// The Outline stage: the shape of the message as a real outline — main points (I.), sub-points (A.),
// and deeper (1., a.). There is one outline for the whole study and one for each chunk (pick which at
// the top). A point can be an illustration, application, quote…, carry minutes, a longer note, a verse's
// words, and cross-references or word studies from its chunk. Print it, share it, or take it as a file.
import { useEffect, useLayoutEffect, useRef, useState } from 'react';
import { useApp } from '../context/AppContext.js';
import { useToast } from '../components/Toasts.jsx';
import StudioShell from '../components/study/StudioShell.jsx';
import { formatChunkReference } from '../utils/bibleUtils.jsx';
import { buildChapterSummary } from '../utils/projectStorage.js';
import { compactPassages } from '../utils/passageSummary.js';
import { attachableFromChunk, fetchPassageText } from '../utils/passageText.js';
import ShareOutlineSheet from '../components/ShareOutlineSheet.jsx';
import { downloadOutlineDocx, downloadOutlineMarkdown, printOutline } from '../utils/outlineExport.js';
import {
  KINDS, STUDY, addAfter, addChild, addRoot, chunkOf, countNodes, flatten, getNode, indent, insertAt, kindLabel, locate,
  moveNode, newNode, outdent, outlineFor, outlineToText, removeNode, seedFromChunks, seedFromVerses, timeSummary, updateNode, withOutline,
} from '../utils/outline.js';

const iconBtn = 'flex h-7 w-7 items-center justify-center rounded-md text-sm text-[var(--r-sub)] hover:bg-black/5 hover:text-[var(--r-text)] disabled:opacity-30 disabled:hover:bg-transparent';
const btn = 'rounded-xl border border-[var(--r-line)] px-3.5 py-2 text-sm hover:bg-black/5 disabled:opacity-50';
const field = 'mt-0.5 block w-full rounded-lg border border-[var(--r-line)] bg-[var(--r-bg)] px-2 py-1.5 text-sm text-[var(--r-text)]';
const chip = 'rounded-full border border-[var(--r-line)] px-2 py-0.5 text-[11px] text-[var(--r-sub)]';

// A text box that grows with what is typed, so a long point never hides behind a scroll bar.
function AutoText({ value, onChange, className, ...rest }) {
  const ref = useRef(null);
  useLayoutEffect(() => {
    const el = ref.current;
    if (!el) return;
    el.style.height = 'auto';
    el.style.height = `${el.scrollHeight}px`;
  }, [value]);
  return <textarea ref={ref} rows={1} value={value} onChange={(e) => onChange(e.target.value)} className={className} {...rest} />;
}
const pointBox = 'block w-full resize-none overflow-hidden rounded-lg border border-transparent bg-transparent px-2 py-1.5 text-[15px] leading-snug text-[var(--r-text)] placeholder:text-[var(--r-sub)] hover:border-[var(--r-line)] focus:border-[var(--r-line)] focus:bg-[var(--r-bg)] focus:outline-none';

export default function OutlinePage() {
  const { project, updateProject, setCurrentPage } = useApp();
  const { toast } = useToast();
  const [chosen, setChosen] = useState(STUDY);
  const scope = chosen === STUDY || chunkOf(project, chosen) ? chosen : STUDY; // a deleted chunk falls back to the whole study
  const scopeChunk = scope === STUDY ? null : chunkOf(project, scope);
  const tree = outlineFor(project, scope);
  const rows = flatten(tree);
  const [pendingFocus, setPendingFocus] = useState(null);
  const [metaOpen, setMetaOpen] = useState(() => new Set()); // points whose detail fields are showing
  const [shareOpen, setShareOpen] = useState(false);
  const [lookup, setLookup] = useState({ id: null, busy: false, error: '' });

  // The one way every change is made, always from the latest outline (typing is fast).
  const edit = (fn) => updateProject((current) => withOutline(current, scope, fn(outlineFor(current, scope))));
  const patch = (id, change) => edit((t) => updateNode(t, id, change));

  useEffect(() => {
    if (!pendingFocus) return;
    document.querySelector(`[data-outline-id="${pendingFocus}"]`)?.focus();
    setPendingFocus(null);
  }, [pendingFocus, tree]);

