import { Popup } from "/vendor/maplibre-gl/maplibre-gl.mjs";
import {
  GPX_ICON,
  NEW_FOLDER_ICON,
  UPLOAD_ICON,
  WAYPOINT_ICON,
  TRACK_ICON,
  ROUTE_ICON,
  MAP_MARKER_ICON,
  POI_ICONS,
} from "/js/icons.js";
import { notifySidePanelOpen, onlyOneSidePanelOpen } from "/js/panels.js";
import { formatActivityType } from "/js/track_profile.js";

const TREE_URL = "/api/gpx/tree";
const UPLOAD_URL = "/api/gpx";
const FOLDER_URL = "/api/gpx/folder";
const MOVE_URL = "/api/gpx/move";
const TRACK_COLOR = "#e63946";
const POI_ICON_KEYS = Object.keys(POI_ICONS);
const POI_ICON_IMAGE_SIZE = 48; // rasterized once at this size, rendered much smaller by icon-size below
const POI_ICON_SIZE = 0.3; // 48 * 0.3 = ~14px, sized to sit inside the marker badge below
const MAP_MARKER_SIZE = 0.55;
const BADGE_IMAGE_PREFIX = "badge-"; // one registered image per distinct badge color actually seen, see _registerBadgeColors

// Custom drag payload MIME type for moving an already-uploaded file between
// folders, as opposed to an OS file drag (type "Files") for uploading a new
// one — both land on the same drop targets, told apart by this.
const MOVE_MIME = "application/x-gpx-path";

// A sidebar icon that opens a side panel for uploading GPX files (via
// drag & drop, stored server-side in a folder hierarchy the user can add to
// and reorganize by dragging), and toggling their tracks/waypoints on and
// off the map.
export class GpxPanelControl {
  constructor(map, profilePanel) {
    this._map = map;
    this._profilePanel = profilePanel;
    this._visible = new Set(); // file paths currently shown on the map
    this._interactiveLayers = new Set(); // point layer ids with click/hover wired up
    this._pointsByPath = new Map(); // path -> its waypoints FeatureCollection, for the category legend

    // setStyle() (switching the Online/Offline base map) tears down all
    // custom sources/layers/images — re-register the category glyphs before
    // putting visible GPX layers back, so a symbol layer added right away
    // doesn't reference a not-yet-existing image. Badge images are handled
    // separately (_registerBadgeColors, called from _addLayers) since which
    // colors are needed depends on which file/category is being shown.
    this._iconsReady = this._registerCategoryGlyphs();
    map.on("style.load", () => {
      this._iconsReady = this._registerCategoryGlyphs();
      this._visible.forEach((path) => this._addLayers(path));
    });
  }

  // Registered once, always white, as plain (non-SDF) images: these used to
  // be SDF images tinted white via icon-color, but MapLibre's SDF rendering
  // assumes the source encodes an actual distance field (a smooth multi-pixel
  // gradient at each edge) — feeding it a normally-antialiased raster (a
  // sharp 1px edge transition) instead made every glyph noticeably softer
  // than the base map's own icons, especially shrunk down to icon-size 0.3.
  // Since the glyph color never varies (always white, unlike the badge
  // below), there's no need for SDF's runtime-tintable alpha mask at all —
  // baking the color into the raster and skipping SDF renders as sharp as
  // any ordinary sprite.
  async _registerCategoryGlyphs() {
    await Promise.all(
      POI_ICON_KEYS.map(async (key) => {
        if (this._map.hasImage(key)) return;
        const whiteSvg = POI_ICONS[key].replace(/currentColor/g, "#fff");
        const imageData = await svgToImageData(whiteSvg, POI_ICON_IMAGE_SIZE);
        if (!this._map.hasImage(key)) this._map.addImage(key, imageData);
      }),
    );
  }

