// Shared frame for every stage of a study project (Outline, Study, Script,
// Export): themed like the Reader, with a slim bar that carries the project title,
// the stage switcher, and save/sync status.
import { useApp } from '../../context/AppContext.js';
import { themeVars, READER_THEMES } from '../reader/readerThemes.js';
import HomeButton from '../reader/HomeButton.jsx';

export const STAGES = [
  { id: 'setup', label: 'Chunks' },
  { id: 'study', label: 'Study' },
  { id: 'outline', label: 'Outline' },
  { id: 'script', label: 'Script' },
  { id: 'export', label: 'Finish' },
];
const THEME_ORDER = ['paper', 'sepia', 'dark'];

export default function StudioShell({ stage, loading = false, fixedHeight = false, children }) {
  const {
    goHome, setCurrentPage, project, allChunks,
    saveStatus, syncStatus, retrySync, syncConflict, keepMyVersion, useServerVersion, mergeBothVersions,
    readerTheme, setReaderTheme,
  } = useApp();
  const noChunks = allChunks.length === 0;
  const cycleTheme = () => setReaderTheme(THEME_ORDER[(THEME_ORDER.indexOf(readerTheme) + 1) % THEME_ORDER.length]);

  return (
    <div className={`bg-[var(--r-bg)] font-sans text-[var(--r-text)] ${fixedHeight ? 'fixed inset-0 flex flex-col overflow-hidden' : 'min-h-dvh'}`} style={themeVars(readerTheme)}>
      <div className="safe-top z-30 shrink-0 border-b border-[var(--r-line)] bg-[var(--r-bar)]">
        <div className="mx-auto flex h-12 max-w-[1600px] items-center gap-3 px-3">
          <HomeButton onClick={goHome} />
          <div className="hidden min-w-0 max-w-[16rem] truncate text-sm font-medium sm:block">{project?.title ?? ''}</div>
          <nav aria-label="Study stages" className="flex min-w-0 flex-1 gap-0.5 overflow-x-auto sm:justify-center [scrollbar-width:none] [&::-webkit-scrollbar]:hidden">
            {STAGES.map((s) => {
              const disabled = s.id !== 'setup' && (!project || noChunks);
              return (
                <button key={s.id} type="button" disabled={disabled} aria-current={stage === s.id ? 'step' : undefined}
                  title={disabled ? 'Add a chunk in Chunks first' : undefined}
                  onClick={() => setCurrentPage(s.id)}
                  className={`shrink-0 rounded-full px-3.5 py-1.5 text-xs ${stage === s.id ? 'bg-[var(--r-text)] text-[var(--r-bg)]' : 'text-[var(--r-sub)] hover:bg-black/5'} disabled:opacity-40 disabled:hover:bg-transparent`}>
                  {s.label}
                </button>
              );
            })}
          </nav>
          <div className="flex shrink-0 items-center justify-end sm:min-w-[7rem] gap-2 text-xs text-[var(--r-sub)]" aria-live="polite">
            {loading ? <span>Loading…</span>
              : saveStatus ? <span className="text-[var(--r-accent)]">{saveStatus}</span>
                : syncStatus === 'syncing' ? <span>Syncing…</span>
                  : syncStatus === 'synced' ? <span>Saved</span>
                    : syncStatus === 'error' ? (
                      <span className="text-[var(--r-danger,#b42318)]">Sync failed <button type="button" onClick={retrySync} className="underline">Retry</button></span>
                    ) : null}
            <button type="button" onClick={cycleTheme} className="rounded-lg px-2 py-1 hover:bg-black/5" title="Change theme">{READER_THEMES[readerTheme]?.label}</button>
          </div>
        </div>
      </div>
      {syncConflict && project && syncConflict.id === project.id && (
        <div role="alert" className="flex shrink-0 flex-wrap items-center justify-center gap-x-4 gap-y-2 border-b border-[var(--r-line)] bg-[var(--r-hl)] px-4 py-2.5 text-sm">
          <span>This study was changed on another device. Your edits here are saved on this device, but not yet synced.</span>
          <span className="flex gap-2">
            <button type="button" onClick={keepMyVersion} className="rounded-full bg-[var(--r-text)] px-3 py-1 text-xs font-medium text-[var(--r-bg)] hover:opacity-90">Keep this version</button>
            <button type="button" onClick={mergeBothVersions} className="rounded-full border border-[var(--r-text)] px-3 py-1 text-xs font-medium hover:bg-black/5" title="Keeps every note from both versions, chunk by chunk">Combine both</button>
            <button type="button" onClick={useServerVersion} className="rounded-full border border-[var(--r-text)] px-3 py-1 text-xs font-medium hover:bg-black/5">Use the other version</button>
          </span>
        </div>
      )}
      {children}
    </div>
  );
}