  // Every chunk, named by passage, for the scope picker and the "linked chunk" choice
  const chunkChoices = [];
  (project?.chapters ?? []).forEach((chapter, chapterIndex) => chapter.chunks.forEach((chunk) => {
    chunkChoices.push({ id: chunk.id, label: formatChunkReference(project, chapterIndex, chunk, '–'), count: countNodes(chunk.outline ?? []) });
  }));
  const scopeLabel = scope === STUDY ? 'Whole study' : chunkChoices.find((c) => c.id === scope)?.label ?? '';
  const title = scope === STUDY ? project.title : `${project.title} — ${scopeLabel}`;
  const subtitle = scope === STUDY ? compactPassages(buildChapterSummary(project)) : `${scopeLabel} · ${project.translation ?? 'BSB'}`;
  const outline = { title, subtitle, tree };

  const addable = scope === STUDY
    ? seedFromChunks(project, tree).length - tree.length
    : seedFromVerses(project, scope, tree).length - tree.length;
  const seedLabel = scope === STUDY ? 'Add my chunks' : 'Add the verses';

  const addMain = () => { const node = newNode(); edit((t) => addRoot(t, node)); setPendingFocus(node.id); };
  const addSub = (id) => { const node = newNode(); edit((t) => addChild(t, id, node)); setPendingFocus(node.id); };
  const addSibling = (id) => { const node = newNode(); edit((t) => addAfter(t, id, node)); setPendingFocus(node.id); };
  const seed = () => {
    edit((t) => (scope === STUDY ? seedFromChunks(project, t) : seedFromVerses(project, scope, t)));
    toast(`Added ${addable} point${addable === 1 ? '' : 's'}`);
  };
  const remove = (id) => {
    const where = locate(tree, id);
    const gone = getNode(tree, id);
    if (!where || !gone) return;
    const index = rows.findIndex((r) => r.node.id === id);
    edit((t) => removeNode(t, id));
    setPendingFocus(rows[index - 1]?.node.id ?? null);
    const count = countNodes([gone]);
    toast(count > 1 ? `Deleted a point and its ${count - 1} sub-point${count > 2 ? 's' : ''}` : 'Deleted a point', {
      action: { label: 'Undo', onClick: () => edit((t) => insertAt(t, where.parentId, where.index, gone)) },
    });
  };

  const onKeyDown = (e, id, text, hasChildren) => {
    if (e.nativeEvent.isComposing) return;
    const at = rows.findIndex((r) => r.node.id === id);
    const el = e.currentTarget;
    if (e.key === 'Enter' && !e.shiftKey) { e.preventDefault(); addSibling(id); }
    else if (e.key === 'Tab') { e.preventDefault(); edit((t) => (e.shiftKey ? outdent(t, id) : indent(t, id))); setPendingFocus(id); }
    else if (e.key === 'Backspace' && text === '' && !hasChildren) { e.preventDefault(); remove(id); }
    else if (e.altKey && (e.key === 'ArrowUp' || e.key === 'ArrowDown')) { e.preventDefault(); edit((t) => moveNode(t, id, e.key === 'ArrowUp' ? -1 : 1)); setPendingFocus(id); }
    else if (e.key === 'ArrowUp' && el.selectionStart === 0 && rows[at - 1]) { e.preventDefault(); setPendingFocus(rows[at - 1].node.id); }
    else if (e.key === 'ArrowDown' && el.selectionStart === text.length && rows[at + 1]) { e.preventDefault(); setPendingFocus(rows[at + 1].node.id); }
  };

