import { Popup } from "/vendor/maplibre-gl/maplibre-gl.mjs";
import { OVERLAYS_ICON, WIKI_ICON, MAP_MARKER_ICON } from "/js/icons.js";
import { notifySidePanelOpen, onlyOneSidePanelOpen } from "/js/panels.js";
import { svgToImageData, badgeImageId, escapeHtml } from "/js/gpx.js";

const ICON_IMAGE_SIZE = 48; // rasterized once at this size, rendered much smaller by icon-size below
const ICON_SIZE = 0.3; // 48 * 0.3 = ~14px, sized to sit inside the marker badge below
const MARKER_SIZE = 0.55;

const WIKI_SOURCE_ID = "wiki-points";
const WIKI_ICON_ID = "wiki-icon";
const WIKI_BADGE_COLOR = "#795548";

// A sidebar side panel (same shell as LiveTrackPanelControl/#livetrack-panel)
// listing live map layers that aren't a base map, a Tracks & Points file, or
// a fixed on/off toggle (Hillshade) — each one refetched from its own
// source as the map moves, not something to add/remove/reorder the way
// Tracks & Points' file tree is, so this is a plain checklist. Wikipedia is
// the first entry; more can join the same #overlays-panel list later
// without a redesign.
export class OverlaysControl {
  constructor(map) {
    this._map = map;
    this._wikiEnabled = false; // the checkbox's own state
    this._wikiMoveHandler = null; // the moveend listener driving its live refetch, while enabled
    this._wikiRequestSeq = 0; // ignores an in-flight refetch a newer one has already superseded
    this._interactivityRegistered = false; // guards against double-registering the click/hover handlers below across enable/disable cycles

    // setStyle() (switching the Online/Offline base map) tears down all
    // custom sources/layers/images — put the wiki layer back afterwards,
    // same as GpxPanelControl does for visible GPX files.
    map.on("style.load", () => {
      if (this._wikiEnabled) this._addWikiLayers().then(() => this._refreshWikiLayer());
    });
  }

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

    this._panel = document.getElementById("overlays-panel");
    this._panel
      .querySelector(".basemap-panel__close")
      .addEventListener("click", () => this._togglePanel(false));
    this._wikiToggle = this._panel.querySelector(".overlays-panel__wiki-toggle");
    this._wikiToggle.addEventListener("change", (event) => {
      if (event.target.checked) this._enableWikiLayer();
      else this._disableWikiLayer();
    });

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

    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);
  }

  // Called once map.js's one-time GET /api/kiwix check resolves — disables
  // (rather than hides) the checkbox rather than the whole panel/icon,
  // since a future second overlay could still be usable with no kiwix-serve
  // configured at all.
  setWikiAvailable(available) {
    this._wikiToggle.disabled = !available;
    if (!available) this._wikiToggle.closest(".overlays-panel__item").title = "No kiwix-serve configured";
  }

  async _enableWikiLayer() {
    this._wikiEnabled = true;
    await this._addWikiLayers();
    this._wikiMoveHandler = () => this._refreshWikiLayer();
    this._map.on("moveend", this._wikiMoveHandler);
    this._refreshWikiLayer();
  }

  _disableWikiLayer() {
    this._wikiEnabled = false;
    if (this._wikiMoveHandler) {
      this._map.off("moveend", this._wikiMoveHandler);
      this._wikiMoveHandler = null;
    }
    this._removeWikiLayers();
  }

  async _registerWikiIcon() {
    if (this._map.hasImage(WIKI_ICON_ID)) return;
    const whiteSvg = WIKI_ICON.replace(/currentColor/g, "#fff");
    const imageData = await svgToImageData(whiteSvg, ICON_IMAGE_SIZE);
    if (!this._map.hasImage(WIKI_ICON_ID)) this._map.addImage(WIKI_ICON_ID, imageData);
  }

