// fleet-core.js
// Shared client primitives for the fleet-platform dashboards.
//
// Server-driven rendering per PRD §8: the API attaches `marker_color`,
// `show_arrow`, `style_class`, etc. The JS just paints what it's told.
//
// Markers (three MapLibre layers stacked on one source):
//   1. circle — `marker_color` (cost-centre colour when moving, grey otherwise)
//   2. arrow  — white SVG icon, rotated by `heading_deg`, visible only when
//               `show_arrow == true`
//   3. label  — `plate_short` (last 4 chars of plate), below the circle

const STORAGE_ACCESS  = 'fleet.accessToken';
const STORAGE_REFRESH = 'fleet.refreshToken';
const STORAGE_EXPIRES = 'fleet.expiresAt';

const VEHICLE_SOURCE = 'vehicles';

/* ---------- authClient ---------- */

export const authClient = {
  isAuthenticated() {
    const expiresAt = Number(localStorage.getItem(STORAGE_EXPIRES) || 0);
    return localStorage.getItem(STORAGE_ACCESS) !== null && Date.now() < expiresAt * 1000;
  },

  async login(username, password) {
    const body = new URLSearchParams({ username, password });
    const res = await fetch('/api/auth/token', {
      method: 'POST',
      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      body,
    });
    if (!res.ok) {
      const detail = await res.json().catch(() => ({ detail: 'login failed' }));
      throw new Error(detail.detail || 'login failed');
    }
    const payload = await res.json();
    const expiresAt = Math.floor(Date.now() / 1000) + Number(payload.expires_in || 900);
    localStorage.setItem(STORAGE_ACCESS, payload.access_token);
    localStorage.setItem(STORAGE_REFRESH, payload.refresh_token);
    localStorage.setItem(STORAGE_EXPIRES, String(expiresAt));
  },

  logout() {
    localStorage.removeItem(STORAGE_ACCESS);
    localStorage.removeItem(STORAGE_REFRESH);
    localStorage.removeItem(STORAGE_EXPIRES);
  },

  getToken() {
    return localStorage.getItem(STORAGE_ACCESS);
  },

  requireSession({ loginPath = '/login.html' } = {}) {
    if (!this.isAuthenticated()) {
      window.location.href = loginPath;
      return false;
    }
    return true;
  },
};

export async function apiFetch(path, { params, ...opts } = {}) {
  const url = new URL(path, window.location.origin);
  if (params) {
    for (const [k, v] of Object.entries(params)) {
      if (v !== undefined && v !== null && v !== '') {
        url.searchParams.set(k, typeof v === 'string' ? v : JSON.stringify(v));
      }
    }
  }
  const token = localStorage.getItem(STORAGE_ACCESS);
  const res = await fetch(url.toString(), {
    ...opts,
    headers: {
      ...(opts.headers || {}),
      ...(token ? { Authorization: `Bearer ${token}` } : {}),
      Accept: 'application/json',
    },
  });
  if (res.status === 401) {
    authClient.logout();
    window.location.href = '/login.html';
    throw new Error('unauthorized');
  }
  if (!res.ok) throw new Error(`${res.status} ${res.statusText}`);
  return res.json();
}

/* ---------- map setup ---------- */

function _addArrowImage(map) {
  if (map.hasImage('arrow-white')) return;
  const svg = `<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24">
    <path d="M12 2 L19.5 19.5 L12 15.5 L4.5 19.5 Z"
          fill="white" stroke="rgba(0,0,0,0.55)" stroke-width="1.2" stroke-linejoin="round"/>
  </svg>`;
  const img = new Image(24, 24);
  img.onload = () => { if (!map.hasImage('arrow-white')) map.addImage('arrow-white', img); };
  img.src = 'data:image/svg+xml;utf8,' + encodeURIComponent(svg);
}

export function initMap(elementId, opts = {}) {
  const center = opts.center || [36.8172, -1.2864]; // Nairobi
  const zoom = opts.zoom ?? 7;
  const styleUrl = opts.styleUrl
    || 'https://basemaps.cartocdn.com/gl/dark-matter-gl-style/style.json';

