/**
 * MiR-style 3-column navigation: primary rail + flyout submenu + content.
 */
(function () {
  const STORAGE_MODULE = "mirNavModule";
  const STORAGE_SECTION = "mirNavSection";
  const STORAGE_FLYOUT = "mirNavFlyoutOpen";

  const MODULES = {
    dashboards: {
      items: [{ section: "dashboard-list", page: "dashboard" }],
      dynamic: true,
    },
    setup: {
      items: [
        { section: "missions", page: "missions" },
        { section: "maps", page: "maps" },
        { section: "sounds", page: "sounds" },
        { section: "build-robot", page: "config" },
      ],
    },
    monitoring: {
      items: [{ section: "monitoring-log", page: "monitoring" }],
    },
    system: {
      items: [{ section: "integrations", page: "integrations" }],
    },
    help: {
      items: [{ section: "help-api", page: "help" }],
    },
  };

  const PAGE_NAV = {
    dashboard: { module: "dashboards", section: "dashboard-list" },
    config: { module: "setup", section: "build-robot" },
    maps: { module: "setup", section: "maps" },
    missions: { module: "setup", section: "missions" },
    sounds: { module: "setup", section: "sounds" },
    integrations: { module: "system", section: "integrations" },
    monitoring: { module: "monitoring", section: "monitoring-log" },
    help: { module: "help", section: "help-api" },
  };

  let activeModule = "setup";
  let activeSection = "missions";
  let flyoutOpen = true;

  const shellEl = () => document.getElementById("mirNavShell");
  const flyoutListEl = () => document.getElementById("mirNavFlyoutList");
  const flyoutTitleEl = () => document.getElementById("mirNavFlyoutTitle");
  const backBtnEl = () => document.getElementById("mirNavBackBtn");

  function t(key) {
    return window.I18n?.t(`nav.${key}`) ?? key;
  }

  function canAccessPage(page) {
    if (window.AuthApp?.canAccessPage) return window.AuthApp.canAccessPage(page);
    return true;
  }

  function moduleItems(moduleId) {
    const mod = MODULES[moduleId];
    if (!mod) return [];
    if (mod.dynamic && moduleId === "dashboards" && window.DashboardApp?.getNavItems) {
      return window.DashboardApp.getNavItems();
    }
    return mod.items;
  }

  function visibleItems(moduleId) {
    const mod = MODULES[moduleId];
    if (!mod) return [];
    return moduleItems(moduleId).filter((item) => canAccessPage(item.page));
  }

  function itemLabel(item) {
    if (item.label) return item.label;
    return t(item.section);
  }

  function moduleHasAccess(moduleId) {
    return visibleItems(moduleId).length > 0;
  }

  function saveState() {
    try {
      localStorage.setItem(STORAGE_MODULE, activeModule);
      localStorage.setItem(STORAGE_SECTION, activeSection);
      localStorage.setItem(STORAGE_FLYOUT, flyoutOpen ? "1" : "0");
    } catch {
      /* ignore */
    }
  }

  function renderFlyout() {
    const list = flyoutListEl();
    const title = flyoutTitleEl();
    if (!list || !title) return;

    const items = visibleItems(activeModule);
    title.textContent = t(activeModule);
    list.replaceChildren();

    items.forEach((item) => {
      const btn = document.createElement("button");
      btn.type = "button";
      btn.className = "mirNavFlyoutItem";
      btn.dataset.section = item.section;
      btn.dataset.page = item.page;
      btn.textContent = itemLabel(item);
      if (item.section === activeSection) {
        btn.classList.add("is-active");
        btn.setAttribute("aria-current", "page");
      }
      btn.addEventListener("click", () => selectSection(item.section, item.page));
      list.appendChild(btn);
    });
  }

  function updateRailUI() {
    document.querySelectorAll(".mirNavRailItem[data-module]").forEach((btn) => {
      const mod = btn.dataset.module || "";
      const allowed = moduleHasAccess(mod);
      btn.hidden = !allowed;
      btn.style.display = allowed ? "" : "none";
      const on = mod === activeModule && flyoutOpen;
      btn.classList.toggle("is-active", on);
      if (on) btn.setAttribute("aria-current", "true");
      else btn.removeAttribute("aria-current");
    });

    const shell = shellEl();
    if (shell) shell.classList.toggle("mirNavShell--flyout-collapsed", !flyoutOpen);

    const back = backBtnEl();
    if (back) {
      const label = flyoutOpen ? t("collapse") : t("expand");
      back.title = label;
      back.setAttribute("aria-label", label);
    }

