logout();
              setUser(null);
            }}
          >
            {t("common.logout")}
          </button>
        </div>
      </header>
      <main className="min-h-0 flex-1 overflow-auto p-3">
        <Outlet />
      </main>
      {/* Fixed device-status footer — relays, readers, cameras, printers. */}
      {user && <DeviceFooter />}
    </div>
  );
}

const indexRoute = createRoute({
  getParentRoute: () => rootRoute,
  path: "/",
  beforeLoad: () => {
    throw redirect({ to: "/booth" });
  },
});

const boothRoute = createRoute({
  getParentRoute: () => rootRoute,
  path: "/booth",
  component: BoothScreen,
});

// Back-compat: the config screens used to be top-level routes. They now live under
// /setup as tabs — redirect the old paths so existing bookmarks/links don't 404.
const legacyRedirects = (
  [
    ["/tariff", "/setup/tariff"],
    ["/subscriptions", "/setup/subscriptions"],
    ["/site", "/setup/site"],
    ["/users", "/setup/users"],
    ["/roles", "/setup/roles"],
  ] as const
).map(([from, to]) =>
  createRoute({
    getParentRoute: () => rootRoute,
    path: from,
    beforeLoad: () => {
      throw redirect({ to });
    },
  }),
);

const shiftRoute = createRoute({
  getParentRoute: () => rootRoute,
  path: "/shift",
  component: function ShiftRoute() {
    const { user } = rootRoute.useRouteContext();
    // "Admin" actions on the shift screen (drawer cash) need shift:cash.
    return <ShiftControl isAdmin={can(user, "shift:cash")} />;
  },
});

/** Guard factory: a route requiring `perm` redirects a user who lacks it back to
 *  the booth. Same permission the server enforces — defence in depth, not the only
 *  gate. */
function requirePerm(perm: Permission) {
  return (ctx: RouterContext) => {
    if (!can(ctx.user, perm)) throw redirect({ to: "/booth" });
  };
}

// The Setup tabs in display order, each with the permission its screen needs. Used
// to land a user on the FIRST tab they may see when they open /setup without
// `site:update` (e.g. an operator who only has shift:read → goes to /setup/shifts).
const SETUP_TABS: { to: string; perm: Permission }[] = [
  { to: "/setup", perm: "site:update" },
  { to: "/setup/tariff", perm: "tariff:read" },
  { to: "/setup/subscriptions", perm: "subscription:read" },
  { to: "/setup/site", perm: "site:read" },
  { to: "/setup/users", perm: "user:read" },
  { to: "/setup/roles", perm: "role:read" },
  { to: "/setup/shifts", perm: "shift:read" },
  { to: "/setup/logs", perm: "log:read" },
];

// /setup is a LAYOUT route (tab bar + <Outlet>); the config screens are its
// children. The layout itself has no permission gate — each child enforces its own
// (so a user who can reach ANY tab gets the hub, but only the tabs they're allowed).
const setupRoute = createRoute({
  getParentRoute: () => rootRoute,
  path: "/setup",
  component: SetupLayout,
});
// Index tab = Devices (the former SetupWizard). Lives at /setup exactly. A user who
// lacks site:update (e.g. an operator) is redirected to the FIRST tab they CAN see
// rather than bounced to the booth — so "Setup" always lands somewhere useful.
const setupDevicesRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "/",
  beforeLoad: ({ context }) => {
    if (can(context.user, "site:update")) return;
    const firstOther = SETUP_TABS.find((tab) => tab.to !== "/setup" && can(context.user, tab.perm));
    throw redirect({ to: firstOther?.to ?? "/booth" });
  },
  component: () => <SetupWizard />,
});
const tariffRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "tariff",
  beforeLoad: ({ context }) => requirePerm("tariff:read")(context),
  component: () => <TariffComposer />,
});
const subscriptionsRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "subscriptions",
  beforeLoad: ({ context }) => requirePerm("subscription:read")(context),
  component: () => <SubscriptionManager />,
});
const siteRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "site",
  beforeLoad: ({ context }) => requirePerm("site:read")(context),
  component: function SiteRoute() {
    const { user } = rootRoute.useRouteContext();
    return <SiteSettings canEdit={can(user, "site:update")} />;
  },
});
const usersRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "users",
  beforeLoad: ({ context }) => requirePerm("user:read")(context),
  component: function UsersRoute() {
    const { user } = rootRoute.useRouteContext();
    return <UsersManager user={user} />;
  },
});
const rolesRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "roles",
  beforeLoad: ({ context }) => requirePerm("role:read")(context),
  component: function RolesRoute() {
    const { user } = rootRoute.useRouteContext();
    return <RolesManager user={user} />;
  },
});
// Shift history. Gated by shift:read (operators have it) — the SERVER scopes the
// data: operators see only their own; shift:cash holders see all + can filter.
const shiftsHistoryRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "shifts",
  beforeLoad: ({ context }) => requirePerm("shift:read")(context),
  component: function ShiftsHistoryRoute() {
    const { user } = rootRoute.useRouteContext();
    return <ShiftsHistory user={user} />;
  },
});

// Diagnostic logs. Gated by log:read (an admin/diagnostic permission).
const logsRoute = createRoute({
  getParentRoute: () => setupRoute,
  path: "logs",
  beforeLoad: ({ context }) => requirePerm("log:read")(context),
  component: LogsViewer,
});

const routeTree = rootRoute.addChildren([
  indexRoute,
  boothRoute,
  ...legacyRedirects,
  shiftRoute,
  setupRoute.addChildren([
    setupDevicesRoute,
    tariffRoute,
    subscriptionsRoute,
    siteRoute,
    usersRoute,
    rolesRoute,
    shiftsHistoryRoute,
    logsRoute,
  ]),
]);

export const router = createRouter({
  routeTree,
  context: { user: null, setUser: () => {} },
  defaultPreload: "intent",
});

declare module "@tanstack/react-router" {
  interface Register {
    router: typeof router;
  }
}