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

// G1000 ACTIVE FLIGHT PLAN page (MFD page group + PFD window). Shows the shared
// plan as WPT / DTK / DIS / CUM / ALT, active leg in magenta. Edit: type an
// ident to insert/append (resolved via X-Plane navdata), ✕ deletes, tap a row to
// make it the active leg; CLEAR / INVERT / EXPORT(.fms).
const R_NM = 3440.065, rad = (d) => d * Math.PI / 180, 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 brng(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;
}
const fmtHrs = (h) => { const m = Math.round(h * 60); return `${Math.floor(m / 60)}:${String(m % 60).padStart(2, '0')}`; };

export default function FplPage({ xp, full = false, onClose }) {
  const { flightPlan, fp, values, exportMsg } = xp;
  const wps = flightPlan.waypoints || [];
  const active = Math.max(1, Math.min(wps.length - 1, flightPlan.activeLeg ?? 1));
  const [entry, setEntry] = useState('');
  const [hits, setHits] = useState([]);
  const [sel, setSel] = useState(-1);          // selected row (insert cursor)
  const [plans, setPlans] = useState(null);    // saved .fms list (load picker)
  const openLoad = async () => setPlans(await fmsList());

  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 addAt = async (ident, index) => {
    const id = (ident || '').trim().toUpperCase();
    if (!id) return;
    const hits2 = await navSearch(id);
    const hit = hits2[0];
    if (!hit) return;
    const next = wps.slice();
    next.splice(index == null ? next.length : index, 0, { id: hit.id, lat: hit.lat, lon: hit.lon, type: hit.type || 'WPT', alt: null });
    fp.set({ name: 'ACTIVE', waypoints: next, activeLeg: flightPlan.activeLeg ?? 1 });
    setEntry(''); setHits([]);
  };
  const invert = () => {
    if (wps.length < 2) return;
    fp.set({ name: 'ACTIVE', waypoints: wps.slice().reverse(), activeLeg: 1 });
  };

  // rows with leg + cumulative distance
  let cum = 0;
  const rows = wps.map((w, i) => {
    const prev = wps[i - 1];
    const d = prev ? distNm(prev, w) : 0;
    cum += d;
    return { w, i, d, cum, dtk: prev ? Math.round(brng(prev, w)) : null, orig: i === 0 };
  });
  const total = cum;
  const gs = num(values.groundspeed) * 1.94384;
  const ete = gs > 30 ? total / gs : null;

  // CURRENT VNV PROFILE: descent to the next waypoint with a lower target
  // altitude (manual S.64/107). VS TGT for a -3° path, VS REQ to make it, V DEV
  // from the path, time-to-top-of-descent.
  const alt = num(values.altitude);
  let vnav = null;
  if (gs > 40) {
    let c = 0, pl = num(values.lat), po = num(values.lon);
    for (let i = Math.max(1, active); i < wps.length; i++) {
      c += distNm({ lat: pl, lon: po }, wps[i]); pl = wps[i].lat; po = wps[i].lon;
      const t = num(wps[i].alt);
      if (t > 0 && t < alt - 50 && (wps[i].dsgn ?? true)) {
        const tan = Math.tan((3 * Math.PI) / 180);
        const vsTgt = -gs * tan * 101.27;
        const vsReq = c > 0 ? (t - alt) / (c / gs * 60) : 0;
        const vDev = alt - (t + c * 6076.12 * tan);
        const todNm = c - (alt - t) / (6076.12 * tan);
        vnav = { wptId: wps[i].id, tgtAlt: t, vsTgt, vsReq, vDev, fpa: 3.0, todSec: todNm > 0 ? (todNm / gs) * 3600 : 0 };
        break;
      }
    }
  }
  const fmtSec = (s) => { const m = Math.floor(s / 60), ss = Math.round(s % 60); return `${m}:${String(ss).padStart(2, '0')}`; };