  // The badge's color is per-category data (arbitrary hex from a GPX file),
  // so unlike the glyphs it can't be a single fixed-color image — but a real
  // POI export only ever has a handful of distinct category colors, so it's
  // cheap to rasterize one sharp, non-SDF image per color actually seen
  // (rather than one shared image SDF-tinted at render time, which is what
  // made these blurry — see _registerCategoryGlyphs above) and cache them by
  // color for reuse across files.
  async _registerBadgeColors(colors) {
    await Promise.all(
      [...colors].map(async (color) => {
        const id = badgeImageId(color);
        if (this._map.hasImage(id)) return;
        const coloredSvg = MAP_MARKER_ICON.replace(/currentColor/g, color);
        const imageData = await svgToImageData(coloredSvg, POI_ICON_IMAGE_SIZE);
        if (!this._map.hasImage(id)) this._map.addImage(id, imageData);
      }),
    );
  }

  mount(sidebar) {
    this._container = document.createElement("div");
    this._container.className = "sidebar-item";
    this._container.innerHTML = `<button type="button" class="sidebar-icon" title="Tracks" aria-label="Tracks">${GPX_ICON}</button>`;
    this._icon = this._container.querySelector(".sidebar-icon");
    this._icon.addEventListener("click", () => this._togglePanel());

    this._panel = document.getElementById("gpx-panel");
    this._treeContainer = this._panel.querySelector(".gpx-tree");
    this._legendContainer = this._panel.querySelector(".gpx-legend");
    this._uploadStatus = this._panel.querySelector(".gpx-upload__status");
    this._panel.querySelector('[data-action="new-folder"]').innerHTML = NEW_FOLDER_ICON;
    this._panel.querySelector('[data-action="upload"]').innerHTML = UPLOAD_ICON;
    this._panel
      .querySelector(".gpx-panel__close")
      .addEventListener("click", () => this._togglePanel(false));

    onlyOneSidePanelOpen(this._panel, () => this._icon.classList.remove("active"));

    this._setupToolbarActions();
    this._setupRootDropTarget();
    this._setupMapDropTarget();

    this._loadTree();

    sidebar.appendChild(this._container);
  }

  _togglePanel(force) {
    const open = force === undefined ? this._panel.hidden : force;
    this._panel.hidden = !open;
    this._icon.classList.toggle("active", open);
    if (open) notifySidePanelOpen(this._panel);
  }

  // Both toolbar actions are icon buttons now (matching OsmAnd's tracks
  // panel) rather than an always-visible dropzone/form: upload triggers the
  // native file picker, new folder prompts for a path.
  _setupToolbarActions() {
    const fileInput = this._panel.querySelector(".gpx-file-input");
    fileInput.addEventListener("change", () => {
      this._uploadFiles(fileInput.files, "");
      fileInput.value = "";
    });

    this._panel.querySelector('[data-action="upload"]').addEventListener("click", () => fileInput.click());
    this._panel.querySelector('[data-action="new-folder"]').addEventListener("click", async () => {
      const path = window.prompt("New folder name (e.g. Hiking/2026):");
      if (!path || !path.trim()) return;

      const response = await fetch(FOLDER_URL, {
        method: "POST",
        headers: { "Content-Type": "application/x-www-form-urlencoded" },
        body: `path=${encodeURIComponent(path.trim())}`,
      });
      if (redirectIfUnauthorized(response)) return;
      if (response.ok) {
        const { tree } = await response.json();
        this._renderTree(tree);
      }
    });
  }

  // The tree itself is the drop target for both an OS file drag (upload to
  // the top level) and, for anywhere that isn't a folder (blank space, or
  // onto another file — folder drop targets call stopPropagation() so this
  // only fires then), an internal file drag (move back to the top level).
  _setupRootDropTarget() {
    this._treeContainer.addEventListener("dragover", (event) => {
      if (!event.dataTransfer.types.includes("Files") && !event.dataTransfer.types.includes(MOVE_MIME)) return;
      event.preventDefault();
      this._treeContainer.classList.add("gpx-drop-hover");
    });
    this._treeContainer.addEventListener("dragleave", (event) => {
      if (event.target === this._treeContainer) this._treeContainer.classList.remove("gpx-drop-hover");
    });
    this._treeContainer.addEventListener("drop", (event) => {
      event.preventDefault();
      this._treeContainer.classList.remove("gpx-drop-hover");
      if (event.dataTransfer.files?.length > 0) {
        this._uploadFiles(event.dataTransfer.files, "");
        return;
      }
      const from = event.dataTransfer.getData(MOVE_MIME);
      if (from) this._moveFile(from, "");
    });
  }