  // Same one-image-per-color story as gpx.js's own _registerBadgeColors,
  // just for this layer's single fixed color rather than a set of them
  // discovered from a file.
  async _registerWikiBadge() {
    const id = badgeImageId(WIKI_BADGE_COLOR);
    if (this._map.hasImage(id)) return;
    const coloredSvg = MAP_MARKER_ICON.replace(/currentColor/g, WIKI_BADGE_COLOR);
    const imageData = await svgToImageData(coloredSvg, ICON_IMAGE_SIZE);
    if (!this._map.hasImage(id)) this._map.addImage(id, imageData);
  }

  async _addWikiLayers() {
    if (this._map.getSource(WIKI_SOURCE_ID)) return;
    await Promise.all([this._registerWikiIcon(), this._registerWikiBadge()]);
    if (this._map.getSource(WIKI_SOURCE_ID)) return; // style.load raced this while awaiting

    this._map.addSource(WIKI_SOURCE_ID, { type: "geojson", data: { type: "FeatureCollection", features: [] } });
    this._map.addLayer({
      id: `${WIKI_SOURCE_ID}-badge`,
      type: "symbol",
      source: WIKI_SOURCE_ID,
      layout: {
        "icon-image": badgeImageId(WIKI_BADGE_COLOR),
        "icon-size": MARKER_SIZE,
        "icon-allow-overlap": true,
        "icon-ignore-placement": true,
      },
    });
    this._map.addLayer({
      id: `${WIKI_SOURCE_ID}-icon`,
      type: "symbol",
      source: WIKI_SOURCE_ID,
      layout: { "icon-image": WIKI_ICON_ID, "icon-size": ICON_SIZE, "icon-allow-overlap": true, "icon-ignore-placement": true },
    });
    this._registerWikiInteractivity(`${WIKI_SOURCE_ID}-badge`);
  }

  _removeWikiLayers() {
    [`${WIKI_SOURCE_ID}-badge`, `${WIKI_SOURCE_ID}-icon`].forEach((layerId) => {
      if (this._map.getLayer(layerId)) this._map.removeLayer(layerId);
    });
    if (this._map.getSource(WIKI_SOURCE_ID)) this._map.removeSource(WIKI_SOURCE_ID);
  }

  _registerWikiInteractivity(layerId) {
    if (this._interactivityRegistered) return;
    this._interactivityRegistered = true;

    this._map.on("click", layerId, (event) => {
      const feature = event.features[0];
      if (!feature) return;
      new Popup({ closeButton: true, maxWidth: "260px" }).setLngLat(event.lngLat).setHTML(wikiPopupHtml(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 = "";
    });
  }

  // seq guards against an out-of-order response — a fast second pan's
  // fetch resolving before a slower first one's — overwriting newer data
  // with stale data; not a full abort-in-flight setup, just the ordering
  // guarantee this actually needs.
  async _refreshWikiLayer() {
    const seq = ++this._wikiRequestSeq;
    const bounds = this._map.getBounds();
    const params = new URLSearchParams({
      south: bounds.getSouth(),
      west: bounds.getWest(),
      north: bounds.getNorth(),
      east: bounds.getEast(),
    });

    let geojson;
    try {
      geojson = await (await fetch(`/api/kiwix/nearby?${params}`)).json();
    } catch {
      return;
    }
    if (seq !== this._wikiRequestSeq) return;

    const source = this._map.getSource(WIKI_SOURCE_ID);
    if (source) source.setData(geojson);
  }
}

// properties come from GET /api/kiwix/nearby — kiwix-serve's own ZIM
// content, not an uploaded file, but still untrusted-by-convention like
// every other popup builder in this app (escaped all the same). link
// already carries the /kiwix prefix this app proxies (lib/maptool/kiwix.rb).
function wikiPopupHtml({ name, link }) {
  const parts = [`<div class="gpx-popup__header"><strong>${escapeHtml(name)}</strong></div>`];
  parts.push(`<p class="gpx-popup__wiki"><a href="${escapeHtml(link)}" target="_blank" rel="noopener noreferrer">Read on Wikipedia →</a></p>`);
  return parts.join("");
}