globalThis.Wegwichtel = globalThis.Wegwichtel || {};

(function (ns) {
  'use strict';

  const STORAGE_PREFIX = 'wegwichtel.local-routes.v1';
  const INDEX_KEY = `${STORAGE_PREFIX}.index`;
  const GPX_NAMESPACE = 'http://www.topografix.com/GPX/1/1';
  const POI_NAMESPACE = 'urn:wegwichtel:poi';
  let poiCounter = 0;

  function storage() {
    const target = globalThis.localStorage;
    if (!target) throw new Error('Lokaler Browser-Speicher ist auf diesem Gerät nicht verfügbar.');
    return target;
  }

  function routeKey(id, suffix) {
    return `${STORAGE_PREFIX}.${encodeURIComponent(String(id))}.${suffix}`;
  }

  function readIndex() {
    const raw = storage().getItem(INDEX_KEY);
    if (!raw) return [];
    try {
      const parsed = JSON.parse(raw);
      return Array.isArray(parsed) ? parsed.map(String) : [];
    } catch {
      return [];
    }
  }

  function writeIndex(ids) {
    storage().setItem(INDEX_KEY, JSON.stringify([...new Set(ids.map(String))]));
  }

  function uuidFromRandomValues(cryptoApi) {
    const bytes = new Uint8Array(16);
    cryptoApi.getRandomValues(bytes);

    bytes[6] = (bytes[6] & 0x0f) | 0x40;
    bytes[8] = (bytes[8] & 0x3f) | 0x80;

    const hex = Array.from(bytes, byte => byte.toString(16).padStart(2, '0'));
    return [
      hex.slice(0, 4).join(''),
      hex.slice(4, 6).join(''),
      hex.slice(6, 8).join(''),
      hex.slice(8, 10).join(''),
      hex.slice(10, 16).join('')
    ].join('-');
  }

  function createRouteId() {
    const cryptoApi = globalThis.crypto;
    if (typeof cryptoApi?.randomUUID === 'function') {
      return `local-${cryptoApi.randomUUID()}`;
    }
    if (typeof cryptoApi?.getRandomValues === 'function') {
      return `local-${uuidFromRandomValues(cryptoApi)}`;
    }
    throw new Error('Keine sichere Zufallsquelle für eine lokale Strecken-ID verfügbar.');
  }

  function createPoiId() {
    poiCounter = (poiCounter + 1) % 1000;
    return (Date.now() * 1000) + poiCounter;
  }

  function escapeXml(value) {
    return String(value ?? '')
      .replaceAll('&', '&')
      .replaceAll('<', '&lt;')
      .replaceAll('>', '&gt;')
      .replaceAll('"', '&quot;')
      .replaceAll("'", '&apos;');
  }

  function emptyGpx(name = 'Neue Strecke') {
    const safeName = escapeXml(name);
    return `<?xml version="1.0" encoding="UTF-8"?>\n`
      + `<gpx version="1.1" creator="Wegwichtel" xmlns="${GPX_NAMESPACE}" xmlns:wegwichtel="${POI_NAMESPACE}">\n`
      + `  <metadata><name>${safeName}</name></metadata>\n`
      + `  <trk><name>${safeName}</name><trkseg></trkseg></trk>\n`
      + '</gpx>';
  }

  function parseXml(gpx) {
    const parser = new DOMParser();
    const document = parser.parseFromString(String(gpx || ''), 'application/xml');
    if (document.querySelector('parsererror') || document.documentElement?.localName !== 'gpx') {
      throw new Error('Die GPX-Datei ist nicht gültig.');
    }
    return document;
  }

  function directChildrenByLocalName(parent, localName) {
    return Array.from(parent?.children || []).filter(node => node.localName === localName);
  }

  function firstDescendantByLocalName(parent, localName) {
    return Array.from(parent?.getElementsByTagName('*') || []).find(node => node.localName === localName) || null;
  }

  function textOfChild(parent, localName) {
    return directChildrenByLocalName(parent, localName)[0]?.textContent?.trim() || '';
  }

  function numberAttribute(node, name) {
    const value = Number.parseFloat(node?.getAttribute(name));
    return Number.isFinite(value) ? value : null;
  }

  function waypointId(node) {
    const extension = firstDescendantByLocalName(node, 'poiId');
    const parsed = Number(extension?.textContent);
    return Number.isSafeInteger(parsed) ? parsed : createPoiId();
  }