  // Dropping a GPX file straight onto the map (not just the panel) uploads
  // it to the top level too.
  _setupMapDropTarget() {
    const mapContainer = this._map.getContainer();
    mapContainer.addEventListener("dragover", (event) => {
      if (!event.dataTransfer.types.includes("Files")) return;
      event.preventDefault();
      mapContainer.classList.add("gpx-drop-hover");
    });
    mapContainer.addEventListener("dragleave", (event) => {
      if (event.target === mapContainer) mapContainer.classList.remove("gpx-drop-hover");
    });
    mapContainer.addEventListener("drop", (event) => {
      mapContainer.classList.remove("gpx-drop-hover");
      if (event.dataTransfer.files?.length > 0) {
        event.preventDefault();
        this._uploadFiles(event.dataTransfer.files, "");
      }
    });
  }

  async _loadTree() {
    const response = await fetch(TREE_URL);
    const tree = await response.json();
    this._renderTree(tree);
  }

  _renderTree(node) {
    this._treeContainer.innerHTML = "";
    this._treeContainer.appendChild(this._renderChildren(node.children));
  }

  _renderChildren(children) {
    const ul = document.createElement("ul");
    if (children.length === 0) {
      const li = document.createElement("li");
      li.className = "gpx-tree__empty";
      li.textContent = "No files yet";
      ul.appendChild(li);
      return ul;
    }

    children.forEach((child) => {
      const li = document.createElement("li");
      if (child.type === "folder") {
        li.appendChild(this._renderFolder(child));
      } else {
        li.appendChild(this._renderFile(child));
      }
      ul.appendChild(li);
    });

    return ul;
  }

  _renderFolder(folder) {
    const details = document.createElement("details");
    details.open = true;

    const summary = document.createElement("summary");
    const row = document.createElement("span");
    row.className = "gpx-tree__folder-row";
    const name = document.createElement("span");
    name.textContent = folder.name;
    row.appendChild(name);
    row.appendChild(this._deleteButton(() => this._deleteFolder(folder.path)));
    summary.appendChild(row);
    this._wireFolderDropTarget(summary, folder.path);

    details.appendChild(summary);
    details.appendChild(this._renderChildren(folder.children));
    return details;
  }

  _renderFile(file) {
    const row = document.createElement("div");
    row.className = "gpx-tree__file";
    row.draggable = true;
    row.addEventListener("dragstart", (event) => {
      event.dataTransfer.setData(MOVE_MIME, file.path);
      event.dataTransfer.effectAllowed = "move";
    });

    const label = document.createElement("label");
    const checkbox = document.createElement("input");
    checkbox.type = "checkbox";
    checkbox.checked = this._visible.has(file.path);
    checkbox.addEventListener("change", () => this._toggleFile(file.path, checkbox.checked, checkbox));
    const name = document.createElement("span");
    name.className = "gpx-tree__file-name";
    name.textContent = file.name;
    name.title = file.name;
    label.appendChild(checkbox);
    (file.kinds || []).forEach((kind) => label.appendChild(this._kindIcon(kind)));
    label.appendChild(name);
    row.appendChild(label);
    row.appendChild(this._deleteButton(() => this._deleteFile(file.path)));

    return row;
  }

  _kindIcon(kind) {
    const icon = document.createElement("span");
    icon.className = "gpx-tree__kind-icon";
    if (kind === "waypoint") {
      icon.innerHTML = WAYPOINT_ICON;
      icon.title = "Has waypoints";
    } else if (kind === "route") {
      icon.innerHTML = ROUTE_ICON;
      icon.title = "Has a route";
    } else {
      icon.innerHTML = TRACK_ICON;
      icon.title = "Has a track";
    }
    return icon;
  }

  _deleteButton(onClick) {
    const button = document.createElement("button");
    button.type = "button";
    button.className = "gpx-tree__delete";
    button.title = "Delete";
    button.textContent = "×";
    button.addEventListener("click", (event) => {
      event.preventDefault();
      event.stopPropagation();
      onClick();
    });
    return button;
  }

