// Flight-route builder used inside the day editor for flight entries.
// Provides a quick "CNX-BKK-DXB-FRA" expander plus editable per-leg rows with
// airport-code autocomplete backed by GET /api/airports. Kept as its own
// module so dayEditor.js stays small.
import { el, clear, toast } from '../dom.js';
import { api } from '../api.js';
import { formatTimeRange } from '../format.js';

const CODE_RE = /^[A-Z0-9]{2,4}$/;

// Per-segment display lines for an entry row: "TG103 CNX→BKK 10:30–11:45".
export function renderSegmentLines(segments) {
  return el(
    'div',
    { class: 'entry-segments' },
    ...segments.map((s) => {
      const legTime = formatTimeRange(s.dep_time, s.arr_time);
      const codes = `${s.from?.code || '?'}→${s.to?.code || '?'}`;
      return el(
        'div',
        { class: 'entry-seg muted' },
        s.flight_no ? el('span', { class: 'seg-flight' }, s.flight_no) : null,
        el('span', {}, codes),
        legTime ? el('span', {}, legTime) : null,
      );
    }),
  );
}

// createFlightRoute({ initialSegments, onChange }) ->
//   { node, read(), hasSegments() }
// read() returns { segments: [...] | null } or { error: 'message' }.
export function createFlightRoute({ initialSegments = null, onChange = () => {} } = {}) {
  const rows = []; // { state:{flight_no,dep_time,arr_time,from,to}, node, refs }
  const listEl = el('div', { class: 'seg-list' });

  const quickInput = el('input', {
    class: 'input seg-quick-input',
    type: 'text',
    placeholder: 'CNX-BKK-DXB-FRA',
    autocomplete: 'off',
    spellcheck: 'false',
    'aria-label': 'Airport code chain',
  });
  const buildBtn = el('button', { class: 'btn btn-sm', type: 'button' }, 'Build route');
  buildBtn.addEventListener('click', () => buildFromChain(quickInput.value));

  const addBtn = el('button', { class: 'btn btn-sm btn-ghost', type: 'button' }, '+ Add leg');
  addBtn.addEventListener('click', () => {
    const prev = rows[rows.length - 1];
    addRow(prev ? { from: { ...prev.state.to } } : {});
    renumber();
    onChange();
  });

  const node = el(
    'div',
    { class: 'flight-route' },
    el('div', { class: 'seg-quick' },
      el('label', { class: 'field field-grow' },
        el('span', { class: 'field-label' }, 'Quick route (airport codes)'),
        quickInput),
      buildBtn),
    listEl,
    addBtn,
  );

  function emptyAirport() {
    return { code: '', name: '', lat: null, lng: null };
  }

  function addRow(seg = {}) {
    const state = {
      flight_no: seg.flight_no || '',
      dep_time: seg.dep_time || '',
      arr_time: seg.arr_time || '',
      from: { ...emptyAirport(), ...(seg.from || {}) },
      to: { ...emptyAirport(), ...(seg.to || {}) },
    };
    const { rowNode, refs } = buildRowDom(state);
    const row = { state, node: rowNode, refs };
    rows.push(row);
    listEl.appendChild(rowNode);
    refreshRowLabels(row);
    return row;
  }

  function removeRow(row) {
    const i = rows.indexOf(row);
    if (i === -1) return;
    rows.splice(i, 1);
    row.node.remove();
    renumber();
    onChange();
  }

  function renumber() {
    rows.forEach((r, i) => { r.refs.num.textContent = String(i + 1); });
  }

  function buildRowDom(state) {
    const num = el('span', { class: 'seg-num' }, '1');
    const flightNo = el('input', { class: 'input input-sm seg-flightno', type: 'text', maxlength: '12', placeholder: 'Flight no.', value: state.flight_no });
    flightNo.addEventListener('input', () => { state.flight_no = flightNo.value; });

    const from = buildAirportField(state.from, 'From');
    const to = buildAirportField(state.to, 'To');