  // ---- taking it out: copy, share, print, files
  const copy = async () => {
    try { await navigator.clipboard.writeText(outlineToText(tree)); toast('Outline copied'); } catch { toast("Couldn't copy. Select the text and copy it instead.", { tone: 'error' }); }
  };
  const print = () => { if (!printOutline(outline)) toast('Allow pop-ups for this site to print or save as PDF.', { tone: 'error' }); };
  const word = async () => { try { await downloadOutlineDocx(outline); } catch { toast("Couldn't make the Word file.", { tone: 'error' }); } };

  const openChunk = (chunkId) => {
    updateProject((current) => ({ ...current, selectedChunkId: chunkId }));
    setCurrentPage('study');
  };
  const toggleMeta = (id) => setMetaOpen((s) => { const next = new Set(s); if (next.has(id)) next.delete(id); else next.add(id); return next; });

  // Puts a passage's words into a point (the point's passage field says which).
  const addVerseText = async (node) => {
    setLookup({ id: node.id, busy: true, error: '' });
    try {
      const got = await fetchPassageText(node.ref, project.translation ?? 'BSB');
      patch(node.id, { scripture: got });
      setLookup({ id: null, busy: false, error: '' });
    } catch (err) {
      setLookup({ id: node.id, busy: false, error: err.message || 'Could not load those verses.' });
    }
  };

  return (
    <StudioShell stage="outline">
      <main className="mx-auto max-w-3xl px-4 py-8">
        <div className="mb-4">
          <h1 className="text-xl font-medium">Outline</h1>
          <p className="mt-1 text-sm text-[var(--r-sub)]">The shape of the message. Keep one for the whole study, and one for each chunk if you like.</p>
        </div>

        <div className="mb-4 flex flex-wrap items-center gap-x-4 gap-y-2">
          <label className="flex items-center gap-2 text-sm text-[var(--r-sub)]">Outline for
            <select value={scope} onChange={(e) => setChosen(e.target.value)} aria-label="Outline for"
              className="rounded-lg border border-[var(--r-line)] bg-[var(--r-bar)] px-2.5 py-1.5 text-sm text-[var(--r-text)]">
              <option value={STUDY}>Whole study{countNodes(project.outline ?? []) ? ` · ${countNodes(project.outline)}` : ''}</option>
              {chunkChoices.map((c) => <option key={c.id} value={c.id}>{c.label}{c.count ? ` · ${c.count}` : ''}</option>)}
            </select>
          </label>
          {timeSummary(tree) && <span className="text-sm text-[var(--r-sub)]">{timeSummary(tree)}</span>}
          {scopeChunk && <button type="button" onClick={() => openChunk(scope)} className="text-sm text-[var(--r-accent)] hover:underline">Open this chunk in Study</button>}
        </div>

        <div className="mb-5 flex flex-wrap items-center gap-2">
          <button type="button" onClick={addMain} className="rounded-xl bg-[var(--r-accent)] px-4 py-2 text-sm font-medium text-[var(--r-on)] hover:opacity-90">+ Main point</button>
          <button type="button" onClick={seed} disabled={addable <= 0} className={btn}
            title={scope === STUDY ? "Adds a main point for each chunk that isn't in the outline yet" : "Adds a point for each verse of this chunk, with its words"}>
            {seedLabel}{addable > 0 ? ` (${addable})` : ''}
          </button>
          <span className="mx-1 hidden h-6 w-px bg-[var(--r-line)] sm:block" aria-hidden="true" />
          <button type="button" onClick={() => setShareOpen(true)} disabled={tree.length === 0} className={btn}>Share</button>
          <button type="button" onClick={print} disabled={tree.length === 0} className={btn}>Print / PDF</button>
          <details className="relative">
            <summary className={`${btn} cursor-pointer list-none ${tree.length === 0 ? 'pointer-events-none opacity-50' : ''}`}>More ▾</summary>
            <div className="absolute left-0 z-20 mt-1 w-48 rounded-xl border border-[var(--r-line)] bg-[var(--r-bar)] p-1 shadow-lg">
              <button type="button" onClick={copy} className="block w-full rounded-lg px-3 py-2 text-left text-sm hover:bg-black/5">Copy as text</button>
              <button type="button" onClick={word} className="block w-full rounded-lg px-3 py-2 text-left text-sm hover:bg-black/5">Download Word (.docx)</button>
              <button type="button" onClick={() => downloadOutlineMarkdown(outline)} className="block w-full rounded-lg px-3 py-2 text-left text-sm hover:bg-black/5">Download Markdown</button>
            </div>
          </details>
        </div>