  // A folder accepts both an OS file drag (upload straight into it) and an
  // internal file drag (move into it).
  _wireFolderDropTarget(summary, folderPath) {
    summary.addEventListener("dragover", (event) => {
      if (!event.dataTransfer.types.includes("Files") && !event.dataTransfer.types.includes(MOVE_MIME)) return;
      event.preventDefault();
      summary.classList.add("gpx-drop-hover");
    });
    summary.addEventListener("dragleave", () => summary.classList.remove("gpx-drop-hover"));
    summary.addEventListener("drop", (event) => {
      event.preventDefault();
      event.stopPropagation();
      summary.classList.remove("gpx-drop-hover");
      if (event.dataTransfer.files?.length > 0) {
        this._uploadFiles(event.dataTransfer.files, folderPath);
        return;
      }
      const from = event.dataTransfer.getData(MOVE_MIME);
      if (from) this._moveFile(from, folderPath);
    });
  }

  async _toggleFile(path, visible, checkbox) {
    if (visible) {
      this._visible.add(path);
      const ok = await this._addLayers(path);
      if (!ok) {
        // Loading failed (see _addLayers) — don't leave the box checked
        // for a file that isn't actually showing anything.
        this._visible.delete(path);
        if (checkbox) checkbox.checked = false;
      }
    } else {
      this._visible.delete(path);
      this._removeLayers(path);
    }
  }

  // Fetches the file's GeoJSON itself (rather than handing maplibre a URL
  // to fetch internally) so a parse failure — a real GPX a device/app
  // wrote in some way REXML doesn't like, say — surfaces as an alert
  // instead of the layer just silently never appearing. Returns whether it
  // succeeded.
  async _addLayers(path) {
    const linesId = linesSourceId(path);
    const pointsId = pointsSourceId(path);
    if (this._map.getSource(linesId) || this._map.getSource(pointsId)) return true;

    let geojson;
    try {
      const response = await fetch(gpxFileUrl(path));
      if (!response.ok) {
        const { error } = await response.json().catch(() => ({}));
        window.alert(error || `Could not load "${path}".`);
        return false;
      }
      geojson = await response.json();
    } catch (err) {
      window.alert(`Could not load "${path}": ${err.message}`);
      return false;
    }

    if (this._map.getSource(linesId) || this._map.getSource(pointsId)) return true; // added concurrently (e.g. a style.load race) while this was fetching

    // Split into two sources: MapLibre's clustering only understands a
    // source made entirely of Point/MultiPoint features, and a file can mix
    // a track/route line with waypoints (or, like a park4night POI export,
    // be thousands of waypoints and nothing else).
    const lines = { type: "FeatureCollection", features: [] };
    const points = { type: "FeatureCollection", features: [] };
    for (const feature of geojson.features) {
      (feature.geometry.type === "Point" ? points : lines).features.push(feature);
    }
    // Normalized here (rather than a ["coalesce", ...] in the layer's
    // icon-image expression) so every point's badge color is known upfront,
    // before registering the per-color badge images below.
    for (const feature of points.features) {
      feature.properties.color ||= TRACK_COLOR;
    }

    this._map.addSource(linesId, { type: "geojson", data: lines });
    this._map.addLayer({
      id: `${linesId}-line`,
      type: "line",
      source: linesId,
      layout: { "line-cap": "round", "line-join": "round" },
      paint: { "line-color": TRACK_COLOR, "line-width": 3 },
    });
    this._registerLineInteractivity(`${linesId}-line`);

    // clusterRadius/clusterMaxZoom are harmless when there's nothing dense
    // enough to cluster (a handful of waypoints just render individually).
    this._map.addSource(pointsId, { type: "geojson", data: points, cluster: true, clusterRadius: 50, clusterMaxZoom: 14 });
    const badgeColors = new Set(points.features.map((f) => f.properties.color));
    await Promise.all([this._iconsReady, this._registerBadgeColors(badgeColors)]);
    if (!this._map.getSource(pointsId)) return true; // a style.load (basemap switch) tore it down while icons were loading

    this._addClusterLayers(pointsId);

    if (points.features.length > 0) this._pointsByPath.set(path, points);
    this._updateLegend();