    const dep = el('input', { class: 'input input-sm', type: 'time', 'aria-label': 'Departure time' });
    dep.value = state.dep_time || '';
    dep.addEventListener('input', () => { state.dep_time = dep.value; });
    const arr = el('input', { class: 'input input-sm', type: 'time', 'aria-label': 'Arrival time' });
    arr.value = state.arr_time || '';
    arr.addEventListener('input', () => { state.arr_time = arr.value; });

    const removeBtn = el('button', { class: 'icon-btn danger', type: 'button', title: 'Remove leg' }, '×');

    const rowNode = el(
      'div',
      { class: 'seg-row' },
      el('div', { class: 'seg-row-head' }, num, flightNo, removeBtn),
      el('div', { class: 'seg-airports' }, from.field, el('span', { class: 'seg-arrow' }, '→'), to.field),
      el('div', { class: 'seg-times' },
        el('label', { class: 'seg-time' }, el('span', {}, 'Dep'), dep),
        el('label', { class: 'seg-time' }, el('span', {}, 'Arr'), arr)),
    );

    const refs = { num, from, to };
    removeBtn.addEventListener('click', () => {
      const row = rows.find((r) => r.node === rowNode);
      if (row) removeRow(row);
    });
    return { rowNode, refs };
  }

  // One airport code input + autocomplete dropdown + resolved-name line.
  function buildAirportField(airportState, label) {
    const input = el('input', {
      class: 'input input-sm seg-code',
      type: 'text',
      maxlength: '4',
      placeholder: label === 'From' ? 'From (e.g. CNX)' : 'To (e.g. BKK)',
      autocomplete: 'off',
      spellcheck: 'false',
      'aria-label': `${label} airport code`,
    });
    input.value = airportState.code || '';
    const results = el('div', { class: 'ap-results' });
    const nameLine = el('span', { class: 'ap-name' });
    const field = el('div', { class: 'seg-ap' }, input, results, nameLine);

    let timer = null;
    let seq = 0;
    input.addEventListener('input', () => {
      const val = input.value.toUpperCase();
      // Manual edit clears any previously resolved coordinates.
      airportState.code = val;
      airportState.name = '';
      airportState.lat = null;
      airportState.lng = null;
      setNameLine(nameLine, airportState);
      clearTimeout(timer);
      const q = input.value.trim();
      if (q.length < 2) { clear(results); return; }
      timer = setTimeout(async () => {
        const mine = ++seq;
        try {
          const data = await api.airports(q);
          if (mine !== seq) return;
          showAirportResults(results, data.results || [], (ap) => {
            applyAirport(airportState, ap);
            input.value = ap.code;
            clear(results);
            setNameLine(nameLine, airportState);
            onChange();
          });
        } catch (err) {
          if (mine !== seq) return;
          clear(results);
        }
      }, 300);
    });

    return { field, input, nameLine, state: airportState };
  }

  function refreshRowLabels(row) {
    setNameLine(row.refs.from.nameLine, row.state.from);
    setNameLine(row.refs.to.nameLine, row.state.to);
  }

  // Quick-build: split codes, make N-1 legs, resolve each code to coords.
  async function buildFromChain(raw) {
    const codes = String(raw || '')
      .split(/[\s,>\-]+/)
      .map((s) => s.trim().toUpperCase())
      .filter(Boolean);
    if (codes.length < 2) {
      toast('Enter at least two airport codes, e.g. CNX-BKK');
      return;
    }
    if (codes.length - 1 > 8) {
      toast('A flight can have at most 8 legs.');
      return;
    }
    // Replace existing rows.
    rows.slice().forEach((r) => { r.node.remove(); });
    rows.length = 0;
    for (let i = 0; i < codes.length - 1; i++) {
      addRow({ from: { code: codes[i] }, to: { code: codes[i + 1] } });
    }
    renumber();
    onChange();

