(function (ns, $) {
  'use strict';

  const state = {
    routes: [],
    route: null,
    position: null,
    triggered: new Set(),
    tracking: false,
    activePage: null,
    routeProgressIndex: null,
    deviceHeading: null
  };

  function escapeHtml(value) {
    return $('<div>').text(value ?? '').html();
  }

  function activate(selector, handler) {
    $(document)
      .on('pointerup', selector, function (event) {
        const pointer = event.originalEvent;
        if (pointer && pointer.isPrimary === false) return;
        if (pointer?.pointerType === 'mouse' && pointer.button !== 0) return;
        event.preventDefault();
        handler.call(this, event);
      })
      .on('keydown', selector, function (event) {
        if (event.key !== 'Enter' && event.key !== ' ') return;
        event.preventDefault();
        handler.call(this, event);
      });
  }

  function navigate(pageSelector, options = {}) {
    const target = $(pageSelector);
    if (!target.length) throw new Error(`Unbekannte Ansicht: ${pageSelector}`);

    const previous = state.activePage;
    $('.app-page').attr('hidden', true).removeClass('is-active');
    target.removeAttr('hidden').addClass('is-active');
    state.activePage = pageSelector;
    window.scrollTo({ top: 0, behavior: options.instant ? 'auto' : 'smooth' });

    if (options.updateHistory === false) return;
    const historyState = { page: pageSelector, previous };
    if (options.replace) history.replaceState(historyState, '', pageSelector);
    else if (previous !== pageSelector) history.pushState(historyState, '', pageSelector);
  }

  function normalizeSearch(value) {
    return String(value ?? '')
      .normalize('NFKD')
      .replace(/[\u0300-\u036f]/g, '')
      .toLocaleLowerCase('de');
  }

  function routeMatchesSearch(route, searchTerm) {
    if (!searchTerm) return true;
    return normalizeSearch([
      route.name,
      route.schoolName,
      route.description
    ].filter(Boolean).join(' ')).includes(searchTerm);
  }

  function renderRouteItems(listSelector, routes, emptyText) {
    const list = $(listSelector).empty();
    if (!routes.length) {
      list.append(`<li><p>${escapeHtml(emptyText)}</p></li>`);
      return;
    }

    routes.forEach(route => {
      const proximity = route.proximityM == null
        ? ''
        : `<small>${escapeHtml(ns.Distance.format(route.proximityM))} entfernt</small>`;

      list.append(`
        <li>
          <button type="button" data-route-id="${route.id}">
            <strong>${escapeHtml(route.name)}</strong>
            <span>${escapeHtml(route.schoolName || route.description || '')}</span>
            ${proximity}
          </button>
        </li>
      `);
    });
  }

  function renderRoutes() {
    const radiusM = ns.Config.routeRadiusKm * 1000;
    const nearbyRoutes = state.position
      ? state.routes
        .filter(route => route.proximityM != null && route.proximityM <= radiusM)
        .sort((a, b) => a.proximityM - b.proximityM)
      : [];

    const searchTerm = normalizeSearch($('#route-search').val());
    const allRoutes = state.routes
      .filter(route => routeMatchesSearch(route, searchTerm))
      .slice()
      .sort((a, b) => a.name.localeCompare(b.name, 'de'));

    const nearbyEmptyText = state.position
      ? `Keine Route im Umkreis von ${ns.Config.routeRadiusKm} km gefunden. Wähle unten eine beliebige Route aus.`
      : 'Für Empfehlungen in der Nähe ist ein Standort erforderlich. Alle Routen bleiben unten auswählbar.';

    renderRouteItems('#nearby-route-list', nearbyRoutes, nearbyEmptyText);
    renderRouteItems(
      '#all-route-list',
      allRoutes,
      searchTerm ? 'Keine Route entspricht dem Suchbegriff.' : 'Es sind noch keine Routen vorhanden.'
    );

    $('#all-routes-summary').text(
      searchTerm
        ? `${allRoutes.length} von ${state.routes.length} Routen gefunden.`
        : `${state.routes.length} Routen verfügbar.`
    );
  }

  function initializeRouteSearch() {
    const input = $('#route-search');
    input.autocomplete({
      minLength: 0,
      source(request, response) {
        const term = normalizeSearch(request.term);
        response(state.routes
          .filter(route => routeMatchesSearch(route, term))
          .slice(0, 12)
          .map(route => ({ label: route.name, value: route.name })));
      },
      select(event, ui) {
        input.val(ui.item.value);
        renderRoutes();
        return false;
      }
    });
  }