    return true;
  }

  // A single-hue, light->dark ramp keyed on point_count (magnitude, not
  // category) for the clustered circles; individual points below that use
  // each waypoint's own category color (see Maptool::Gpx#waypoint_color),
  // falling back to the plain track color for waypoints with no category
  // (e.g. a hand-placed GNSS pin, not from a POI export).
  _addClusterLayers(pointsId) {
    this._map.addLayer({
      id: `${pointsId}-clusters`,
      type: "circle",
      source: pointsId,
      filter: ["has", "point_count"],
      paint: {
        "circle-radius": ["step", ["get", "point_count"], 16, 25, 20, 100, 26],
        "circle-color": ["step", ["get", "point_count"], "#a8c8ea", 25, "#5b9bd5", 100, "#2e6da4"],
        "circle-stroke-color": "#fff",
        "circle-stroke-width": 1.5,
      },
    });
    this._map.addLayer({
      id: `${pointsId}-cluster-count`,
      type: "symbol",
      source: pointsId,
      filter: ["has", "point_count"],
      layout: { "text-field": ["get", "point_count_abbreviated"], "text-font": ["Noto Sans Regular"], "text-size": 11 },
      paint: { "text-color": "#fff" },
    });
    // A rounded-square badge (icons.js's MAP_MARKER_ICON), not a plain
    // circle: a flat colored dot looked too much like a base map style's
    // own small circular POI icons, so individual waypoints blended in
    // instead of standing out as "your data". A rounded square rather than
    // a pin/teardrop specifically to match how the NPS itself frames these
    // exact category symbols (POI_ICONS below) on its own maps. Centered on
    // the coordinate — a square has no natural "tip" the way a pin does, so
    // default center anchoring is simplest and also means the glyph layer
    // below needs no offset, just the same center anchor.
    this._map.addLayer({
      id: `${pointsId}-unclustered`,
      type: "symbol",
      source: pointsId,
      filter: ["!", ["has", "point_count"]],
      layout: {
        "icon-image": ["concat", BADGE_IMAGE_PREFIX, ["get", "color"]],
        "icon-size": MAP_MARKER_SIZE,
        "icon-allow-overlap": true,
        "icon-ignore-placement": true,
      },
    });
    // Only for the curated POI_ICON_KEYS (see icons.js) — anything else
    // (a plain hand-placed waypoint, or a category p4n2gpx/OsmAnd hasn't
    // been taught here) just keeps the plain badge above with no glyph.
    this._map.addLayer({
      id: `${pointsId}-unclustered-icon`,
      type: "symbol",
      source: pointsId,
      filter: ["all", ["!", ["has", "point_count"]], ["in", ["get", "icon"], ["literal", POI_ICON_KEYS]]],
      layout: {
        "icon-image": ["get", "icon"],
        "icon-size": POI_ICON_SIZE,
        "icon-allow-overlap": true,
        "icon-ignore-placement": true,
      },
    });

    this._registerClusterInteractivity(pointsId);
    this._registerPointInteractivity(`${pointsId}-unclustered`);
  }

  // Clicking a cluster zooms in just far enough to break it apart, the
  // standard MapLibre cluster-expansion pattern.
  _registerClusterInteractivity(pointsId) {
    const clusterId = `${pointsId}-clusters`;
    if (this._interactiveLayers.has(clusterId)) return;
    this._interactiveLayers.add(clusterId);

    this._map.on("click", clusterId, async (event) => {
      const feature = this._map.queryRenderedFeatures(event.point, { layers: [clusterId] })[0];
      if (!feature) return;
      const zoom = await this._map.getSource(pointsId).getClusterExpansionZoom(feature.properties.cluster_id);
      this._map.easeTo({ center: feature.geometry.coordinates, zoom });
    });
    this._map.on("mouseenter", clusterId, () => {
      this._map.getCanvas().style.cursor = "pointer";
    });
    this._map.on("mouseleave", clusterId, () => {
      this._map.getCanvas().style.cursor = "";
    });
  }

  // Registered once per layer id, ever — map.on(type, layerId, fn) is a
  // delegated listener that lives on the map itself and keeps matching
  // that layer id after setStyle() removes and (via _addLayers) re-adds
  // it, so re-registering on every re-add would stack duplicate popups.
  _registerPointInteractivity(layerId) {
    if (this._interactiveLayers.has(layerId)) return;
    this._interactiveLayers.add(layerId);

    this._map.on("click", layerId, (event) => {
      const feature = event.features[0];
      if (!feature) return;
      new Popup({ closeButton: true, maxWidth: "260px" })
        .setLngLat(event.lngLat)
        .setHTML(popupHtml(feature.properties))
        .addTo(this._map);
    });
    this._map.on("mouseenter", layerId, () => {
      this._map.getCanvas().style.cursor = "pointer";
    });
    this._map.on("mouseleave", layerId, () => {
      this._map.getCanvas().style.cursor = "";
    });
  }

