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 districtLayer = null;
let districtGeoJson = null;
let districtFetchStarted = false;
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: "", selectedDistricts: [], flats: [] };
  let flats = [];
  try {
    const parsed = JSON.parse(script.textContent || "[]");
    flats = Array.isArray(parsed) ? parsed : [];
  } catch (e) {
    flats = [];
  }
  const csv = script.dataset.selectedDistricts || "";
  const selectedDistricts = csv
    .split(",")
    .map((s) => s.trim())
    .filter(Boolean);
  return {
    csrf: script.dataset.csrf || "",
    selectedDistricts,
    flats,
  };
}

function fingerprintOf(data, selectedDistricts) {
  const flatPart = 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("|");
  // Include selected districts so changing the Bezirk filter re-renders the
  // overlay even when no flat-level field changed.
  return flatPart + "||" + selectedDistricts.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>`;
  }
  // Once the user has successfully applied, both action buttons disappear —
  // matches the list view, which hides them on success too.
  const applied = !!(f.status && f.status.chip === "ok");
  if (!applied) {
    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>`;
  }
  html += `</div>`;
  return html;
}

// Custom pin icon — divIcon with inline SVG so we can color it per-state
// without shipping marker images. Successful apply → green; everything else
// → brand blue. Sized + anchored to roughly match Leaflet's default pin.
function pinIcon(color) {
  const svg =
    `<svg width="28" height="38" viewBox="0 0 28 38" xmlns="http://www.w3.org/2000/svg">` +
      `<path d="M14 1C7 1 1 6.6 1 13.4c0 9.5 13 23.6 13 23.6s13-14.1 13-23.6C27 6.6 21 1 14 1z" ` +
            `fill="${color}" stroke="rgba(0,0,0,0.25)" stroke-width="1"/>` +
      `<circle cx="14" cy="13.5" r="4.5" fill="white"/>` +
    `</svg>`;
  return L.divIcon({
    className: "lazyflat-pin",
    html: svg,
    iconSize: [28, 38],
    iconAnchor: [14, 38],
    popupAnchor: [0, -34],
  });
}

function renderMarkers(payload) {
  if (!mapInstance) return;
  const { csrf, flats, selectedDistricts } = payload;
  const fp = fingerprintOf(flats, selectedDistricts);
  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;
    const applied = !!(f.status && f.status.chip === "ok");
    const color = applied ? "#1f8a4a" : "#2f8ae0";
    L.marker([f.lat, f.lng], { icon: pinIcon(color) })
      .addTo(markerLayer)
      .bindPopup(popupHtml(f, csrf), { minWidth: 240, closeButton: true });
  });

  ensureDistrictLayer(selectedDistricts);
}

// Faintly highlight Bezirke the user's filter EXCLUDES so the active
// selection is obvious at a glance. When the filter is empty (no district
// narrowing) the layer is hidden — nothing is excluded.
function districtStyle(selectedSet) {
  const showShading = selectedSet.size > 0;
  return (feature) => {
    const name = feature.properties && feature.properties.name;
    const excluded = showShading && !selectedSet.has(name);
    return {
      stroke: excluded,
      color: "#c84545",
      weight: 1,
      opacity: 0.6,
      fill: excluded,
      fillColor: "#fca5a5",
      fillOpacity: 0.3,
    };
  };
}

function ensureDistrictLayer(selectedDistricts) {
  if (!mapInstance) return;
  // Lazy-fetch the GeoJSON once. The /static/ asset is small (~80KB gzipped).
  if (!districtGeoJson && !districtFetchStarted) {
    districtFetchStarted = true;
    fetch("/static/berlin-districts.geojson")
      .then((r) => r.json())
      .then((g) => {
        districtGeoJson = g;
        ensureDistrictLayer(readMapData().selectedDistricts);
      })
      .catch((e) => console.warn("[lazyflat.map] district geojson load failed:", e));
    return;
  }
  if (!districtGeoJson) return;
  const set = new Set(selectedDistricts);
  if (districtLayer) {
    districtLayer.setStyle(districtStyle(set));
  } else {
    districtLayer = L.geoJSON(districtGeoJson, {
      style: districtStyle(set),
      interactive: false,
    });
    districtLayer.addTo(mapInstance);
    // Markers must paint above the overlay; re-add marker layer to ensure
    // it ends up on top regardless of insertion order.
    if (markerLayer) {
      markerLayer.bringToFront();
    }
  }
}

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);
  // Drop the "Leaflet" prefix — not legally required. OSM (ODbL) and CARTO's
  // basemap terms both REQUIRE attribution, so those credits stay.
  mapInstance.attributionControl.setPrefix(false);
  // 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;
    districtLayer = 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);