  function hideNavigation() {
    $('#navigation-footer').prop('hidden', true);
    $('#app-shell').removeClass('has-navigation');
  }

  function showNavigation(message = 'Position wird ermittelt', distance = '–') {
    $('#navigation-mode').text(message);
    $('#navigation-distance').text(distance);
    $('#navigation-footer').prop('hidden', false);
    $('#app-shell').addClass('has-navigation');
  }

  function updateTrackingButton() {
    const button = $('#start-tracking');
    button.button('option', {
      label: state.tracking ? 'GPS-Begleitung stoppen' : 'GPS-Begleitung starten',
      icon: state.tracking ? 'ui-icon-stop' : 'ui-icon-pin-s'
    });
  }

  function stopTracking() {
    state.tracking = false;
    state.routeProgressIndex = null;
    state.deviceHeading = null;
    ns.Geo.stop();
    ns.Orientation.stop();
    $('#tracking-status').prop('hidden', true).text('');
    hideNavigation();
    updateTrackingButton();
  }

  function renderRoute(route) {
    if (state.tracking) stopTracking();

    state.route = route;
    state.triggered.clear();
    state.routeProgressIndex = null;
    $('#route-title').text(route.name);
    $('#route-description').text(route.description || '');
    $('#route-distance').text(ns.Distance.format(route.distanceM));
    $('#route-elevation').text(`${Math.round(route.elevationGainM)} m`);
    $('#route-poi-count').text(route.pois.length);

    const list = $('#poi-list').empty();
    if (!route.pois.length) {
      list.append('<li><p>Diese Route enthält noch keine Stationen.</p></li>');
      return;
    }

    route.pois.forEach(poi => {
      list.append(`
        <li>
          <button type="button" data-poi-id="${poi.id}">
            <strong>${escapeHtml(poi.title)}</strong>
            <span>${escapeHtml(poi.description || '')}</span>
          </button>
        </li>
      `);
    });
  }

  function showPoi(poi, automatic) {
    $('#poi-title').text(poi.title);
    $('#poi-description').text(poi.description || '');
    ns.Slideshow.show(poi.images);
    ns.AudioPlayer.load(poi.audioUrl);
    navigate('#poi-page');
    if (automatic && poi.audioUrl) ns.AudioPlayer.play().catch(() => {});
  }

  function nearestRoutePointIndex(position) {
    const points = state.route?.points || [];
    if (!points.length) return null;

    let start = 0;
    let end = points.length;
    if (state.routeProgressIndex != null) {
      start = Math.max(0, state.routeProgressIndex - 3);
      end = Math.min(points.length, state.routeProgressIndex + 201);
    }

    let nearestIndex = start;
    let nearestDistance = Number.POSITIVE_INFINITY;
    for (let index = start; index < end; index += 1) {
      const distance = ns.Distance.meters(position, points[index]);
      if (distance < nearestDistance) {
        nearestDistance = distance;
        nearestIndex = index;
      }
    }

    return nearestIndex;
  }

  function updateNavigation(position) {
    const points = state.route?.points || [];
    if (!state.tracking || !points.length) return;

    const nearestIndex = nearestRoutePointIndex(position);
    if (nearestIndex == null) return;

    state.routeProgressIndex = state.routeProgressIndex == null
      ? nearestIndex
      : Math.max(state.routeProgressIndex, nearestIndex);

    const lastIndex = points.length - 1;
    let targetIndex = Math.min(lastIndex, state.routeProgressIndex + 1);
    let target = points[targetIndex];
    let distance = ns.Distance.meters(position, target);
    const reachedRadius = Math.max(4, Math.min(12, Math.round(position.accuracy || 4)));

    while (targetIndex < lastIndex && distance <= reachedRadius) {
      state.routeProgressIndex = targetIndex;
      targetIndex += 1;
      target = points[targetIndex];
      distance = ns.Distance.meters(position, target);
    }

    if (targetIndex === lastIndex && distance <= reachedRadius) {
      state.routeProgressIndex = lastIndex;
      $('#navigation-arrow').css('transform', 'rotate(0deg)');
      showNavigation('Ziel der Route erreicht', '0 m');
      $('#navigation-footer').attr('aria-label', 'Ziel der Route erreicht');
      return;
    }

    const bearing = ns.Distance.bearing(position, target);
    const movementHeading = Number.isFinite(position.heading) && Number(position.speed) > 0.5
      ? position.heading
      : null;
    const heading = state.deviceHeading ?? movementHeading;
    const rotation = heading == null
      ? bearing
      : ns.Distance.normalizeDegrees(bearing - heading);