  // Hover shows a quick summary (unlike a waypoint popup, which is
  // click-triggered — a track's summary describes the whole line, not
  // whatever point along it happens to get hovered, so there's no single
  // right anchor point worth waiting for a click on). Click opens the full
  // profile panel, which does need the click gesture to avoid flashing
  // open on every casual hover.
  _registerLineInteractivity(layerId) {
    if (this._interactiveLayers.has(layerId)) return;
    this._interactiveLayers.add(layerId);

    let popup = null;
    this._map.on("mouseenter", layerId, (event) => {
      this._map.getCanvas().style.cursor = "pointer";
      const feature = event.features[0];
      if (!feature) return;
      popup = new Popup({ closeButton: false, closeOnClick: false, maxWidth: "260px" })
        .setLngLat(event.lngLat)
        .setHTML(trackPopupHtml(feature.properties))
        .addTo(this._map);
    });
    this._map.on("mouseleave", layerId, () => {
      this._map.getCanvas().style.cursor = "";
      popup?.remove();
      popup = null;
    });
    this._map.on("click", layerId, (event) => {
      const feature = event.features[0];
      if (feature) this._profilePanel?.show(feature.properties);
    });
  }

  _removeLayers(path) {
    const linesId = linesSourceId(path);
    const pointsId = pointsSourceId(path);
    [
      `${linesId}-line`,
      `${pointsId}-clusters`,
      `${pointsId}-cluster-count`,
      `${pointsId}-unclustered`,
      `${pointsId}-unclustered-icon`,
    ].forEach((layerId) => {
      if (this._map.getLayer(layerId)) this._map.removeLayer(layerId);
    });
    if (this._map.getSource(linesId)) this._map.removeSource(linesId);
    if (this._map.getSource(pointsId)) this._map.removeSource(pointsId);

    this._pointsByPath.delete(path);
    this._updateLegend();
  }

  // Rebuilt from whichever visible files actually carry categorized
  // waypoints (a park4night/OsmAnd POI export) — a plain GPS track has none
  // and the legend just stays hidden.
  _updateLegend() {
    const categories = new Map(); // category name -> color
    for (const points of this._pointsByPath.values()) {
      for (const feature of points.features) {
        const category = feature.properties.category;
        if (category && !categories.has(category)) categories.set(category, feature.properties.color || TRACK_COLOR);
      }
    }

    this._legendContainer.innerHTML = "";
    this._legendContainer.hidden = categories.size === 0;
    [...categories].sort(([a], [b]) => a.localeCompare(b)).forEach(([category, color]) => {
      const item = document.createElement("div");
      item.className = "gpx-legend__item";
      const swatch = document.createElement("span");
      swatch.className = "gpx-legend__swatch";
      swatch.style.background = color; // a malformed/malicious value from an uploaded file is simply ignored by the CSSOM, never parsed as markup
      const label = document.createElement("span");
      label.textContent = category;
      item.appendChild(swatch);
      item.appendChild(label);
      this._legendContainer.appendChild(item);
    });
  }

  async _uploadFiles(fileList, folder) {
    // .zip: Garmin's bulk/FIT export format — the server expands it into
    // its .gpx/.fit entries, so it's accepted here even though the tree
    // never shows a .zip itself.
    const files = [...fileList].filter((file) => /\.(gpx|fit|zip)$/i.test(file.name));
    if (files.length === 0) return;

    this._setStatus(files.length === 1 ? "Uploading…" : `Uploading ${files.length} files…`);
    let tree = null;
    let failed = 0;

    for (const file of files) {
      const formData = new FormData();
      formData.append("file", file);
      formData.append("folder", folder);
      try {
        const response = await fetch(UPLOAD_URL, { method: "POST", body: formData });
        if (redirectIfUnauthorized(response)) return;
        if (!response.ok) throw new Error("upload failed");
        ({ tree } = await response.json());
      } catch (err) {
        failed += 1;
      }
    }

    if (tree) this._renderTree(tree);
    this._setStatus(failed > 0 ? `${failed} of ${files.length} uploads failed.` : "Uploaded.");
  }

