'use strict';

// ---------------------------------------------------------------------------
// Margin panel — a "page margin" strip left of the reader content. Shows small
// markers next to the on-screen highlights/notes, and lets you click empty
// space to anchor a freeform note at that line's height (EPUB only).
// ---------------------------------------------------------------------------
let readerAnnotationsMarginOpen = false;

function toggleAnnotationsMargin() {
  const el = $('reader-margin');
  const markersEl = $('reader-margin-markers');
  if (!el || !markersEl || currentPdfDoc) return;
  readerAnnotationsMarginOpen = !readerAnnotationsMarginOpen;
  el.classList.toggle('open', readerAnnotationsMarginOpen);
  if (readerAnnotationsMarginOpen) {
    // Reposition once now (pre-transition) and once more after the width
    // transition settles, since content reflow can shift line heights.
    _repositionMarginMarkers();
    el.addEventListener('transitionend', _repositionMarginMarkers, {once: true});
  } else {
    markersEl.innerHTML = '';
  }
}

// Renders each highlight/note at its text position in the margin. Entries
// with note text become a readable "post-it" card (the whole point of the
// margin — you can read notes there, not just see that one exists); a plain
// highlight with no note is just a small color dot. Cards are stacked
// top-to-bottom so overlapping anchors don't overlap visually.
// Where each highlight sits in the book's scroll coordinates. Finding a range
// and measuring it is the expensive part, and scrolling doesn't change it:
// kept until the layout does (content, width, height) or the anchor changes.
let _marginPosCache = null;
const _marginCardHeights = new Map(); // `${stripWidth}|${note}` (or 'dot') → px

function _marginDocY(h, contentEl) {
  const {blocks} = _epubBlocks(contentEl);
  const key = `${contentEl.clientWidth}x${contentEl.scrollHeight}`;
  if (!_marginPosCache || _marginPosCache.blocks !== blocks || _marginPosCache.key !== key) {
    _marginPosCache = {blocks, key, byId: new Map()};
  }
  const hit = _marginPosCache.byId.get(h.id);
  if (hit && hit.anchor === h.anchor) return hit.y;
  let y = null;
  try {
    const range = resolveAnchorRange(h);
    const rect = range && range.getBoundingClientRect();
    if (rect && (rect.width || rect.height)) {
      y = rect.top + rect.height / 2 - contentEl.getBoundingClientRect().top + contentEl.scrollTop;
    }
  } catch (e) {}
  _marginPosCache.byId.set(h.id, {anchor: h.anchor, y});
  return y;
}

// The cards live on one layer in the book's coordinates, built when the
// highlights or the layout change; scrolling only moves the layer (a transform,
// no layout). Rebuilding and measuring the cards on every scroll frame made a
// long book with the margin open stutter.
let _marginLayerKey = null;

function _repositionMarginMarkers() {
  const markersEl = $('reader-margin-markers');
  if (!markersEl) return;
  if (!readerAnnotationsMarginOpen || currentPdfDoc) {
    markersEl.innerHTML = '';
    _marginLayerKey = null;
    return;
  }
  if (markersEl.querySelector('.margin-note-editor')) return; // don't blow away an active inline edit
  const contentEl = $('reader-content');
  if (!contentEl) return;

  const {blocks} = _epubBlocks(contentEl);
  const areaRect = markersEl.getBoundingClientRect();
  const width = Math.round(areaRect.width);
  const key = `${width}x${contentEl.clientWidth}x${contentEl.scrollHeight}|` +
    currentHighlights.map(h => `${h.id}:${h.color || ''}:${h.note || ''}`).join('|');
  let layer = markersEl.querySelector('.margin-layer');
  if (!layer || key !== _marginLayerKey || !_marginPosCache || _marginPosCache.blocks !== blocks) {
    markersEl.innerHTML = '';
    layer = document.createElement('div');
    layer.className = 'margin-layer';
    markersEl.appendChild(layer);
    _renderMarginLayer(layer, contentEl, width);
    _marginLayerKey = key;
  }
  // Book coordinates → this strip's.
  const shift = contentEl.getBoundingClientRect().top - contentEl.scrollTop - areaRect.top;
  layer.style.transform = `translateY(${Math.round(shift)}px)`;
}