    renderFlyout();
  }

  function selectModule(moduleId, opts = {}) {
    if (!MODULES[moduleId] || !moduleHasAccess(moduleId)) return;

    if (moduleId === activeModule && flyoutOpen && !opts.forceSection) {
      flyoutOpen = false;
      saveState();
      updateRailUI();
      return;
    }

    activeModule = moduleId;
    flyoutOpen = true;

    const items = visibleItems(moduleId);
    const keepSection = items.some((i) => i.section === activeSection);
    if (!keepSection || opts.forceSection) {
      const preferred = items.find((i) => i.section === opts.section) || items[0];
      if (preferred) {
        activeSection = preferred.section;
        if (!opts.skipPage) navigateToPage(preferred.page);
      }
    } else if (!opts.skipPage) {
      const current = items.find((i) => i.section === activeSection);
      if (current) navigateToPage(current.page);
    }

    saveState();
    updateRailUI();
  }

  function selectSection(section, page) {
    activeSection = section;
    saveState();
    updateRailUI();
    navigateToPage(page);
    if (page === "dashboard") window.DashboardApp?.handleNav?.(section);
  }

  function syncDashboardSection(section) {
    activeModule = "dashboards";
    activeSection = section.startsWith("dashboard-") || section === "dashboard-list" ? section : `dashboard-${section}`;
    saveState();
    updateRailUI();
  }

  function navigateToPage(page) {
    if (window.LmApp?.setActivePage) window.LmApp.setActivePage(page);
  }

  function syncFromPage(page) {
    const nav = PAGE_NAV[page];
    if (!nav) return;
    activeModule = nav.module;
    activeSection = nav.section;
    saveState();
    updateRailUI();
    if (page === "dashboard") window.DashboardApp?.handleNav?.(activeSection);
  }

  function toggleFlyout() {
    flyoutOpen = !flyoutOpen;
    saveState();
    updateRailUI();
  }

  function applyPermissions() {
    const modules = Object.keys(MODULES);
    if (!moduleHasAccess(activeModule)) {
      const fallback = modules.find((m) => moduleHasAccess(m));
      if (fallback) selectModule(fallback, { forceSection: true, skipPage: false });
    } else {
      const items = visibleItems(activeModule);
      if (!items.some((i) => i.section === activeSection)) {
        activeSection = items[0]?.section || activeSection;
      }
    }
    updateRailUI();
  }

  function restoreInitialPage() {
    let page = "missions";
    try {
      const saved = localStorage.getItem("activePage");
      if (saved && PAGE_NAV[saved]) page = saved;
    } catch {
      /* ignore */
    }

    try {
      const savedMod = localStorage.getItem(STORAGE_MODULE);
      const savedSec = localStorage.getItem(STORAGE_SECTION);
      const savedFlyout = localStorage.getItem(STORAGE_FLYOUT);
      if (savedMod && MODULES[savedMod]) activeModule = savedMod;
      if (savedSec) activeSection = savedSec;
      if (savedFlyout === "0") flyoutOpen = false;
    } catch {
      /* ignore */
    }

    const nav = PAGE_NAV[page];
    if (nav && moduleHasAccess(nav.module)) {
      activeModule = nav.module;
      activeSection = nav.section;
    } else {
      const modItems = visibleItems(activeModule);
      const match = modItems.find((i) => i.page === page) || modItems[0];
      if (match) {
        activeSection = match.section;
        page = match.page;
      }
    }

    updateRailUI();
    navigateToPage(page);
  }

  function refreshFlyout() {
    updateRailUI();
  }

  function refreshLabels() {
    window.I18n?.applyDOM?.();
    updateRailUI();
  }

  function bindEvents() {
    document.querySelectorAll(".mirNavRailItem[data-module]").forEach((btn) => {
      btn.addEventListener("click", () => selectModule(btn.dataset.module || "setup"));
    });

    backBtnEl()?.addEventListener("click", toggleFlyout);

    document.getElementById("mirNavLogout")?.addEventListener("click", () => {
      window.AuthApp?.logout?.();
    });

    window.addEventListener("lm:locale-change", () => refreshLabels());
  }

  function init() {
    refreshLabels();
    bindEvents();
    applyPermissions();
    restoreInitialPage();
  }

  window.NavApp = {
    init,
    syncFromPage,
    syncDashboardSection,
    applyPermissions,
    selectModule,
    selectSection,
    toggleFlyout,
    refreshFlyout,
  };
})();