  async _deleteFile(path) {
    if (!window.confirm(`Delete "${path}"?`)) return;

    const response = await fetch(gpxFileUrl(path), { method: "DELETE" });
    if (redirectIfUnauthorized(response)) return;
    if (!response.ok) return;

    if (this._visible.has(path)) {
      this._visible.delete(path);
      this._removeLayers(path);
    }
    const { tree } = await response.json();
    this._renderTree(tree);
  }

  async _deleteFolder(path) {
    if (!window.confirm(`Delete "${path}" and everything in it?`)) return;

    const response = await fetch(`/api/gpx/folder/${path.split("/").map(encodeURIComponent).join("/")}`, {
      method: "DELETE",
    });
    if (redirectIfUnauthorized(response)) return;
    if (!response.ok) return;

    const prefix = `${path}/`;
    [...this._visible].forEach((visiblePath) => {
      if (visiblePath === path || visiblePath.startsWith(prefix)) {
        this._visible.delete(visiblePath);
        this._removeLayers(visiblePath);
      }
    });

    const { tree } = await response.json();
    this._renderTree(tree);
  }

  async _moveFile(from, toFolder) {
    if (from === toFolder) return;

    const response = await fetch(MOVE_URL, {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: `from=${encodeURIComponent(from)}&to_folder=${encodeURIComponent(toFolder)}`,
    });
    if (redirectIfUnauthorized(response)) return;
    if (!response.ok) return;

    const { path: newPath, tree } = await response.json();
    if (this._visible.has(from)) {
      this._visible.delete(from);
      this._removeLayers(from);
      this._visible.add(newPath);
      this._addLayers(newPath);
    }
    this._renderTree(tree);
  }

  _setStatus(text) {
    this._uploadStatus.hidden = false;
    this._uploadStatus.textContent = text;
  }
}

// Write endpoints require login (see app.rb); a 401 means the session
// expired or was never established — send the user to log in rather than
// silently failing.
function redirectIfUnauthorized(response) {
  if (response.status !== 401) return false;
  window.location.href = "/login";
  return true;
}

// Rasterizes a hand-authored SVG icon to ImageData for map.addImage(), at a
// fixed square size (the source SVGs have no explicit width/height, just a
// viewBox, so one is injected — otherwise an <img> falls back to the CSS
// default replaced-element size instead of the viewBox's aspect).
async function svgToImageData(svgMarkup, size) {
  // xmlns is required here even though the other hand-drawn icons in this
  // app get away without it — those are inlined via innerHTML, where the
  // HTML parser assigns the SVG namespace from context, but a standalone
  // <img src="blob:..."> loads it as its own XML document, which needs an
  // explicit namespace or every browser refuses to decode it.
  const sized = svgMarkup.replace("<svg ", `<svg xmlns="http://www.w3.org/2000/svg" width="${size}" height="${size}" `);
  const url = URL.createObjectURL(new Blob([sized], { type: "image/svg+xml" }));
  try {
    const img = new Image();
    img.src = url;
    await img.decode();
    const canvas = document.createElement("canvas");
    canvas.width = size;
    canvas.height = size;
    const ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0, size, size);
    return ctx.getImageData(0, 0, size, size);
  } finally {
    URL.revokeObjectURL(url);
  }
}

function badgeImageId(color) {
  return `${BADGE_IMAGE_PREFIX}${color}`;
}

function linesSourceId(path) {
  return `gpx-${path}-lines`;
}

function pointsSourceId(path) {
  return `gpx-${path}-points`;
}

function gpxFileUrl(path) {
  return `/api/gpx/file/${path.split("/").map(encodeURIComponent).join("/")}`;
}

// properties come straight from an uploaded GPX file — untrusted input —
// so every value is escaped before landing in the popup's HTML.
function popupHtml({ name, description, time, category }) {
  const parts = [];
  if (name) parts.push(`<strong>${escapeHtml(name)}</strong>`);
  if (category) parts.push(`<p class="gpx-popup__category">${escapeHtml(category)}</p>`);
  if (description) parts.push(formatDescription(description));
  if (time) {
    const parsed = new Date(time);
    if (!Number.isNaN(parsed.getTime())) {
      parts.push(`<p class="gpx-popup__time">${escapeHtml(parsed.toLocaleString())}</p>`);
    }
  }
  return parts.length > 0 ? parts.join("") : "<em>No details</em>";
}