    $('#navigation-arrow').css('transform', `rotate(${rotation.toFixed(1)}deg)`);
    showNavigation(
      heading == null ? 'Norden oben · nächster Routenpunkt' : 'Nächster Routenpunkt',
      `${Math.round(distance)} m`
    );
    $('#navigation-footer').attr(
      'aria-label',
      `Nächster Routenpunkt in ${Math.round(distance)} Metern`
    );
  }

  function updateHeading(heading) {
    if (state.deviceHeading == null) {
      state.deviceHeading = heading;
    } else {
      const delta = ((heading - state.deviceHeading + 540) % 360) - 180;
      state.deviceHeading = ns.Distance.normalizeDegrees(state.deviceHeading + delta * 0.25);
    }

    if (state.position) updateNavigation(state.position);
  }

  function evaluatePosition(position) {
    state.position = position;
    if (!state.route || !state.tracking) return;

    updateNavigation(position);

    let nearest = null;
    state.route.pois.forEach(poi => {
      if (state.triggered.has(poi.id)) return;
      const distance = ns.Distance.meters(position, poi);
      if (!nearest || distance < nearest.distance) nearest = { poi, distance };
    });

    $('#tracking-status').text(
      `GPS aktiv · Genauigkeit ${Math.round(position.accuracy)} m`
      + (nearest ? ` · nächste Station ${Math.round(nearest.distance)} m` : '')
    );

    if (nearest && nearest.distance <= nearest.poi.triggerRadiusM) {
      state.triggered.add(nearest.poi.id);
      if (navigator.vibrate) navigator.vibrate([120, 80, 120]);
      showPoi(nearest.poi, true);
    }
  }

  async function startTracking() {
    state.tracking = true;
    state.routeProgressIndex = null;
    state.deviceHeading = null;
    updateTrackingButton();
    $('#tracking-status').prop('hidden', false).text('GPS wird gestartet.');
    showNavigation();

    ns.Geo.start(
      evaluatePosition,
      error => $('#tracking-status').text(`GPS-Fehler: ${error.message}`)
    );

    const orientationAvailable = await ns.Orientation.start(updateHeading);
    if (!orientationAvailable && state.tracking) {
      $('#navigation-mode').text('Norden oben · nächster Routenpunkt');
    }
  }

  function bindEvents() {
    $(document).on('input', '#route-search', renderRoutes);

    activate('#clear-route-search', function () {
      $('#route-search').val('').trigger('input').trigger('focus');
    });

    activate('[data-route-id]', async function () {
      const button = $(this);
      button.prop('disabled', true);
      try {
        const route = await ns.Api.route(button.data('route-id'));
        renderRoute(route);
        navigate('#route-page');
      } catch (error) {
        alert(error.responseJSON?.message || error.statusText || error.message);
      } finally {
        button.prop('disabled', false);
      }
    });

    activate('[data-poi-id]', function () {
      const poi = state.route?.pois.find(item => item.id === Number($(this).data('poi-id')));
      if (poi) showPoi(poi, false);
    });

    activate('[data-page-target]', function () {
      const target = $(this).data('page-target');
      if (history.state?.previous === target) history.back();
      else navigate(target, { replace: true });
    });

    activate('#start-tracking', async function () {
      if (state.tracking) stopTracking();
      else await startTracking();
    });

    window.addEventListener('popstate', event => {
      const page = event.state?.page || '#routes-page';
      navigate(page, { updateHistory: false, instant: true });
    });
  }

  ns.App = {
    navigate,

    async initialize(context) {
      bindEvents();
      await ns.Api.health();
      context.markStep('server', 'done');

      const response = await ns.Api.routes(null);
      state.routes = response.routes;
      context.markStep('routes', 'done');

      try {
        const position = await ns.Geo.current();
        state.position = position;
        $('#location-hint').text(
          `Standort ermittelt (Genauigkeit ${Math.round(position.accuracy)} m). `
          + `Nahe Routen werden bis ${ns.Config.routeRadiusKm} km empfohlen.`
        );
        state.routes = state.routes.map(route => ({
          ...route,
          proximityM: route.start ? ns.Distance.meters(position, route.start) : null
        }));
      } catch (error) {
        $('#location-hint').text(
          `Standort nicht verfügbar: ${error.message}. Alle Routen können weiterhin ausgewählt werden.`
        );
      }

      context.markStep('location', 'done');
      initializeRouteSearch();
      renderRoutes();
      updateTrackingButton();
      hideNavigation();
    }
  };
}(window.Wegwichtel, window.jQuery));