  function parseWaypoints(gpx) {
    const document = parseXml(gpx);
    return Array.from(document.getElementsByTagNameNS('*', 'wpt')).map((node, index) => ({
      id: waypointId(node),
      title: textOfChild(node, 'name') || `Station ${index + 1}`,
      description: textOfChild(node, 'desc'),
      lat: numberAttribute(node, 'lat'),
      lon: numberAttribute(node, 'lon'),
      triggerRadiusM: 25,
      sequence: index,
      audio: null,
      images: []
    })).filter(poi => poi.lat != null && poi.lon != null);
  }

  function createElement(document, localName, text = null) {
    const element = document.createElementNS(GPX_NAMESPACE, localName);
    if (text != null) element.textContent = String(text);
    return element;
  }

  function updateMetadataName(document, name) {
    const root = document.documentElement;
    let metadata = directChildrenByLocalName(root, 'metadata')[0];
    if (!metadata) {
      metadata = createElement(document, 'metadata');
      root.insertBefore(metadata, root.firstChild);
    }
    let nameElement = directChildrenByLocalName(metadata, 'name')[0];
    if (!nameElement) {
      nameElement = createElement(document, 'name');
      metadata.appendChild(nameElement);
    }
    nameElement.textContent = name;
  }

  function ensureTrackSegment(document, routeName) {
    const root = document.documentElement;
    let track = directChildrenByLocalName(root, 'trk')[0];
    if (!track) {
      track = createElement(document, 'trk');
      root.appendChild(track);
    }

    let trackName = directChildrenByLocalName(track, 'name')[0];
    if (!trackName) {
      trackName = createElement(document, 'name');
      track.insertBefore(trackName, track.firstChild);
    }
    trackName.textContent = routeName;

    let segment = directChildrenByLocalName(track, 'trkseg')[0];
    if (!segment) {
      segment = createElement(document, 'trkseg');
      track.appendChild(segment);
    }
    return segment;
  }

  function isManagedTrackPoint(node) {
    return Boolean(firstDescendantByLocalName(node, 'poiId'));
  }

  function syncGpx(gpx, route, pois) {
    const routeName = route?.name || 'Neue Strecke';
    const document = parseXml(gpx || emptyGpx(routeName));
    updateMetadataName(document, routeName);

    // Wegwichtel verwaltet neue Streckenpunkte direkt als GPX-Trackpunkte.
    // Fremde/importierte Trackpunkte ohne Wegwichtel-ID bleiben erhalten.
    Array.from(document.getElementsByTagNameNS('*', 'wpt')).forEach(node => node.remove());
    Array.from(document.getElementsByTagNameNS('*', 'trkpt'))
      .filter(isManagedTrackPoint)
      .forEach(node => node.remove());

    const segment = ensureTrackSegment(document, routeName);
    const orderedPois = [...(pois || [])].sort((left, right) => Number(left.sequence) - Number(right.sequence));
    orderedPois.forEach((poi, index) => {
      const title = poi.title || `Trackpunkt ${index + 1}`;
      if (!Number.isFinite(Number(poi.lat)) || !Number.isFinite(Number(poi.lon))) {
        throw new TypeError(`Für ${title} fehlen gültige Koordinaten.`);
      }

      const trackPoint = createElement(document, 'trkpt');
      trackPoint.setAttribute('lat', String(Number(poi.lat)));
      trackPoint.setAttribute('lon', String(Number(poi.lon)));
      trackPoint.appendChild(createElement(document, 'name', title));
      if (poi.description) trackPoint.appendChild(createElement(document, 'desc', poi.description));
      const extensions = createElement(document, 'extensions');
      const poiId = document.createElementNS(POI_NAMESPACE, 'wegwichtel:poiId');
      poiId.textContent = String(poi.id);
      extensions.appendChild(poiId);
      trackPoint.appendChild(extensions);
      segment.appendChild(trackPoint);
    });

    return new XMLSerializer().serializeToString(document);
  }

  function readPackage(id) {
    const target = storage();
    const gpx = target.getItem(routeKey(id, 'gpx'));
    const rawJson = target.getItem(routeKey(id, 'json'));
    if (!gpx || !rawJson) return null;
    try {
      const metadata = JSON.parse(rawJson);
      return {
        id: String(id),
        gpx,
        route: metadata.route || {},
        pois: Array.isArray(metadata.pois) ? metadata.pois : [],
        schemaVersion: metadata.schemaVersion || 1
      };
    } catch {
      return null;
    }
  }