// properties come straight from an uploaded GPX/FIT file — untrusted input.
function trackPopupHtml({ name, activity_type, distance_meters, elevation_gain_meters, duration_secs }) {
  const parts = [];
  if (name) parts.push(`<strong>${escapeHtml(name)}</strong>`);

  const stats = [];
  if (activity_type) stats.push(escapeHtml(formatActivityType(activity_type)));
  if (typeof distance_meters === "number") stats.push(`${(distance_meters / 1000).toFixed(1)} km`);
  if (typeof elevation_gain_meters === "number") stats.push(`↑ ${Math.round(elevation_gain_meters)} m`);
  if (typeof duration_secs === "number") stats.push(formatDuration(duration_secs));
  if (stats.length > 0) parts.push(`<p>${stats.join(" · ")}</p>`);
  parts.push(`<p class="gpx-popup__time">Click for the full profile</p>`);

  return parts.length > 0 ? parts.join("") : "<em>No details</em>";
}

function formatDuration(totalSeconds) {
  const hours = Math.floor(totalSeconds / 3600);
  const minutes = Math.floor((totalSeconds % 3600) / 60);
  return hours > 0 ? `${hours}h ${minutes}m` : `${minutes}m`;
}

function escapeHtml(text) {
  const div = document.createElement("div");
  div.textContent = text;
  return div.innerHTML;
}

// park4night exports pack a free-text description and several lines of
// structured data (address, rating, services, activities, the listing URL)
// into one <desc> blob, separated only by newlines — rendered as one plain
// paragraph, it read as a wall of run-together text. Lines matching a
// recognizable "Label: value" or bare-URL shape get pulled out and rendered
// as their own visually distinct rows instead; anything else (the actual
// narrative, or a plain GPX file's <desc> with no such structure at all)
// stays exactly as before, one paragraph with line breaks — so this only
// ever adds structure, never loses any text.
const DESCRIPTION_META_LINE = /^(Rating|Services|Activities):\s*(.+)$/i;
const DESCRIPTION_LINK_LINE = /^https?:\/\/\S+$/;

function formatDescription(description) {
  const body = [];
  const meta = [];
  const links = [];

  for (const line of description.split("\n")) {
    const trimmed = line.trim();
    const metaMatch = trimmed.match(DESCRIPTION_META_LINE);
    if (DESCRIPTION_LINK_LINE.test(trimmed)) {
      links.push(trimmed);
    } else if (metaMatch) {
      meta.push(metaMatch);
    } else {
      body.push(line);
    }
  }

  const parts = [];
  const bodyText = body.join("\n").trim();
  if (bodyText) parts.push(`<p class="gpx-popup__description">${linkify(bodyText).replace(/\n/g, "<br>")}</p>`);
  if (meta.length > 0) {
    const rows = meta
      .map(
        ([, label, value]) =>
          `<div class="gpx-popup__meta-row"><span class="gpx-popup__meta-label">${escapeHtml(label)}</span> ${escapeHtml(value)}</div>`,
      )
      .join("");
    parts.push(`<div class="gpx-popup__meta">${rows}</div>`);
  }
  links.forEach((url) => parts.push(`<p class="gpx-popup__link">${urlToLink(url)}</p>`));

  return parts.join("");
}

// Turns bare URLs in untrusted text into safe <a> links: the string is
// split on the URL pattern and every piece is escaped — including the URL
// itself, both as href and as link text — before any HTML is assembled, so
// nothing bypasses escaping. The URL pattern excludes quote characters, so
// a matched URL can never break out of the href="..." attribute.
const URL_PATTERN = /(https?:\/\/[^\s<>"']+)/g;

function linkify(text) {
  return text
    .split(URL_PATTERN)
    .map((part, i) => (i % 2 === 1 ? urlToLink(part) : escapeHtml(part)))
    .join("");
}

function urlToLink(url) {
  // Keep trailing sentence punctuation (e.g. "...place/1234.") out of the
  // link itself.
  const [, core, trailing] = url.match(/^(.*?)([.,;:!?]*)$/);
  const href = escapeHtml(core);
  return `<a href="${href}" target="_blank" rel="noopener noreferrer">${href}</a>${escapeHtml(trailing)}`;
}