// What someone sees when they open a read-only outline link: a calm page with the outline, a switcher
// when there is more than one, and Print / PDF. Nothing is editable.
import { useCallback, useEffect, useState } from 'react';
import { getSharedOutline } from '../syncService.js';
import { themeVars } from './reader/readerThemes.js';
import SharedPasscodeForm from './SharedPasscodeForm.jsx';
import OutlineDocument from './OutlineDocument.jsx';
import { printOutline } from '../utils/outlineExport.js';
import { flatten } from '../utils/outline.js';

const pill = (active) => `shrink-0 rounded-full px-3.5 py-1.5 text-sm transition ${active ? 'bg-[var(--r-text)] text-[var(--r-bg)]' : 'text-[var(--r-sub)] hover:bg-black/5'}`;

function Frame({ children }) {
  return <div className="min-h-dvh bg-[var(--r-bg)] font-sans text-[var(--r-text)]" style={themeVars('paper')}>{children}</div>;
}

export default function SharedOutlineView({ token }) {
  const [data, setData] = useState(null);
  const [error, setError] = useState('');
  const [scope, setScope] = useState('study');
  const [needsPasscode, setNeedsPasscode] = useState(false);
  const [passcodeError, setPasscodeError] = useState('');
  const [checking, setChecking] = useState(false);

  const load = useCallback((passcode) => {
    setChecking(true);
    return getSharedOutline(token, passcode).then((result) => {
      setChecking(false);
      if (result.ok) { setData(result.data); setNeedsPasscode(false); setScope(result.data.outlines[0]?.scope ?? 'study'); return; }
      if (result.data?.needsPasscode) { setNeedsPasscode(true); setPasscodeError(passcode ? result.error : ''); return; }
      setNeedsPasscode(false);
      setError(result.error ?? 'This outline link is invalid or has been turned off.');
    });
  }, [token]);

  useEffect(() => { load(); }, [load]);

  useEffect(() => { if (data?.title) document.title = `${data.title} — Outline`; }, [data]);

  if (needsPasscode) return <Frame><SharedPasscodeForm error={passcodeError} busy={checking} onSubmit={load} /></Frame>;

  if (error) {
    return (
      <Frame>
        <div className="flex min-h-dvh items-center justify-center px-5">
          <div className="max-w-sm text-center">
            <p className="text-[11px] font-semibold uppercase tracking-[0.18em] text-[var(--r-accent)]">Bible Study Project</p>
            <p className="mt-4 text-base">{error}</p>
          </div>
        </div>
      </Frame>
    );
  }
  if (!data) return <Frame><p className="flex min-h-dvh items-center justify-center text-sm text-[var(--r-sub)]">Loading outline…</p></Frame>;

  const current = data.outlines.find((o) => o.scope === scope) ?? data.outlines[0];
  const title = current && current.scope !== 'study' ? `${data.title} — ${current.label}` : data.title;
  const minutes = current ? flatten(current.tree).reduce((sum, { node }) => sum + (Number.isFinite(node.minutes) ? node.minutes : 0), 0) : 0;
  const meta = current ? [current.scope === 'study' ? data.translation : `${current.label} · ${data.translation}`, minutes > 0 ? `About ${minutes} minute${minutes === 1 ? '' : 's'}` : ''].filter(Boolean).join('  ·  ') : '';
  const outline = current ? { title, subtitle: current.scope === 'study' ? data.translation : `${current.label} · ${data.translation}`, tree: current.tree } : null;

  return (
    <Frame>
      <header className="sticky top-0 z-10 border-b border-[var(--r-line)] bg-[var(--r-bar)]/95 backdrop-blur">
        <div className="mx-auto flex max-w-[44rem] flex-wrap items-center gap-x-3 gap-y-2 px-5 py-2.5 sm:px-8">
          <span className="shrink-0 text-sm font-medium">Bible Study</span>
          {data.outlines.length > 1 ? (
            <nav aria-label="Outline" className="order-last flex w-full min-w-0 gap-1 overflow-x-auto sm:order-none sm:w-auto sm:flex-1">
              {data.outlines.map((o) => (
                <button key={o.scope} type="button" onClick={() => setScope(o.scope)} aria-current={current?.scope === o.scope ? 'true' : undefined} className={pill(current?.scope === o.scope)}>{o.label}</button>
              ))}
            </nav>
          ) : <span className="flex-1" />}
          {outline && <button type="button" onClick={() => printOutline(outline)} className="ml-auto shrink-0 sm:ml-0 rounded-full border border-[var(--r-line)] px-3.5 py-1.5 text-sm hover:bg-black/5">Print / PDF</button>}
        </div>
      </header>
      {current ? <OutlineDocument title={title} meta={meta} tree={current.tree} /> : <p className="p-10 text-center text-sm text-[var(--r-sub)]">This study doesn’t have an outline yet.</p>}
    </Frame>
  );
}