  // eslint-disable-next-line no-undef
  const map = new maplibregl.Map({
    container: elementId,
    style: styleUrl,
    center,
    zoom,
    attributionControl: true,
  });

  map.on('load', () => {
    _addArrowImage(map);

    map.addSource(VEHICLE_SOURCE, {
      type: 'geojson',
      data: { type: 'FeatureCollection', features: [] },
    });

    map.addLayer({
      id: 'vehicles-circle',
      type: 'circle',
      source: VEHICLE_SOURCE,
      paint: {
        // Scale dot size with zoom — small at country/city overview to keep
        // the Nairobi cluster legible, full size once you're zoomed into a
        // neighbourhood. text-offset on the label layer is in ems so it
        // scales naturally with text-size; no extra interpolation needed.
        'circle-radius': [
          'interpolate', ['linear'], ['zoom'],
          5, 2,
          9, 4,
          12, 7,
          15, 13,
          18, 20,
        ],
        'circle-color': ['get', 'marker_color'],
        'circle-stroke-color': '#0b1220',
        'circle-stroke-width': [
          'interpolate', ['linear'], ['zoom'],
          5, 0.5,
          12, 1.5,
          16, 2,
        ],
      },
    });

    map.addLayer({
      id: 'vehicles-arrow',
      type: 'symbol',
      source: VEHICLE_SOURCE,
      filter: ['==', ['get', 'show_arrow'], true],
      layout: {
        'icon-image': 'arrow-white',
        'icon-rotate': ['coalesce', ['get', 'heading_deg'], 0],
        'icon-rotation-alignment': 'map',
        'icon-allow-overlap': true,
        'icon-ignore-placement': true,
        'icon-size': [
          'interpolate', ['linear'], ['zoom'],
          5, 0.2,
          12, 0.45,
          15, 0.7,
          18, 1.0,
        ],
      },
    });

    map.addLayer({
      id: 'vehicles-label',
      type: 'symbol',
      source: VEHICLE_SOURCE,
      // Plate-tail labels add nothing but clutter at city-overview zoom —
      // skip them until you're zoomed in enough that they don't overlap.
      minzoom: 11,
      layout: {
        'text-field': ['get', 'plate_short'],
        'text-font': ['Open Sans Regular', 'Arial Unicode MS Regular'],
        'text-size': [
          'interpolate', ['linear'], ['zoom'],
          11, 8,
          14, 11,
          17, 14,
        ],
        'text-offset': [0, 1.7],
        'text-anchor': 'top',
        'text-allow-overlap': true,
        'text-ignore-placement': true,
        'text-letter-spacing': 0.04,
      },
      paint: {
        'text-color': '#f1f5f9',
        'text-halo-color': '#0f172a',
        'text-halo-width': 2,
      },
    });

    _wireHoverPopup(map);
  });

  return map;
}

/* ---------- hover popup ---------- */

function _wireHoverPopup(map) {
  // eslint-disable-next-line no-undef
  const popup = new maplibregl.Popup({
    closeButton: false,
    closeOnClick: false,
    offset: 16,
    className: 'fleet-popup',
  });

  const show = (e) => {
    const f = e.features && e.features[0];
    if (!f) return;
    map.getCanvas().style.cursor = 'pointer';
    popup.setLngLat(f.geometry.coordinates).setHTML(_popupHtml(f.properties)).addTo(map);
  };
  const hide = () => { map.getCanvas().style.cursor = ''; popup.remove(); };

  for (const layer of ['vehicles-circle', 'vehicles-arrow', 'vehicles-label']) {
    map.on('mouseenter', layer, show);
    map.on('mousemove',  layer, show);
    map.on('mouseleave', layer, hide);
  }
}

function _esc(s) {
  return String(s ?? '').replace(/[&<>"']/g, c => `&#${c.charCodeAt(0)};`);
}

function _formatAge(sec) {
  if (sec == null) return '—';
  const s = Math.max(0, Math.round(Number(sec)));
  if (s < 60) return `${s}s ago`;
  if (s < 3600) return `${Math.round(s / 60)}m ago`;
  if (s < 86400) return `${Math.round(s / 3600)}h ago`;
  return `${Math.round(s / 86400)}d ago`;
}

