import React, { useState, useEffect } from 'react';
import { num, navSearch } from '../api/useXplane.js';

const R_NM = 3440.065;
const rad = (d) => (d * Math.PI) / 180;
const deg = (r) => (r * 180) / Math.PI;
function distNm(a, b) {
  const dLat = rad(b.lat - a.lat), dLon = rad(b.lon - a.lon);
  const s = Math.sin(dLat / 2) ** 2 + Math.cos(rad(a.lat)) * Math.cos(rad(b.lat)) * Math.sin(dLon / 2) ** 2;
  return 2 * R_NM * Math.asin(Math.min(1, Math.sqrt(s)));
}
function bearing(a, b) {
  const y = Math.sin(rad(b.lon - a.lon)) * Math.cos(rad(b.lat));
  const x = Math.cos(rad(a.lat)) * Math.sin(rad(b.lat)) -
            Math.sin(rad(a.lat)) * Math.cos(rad(b.lat)) * Math.cos(rad(b.lon - a.lon));
  return (deg(Math.atan2(y, x)) + 360) % 360;
}

export default function FMS({ xp }) {
  const { flightPlan, fp, values, exportMsg } = xp;
  const wps = flightPlan.waypoints || [];
  const [entry, setEntry] = useState('');
  const [hits, setHits] = useState([]);

  // live ident search against X-Plane's nav database
  useEffect(() => {
    const q = entry.trim();
    if (q.length < 2 || /[,\s]/.test(q)) { setHits([]); return; }
    let alive = true;
    navSearch(q).then((r) => alive && setHits(r.slice(0, 6)));
    return () => { alive = false; };
  }, [entry]);

  const add = (id) => { fp.add(id || entry.trim()); setEntry(''); setHits([]); };

  let total = 0;
  const rows = wps.map((w, i) => {
    const prev = wps[i - 1];
    const d = prev ? distNm(prev, w) : 0;
    const brg = prev ? bearing(prev, w) : null;
    total += d;
    return { w, i, d, brg };
  });

  const gs = num(values.groundspeed) * 1.94384;
  const ete = gs > 20 ? total / gs : null; // hours
  const active = Math.max(1, Math.min(wps.length - 1, flightPlan?.activeLeg ?? 1));

  return (
    <div className="fms">
      <div className="fms-head">
        <span>FLIGHT PLAN</span>
        <span className="fms-total">
          {total.toFixed(0)} NM{ete ? ` · ETE ${fmtHrs(ete)}` : ''}
        </span>
      </div>

      <div className="fms-rows">
        <div className="fms-row fms-colhead">
          <span>#</span><span>WPT</span><span>DTK</span><span>DIST</span><span></span>
        </div>
        {rows.length === 0 && <div className="fms-empty">Kein Flugplan — Wegpunkt eingeben oder auf der Map tippen.</div>}
        {rows.map(({ w, i, d, brg }) => (
          <div className={`fms-row ${i === 0 ? 'orig' : ''} ${i === active ? 'active' : ''}`} key={i}
            onClick={() => i >= 1 && fp.setActive(i)} title={i >= 1 ? 'Als aktives Bein setzen' : ''}>
            <span className="idx">{i + 1}</span>
            <span className="wid">{w.id}<i className="wtype">{w.type}</i></span>
            <span className="dtk">{brg == null ? '—' : `${String(Math.round(brg)).padStart(3, '0')}°`}</span>
            <span className="dist">{i === 0 ? 'ORIG' : `${d.toFixed(1)}`}</span>
            <button className="del" onClick={(e) => { e.stopPropagation(); fp.remove(i); }}>✕</button>
          </div>
        ))}
      </div>

      <div className="fms-scratch">
        {hits.length > 0 && (
          <div className="fms-hits">
            {hits.map((h) => (
              <button key={h.id + h.lat} onClick={() => add(h.id)}>
                <b>{h.id}</b> <i>{h.type}</i> <span>{h.lat.toFixed(2)}, {h.lon.toFixed(2)}</span>
              </button>
            ))}
          </div>
        )}
        <div className="fms-input">
          <input
            value={entry}
            onChange={(e) => setEntry(e.target.value.toUpperCase())}
            onKeyDown={(e) => e.key === 'Enter' && add()}
            placeholder="IDENT (z.B. KSEA, SEA) oder LAT,LON"
            autoCapitalize="characters" autoCorrect="off" spellCheck="false"
          />
          <button className="fbtn add" onClick={() => add()}>ADD</button>
        </div>
        <div className="fms-actions">
          <button className="fbtn" onClick={() => fp.clear()} disabled={!wps.length}>CLEAR</button>
          <button className="fbtn export" onClick={() => fp.export('WEBFPL')} disabled={wps.length < 2}>
            EXPORT → X-PLANE (.fms)
          </button>
        </div>
        {exportMsg && (
          <div className={`fms-export ${exportMsg.ok ? 'ok' : 'err'}`}>
            {exportMsg.ok
              ? (exportMsg.intoXplane
                  ? `✓ Gespeichert in X-Plane: ${shorten(exportMsg.file)} — im Flieger-FMS unter „Load" wählen.`
                  : `✓ Datei geschrieben: ${shorten(exportMsg.file)} (X-Plane-Ordner nicht gefunden — XPLANE_ROOT setzen).`)
              : `✗ ${exportMsg.error}`}
          </div>
        )}
      </div>
    </div>
  );
}

function fmtHrs(h) {
  const m = Math.round(h * 60);
  return `${Math.floor(m / 60)}:${String(m % 60).padStart(2, '0')}`;
}
function shorten(p) {
  return p && p.length > 48 ? '…' + p.slice(-46) : p;
}