    // Resolve unique codes once, then apply to every matching field.
    const unique = [...new Set(codes)];
    const resolved = {};
    await Promise.all(unique.map(async (code) => {
      resolved[code] = await resolveCode(code);
    }));
    for (const row of rows) {
      applyResolved(row.state.from, resolved[row.state.from.code], row.refs.from);
      applyResolved(row.state.to, resolved[row.state.to.code], row.refs.to);
    }
    onChange();
  }

  function applyResolved(airportState, ap, ref) {
    if (ap) {
      applyAirport(airportState, ap);
      ref.input.value = ap.code;
      ref.field.classList.remove('ap-unresolved');
    } else {
      // Keep the typed code but flag that it has no coordinates.
      ref.field.classList.add('ap-unresolved');
    }
    setNameLine(ref.nameLine, airportState);
  }

  async function resolveCode(code) {
    try {
      const data = await api.airports(code);
      const list = data.results || [];
      return list.find((r) => (r.code || '').toUpperCase() === code) || null;
    } catch {
      return null;
    }
  }

  function read() {
    if (rows.length === 0) return { segments: null };
    if (rows.length > 8) return { error: 'A flight can have at most 8 legs.' };
    const segments = [];
    for (const r of rows) {
      const fromCode = (r.state.from.code || '').trim().toUpperCase();
      const toCode = (r.state.to.code || '').trim().toUpperCase();
      if (!CODE_RE.test(fromCode) || !CODE_RE.test(toCode)) {
        return { error: 'Every leg needs a valid from and to airport code (2–4 characters).' };
      }
      const seg = { from: airportOut(r.state.from, fromCode), to: airportOut(r.state.to, toCode) };
      if (r.state.flight_no.trim()) seg.flight_no = r.state.flight_no.trim();
      if (r.state.dep_time) seg.dep_time = r.state.dep_time;
      if (r.state.arr_time) seg.arr_time = r.state.arr_time;
      segments.push(seg);
    }
    return { segments };
  }

  // Replace all rows from a segments array (used when editing an entry).
  function load(segments) {
    rows.slice().forEach((r) => { r.node.remove(); });
    rows.length = 0;
    if (Array.isArray(segments)) {
      for (const seg of segments) addRow(seg);
    }
    renumber();
    onChange();
  }

  // Prefill from an existing entry's segments (edit).
  if (Array.isArray(initialSegments)) {
    for (const seg of initialSegments) addRow(seg);
    renumber();
  }

  return { node, read, load, hasSegments: () => rows.length > 0 };
}

function applyAirport(airportState, ap) {
  airportState.code = (ap.code || '').toUpperCase();
  airportState.name = ap.name || '';
  airportState.lat = ap.lat != null ? ap.lat : null;
  airportState.lng = ap.lng != null ? ap.lng : null;
}

function airportOut(airportState, code) {
  const out = { code };
  if (airportState.name) out.name = airportState.name;
  if (airportState.lat != null && airportState.lng != null) {
    out.lat = airportState.lat;
    out.lng = airportState.lng;
  }
  return out;
}

function setNameLine(nameLine, airportState) {
  if (airportState.name) {
    nameLine.textContent = airportState.name;
    nameLine.classList.remove('muted');
  } else if (airportState.code) {
    nameLine.textContent = 'no coordinates — pick from the list';
    nameLine.classList.add('muted');
  } else {
    nameLine.textContent = '';
  }
}

function showAirportResults(box, results, onPick) {
  clear(box);
  if (!results.length) {
    box.appendChild(el('div', { class: 'ap-empty muted' }, 'No airports found'));
    return;
  }
  for (const r of results) {
    const meta = [r.city, r.country].filter(Boolean).join(', ');
    box.appendChild(
      el('button', { class: 'ap-result', type: 'button', onClick: () => onPick(r) },
        el('span', { class: 'ap-code' }, r.code),
        el('span', { class: 'ap-desc' }, `${r.name}${meta ? ` — ${meta}` : ''}`)),
    );
  }
}