lazyflat/web/static/map.js

// lazyflat — Leaflet flat map.
//
// Two important properties:
// 1. The map must only be *built* once the container has a real size, because
//    Leaflet initialised on a hidden 0×0 element never loads its tiles.
// 2. The `#wohnungen-body` partial is re-swapped by HTMX every few seconds.
//    To avoid rebuilding Leaflet (and all its tile/marker state) on every
//    poll — which caused the whitescreen + out-of-frame glitches — the map
//    container itself is preserved across swaps via `hx-preserve`, and the
//    marker data is pushed in through a sibling <script id="flats-map-data">
//    element that DOES get swapped. On each swap we diff markers against the
//    fresh data and update in place.

let mapInstance = null;
let markerLayer = null;
let currentFingerprint = "";
const BERLIN_CENTER = [52.52, 13.405];
const BERLIN_ZOOM = 11;

function readMapData() {
  const script = document.getElementById("flats-map-data");
  if (!script) return { csrf: "", flats: [] };
  try {
    const flats = JSON.parse(script.textContent || "[]");
    return {
      csrf: script.dataset.csrf || "",
      flats: Array.isArray(flats) ? flats : [],
    };
  } catch (e) {
    return { csrf: "", flats: [] };
  }
}

function fingerprintOf(data) {
  return data
    .map((f) =>
      [f.id, f.lat, f.lng, (f.status && f.status.label) || "",
       f.can_apply ? 1 : 0, f.is_running ? 1 : 0].join(","),
    )
    .join("|");
}

function escHtml(s) {
  return String(s == null ? "" : s).replace(/[&<>"']/g, (c) => ({
    "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;",
  }[c]));
}

function popupHtml(f, csrf) {
  const addrText = f.address || f.link || "—";
  const addr = escHtml(addrText);
  const link = escHtml(f.link || "#");
  const metaParts = [];
  if (f.rooms) metaParts.push(escHtml(f.rooms) + " Zi");
  if (f.size)  metaParts.push(Math.round(f.size) + " m²");
  if (f.rent)  metaParts.push(Math.round(f.rent) + " €");
  const meta = metaParts.join(" · ");

  let html = `<div class="map-popup">` +
    `<a class="map-popup-title" href="${link}" target="_blank" rel="noopener">${addr}</a>`;
  if (meta) html += `<div class="map-popup-meta">${meta}</div>`;
  if (f.status) {
    html += `<div class="map-popup-status">` +
      `<span class="chip chip-${escHtml(f.status.chip)}">${escHtml(f.status.label)}</span>` +
      `</div>`;
  }
  html += `<div class="map-popup-actions">`;
  if (f.can_apply) {
    const confirm = `Bewerbung für ${addrText.replace(/"/g, "'")} starten?`;
    html +=
      `<form hx-post="/actions/apply" hx-target="#wohnungen-body" hx-swap="outerHTML">` +
        `<input type="hidden" name="csrf" value="${escHtml(csrf)}">` +
        `<input type="hidden" name="flat_id" value="${escHtml(f.id)}">` +
        `<button class="btn btn-primary text-xs" type="submit"` +
        (f.is_running ? " disabled" : "") +
        ` hx-confirm="${escHtml(confirm)}">` +
        (f.is_running ? "läuft…" : "Bewerben") +
        `</button>` +
      `</form>`;
  }
  html +=
    `<form hx-post="/actions/reject" hx-target="#wohnungen-body" hx-swap="outerHTML">` +
      `<input type="hidden" name="csrf" value="${escHtml(csrf)}">` +
      `<input type="hidden" name="flat_id" value="${escHtml(f.id)}">` +
      `<button class="btn btn-ghost text-xs" type="submit"` +
      ` hx-confirm="Ablehnen und aus der Liste entfernen?">Ablehnen</button>` +
    `</form>`;
  html += `</div></div>`;
  return html;
}