        {tree.length === 0 ? (
          <div className="rounded-2xl border border-dashed border-[var(--r-line)] p-10 text-center">
            <p className="text-base font-medium">No outline yet{scope === STUDY ? '' : ` for ${scopeLabel}`}</p>
            <p className="mx-auto mt-2 max-w-md text-sm text-[var(--r-sub)]">
              {scope === STUDY
                ? 'Start from your chunks to get a main point for each passage you studied, or start blank and write your own.'
                : 'Start from the verses to get a point for each one, with its words, or start blank and write your own.'}
            </p>
            <div className="mt-5 flex flex-wrap justify-center gap-2">
              <button type="button" onClick={seed} disabled={addable <= 0} className="rounded-xl bg-[var(--r-accent)] px-4 py-2 text-sm font-medium text-[var(--r-on)] hover:opacity-90 disabled:opacity-50">
                {scope === STUDY ? 'Start from my chunks' : 'Start from the verses'}
              </button>
              <button type="button" onClick={addMain} className={btn}>Start blank</button>
            </div>
          </div>
        ) : (
          <ul aria-label="Outline" className="space-y-0.5">
            {rows.map(({ node, depth, label }, at) => {
              const hasChildren = node.children.length > 0;
              const showMeta = metaOpen.has(node.id);
              const linked = chunkChoices.find((c) => c.id === node.chunkId);
              const siblings = rows.filter((r) => r.parentId === rows[at].parentId);
              const place = siblings.findIndex((r) => r.node.id === node.id);
              const attachSource = chunkOf(project, node.chunkId ?? scopeChunk?.id);
              const attached = new Set((node.attachments ?? []).map((a) => a.id));
              const available = attachableFromChunk(attachSource).filter((a) => !attached.has(a.key));
              const mins = Number.isFinite(node.minutes) && node.minutes > 0;
              const noteLine = (node.note ?? '').trim().split('\n')[0];
              return (
                <li key={node.id} className="group" style={{ paddingLeft: `${depth * 1.75}rem` }}>
                  <div className="flex items-start gap-1.5">
                    <span className="w-9 shrink-0 pt-1.5 text-right font-serif text-sm text-[var(--r-sub)]" aria-hidden="true">{label}</span>
                    <div className="min-w-0 flex-1">
                      <AutoText
                        value={node.text} data-outline-id={node.id} className={pointBox}
                        aria-label={`Point ${label}`} placeholder={depth === 0 ? 'Main point' : 'Sub-point'}
                        onChange={(value) => patch(node.id, { text: value })}
                        onKeyDown={(e) => onKeyDown(e, node.id, node.text, hasChildren)}
                      />

                      {/* What the point carries, at a glance */}
                      {(node.kind || mins || node.ref || linked) && (
                        <p className="flex flex-wrap items-center gap-x-2 gap-y-1 px-2 text-xs text-[var(--r-sub)]">
                          {node.kind && <span className={`${chip} border-[var(--r-accent)] text-[var(--r-accent)]`}>{kindLabel(node.kind)}</span>}
                          {mins && <span>{node.minutes} min</span>}
                          {node.ref && <span>{node.ref}</span>}
                          {linked && node.chunkId !== scope && <button type="button" onClick={() => openChunk(node.chunkId)} className="text-[var(--r-accent)] hover:underline">Open chunk in Study</button>}
                        </p>
                      )}
                      {noteLine && !showMeta && <p className="truncate px-2 text-xs italic text-[var(--r-sub)]">{noteLine}</p>}
                      {node.scripture?.text && !showMeta && (
                        <blockquote className="mx-2 mt-1 border-l-2 border-[var(--r-line)] pl-2.5 font-serif text-sm italic text-[var(--r-sub)]">“{node.scripture.text.length > 220 ? `${node.scripture.text.slice(0, 220)}…` : node.scripture.text}” <span className="not-italic">— {node.scripture.ref}</span></blockquote>
                      )}
                      {(node.attachments ?? []).length > 0 && !showMeta && (
                        <div className="mt-1 flex flex-wrap gap-1 px-2">
                          {node.attachments.map((a) => <span key={a.id} className={chip} title={a.detail}>{a.type === 'word' ? 'Word' : 'See'}: {a.label}</span>)}
                        </div>
                      )}

