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

// G1000 PROC dialog. Pick a destination/airport, a category (Departure / Arrival
// / Approach), then a procedure + transition; LOAD inserts the procedure's leg
// fixes into the active flight plan. Procedures come from X-Plane's own CIFP data
// via /api/nav/procs and /api/nav/proc (resolved to coordinates server-side).
const CATS = [
  { id: 'approach', label: 'APPROACH', key: 'approaches', t: 'approach' },
  { id: 'arrival', label: 'ARRIVAL', key: 'stars', t: 'star' },
  { id: 'departure', label: 'DEPARTURE', key: 'sids', t: 'sid' },
];

export default function Proc({ xp, onClose }) {
  const { flightPlan, fp, values } = xp;
  // Default airport: the plan's destination if it's an airport, else blank.
  const wps = flightPlan?.waypoints || [];
  const destGuess = [...wps].reverse().find((w) => w.type === 'APT')?.id || '';
  const [icao, setIcao] = useState(destGuess);
  const [query, setQuery] = useState(destGuess);
  const [procs, setProcs] = useState(null);
  const [err, setErr] = useState('');
  const [cat, setCat] = useState('approach');
  const [view, setView] = useState('menu');          // 'menu' (PDF action list) | 'pick'
  const [selProc, setSelProc] = useState(null);     // { name, transitions }
  const [selTrans, setSelTrans] = useState('');
  const [legs, setLegs] = useState([]);

  // Fetch the procedure summary whenever the airport changes.
  useEffect(() => {
    const id = icao.trim().toUpperCase();
    if (id.length < 3) { setProcs(null); return; }
    let alive = true;
    setErr(''); setProcs(null); setSelProc(null); setSelTrans(''); setLegs([]);
    fetch(`/api/nav/procs?icao=${id}`).then((r) => r.ok ? r.json() : Promise.reject(r.status))
      .then((d) => { if (alive) setProcs(d); })
      .catch(() => { if (alive) setErr(`keine Prozeduren für ${id}`); });
    return () => { alive = false; };
  }, [icao]);

  // Preview the resolved legs when a procedure+transition is chosen.
  useEffect(() => {
    if (!procs || !selProc) { setLegs([]); return; }
    const c = CATS.find((c) => c.id === cat);
    let alive = true;
    const t = encodeURIComponent(selTrans || '');
    fetch(`/api/nav/proc?icao=${procs.icao}&type=${c.t}&name=${encodeURIComponent(selProc.name)}&trans=${t}`)
      .then((r) => r.ok ? r.json() : []).then((d) => { if (alive) setLegs(d); });
    return () => { alive = false; };
  }, [procs, cat, selProc, selTrans]);

  const catList = procs ? (procs[CATS.find((c) => c.id === cat).key] || []) : [];

  const load = () => {
    if (!legs.length) return;
    const existing = wps.slice();
    // Departures go to the front, arrivals/approaches to the end.
    const merged = cat === 'departure' ? [...legs, ...existing] : [...existing, ...legs];
    fp.set({ name: 'ACTIVE', waypoints: merged, activeLeg: cat === 'departure' ? 1 : existing.length || 1 });
    onClose();
  };

  const catLabel = CATS.find((c) => c.id === cat).label;

  // The PDF's action menu. SELECT … opens our picker for that category;
  // ACTIVATE … are shown for authenticity (armed-procedure actions).
  if (view === 'menu') {
    const item = (label, onClick, sel) => (
      <button className={`proc-menu-i ${sel ? 'sel' : ''}`} onClick={onClick}>{label}</button>
    );
    const sel = (c) => { setCat(c); setSelProc(null); setSelTrans(''); setView('pick'); };
    return (
      <div className="gwin-backdrop" onClick={onClose}>
        <div className="dlg proc menu" onClick={(e) => e.stopPropagation()}>
          <div className="dlg-head">PROCEDURES</div>
          <div className="proc-menu">
            {item('ACTIVATE VECTOR-TO-FINAL', () => {})}
            {item('ACTIVATE APPROACH', () => {})}
            {item('ACTIVATE MISSED APPROACH', () => {})}
            {item('SELECT APPROACH', () => sel('approach'), true)}
            {item('SELECT ARRIVAL', () => sel('arrival'))}
            {item('SELECT DEPARTURE', () => sel('departure'))}
          </div>
        </div>
      </div>
    );
  }

  return (
    <div className="gwin-backdrop" onClick={onClose}>
      <div className="dlg proc" onClick={(e) => e.stopPropagation()}>
        <div className="dlg-head">{catLabel}</div>
        <div className="proc-body">
          <div className="proc-apt">
            <button className="proc-back" onClick={() => setView('menu')}>‹</button>
            <label>APT</label>
            <input value={query} onChange={(e) => setQuery(e.target.value.toUpperCase())}
              onKeyDown={(e) => e.key === 'Enter' && setIcao(query)}
              placeholder="ICAO (z.B. KSEA)" autoCapitalize="characters" autoCorrect="off" spellCheck="false" />
            <button className="fbtn" onClick={() => setIcao(query)}>LOAD</button>
          </div>
          {err && <div className="proc-err">{err}</div>}

          <div className="proc-cols">
            <div className="proc-list">
              <div className="proc-coltitle">{procs ? `${catList.length}` : '—'} PROC</div>
              {catList.map((p) => (
                <button key={p.name} className={selProc?.name === p.name ? 'on' : ''}
                  onClick={() => { setSelProc(p); setSelTrans(p.transitions[0] || ''); }}>{p.name}</button>
              ))}
              {procs && catList.length === 0 && <div className="proc-empty">keine</div>}
            </div>
            <div className="proc-list">
              <div className="proc-coltitle">TRANS</div>
              {selProc?.transitions.map((t) => (
                <button key={t} className={selTrans === t ? 'on' : ''} onClick={() => setSelTrans(t)}>{t}</button>
              ))}
              {selProc && selProc.transitions.length === 0 && <div className="proc-empty">—</div>}
            </div>
            <div className="proc-preview">
              <div className="proc-coltitle">{legs.length} FIXES</div>
              {legs.map((l, i) => (
                <div key={l.id + i} className="proc-leg">
                  <b>{l.id}</b>{l.alt ? <u>{l.alt}ft</u> : null}
                </div>
              ))}
            </div>
          </div>
        </div>
        <div className="dlg-actions">
          <button className="fbtn" onClick={onClose}>CANCEL</button>
          <button className="fbtn add" disabled={!legs.length} onClick={load}>LOAD → FPL</button>
        </div>
      </div>
    </div>
  );
}