function _formatLocal(iso) {
  if (!iso) return '—';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return iso;
  return d.toLocaleString('en-GB', {
    timeZone: 'Africa/Nairobi',
    year: 'numeric', month: '2-digit', day: '2-digit',
    hour: '2-digit', minute: '2-digit', second: '2-digit',
    hour12: false,
  }).replace(',', '');
}

function _popupHtml(props) {
  const state = String(props.operational_state || 'unknown').toLowerCase();
  const speed = Math.round(Number(props.speed_kmh || 0));
  const pillText = state === 'moving'
    ? `MOVING · ${speed} KMH`
    : (state === 'parked' ? 'PARKED' : state.toUpperCase());

  const tagLine = [props.cost_centre, props.assigned_city]
    .filter(Boolean).join(' · ').toLowerCase();
  const addressLine = props.address_short || props.address || null;

  const headingPart = (props.heading_deg != null)
    ? `heading ${Math.round(Number(props.heading_deg))}°` : null;
  const sigPart = (props.gps_signal != null) ? `gps signal ${props.gps_signal}` : null;
  const headingLine = [headingPart, sigPart].filter(Boolean).join(' · ');

  let mileageLine = null;
  if (props.current_mileage_km != null) {
    const km = Number(props.current_mileage_km);
    if (!Number.isNaN(km)) {
      mileageLine = `${km.toLocaleString('en-US', { maximumFractionDigits: 2 })} km on the clock`;
    }
  }

  const sourceLine = [props.mc_type, props.device_type].filter(Boolean).join(' · ');
  const ageLine = `last fix ${_formatAge(props.age_sec)} · ${_formatLocal(props.occurred_at)}`;

  return `
    <div class="popup-card">
      <div class="popup-header">
        <strong class="popup-plate">${_esc(props.plate)}</strong>
        <span class="popup-pill pill-${_esc(state)}">${_esc(pillText)}</span>
      </div>
      ${props.driver_name ? `<div class="popup-driver">${_esc(props.driver_name)}</div>` : ''}
      ${tagLine ? `<div class="popup-meta">${_esc(tagLine)}</div>` : ''}
      ${addressLine ? `<div class="popup-address">${_esc(addressLine)}</div>` : ''}
      ${headingLine ? `<div class="popup-row">${_esc(headingLine)}</div>` : ''}
      ${mileageLine ? `<div class="popup-row">${_esc(mileageLine)}</div>` : ''}
      <div class="popup-row">${_esc(ageLine)}</div>
      ${sourceLine ? `<div class="popup-row">source ${_esc(sourceLine)}</div>` : ''}
    </div>
  `;
}

/* ---------- render ---------- */

export function renderView(map, payload, { summaryRoot, sloRoot } = {}) {
  if (!payload || !payload.geojson) return;
  const src = map.getSource(VEHICLE_SOURCE);
  if (src) src.setData(payload.geojson);
  if (summaryRoot) _renderSummary(summaryRoot, payload.summary || {});
  if (sloRoot) _renderSlos(sloRoot, payload.slo_status || {});
}

function _renderSummary(root, summary) {
  const tiles = [
    { label: 'Active', value: summary.total_active ?? '—' },
    { label: 'Moving', value: summary.moving ?? '—' },
    { label: 'Parked', value: summary.parked ?? '—' },
    { label: 'Offline', value: summary.offline ?? '—' },
    { label: 'Below freshness SLO', value: summary.below_freshness_slo ?? '—' },
  ];
  root.innerHTML = tiles
    .map(t => `
      <div class="tile">
        <div class="tile-label">${t.label}</div>
        <div class="tile-value">${t.value}</div>
      </div>`).join('');
}

function _renderSlos(root, slos) {
  const entries = Object.entries(slos);
  if (entries.length === 0) {
    root.innerHTML = '<div class="slo-empty">SLO data not yet available</div>';
    return;
  }
  root.innerHTML = entries.map(([metric, info]) => {
    const status = info.status || 'unknown';
    const current = info.current ?? '—';
    const threshold = info.threshold ?? '—';
    return `
      <div class="slo slo-${status}">
        <span class="slo-name">${metric}</span>
        <span class="slo-value">${current} / ${threshold}</span>
        <span class="slo-status">${status}</span>
      </div>`;
  }).join('');
}