                      {showMeta && (
                        <div className="mb-2 mt-1 space-y-3 rounded-xl border border-[var(--r-line)] bg-[var(--r-bar)] p-3">
                          <div className="grid gap-3 sm:grid-cols-[1fr_6rem]">
                            <label className="text-xs text-[var(--r-sub)]">Type
                              <select value={node.kind ?? ''} onChange={(e) => patch(node.id, { kind: e.target.value })} className={field}>
                                {KINDS.map(([id, text]) => <option key={id} value={id}>{text}</option>)}
                              </select>
                            </label>
                            <label className="text-xs text-[var(--r-sub)]">Minutes
                              <input type="number" min="0" max="240" inputMode="numeric" value={node.minutes ?? ''}
                                onChange={(e) => patch(node.id, { minutes: e.target.value === '' ? null : Math.max(0, Math.min(240, Math.round(Number(e.target.value)))) })} className={field} />
                            </label>
                          </div>

                          <label className="block text-xs text-[var(--r-sub)]">Notes
                            <AutoText value={node.note ?? ''} onChange={(value) => patch(node.id, { note: value })} placeholder="Anything to remember when you speak or write this point"
                              className={`${field} min-h-[4.5rem] resize-none overflow-hidden`} aria-label={`Notes for ${label}`} />
                          </label>

                          <div className="grid gap-3 sm:grid-cols-2">
                            <div>
                              <label className="text-xs text-[var(--r-sub)]">Passage
                                <input value={node.ref ?? ''} onChange={(e) => patch(node.id, { ref: e.target.value })} placeholder="e.g. Titus 1:5–9" className={field} />
                              </label>
                              <div className="mt-1.5 flex items-center gap-2">
                                <button type="button" disabled={!node.ref?.trim() || (lookup.busy && lookup.id === node.id)} onClick={() => addVerseText(node)} className={`${btn} !px-3 !py-1 text-xs`}>
                                  {lookup.busy && lookup.id === node.id ? 'Loading…' : node.scripture ? 'Replace verse text' : 'Add verse text'}
                                </button>
                                {node.scripture && <button type="button" onClick={() => patch(node.id, { scripture: null })} className="text-xs text-[var(--r-sub)] hover:text-[var(--r-danger,#b42318)]">Remove</button>}
                              </div>
                              {lookup.id === node.id && lookup.error && <p role="alert" className="mt-1 text-xs text-[var(--r-danger,#b42318)]">{lookup.error}</p>}
                            </div>
                            <label className="text-xs text-[var(--r-sub)]">Linked chunk
                              <select value={node.chunkId ?? ''} onChange={(e) => patch(node.id, {
                                chunkId: e.target.value || null,
                                ...(e.target.value && !node.ref ? { ref: chunkChoices.find((c) => c.id === e.target.value)?.label ?? '' } : {}),
                              })} className={field}>
                                <option value="">None</option>
                                {chunkChoices.map((c) => <option key={c.id} value={c.id}>{c.label}</option>)}
                              </select>
                            </label>
                          </div>

                          {node.scripture?.text && (
                            <blockquote className="border-l-2 border-[var(--r-line)] pl-2.5 font-serif text-sm italic text-[var(--r-sub)]">“{node.scripture.text}” <span className="not-italic">— {node.scripture.ref} ({node.scripture.translation})</span></blockquote>
                          )}