// Renders each highlight/note at its text position, in book coordinates.
// Entries with note text become a readable "post-it" card (the whole point of
// the margin — you can read notes there, not just see that one exists); a
// plain highlight with no note is a small colour dot. Cards are stacked top to
// bottom so overlapping anchors don't overlap visually.
function _renderMarginLayer(layer, contentEl, width) {
  const entries = [];
  for (const h of currentHighlights) {
    const y = _marginDocY(h, contentEl);
    if (y !== null) entries.push({h, y});
  }
  entries.sort((a, b) => a.y - b.y);

  // All cards first, then their heights in one go (each measured right after
  // adding it, the browser laid out the whole book once per card). Heights are
  // kept per note text and strip width.
  const cards = entries.map(({h, y}) => {
    const hasText = !!h.note;
    const el = document.createElement('div');
    el.className = 'margin-note ' + (hasText ? 'margin-note-text' : 'margin-note-dot');
    el.dataset.highlightId = h.id;
    if (h.type === 'note') {
      if (hasText) el.classList.add('margin-note-freeform');
    } else {
      el.dataset.color = h.color || 'yellow';
    }
    if (hasText) el.textContent = h.note;
    layer.appendChild(el);
    return {el, y, hasText, key: hasText ? `${width}|${h.note}` : 'dot'};
  });
  if (_marginCardHeights.size > 500) _marginCardHeights.clear();
  const unmeasured = cards.filter(c => !_marginCardHeights.has(c.key));
  for (const c of unmeasured) _marginCardHeights.set(c.key, c.el.getBoundingClientRect().height || (c.hasText ? 20 : 12));

  let nextTop = -Infinity;
  const GAP = 4;
  for (const {el, y, hasText, key} of cards) {
    const top = Math.max(hasText ? y - 8 : y - 6, nextTop);
    el.style.top = top + 'px';
    nextTop = top + _marginCardHeights.get(key) + GAP;
  }
}

function handleMarginClick(e) {
  const markerBtn = e.target.closest('.margin-note');
  if (markerBtn) {
    const h = currentHighlights.find(x => x.id === markerBtn.dataset.highlightId);
    if (h) _openNoteEditor(h);
    return;
  }

  // Empty space in the markers area → place a new freeform note anchored to
  // the first word of whatever line sits at this click height.
  if (!readerAnnotationsMarginOpen || currentPdfDoc) return;
  const markersEl = $('reader-margin-markers');
  if (!markersEl || !markersEl.contains(e.target)) return;
  // If an editor is already open, this click just blurs/commits it (see its
  // own blur handler) — it shouldn't also create a second, unrelated note.
  if (markersEl.querySelector('.margin-note-editor')) return;
  const contentEl = $('reader-content');
  if (!contentEl) return;

  const x = contentEl.getBoundingClientRect().left + 4;
  const range = _wordRangeAtPoint(x, e.clientY);
  if (range) createFreeformNote(range);
}

// Finds the word starting at (or just after) the given viewport point, by
// probing near the left edge of the reader content at that height — since
// text is left-aligned, that lands at (or very near) the start of the line.
function _wordRangeAtPoint(x, y) {
  let caret = null;
  if (document.caretRangeFromPoint) {
    caret = document.caretRangeFromPoint(x, y);
  } else if (document.caretPositionFromPoint) {
    const pos = document.caretPositionFromPoint(x, y);
    if (pos) {
      caret = document.createRange();
      caret.setStart(pos.offsetNode, pos.offset);
    }
  }
  if (!caret) return null;

  const contentEl = $('reader-content');
  if (!contentEl || !contentEl.contains(caret.startContainer)) return null;

  let node = caret.startContainer;
  let offset = caret.startOffset;
  if (node.nodeType !== Node.TEXT_NODE) {
    const walker = document.createTreeWalker(contentEl, NodeFilter.SHOW_TEXT);
    walker.currentNode = node;
    node = walker.nextNode();
    if (!node) return null;
    offset = 0;
  }

  const text = node.textContent;
  let start = offset;
  while (start < text.length && /\s/.test(text[start])) start++;
  if (start >= text.length) return null;
  let wordStart = start;
  while (wordStart > 0 && !/\s/.test(text[wordStart - 1])) wordStart--;
  let wordEnd = start;
  while (wordEnd < text.length && !/\s/.test(text[wordEnd])) wordEnd++;
  if (wordEnd <= wordStart) return null;

