// ===== Map setup =====
const map = L.map("map").setView([55.6761, 12.5683], 13);

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

// ===== UI =====
const statusEl = document.getElementById("status");
const alertsEl = document.getElementById("presenceAlerts");

// ===== State =====
let simTime = 0;
let running = false;
let timer = null;

// Group events per vehicle
const vehicles = {};
for (const ev of VEHICLE_EVENTS) {
  if (!vehicles[ev.vehicle]) vehicles[ev.vehicle] = [];
  vehicles[ev.vehicle].push(ev);
}

// Sort each vehicle timeline
for (const v in vehicles) {
  vehicles[v].sort((a, b) => a.ts - b.ts);
}

// Runtime objects
const runtime = {};

function metersBetween(lat1, lon1, lat2, lon2) {
  const R = 6371000;
  const toRad = x => x * Math.PI / 180;
  const dLat = toRad(lat2 - lat1);
  const dLon = toRad(lon2 - lon1);
  const a =
    Math.sin(dLat / 2) ** 2 +
    Math.cos(toRad(lat1)) *
      Math.cos(toRad(lat2)) *
      Math.sin(dLon / 2) ** 2;
  return 2 * R * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
}

function distanceToBoundsMeters(lat, lon, bounds) {
  const clampedLat = Math.max(bounds.getSouth(), Math.min(bounds.getNorth(), lat));
  const clampedLon = Math.max(bounds.getWest(), Math.min(bounds.getEast(), lon));
  return metersBetween(lat, lon, clampedLat, clampedLon);
}

function farthestCornerDistanceMeters(lat, lon, bounds) {
  const corners = [
    bounds.getSouthWest(),
    bounds.getSouthEast(),
    bounds.getNorthWest(),
    bounds.getNorthEast()
  ];
  let max = 0;
  for (const c of corners) {
    const d = metersBetween(lat, lon, c.lat, c.lng);
    if (d > max) max = d;
  }
  return max;
}

// ===== Core classification =====
function getPresenceState(lat, lon, uncertaintyM) {
  const bounds = map.getBounds();
  const inside = bounds.contains([lat, lon]);

  if (inside) return "inside";

  if (uncertaintyM > 0) {
    const dist = distanceToBoundsMeters(lat, lon, bounds);

    if (dist <= uncertaintyM) {
      const far = farthestCornerDistanceMeters(lat, lon, bounds);

      if (far <= uncertaintyM) return "cover_all";
      return "overlap";
    }
  }

  return "outside";
}

// ===== Render =====
function updateVehicles() {
  alertsEl.innerHTML = "";

  for (const name in vehicles) {
    const events = vehicles[name];

    // Find latest event <= simTime
    let ev = null;
    for (const e of events) {
      if (e.ts <= simTime) ev = e;
    }

    if (!ev) continue; // not yet appeared

    const state = getPresenceState(ev.lat, ev.lon, ev.uncertaintyM);

    // Ensure runtime object exists
    if (!runtime[name]) {
      runtime[name] = {
        marker: L.marker([ev.lat, ev.lon])
      };
    }

    const r = runtime[name];

    if (state === "inside") {
      r.marker.setLatLng([ev.lat, ev.lon]);
      if (!map.hasLayer(r.marker)) {
        r.marker.addTo(map);
      }
    } else {
      if (map.hasLayer(r.marker)) {
        map.removeLayer(r.marker);
      }
    }

    // ===== Corner panel =====
    if (state === "overlap" || state === "cover_all") {
      const div = document.createElement("div");
      div.className = "alert-item";

      if (state === "cover_all") {
        div.innerHTML = `<strong>${name}</strong> Usikkerhed dækker hele kortet`;
      } else {
        div.innerHTML = `<strong>${name}</strong> Kan være i kortudsnittet`;
      }

      alertsEl.appendChild(div);
    }
  }

  statusEl.textContent = `Tid: ${simTime}s`;
}

// ===== Simulation =====
function tick() {
  simTime += 1;
  updateVehicles();
}

document.getElementById("playBtn").onclick = () => {
  if (!running) {
    running = true;
    timer = setInterval(tick, 1000);
  }
};

document.getElementById("pauseBtn").onclick = () => {
  running = false;
  clearInterval(timer);
};

document.getElementById("resetBtn").onclick = () => {
  simTime = 0;
  running = false;
  clearInterval(timer);

  // remove markers
  for (const name in runtime) {
    if (map.hasLayer(runtime[name].marker)) {
      map.removeLayer(runtime[name].marker);
    }
  }

  updateVehicles();
};

// Initial draw
updateVehicles();