                          <div>
                            <p className="text-xs text-[var(--r-sub)]">Attach from {attachSource ? 'its chunk' : 'a chunk'}</p>
                            {(node.attachments ?? []).length > 0 && (
                              <div className="mt-1 flex flex-wrap gap-1">
                                {node.attachments.map((a) => (
                                  <span key={a.id} className={`${chip} inline-flex items-center gap-1`} title={a.detail}>
                                    {a.type === 'word' ? 'Word' : 'See'}: {a.label}
                                    <button type="button" aria-label={`Remove ${a.label}`} onClick={() => patch(node.id, { attachments: node.attachments.filter((x) => x.id !== a.id) })} className="hover:text-[var(--r-danger,#b42318)]">×</button>
                                  </span>
                                ))}
                              </div>
                            )}
                            {!attachSource ? (
                              <p className="mt-1 text-xs text-[var(--r-sub)]">Link a chunk above to attach its cross-references and word studies.</p>
                            ) : available.length === 0 ? (
                              <p className="mt-1 text-xs text-[var(--r-sub)]">{(node.attachments ?? []).length ? 'Everything from this chunk is attached.' : 'This chunk has no cross-references or word studies yet. Add some in the Study stage.'}</p>
                            ) : (
                              <select value="" aria-label={`Attach to ${label}`} className={field}
                                onChange={(e) => {
                                  const pick = available.find((a) => a.key === e.target.value);
                                  if (pick) patch(node.id, { attachments: [...(node.attachments ?? []), { id: pick.key, type: pick.type, label: pick.label, detail: pick.detail }] });
                                }}>
                                <option value="">Choose a cross-reference or word…</option>
                                {available.map((a) => <option key={a.key} value={a.key}>{a.type === 'word' ? 'Word' : 'See'}: {a.label}</option>)}
                              </select>
                            )}
                          </div>
                        </div>
                      )}
                    </div>
                    <div className="flex shrink-0 items-center opacity-0 transition focus-within:opacity-100 group-hover:opacity-100 [@media(hover:none)]:opacity-100">
                      <button type="button" className={iconBtn} aria-label={`Move ${label} out a level`} title="Out a level (Shift+Tab)" disabled={depth === 0} onClick={() => edit((t) => outdent(t, node.id))}>←</button>
                      <button type="button" className={iconBtn} aria-label={`Move ${label} in a level`} title="In a level (Tab)" disabled={place === 0} onClick={() => edit((t) => indent(t, node.id))}>→</button>
                      <button type="button" className={iconBtn} aria-label={`Move ${label} up`} title="Up (Alt+↑)" disabled={place === 0} onClick={() => edit((t) => moveNode(t, node.id, -1))}>↑</button>
                      <button type="button" className={iconBtn} aria-label={`Move ${label} down`} title="Down (Alt+↓)" disabled={place === siblings.length - 1} onClick={() => edit((t) => moveNode(t, node.id, 1))}>↓</button>
                      <button type="button" className={iconBtn} aria-label={`Add a sub-point under ${label}`} title="Add a sub-point" onClick={() => addSub(node.id)}>+</button>
                      <button type="button" className={iconBtn} aria-label={`Details for ${label}`} aria-expanded={showMeta} title="Type, minutes, notes, verse text, attachments" onClick={() => toggleMeta(node.id)}>⋯</button>
                      <button type="button" className={`${iconBtn} hover:!text-[var(--r-danger,#b42318)]`} aria-label={`Delete ${label}`} title="Delete" onClick={() => remove(node.id)}>×</button>
                    </div>
                  </div>
                </li>
              );
            })}
          </ul>
        )}

        {tree.length > 0 && (
          <p className="mt-6 text-xs text-[var(--r-sub)]">
            Enter adds a point · Tab and Shift+Tab change its level · Alt+↑ / ↓ moves it · Backspace on an empty point deletes it · ⋯ opens its details.
          </p>
        )}
      </main>
      <ShareOutlineSheet open={shareOpen} onClose={() => setShareOpen(false)} projectId={project.id} outline={outline} />
    </StudioShell>
  );
}