/* ---------- filters ---------- */

export function initFilters(formEl, onChange) {
  const handler = () => {
    const fd = new FormData(formEl);
    const filters = {};
    for (const [k, v] of fd.entries()) if (v) filters[k] = v;
    onChange(filters);
  };
  formEl.addEventListener('change', handler);
  formEl.addEventListener('submit', (e) => { e.preventDefault(); handler(); });
}

/* ---------- trip panel ---------- */

const TRIP_PATH_SOURCE = 'trip-path-source';
const TRIP_MARKER_SOURCE = 'trip-marker-source';
const TRIP_PATH_LAYER = 'trip-path-line';
const TRIP_MARKER_LAYER = 'trip-marker-dot';
const TRIP_ANIM_MS = 10000;

let _tripAnimRAF = null;
let _tripState = { vehicleId: null, date: null, payload: null };

export function initTripPanel(map, panelRoot) {
  const els = {
    plate:   panelRoot.querySelector('#trip-plate'),
    driver:  panelRoot.querySelector('#trip-driver'),
    date:    panelRoot.querySelector('#trip-date'),
    csv:     panelRoot.querySelector('#trip-csv'),
    totals:  panelRoot.querySelector('#trip-totals'),
    list:    panelRoot.querySelector('#trip-list'),
    close:   panelRoot.querySelector('#trip-close'),
  };

  els.close.addEventListener('click', () => _closeTripPanel(map, panelRoot, els));
  els.date.addEventListener('change', () => {
    if (_tripState.vehicleId) {
      _loadTrips(map, panelRoot, els, _tripState.vehicleId, els.date.value);
    }
  });
  els.csv.addEventListener('click', () => {
    if (_tripState.vehicleId) _downloadTripsCsv(_tripState.vehicleId, els.date.value);
  });

  const layers = ['vehicles-circle', 'vehicles-arrow', 'vehicles-label'];
  map.on('click', (e) => {
    const features = map.queryRenderedFeatures(e.point, { layers });
    if (!features || features.length === 0) return;
    const f = features[0];
    const vid = f.properties.vehicle_id;
    if (!vid) return;
    els.plate.textContent = f.properties.plate || `Vehicle ${vid}`;
    els.driver.textContent = f.properties.driver_name || '';
    if (!els.date.value) els.date.value = _todayEat();
    panelRoot.classList.add('open');
    panelRoot.setAttribute('aria-hidden', 'false');
    _loadTrips(map, panelRoot, els, vid, els.date.value);
  });
}

async function _loadTrips(map, panelRoot, els, vehicleId, dateStr) {
  _tripState.vehicleId = vehicleId;
  _tripState.date = dateStr;
  _tripState.payload = null;
  _cancelTripAnim();
  _clearTripLayers(map);
  els.totals.innerHTML = 'Loading…';
  els.list.innerHTML = '';
  try {
    const payload = await apiFetch(
      `/api/views/vehicle/${vehicleId}/trips`,
      { params: { date: dateStr } },
    );
    _tripState.payload = payload;
    _renderTripPanel(map, els, payload);
  } catch (err) {
    els.totals.innerHTML = `<span style="color:var(--bad)">${_esc(err.message || err)}</span>`;
  }
}

function _renderTripPanel(map, els, payload) {
  const t = payload.totals || {};
  const q = payload.data_quality || {};
  const reportingTime = payload.reporting_time
    ? _formatTimeOnly(payload.reporting_time) : '—';
  els.totals.innerHTML = `
    <div>Reporting time: <strong>${_esc(reportingTime)}</strong></div>
    <div style="margin-top:6px">
      <strong>${t.trip_count ?? 0}</strong> trips ·
      <strong>${_fmtNum(t.distance_km, 1)}</strong> km
    </div>
    <div style="margin-top:4px">
      drive ${_fmtNum(t.driving_min, 0)}m · idle ${_fmtNum(t.idling_min, 0)}m · stop ${_fmtNum(t.stopped_min, 0)}m
    </div>
    <div class="quality">${q.fix_count ?? 0} fixes · ACC ${q.has_acc_data ? 'on' : 'off'}</div>
  `;