  return (
    <div className={`fpl ${full ? 'full' : 'win'}`}>
      <div className="fpl-head">
        <span>{full ? 'ACTIVE FLIGHT PLAN' : 'FLIGHTPLAN'}</span>
        <span className="fpl-tot">{total.toFixed(0)} NM{ete ? ` · ${fmtHrs(ete)}` : ''}</span>
      </div>
      {!full && wps.length > 0 && (
        <div className="fpl-od">{wps[0].id} / {wps[wps.length - 1].id}</div>
      )}
      <div className="fpl-cols"><span>WPT</span><span>DTK</span><span>DIS</span><span>CUM</span><span>ALT</span></div>
      <div className="fpl-rows">
        {rows.length === 0 && <div className="fpl-empty">— leer — Ident unten eingeben</div>}
        {rows.map(({ w, i, d, cum, dtk, orig }) => (
          <div key={i} className={`fpl-row ${i === active ? 'act' : ''} ${i === sel ? 'sel' : ''}`}
            onClick={() => { setSel(i); if (i >= 1) fp.setActive(i); }}>
            <span className="r-wpt"><b className={i === active ? 'cur' : ''}>{w.id}</b><i>{w.type}</i></span>
            <span className="r-dtk">{dtk == null ? '___' : `${String(dtk).padStart(3, '0')}°`}</span>
            <span className="r-dis">{orig ? '—' : d.toFixed(1)}</span>
            <span className="r-cum">{orig ? '—' : cum.toFixed(0)}</span>
            <span className={`r-alt ${w.alt ? ((w.dsgn ?? true) ? 'dsgn' : 'refr') : ''}`}
              title={w.alt ? 'Klick: Designated ↔ Reference' : ''}
              onClick={(e) => {
                e.stopPropagation(); if (!w.alt) return;
                const next = wps.map((x, j) => (j === i ? { ...x, dsgn: !(x.dsgn ?? true) } : x));
                fp.set({ name: 'ACTIVE', waypoints: next, activeLeg: flightPlan.activeLeg ?? 1 });
              }}>{w.alt ? `${w.alt}FT` : '_____'}</span>
            <button className="r-del" onClick={(e) => { e.stopPropagation(); fp.remove(i); }}>✕</button>
          </div>
        ))}
      </div>
      {full && (
        <div className="fpl-vnav">
          <div className="fpl-vnav-h">CURRENT VNV PROFILE</div>
          {vnav ? (
            <div className="fpl-vnav-grid">
              <b>ACTIVE VNV WPT</b><span className="vwpt">{vnav.tgtAlt}<u>FT</u> at {vnav.wptId}</span>
              <b>VS TGT</b><span>{Math.round(vnav.vsTgt)}<u>FPM</u></span><b>FPA</b><span>{vnav.fpa.toFixed(1)}°</span>
              <b>VS REQ</b><span>{Math.round(vnav.vsReq)}<u>FPM</u></span><b>TIME TO TOD</b><span>{fmtSec(vnav.todSec)}</span>
              <b>V DEV</b><span>{vnav.vDev >= 0 ? '+' : ''}{Math.round(vnav.vDev)}<u>FT</u></span>
            </div>
          ) : <div className="fpl-vnav-none">— no active VNAV profile —</div>}
        </div>
      )}
      <div className="fpl-entry">
        {hits.length > 0 && (
          <div className="fpl-hits">
            {hits.map((h) => (
              <button key={h.id + h.lat} onClick={() => addAt(h.id, sel >= 0 ? sel : null)}>
                <b>{h.id}</b><i>{h.type}</i><span>{h.lat.toFixed(2)}, {h.lon.toFixed(2)}</span>
              </button>
            ))}
          </div>
        )}
        <div className="fpl-inrow">
          <input value={entry} onChange={(e) => setEntry(e.target.value.toUpperCase())}
            onKeyDown={(e) => e.key === 'Enter' && addAt(entry, sel >= 0 ? sel : null)}
            placeholder={sel >= 0 ? `Einfügen vor #${sel + 1}` : 'IDENT anhängen (z.B. ELN)'}
            autoCapitalize="characters" autoCorrect="off" spellCheck="false" />
          <button className="fpl-btn add" onClick={() => addAt(entry, sel >= 0 ? sel : null)}>EINFÜGEN</button>
        </div>
        <div className="fpl-actions">
          <button className="fpl-btn" onClick={openLoad}>LADEN</button>
          <button className="fpl-btn" onClick={() => { setSel(-1); fp.clear(); }} disabled={!wps.length}>CLEAR</button>
          <button className="fpl-btn" onClick={invert} disabled={wps.length < 2}>INVERT</button>
          <button className="fpl-btn" onClick={() => fp.export('WEBFPL')} disabled={wps.length < 2}>EXPORT →.fms</button>
        </div>
        {exportMsg && <div className={`fpl-msg ${exportMsg.ok ? 'ok' : 'err'}`}>{exportMsg.ok ? 'Exportiert ✓' : exportMsg.error}</div>}
      </div>

      {plans && (
        <div className="fpl-load" onClick={() => setPlans(null)}>
          <div className="fpl-load-box" onClick={(e) => e.stopPropagation()}>
            <div className="fpl-load-head"><span>Gespeicherte Flugpläne</span><button onClick={() => setPlans(null)}>✕</button></div>
            <div className="fpl-load-list">
              {plans.length === 0 && <div className="fpl-empty">keine .fms in „Output/FMS plans"</div>}
              {plans.map((n) => (
                <button key={n} onClick={() => { fp.load(n); setPlans(null); }}>{n}<i>.fms</i></button>
              ))}
            </div>
          </div>
        </div>
      )}
    </div>
  );
}