function renderMarkers(payload) {
  if (!mapInstance) return;
  const { csrf, flats } = payload;
  const fp = fingerprintOf(flats);
  if (fp === currentFingerprint) return;
  currentFingerprint = fp;
  const geo = flats.filter((f) => typeof f.lat === "number" && typeof f.lng === "number").length;
  console.log(`[lazyflat.map] rendering ${geo}/${flats.length} markers`);

  if (markerLayer) {
    markerLayer.clearLayers();
  } else {
    markerLayer = L.layerGroup().addTo(mapInstance);
  }

  flats.forEach((f) => {
    if (typeof f.lat !== "number" || typeof f.lng !== "number") return;
    L.marker([f.lat, f.lng])
      .addTo(markerLayer)
      .bindPopup(popupHtml(f, csrf), { minWidth: 240, closeButton: true });
  });
}

function buildMap(el) {
  console.log(`[lazyflat.map] building Leaflet instance (container ${el.clientWidth}×${el.clientHeight})`);
  mapInstance = L.map(el, {
    zoomControl: false,
    scrollWheelZoom: false,
    doubleClickZoom: false,
    boxZoom: false,
    touchZoom: false,
    keyboard: false,
  }).setView(BERLIN_CENTER, BERLIN_ZOOM);
  // CartoDB Voyager — clean, Google-Maps-ish base style.
  L.tileLayer("https://{s}.basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}{r}.png", {
    attribution: "© OpenStreetMap · © CARTO",
    subdomains: "abcd",
    maxZoom: 19,
  }).addTo(mapInstance);
  markerLayer = L.layerGroup().addTo(mapInstance);

  // Leaflet injects popup HTML directly into the DOM — HTMX hasn't scanned it,
  // so the hx-* attributes on Bewerben/Ablehnen wouldn't bind. Poke htmx.process
  // at the popup element each time one opens.
  mapInstance.on("popupopen", (e) => {
    const el = e.popup && e.popup.getElement();
    if (el && window.htmx) {
      window.htmx.process(el);
    }
  });
}

function ensureMap() {
  const el = document.getElementById("flats-map");
  if (!el || typeof L === "undefined") return;

  // Hidden (0×0) container → tiles would never load; retry after view toggle.
  if (el.clientHeight < 10) return;

  if (!mapInstance) {
    buildMap(el);
  } else if (mapInstance._container !== el) {
    // Container node changed (shouldn't happen thanks to hx-preserve, but
    // defensive: rebuild so Leaflet rebinds to the live element).
    try { mapInstance.remove(); } catch (e) {}
    mapInstance = null;
    markerLayer = null;
    currentFingerprint = "";
    buildMap(el);
  } else {
    try { mapInstance.invalidateSize(); } catch (e) {}
  }
  renderMarkers(readMapData());
}

function wireViewToggle() {
  document.querySelectorAll('input[name="view_mode"]').forEach((r) => {
    if (r.dataset.wired === "1") return;
    r.dataset.wired = "1";
    r.addEventListener("change", (e) => {
      try { localStorage.setItem("lazyflat_view_mode", e.target.value); } catch (err) {}
      requestAnimationFrame(() => requestAnimationFrame(ensureMap));
      setTimeout(ensureMap, 120);
      setTimeout(ensureMap, 400);
    });
  });
}

function restoreView() {
  let stored = null;
  try { stored = localStorage.getItem("lazyflat_view_mode"); } catch (e) {}
  if (!stored) return;
  const el = document.querySelector(`input[name="view_mode"][value="${stored}"]`);
  if (el && !el.checked) {
    el.checked = true;
    requestAnimationFrame(() => requestAnimationFrame(ensureMap));
    setTimeout(ensureMap, 120);
    setTimeout(ensureMap, 400);
  }
}

function onReady() {
  wireViewToggle();
  restoreView();
  ensureMap();
}

document.addEventListener("DOMContentLoaded", onReady);
document.body && document.body.addEventListener("htmx:afterSwap", onReady);