  const trips = payload.trips || [];
  if (trips.length === 0) {
    els.list.innerHTML = '<div class="trip-list-empty">No trips on this day.</div>';
    return;
  }
  els.list.innerHTML = trips.map(trip => `
    <div class="trip-row" data-trip-id="${trip.trip_id}">
      <div class="trip-row-top">
        <span>Trip ${trip.trip_id}</span>
        <span>${_fmtNum(trip.distance_km, 1)} km</span>
      </div>
      <div class="trip-row-meta">
        <span>${_formatTimeOnly(trip.started_at)} → ${_formatTimeOnly(trip.ended_at)}</span>
        <span>${_fmtNum(trip.duration_min, 0)} min</span>
        ${trip.idling_min > 0 ? `<span>idle ${_fmtNum(trip.idling_min, 0)}m</span>` : ''}
      </div>
      <div class="trip-row-reason ${_reasonClass(trip.end_reason)}">
        ${_reasonLabel(trip.end_reason)}
      </div>
    </div>
  `).join('');
  for (const row of els.list.querySelectorAll('.trip-row')) {
    row.addEventListener('click', () => {
      els.list.querySelectorAll('.trip-row.selected')
        .forEach(r => r.classList.remove('selected'));
      row.classList.add('selected');
      const tid = Number(row.dataset.tripId);
      const trip = trips.find(x => x.trip_id === tid);
      if (trip) _showAndAnimateTrip(map, trip);
    });
  }
}

function _reasonClass(r) {
  if (r === 'work_stop')  return 'work-stop';
  if (r === 'nofix_stop') return 'nofix-stop';
  if (r === 'long_gap')   return 'long-gap';
  return '';
}
function _reasonLabel(r) {
  return ({
    work_stop:  'Stopped for work',
    nofix_stop: 'Reporting silence',
    long_gap:   'Long gap',
    day_end:    'Day end',
  })[r] || (r || '—');
}

function _showAndAnimateTrip(map, trip) {
  _cancelTripAnim();
  _clearTripLayers(map);
  if (!trip.path || !trip.path.coordinates || trip.path.coordinates.length < 2) return;
  const coords = trip.path.coordinates;

  map.addSource(TRIP_PATH_SOURCE, { type: 'geojson', data: trip.path });
  map.addLayer({
    id: TRIP_PATH_LAYER,
    type: 'line',
    source: TRIP_PATH_SOURCE,
    layout: { 'line-join': 'round', 'line-cap': 'round' },
    paint: {
      'line-color': '#10b981',
      'line-width': ['interpolate', ['linear'], ['zoom'], 8, 2, 14, 4, 17, 6],
      'line-opacity': 0.85,
    },
  });

  map.addSource(TRIP_MARKER_SOURCE, {
    type: 'geojson',
    data: { type: 'Feature', geometry: { type: 'Point', coordinates: coords[0] }, properties: {} },
  });
  map.addLayer({
    id: TRIP_MARKER_LAYER,
    type: 'circle',
    source: TRIP_MARKER_SOURCE,
    paint: {
      'circle-radius': ['interpolate', ['linear'], ['zoom'], 8, 4, 14, 8, 17, 12],
      'circle-color': '#ffffff',
      'circle-stroke-color': '#10b981',
      'circle-stroke-width': 3,
    },
  });

  // eslint-disable-next-line no-undef
  const bounds = coords.reduce(
    (b, c) => b.extend(c),
    // eslint-disable-next-line no-undef
    new maplibregl.LngLatBounds(coords[0], coords[0]),
  );
  map.fitBounds(bounds, { padding: { top: 80, right: 380, bottom: 60, left: 60 }, duration: 600 });

