// Leaflet map: numbered markers for located stops, a polyline through them,
// per-leg km labels, and a leg-by-leg list. Graceful empty state when the
// trip has no located entries yet. Uses the /route response from tctx.route.
import { el } from '../dom.js';
import { typeInfo } from '../format.js';

export function renderMap(tctx) {
  const route = tctx.route || { stops: [], legs: [], totalKm: 0 };
  const stops = route.stops || [];

  const section = el('section', { class: 'card map-section' });
  section.appendChild(
    el(
      'div',
      { class: 'section-head' },
      el('h2', {}, 'Map'),
      el('p', { class: 'muted' }, stops.length
        ? `${stops.length} located ${stops.length === 1 ? 'stop' : 'stops'} · ${fmtKm(route.totalKm)} km total`
        : 'Add a location to an entry to see it here.'),
    ),
  );

  if (!stops.length) {
    section.appendChild(
      el(
        'div',
        { class: 'map-empty' },
        el('div', { class: 'empty-icon' }, '🗺️'),
        el('p', {}, 'No located entries yet.'),
        el('p', { class: 'muted' }, 'Open a day, add an entry, and give it a location to plot it on the map.'),
      ),
    );
    return section;
  }

  const mapDiv = el('div', { class: 'leaflet-map', id: `map-${tctx.tripId}` });
  section.appendChild(mapDiv);
  section.appendChild(legList(route, stops));

  // Leaflet needs the container attached with a real size, so init on the
  // next tick after this section is mounted into the page.
  setTimeout(() => initMap(mapDiv, route, stops), 0);

  return section;
}

function initMap(mapDiv, route, stops) {
  const L = window.L;
  if (!L) {
    mapDiv.appendChild(el('p', { class: 'muted' }, 'Map library failed to load.'));
    return;
  }

  const map = L.map(mapDiv, { scrollWheelZoom: true });
  L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
    attribution: '© OpenStreetMap contributors',
    maxZoom: 19,
  }).addTo(map);

  // Geometry is driven by stop ORDER, not entryId: a multi-leg flight expands
  // into several airport stops that all share the same entryId, so keying by
  // entryId would collapse them.
  const points = stops.map((s) => [s.lat, s.lng]);
  stops.forEach((stop, i) => {
    const info = typeInfo(stop.type);
    L.marker(points[i], { icon: numberedIcon(L, i + 1, info.color) })
      .addTo(map)
      .bindPopup(popupHtml(stop, info));
  });

  // One polyline per measured leg, styled by mode (air = dashed blue, ground =
  // solid teal), each with a km label at its midpoint. Legs are matched to
  // consecutive non-coincident stop pairs (skip <0.05km, the server's rule).
  const legs = route.legs || [];
  let li = 0;
  for (let i = 0; i < stops.length - 1 && li < legs.length; i++) {
    const a = points[i];
    const b = points[i + 1];
    if (haversineKm(a[0], a[1], b[0], b[1]) < 0.05) continue;
    const leg = legs[li];
    li += 1;
    const air = leg.mode === 'air';
    L.polyline([a, b], {
      color: air ? '#2563eb' : '#0f766e',
      weight: 3,
      opacity: 0.75,
      dashArray: air ? '6 6' : null,
    }).addTo(map);
    const mid = [(a[0] + b[0]) / 2, (a[1] + b[1]) / 2];
    L.marker(mid, { icon: kmLabel(L, leg.km), interactive: false }).addTo(map);
  }

  if (points.length === 1) {
    map.setView(points[0], 10);
  } else {
    map.fitBounds(L.latLngBounds(points).pad(0.2));
  }
  map.invalidateSize();
}

// Great-circle km — mirrors the server rule for skipping zero-distance legs.
function haversineKm(lat1, lng1, lat2, lng2) {
  const R = 6371;
  const toRad = (d) => (d * Math.PI) / 180;
  const dLat = toRad(lat2 - lat1);
  const dLng = toRad(lng2 - lng1);
  const a = Math.sin(dLat / 2) ** 2 +
    Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLng / 2) ** 2;
  return 2 * R * Math.asin(Math.min(1, Math.sqrt(a)));
}

function numberedIcon(L, n, color) {
  return L.divIcon({
    className: 'map-pin-wrap',
    html: `<span class="map-pin" style="background:${color}">${n}</span>`,
    iconSize: [26, 26],
    iconAnchor: [13, 26],
    popupAnchor: [0, -24],
  });
}

function kmLabel(L, km) {
  return L.divIcon({
    className: 'km-label-wrap',
    html: `<span class="km-label">${fmtKm(km)} km</span>`,
    iconSize: [0, 0],
  });
}

// Built from server-provided fields; escape to keep the popup injection-safe.
function popupHtml(stop, info) {
  const isAirport = stop.kind === 'airport' && stop.code;
  const heading = isAirport ? `${info.icon} ${esc(stop.code)}` : `${info.icon} ${esc(stop.title)}`;
  const sub = isAirport
    ? `${esc(info.label)} · ${esc(stop.date)}${stop.title ? ` · ${esc(stop.title)}` : ''}`
    : `${esc(info.label)} · ${esc(stop.date)}`;
  const locIcon = isAirport ? '✈️' : '📍';
  return (
    `<div class="map-popup">` +
    `<strong>${heading}</strong>` +
    `<div class="map-popup-sub">${sub}</div>` +
    (stop.location_name ? `<div class="map-popup-loc">${locIcon} ${esc(stop.location_name)}</div>` : '') +
    `</div>`
  );
}

function stopLabel(stop) {
  if (stop.kind === 'airport' && stop.code) return stop.code;
  return stop.location_name || stop.title || '?';
}

function legList(route, stops) {
  const legs = route.legs || [];
  if (!legs.length) return el('div', { class: 'leg-list-empty muted' }, 'A single stop — no legs to measure yet.');

  const wrap = el('div', { class: 'leg-list' }, el('h3', {}, 'Legs'));
  let li = 0;
  let shown = 0;
  for (let i = 0; i < stops.length - 1 && li < legs.length; i++) {
    const a = stops[i];
    const b = stops[i + 1];
    if (haversineKm(a.lat, a.lng, b.lat, b.lng) < 0.05) continue;
    const leg = legs[li++];
    shown += 1;
    const air = leg.mode === 'air';
    wrap.appendChild(
      el(
        'div',
        { class: 'leg-row' },
        el('span', { class: 'leg-index' }, String(shown)),
        el('span', { class: 'leg-mode', title: air ? 'Flight' : 'Ground' }, air ? '✈️' : '🚗'),
        el('span', { class: 'leg-path' }, stopLabel(a), ' → ', stopLabel(b)),
        el('span', { class: 'leg-km' }, `${fmtKm(leg.km)} km`),
      ),
    );
  }
  return wrap;
}

function fmtKm(n) {
  return (Math.round((Number(n) || 0) * 10) / 10).toLocaleString();
}

function esc(str) {
  return String(str == null ? '' : str)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;');
}