  const range = document.createRange();
  range.setStart(node, wordStart);
  range.setEnd(node, wordEnd);
  return range;
}

function createFreeformNote(range) {
  const anchor = buildEpubAnchor(range);
  // Where the note's card/dot would sit in the margin, computed from the live
  // range right now (before it goes stale) — used to position the editor,
  // whether or not the margin is actually open.
  let top = 0;
  const markersEl = $('reader-margin-markers');
  if (markersEl) {
    const areaRect = markersEl.getBoundingClientRect();
    const rangeRect = range.getBoundingClientRect();
    top = Math.max(0, rangeRect.top + rangeRect.height / 2 - areaRect.top - 8);
  }
  // The highlight object itself isn't created yet — see _openNoteEditor's
  // `pending` param — so a tap that's immediately cancelled or left empty
  // never leaves a ghost entry in currentHighlights.
  _openNoteEditor(null, {anchor, top});
}

// Commits an edit for both note-editor UIs (inline margin + mobile bottom
// sheet): updates an existing note in place, or — only if there's actual
// text — creates and persists a not-yet-existing freeform note. An empty
// tap/cancel on a pending note must never leave a permanent ghost entry.
function _commitNoteEdit(h, pending, text) {
  if (h) {
    if (h.note !== text) {
      h.note = text;
      highlightsDirty = true;
      debounceSaveHighlights();
    }
    return h;
  }
  if (!text) return null;
  const newH = {
    id: crypto.randomUUID(), type: 'note', anchor: pending.anchor,
    color: null, note: text, createdAt: new Date().toISOString(),
  };
  currentHighlights.push(newH);
  highlightsDirty = true;
  debounceSaveHighlights();
  return newH;
}

// Edit a note's text right where it lives in the margin, instead of jumping
// to the separate right-hand sidebar — the whole point of setting a note in
// the margin is that you shouldn't have to look away from it to write it.
// `h` is null for a not-yet-created freeform note (see createFreeformNote);
// `pending` then carries its anchor + intended margin position instead.
function editNoteInlineInMargin(h, pending) {
  const markersEl = $('reader-margin-markers');
  if (!markersEl) return;
  markersEl.querySelector('.margin-note-editor')?.remove();

  let top = pending?.top || 0;
  if (h) {
    const existingCard = markersEl.querySelector(`[data-highlight-id="${h.id}"]`);
    // The card sits on the moving layer: where it shows in the strip right now.
    top = existingCard ? existingCard.getBoundingClientRect().top - markersEl.getBoundingClientRect().top : 0;
    if (existingCard) existingCard.style.display = 'none';
  }

  const editor = document.createElement('div');
  editor.className = 'margin-note-editor';
  editor.style.top = top + 'px';
  editor.innerHTML = '<textarea class="margin-note-textarea"></textarea>';
  markersEl.appendChild(editor);
  const textarea = editor.querySelector('textarea');
  textarea.value = h?.note || '';

  function commit() {
    _commitNoteEdit(h, pending, textarea.value.trim());
    editor.remove();
    _marginLayerKey = null; // the edited card was hidden: draw the layer anew
    _repositionMarginMarkers();
  }

  textarea.addEventListener('blur', commit);
  textarea.addEventListener('keydown', e => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      e.stopPropagation();
      textarea.blur(); // triggers commit()
    } else if (e.key === 'Escape') {
      // Stop this from bubbling to the document-level Escape handler, which
      // would otherwise close the whole reader (it doesn't know we just want
      // to cancel this one edit) — see the global keydown listener.
      e.stopPropagation();
      textarea.removeEventListener('blur', commit); // discard, don't save
      editor.remove();
      _marginLayerKey = null;
      _repositionMarginMarkers();
    }
  });

  textarea.focus();
  textarea.select();
}

// Mobile alternative to editNoteInlineInMargin — a full-width sheet instead
// of squeezing a textarea into the 150px margin column (see _openNoteEditor).
let currentNoteBottomSheet = null;

function dismissNoteBottomSheet() {
  currentNoteBottomSheet?.remove();
  currentNoteBottomSheet = null;
}

function showNoteBottomSheet(h, pending) {
  dismissNoteBottomSheet();