  function restoreValue(target, key, value) {
    if (value == null) target.removeItem(key);
    else target.setItem(key, value);
  }

  function notify(id, action) {
    if (typeof document === 'undefined' || typeof CustomEvent === 'undefined') return;
    document.dispatchEvent(new CustomEvent('wegwichtel:local-routes-changed', {
      detail: { action, id: String(id) }
    }));
  }

  function savePackage(routePackage) {
    const target = storage();
    const id = String(routePackage.id || routePackage.route?.id || createRouteId());
    const previousIndex = target.getItem(INDEX_KEY);
    const gpxKey = routeKey(id, 'gpx');
    const jsonKey = routeKey(id, 'json');
    const previousGpx = target.getItem(gpxKey);
    const previousJson = target.getItem(jsonKey);
    const now = new Date().toISOString();
    const inputRoute = routePackage.route || {};
    const route = {
      id,
      name: String(inputRoute.name || ''),
      description: String(inputRoute.description || ''),
      createdAt: inputRoute.createdAt || now,
      updatedAt: now,
      serverRouteId: inputRoute.serverRouteId ?? null,
      uploadedAt: inputRoute.uploadedAt || null
    };
    const pois = (routePackage.pois || []).map((poi, index) => ({
      ...poi,
      id: Number.isSafeInteger(Number(poi.id)) ? Number(poi.id) : createPoiId(),
      sequence: index
    }));
    const gpx = syncGpx(routePackage.gpx || emptyGpx(route.name), route, pois);
    const metadata = JSON.stringify({ schemaVersion: 1, route, pois });

    try {
      target.setItem(gpxKey, gpx);
      target.setItem(jsonKey, metadata);
      writeIndex([...readIndex(), id]);
    } catch (error) {
      try {
        restoreValue(target, gpxKey, previousGpx);
        restoreValue(target, jsonKey, previousJson);
        restoreValue(target, INDEX_KEY, previousIndex);
      } catch {
        // Die ursprüngliche Speicherfehlermeldung ist aussagekräftiger.
      }
      const name = error?.name === 'QuotaExceededError' ? 'Der lokale Browser-Speicher ist voll.' : 'Die lokale Strecke konnte nicht gespeichert werden.';
      throw new Error(`${name} Bilder und Audiodateien können das Local-Storage-Limit schnell erreichen.`, { cause: error });
    }

    notify(id, 'saved');
    return readPackage(id);
  }

  function remove(id) {
    const target = storage();
    const routeId = String(id);
    target.removeItem(routeKey(routeId, 'gpx'));
    target.removeItem(routeKey(routeId, 'json'));
    writeIndex(readIndex().filter(item => item !== routeId));
    notify(routeId, 'removed');
  }

  function listPackages() {
    return readIndex().map(readPackage).filter(Boolean);
  }

  function routePoints(gpx) {
    const document = parseXml(gpx);
    const trackPoints = Array.from(document.getElementsByTagNameNS('*', 'trkpt'));
    const routePoints = Array.from(document.getElementsByTagNameNS('*', 'rtept'));
    const selected = trackPoints.length ? trackPoints : routePoints;
    return selected.map(node => {
      const elevation = Number.parseFloat(textOfChild(node, 'ele'));
      return {
        lat: numberAttribute(node, 'lat'),
        lon: numberAttribute(node, 'lon'),
        elevation: Number.isFinite(elevation) ? elevation : null,
        recordedAt: textOfChild(node, 'time') || null
      };
    }).filter(point => point.lat != null && point.lon != null);
  }

  function gpxForUpload(routePackage) {
    if (!routePackage?.gpx) throw new Error('Für die lokale Strecke ist keine GPX-Datei vorhanden.');
    if (!routePoints(routePackage.gpx).length) {
      throw new Error('Die lokale Strecke enthält noch keine GPX-Trackpunkte.');
    }
    return routePackage.gpx;
  }

  function radians(value) {
    return value * (Math.PI / 180);
  }

  function meters(left, right) {
    const earthRadius = 6371008.8;
    const latDelta = radians(right.lat - left.lat);
    const lonDelta = radians(right.lon - left.lon);
    const leftLat = radians(left.lat);
    const rightLat = radians(right.lat);
    const value = Math.sin(latDelta / 2) ** 2
      + Math.cos(leftLat) * Math.cos(rightLat) * (Math.sin(lonDelta / 2) ** 2);
    return earthRadius * 2 * Math.atan2(Math.sqrt(value), Math.sqrt(1 - value));
  }