  _animatePathMarker(map, coords, TRIP_ANIM_MS);
}

function _animatePathMarker(map, coords, durationMs) {
  // Pre-compute cumulative segment lengths (planar — fine for animation interpolation).
  let total = 0;
  const cum = [0];
  for (let i = 1; i < coords.length; i++) {
    const dx = coords[i][0] - coords[i - 1][0];
    const dy = coords[i][1] - coords[i - 1][1];
    total += Math.sqrt(dx * dx + dy * dy);
    cum.push(total);
  }
  if (total === 0) return;
  const startMs = performance.now();
  const src = map.getSource(TRIP_MARKER_SOURCE);
  const frame = (now) => {
    if (!map.getSource(TRIP_MARKER_SOURCE)) return; // panel closed
    const t = Math.min(1, (now - startMs) / durationMs);
    const target = total * t;
    // Binary search the segment containing `target`
    let lo = 1, hi = cum.length - 1;
    while (lo < hi) {
      const mid = (lo + hi) >> 1;
      if (cum[mid] < target) lo = mid + 1; else hi = mid;
    }
    const i = lo;
    const segStart = cum[i - 1], segEnd = cum[i];
    const segT = segEnd > segStart ? (target - segStart) / (segEnd - segStart) : 0;
    const a = coords[i - 1], b = coords[i];
    const pos = [a[0] + (b[0] - a[0]) * segT, a[1] + (b[1] - a[1]) * segT];
    src.setData({ type: 'Feature', geometry: { type: 'Point', coordinates: pos }, properties: {} });
    if (t < 1) {
      _tripAnimRAF = requestAnimationFrame(frame);
    } else {
      _tripAnimRAF = null;
    }
  };
  _tripAnimRAF = requestAnimationFrame(frame);
}

function _cancelTripAnim() {
  if (_tripAnimRAF !== null) {
    cancelAnimationFrame(_tripAnimRAF);
    _tripAnimRAF = null;
  }
}

function _clearTripLayers(map) {
  for (const id of [TRIP_MARKER_LAYER, TRIP_PATH_LAYER]) {
    if (map.getLayer(id)) map.removeLayer(id);
  }
  for (const id of [TRIP_MARKER_SOURCE, TRIP_PATH_SOURCE]) {
    if (map.getSource(id)) map.removeSource(id);
  }
}

function _closeTripPanel(map, panelRoot, els) {
  _cancelTripAnim();
  _clearTripLayers(map);
  panelRoot.classList.remove('open');
  panelRoot.setAttribute('aria-hidden', 'true');
  els.totals.innerHTML = 'Click a vehicle to see its trips.';
  els.list.innerHTML = '';
  _tripState = { vehicleId: null, date: null, payload: null };
}

function _todayEat() {
  const now = new Date();
  const eat = new Date(now.getTime() + 3 * 3600 * 1000);
  return eat.toISOString().slice(0, 10);
}

function _formatTimeOnly(iso) {
  if (!iso) return '—';
  const d = new Date(iso);
  if (isNaN(d.getTime())) return iso;
  return d.toLocaleTimeString('en-GB', {
    timeZone: 'Africa/Nairobi', hour: '2-digit', minute: '2-digit', hour12: false,
  });
}

function _fmtNum(v, digits) {
  if (v == null || isNaN(Number(v))) return '—';
  return Number(v).toFixed(digits);
}

async function _downloadTripsCsv(vehicleId, dateStr) {
  const url = `/api/views/vehicle/${vehicleId}/trips.csv?date=${encodeURIComponent(dateStr)}`;
  try {
    const r = await fetch(url, {
      headers: { Authorization: `Bearer ${authClient.getToken()}` },
    });
    if (!r.ok) throw new Error(`HTTP ${r.status}`);
    const blob = await r.blob();
    const cd = r.headers.get('Content-Disposition') || '';
    const m = cd.match(/filename="([^"]+)"/);
    const filename = (m && m[1]) || `trips_${vehicleId}_${dateStr}.csv`;
    const a = document.createElement('a');
    a.href = URL.createObjectURL(blob);
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    a.remove();
    URL.revokeObjectURL(a.href);
  } catch (err) {
    alert(`CSV download failed: ${err.message || err}`);
  }
}

/* ---------- clockEAT ---------- */

export function clockEAT(elementId) {
  const el = document.getElementById(elementId);
  if (!el) return;
  const tick = () => {
    const fmt = new Intl.DateTimeFormat('en-GB', {
      timeZone: 'Africa/Nairobi',
      hour: '2-digit', minute: '2-digit', second: '2-digit', hour12: false,
    });
    el.textContent = `${fmt.format(new Date())} EAT`;
  };
  tick();
  setInterval(tick, 1000);
}