  const sheet = document.createElement('div');
  sheet.className = 'note-bottom-sheet';
  sheet.innerHTML = `
    <div class="note-bottom-sheet-backdrop"></div>
    <div class="note-bottom-sheet-panel">
      <textarea class="note-bottom-sheet-textarea" placeholder="Notiz…"></textarea>
      <div class="note-bottom-sheet-actions">
        <button class="btn btn-sm" data-nbs-cancel>Abbrechen</button>
        <button class="btn btn-sm btn-primary" data-nbs-save>Speichern</button>
      </div>
    </div>
  `;
  document.body.appendChild(sheet);
  currentNoteBottomSheet = sheet;

  const textarea = sheet.querySelector('.note-bottom-sheet-textarea');
  textarea.value = h?.note || '';

  function commit() {
    _commitNoteEdit(h, pending, textarea.value.trim());
    dismissNoteBottomSheet();
    if (readerAnnotationsMarginOpen) _repositionMarginMarkers();
  }
  function cancel() { dismissNoteBottomSheet(); }

  sheet.querySelector('[data-nbs-save]').addEventListener('click', commit);
  sheet.querySelector('[data-nbs-cancel]').addEventListener('click', cancel);
  sheet.querySelector('.note-bottom-sheet-backdrop').addEventListener('click', cancel);
  textarea.addEventListener('keydown', e => {
    if (e.key === 'Escape') { e.stopPropagation(); cancel(); }
  });

  requestAnimationFrame(() => {
    sheet.classList.add('open');
    textarea.focus();
  });
}

// Same plain-text export as exportAnnotations(), but callable straight from the
// book list (no open reader, so no live DOM/TOC to resolve percent position or
// chapter titles against — falls back to the raw chapterSrc path and orders by
// the anchor's block index, which is already a global reading-order index).
async function downloadBookAnnotationsFromList(bookId, btnEl) {
  if (btnEl) btnEl.disabled = true;
  try {
    const res = await fetch(`/books/${bookId}/highlights/`);
    const {ct, iv} = await res.json();
    if (!ct) { await customAlert('In diesem Buch gibt es noch keine Markierungen oder Notizen.'); return; }
    const key = await getOrCreateEncKey();
    const plain = await decryptBytes(key, iv, ct);
    const highlights = JSON.parse(new TextDecoder().decode(plain));
    if (!highlights.length) { await customAlert('In diesem Buch gibt es noch keine Markierungen oder Notizen.'); return; }

    highlights.sort((a, b) => {
      const ab = a.anchor?.startBlockIndex ?? 0, bb = b.anchor?.startBlockIndex ?? 0;
      if (ab !== bb) return ab - bb;
      return (a.anchor?.startChar ?? 0) - (b.anchor?.startChar ?? 0);
    });

    const bookTitle = bookMetaCache[bookId]?.title || `Buch #${bookId}`;
    const lines = [`${bookTitle} — Markierungen & Notizen`, `Exportiert: ${new Date().toISOString().slice(0, 10)}`, ''];

    let lastChapter = null;
    for (const h of highlights) {
      const chapterTitle = h.anchor?.chapterSrc || '';
      if (chapterTitle !== lastChapter) {
        lines.push(`── ${chapterTitle || 'Abschnitt ohne Titel'} ──`);
        lastChapter = chapterTitle;
      }
      if (h.type === 'note') {
        lines.push(`[Notiz] bei: „${(h.anchor?.quote || '').trim()}“`);
        if (h.note) lines.push(`    ${h.note}`);
      } else {
        lines.push(`[Markierung · ${_hlColorName(h.color || 'yellow')}] „${(h.anchor?.quote || '').trim()}“`);
        if (h.note) lines.push(`    Notiz: ${h.note}`);
      }
      lines.push('');
    }

    const blob = new Blob([lines.join('\n')], {type: 'text/plain;charset=utf-8'});
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = `${bookTitle.replace(/[^\w\-]+/g, '_')}-notizen.txt`;
    document.body.appendChild(a);
    a.click();
    a.remove();
    URL.revokeObjectURL(url);
  } catch (e) {
    await customAlert('Export fehlgeschlagen: ' + e.message);
  } finally {
    if (btnEl) btnEl.disabled = false;
  }
}