  function metrics(points) {
    if (!points.length) {
      return {
        bounds: null,
        center: null,
        distanceM: 0,
        elevationGainM: 0,
        start: null
      };
    }
    let distanceM = 0;
    let elevationGainM = 0;
    for (let index = 1; index < points.length; index += 1) {
      distanceM += meters(points[index - 1], points[index]);
      const previous = points[index - 1].elevation;
      const current = points[index].elevation;
      if (Number.isFinite(previous) && Number.isFinite(current) && current > previous) elevationGainM += current - previous;
    }
    const lats = points.map(point => point.lat);
    const lons = points.map(point => point.lon);
    const bounds = {
      minLat: Math.min(...lats),
      minLon: Math.min(...lons),
      maxLat: Math.max(...lats),
      maxLon: Math.max(...lons)
    };
    return {
      bounds,
      center: {
        lat: (bounds.minLat + bounds.maxLat) / 2,
        lon: (bounds.minLon + bounds.maxLon) / 2
      },
      distanceM,
      elevationGainM,
      start: { lat: points[0].lat, lon: points[0].lon }
    };
  }

  function appPoi(poi) {
    return {
      id: Number(poi.id),
      title: poi.title || 'Unbenannte Station',
      description: poi.description || '',
      lat: Number(poi.lat),
      lon: Number(poi.lon),
      triggerRadiusM: Number(poi.triggerRadiusM) || 25,
      sequence: Number(poi.sequence) || 0,
      audioUrl: poi.audio?.dataUrl || null,
      images: (poi.images || []).map((image, index) => ({
        id: image.id || `${poi.id}-${index}`,
        caption: image.caption || '',
        sequence: index,
        url: image.dataUrl
      })).filter(image => image.url)
    };
  }

  function toAppRoute(routePackage) {
    const pois = (routePackage.pois || []).map(appPoi).sort((left, right) => left.sequence - right.sequence);
    const parsedPoints = routePoints(routePackage.gpx);
    const points = parsedPoints.length
      ? parsedPoints
      : pois.map(poi => ({ lat: poi.lat, lon: poi.lon, elevation: null, recordedAt: null }));
    const routeMetrics = metrics(points);
    return {
      id: String(routePackage.id),
      source: 'local',
      local: true,
      name: routePackage.route?.name || 'Unbenannte Strecke',
      description: routePackage.route?.description || '',
      schoolName: 'Lokal gespeichert',
      status: 'local',
      activatedAt: null,
      points,
      pois,
      pointCount: points.length,
      gpxUrl: null,
      createdAt: routePackage.route?.createdAt || null,
      updatedAt: routePackage.route?.updatedAt || null,
      ...routeMetrics
    };
  }

  function listAppRoutes() {
    return listPackages().map(toAppRoute);
  }

  function getAppRoute(id) {
    const routePackage = readPackage(id);
    if (!routePackage) throw new Error('Die lokale Strecke wurde nicht gefunden.');
    return toAppRoute(routePackage);
  }

  function readFileAsText(file) {
    if (!file) return Promise.resolve('');
    if (typeof file.text !== 'function') {
      return Promise.reject(new TypeError('Die ausgewählte Datei unterstützt Blob.text() nicht.'));
    }
    return file.text();
  }

  function fileToDataUrl(file) {
    if (!file) return Promise.resolve(null);
    return new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.addEventListener('load', () => {
        if (typeof reader.result !== 'string') {
          reject(new TypeError('Die Datei konnte nicht als Data-URL gelesen werden.'));
          return;
        }
        resolve({
          dataUrl: reader.result,
          name: file.name || 'Datei',
          size: Number(file.size) || 0,
          type: file.type || 'application/octet-stream'
        });
      }, { once: true });
      reader.addEventListener('error', () => reject(reader.error || new Error('Datei konnte nicht gelesen werden.')), { once: true });
      reader.readAsDataURL(file);
    });
  }

  ns.LocalRoutes = Object.freeze({
    STORAGE_PREFIX,
    createPoiId,
    createRouteId,
    emptyGpx,
    fileToDataUrl,
    get: readPackage,
    getAppRoute,
    gpxForUpload,
    list: listPackages,
    listAppRoutes,
    parseWaypoints,
    readFileAsText,
    remove,
    save: savePackage,
    syncGpx,
    toAppRoute
  });
}(globalThis.Wegwichtel));