'use strict';

// ---------------------------------------------------------------------------
// Reader Search
// ---------------------------------------------------------------------------

let _readerSearchDebounce = null;

function toggleReaderSearch() {
  const overlay = $('reader-overlay');
  const contentEl = $('reader-content');
  if (!overlay || !contentEl) return;

  const existing = document.getElementById('reader-search-bar');
  if (existing) {
    existing.remove();
    readerSearchOpen = false;
    clearReaderSearch();
    return;
  }

  readerSearchOpen = true;
  const bar = document.createElement('div');
  bar.id = 'reader-search-bar';
  bar.className = 'reader-search-bar';
  bar.innerHTML = `
    <input type="text" id="reader-search-input" class="search-input" placeholder="Suchen …" style="width:160px;">
    <button class="btn-icon" id="rs-search-prev" title="Vorheriger Treffer">↑</button>
    <button class="btn-icon" id="rs-search-next" title="Nächster Treffer">↓</button>
    <span id="rs-search-count" class="muted"></span>
    <button class="btn-icon" id="rs-search-clear" title="Close">✕</button>
  `;
  overlay.insertBefore(bar, $('reader-body-row'));

  const input = bar.querySelector('#reader-search-input');
  input.focus();
  input.addEventListener('input', () => {
    clearTimeout(_readerSearchDebounce);
    _readerSearchDebounce = setTimeout(() => doReaderSearch(input.value.trim()), 300);
  });
  input.addEventListener('keydown', e => {
    if (e.key === 'Enter') { e.shiftKey ? readerSearchPrev() : readerSearchNext(); }
    if (e.key === 'Escape') { toggleReaderSearch(); }
  });
  bar.querySelector('#rs-search-prev').addEventListener('click', readerSearchPrev);
  bar.querySelector('#rs-search-next').addEventListener('click', readerSearchNext);
  bar.querySelector('#rs-search-clear').addEventListener('click', toggleReaderSearch);
}

async function doReaderSearch(query) {
  const contentEl = $('reader-content');
  if (!contentEl) return;
  const countEl = document.getElementById('rs-search-count');

  clearReaderSearchHighlights();
  searchMatches = [];
  searchMatchIndex = -1;

  if (!query) { if (countEl) countEl.textContent = ''; return; }

  if (!currentPdfDoc) {
    // EPUB: snapshot original content
    if (!searchOriginalContent) {
      searchOriginalContent = contentEl.innerHTML;
    } else {
      contentEl.innerHTML = searchOriginalContent;
      applyHighlightsToContent();
    }

    const walker = document.createTreeWalker(contentEl, NodeFilter.SHOW_TEXT);
    const lq = query.toLowerCase();
    const ranges = [];
    let node;
    while ((node = walker.nextNode())) {
      const text = node.textContent;
      const lt = text.toLowerCase();
      let idx = 0;
      while ((idx = lt.indexOf(lq, idx)) !== -1) {
        const range = document.createRange();
        range.setStart(node, idx);
        range.setEnd(node, idx + query.length);
        ranges.push(range);
        idx += query.length;
      }
    }

    // Insert marks in reverse to preserve range validity
    for (let i = ranges.length - 1; i >= 0; i--) {
      try {
        const mark = document.createElement('mark');
        mark.className = 'reader-search-match';
        ranges[i].surroundContents(mark);
        searchMatches.unshift(mark);
      } catch (e) {}
    }
  } else {
    // PDF: the whole document, page by page (not only the pages drawn now).
    _pdfSearchAll(query);
    return;
  }

  if (countEl) countEl.textContent = searchMatches.length ? `1 / ${searchMatches.length}` : '0';
  if (searchMatches.length) {
    searchMatchIndex = 0;
    scrollToSearchMatch(0);
  }
}

function clearReaderSearchHighlights() {
  if (!currentPdfDoc) {
    // EPUB: restore from snapshot
    if (searchOriginalContent !== null) {
      const contentEl = $('reader-content');
      if (contentEl) {
        contentEl.innerHTML = searchOriginalContent;
        applyHighlightsToContent();
      }
      searchOriginalContent = null;
    } else {
      // Just remove marks without full restore
      document.querySelectorAll('mark.reader-search-match').forEach(m => {
        const parent = m.parentNode;
        while (m.firstChild) parent.insertBefore(m.firstChild, m);
        parent.removeChild(m);
      });
    }
  } else {
    _pdfSearchStop();
  }
  searchMatches = [];
  searchMatchIndex = -1;
}

function clearReaderSearch() {
  clearTimeout(_readerSearchDebounce);
  clearReaderSearchHighlights();
  readerSearchOpen = false;
  const countEl = document.getElementById('rs-search-count');
  if (countEl) countEl.textContent = '';
}

function scrollToSearchMatch(idx) {
  if (!searchMatches.length) return;
  if (currentPdfDoc) { _pdfShowMatch(idx); return; }
  _suppressScrollJumpDetect();
  searchMatches.forEach((m, i) => m.classList.toggle('active', i === idx));
  searchMatches[idx].scrollIntoView({behavior: 'smooth', block: 'center'});
  const countEl = document.getElementById('rs-search-count');
  if (countEl) countEl.textContent = `${idx + 1} / ${searchMatches.length}`;
}

// ---------------------------------------------------------------------------
// PDF search: through the text of every page (58-pdf.js keeps it), in order; the matches
// marked in the text layer of the pages drawn, and of those drawn later.
// ---------------------------------------------------------------------------

let _pdfSearchState = null;   // {query, matches: [{page, start, end}], done}
let _pdfSearchGen = 0;

function _pdfSearchCount() {
  const countEl = document.getElementById('rs-search-count');
  const st = _pdfSearchState;
  if (!countEl || !st) return;
  const more = st.done ? '' : ' …';
  countEl.textContent = st.matches.length
    ? `${searchMatchIndex >= 0 ? searchMatchIndex + 1 : '–'} / ${st.matches.length}${more}`
    : (st.done ? '0' : '…');
}

async function _pdfSearchAll(query) {
  const pdf = currentPdfDoc;
  const gen = ++_pdfSearchGen;
  const lq = query.toLowerCase();
  const st = {query, matches: [], done: false};
  _pdfSearchState = st;
  searchMatches = st.matches;
  searchMatchIndex = -1;
  _pdfSearchCount();
  // The first match from the page being read on is shown as soon as it's found.
  const from = pdfCurrentPage || 1;
  for (let n = 1; n <= pdf.numPages; n++) {
    const tc = await _pdfPageText(pdf, n);
    if (gen !== _pdfSearchGen || pdf !== currentPdfDoc) return;
    const {str} = _pdfPageString(tc);
    const before = st.matches.length;
    let i = 0;
    while (lq && (i = str.indexOf(lq, i)) !== -1) {
      st.matches.push({page: n, start: i, end: i + lq.length});
      i += lq.length;
    }
    if (st.matches.length > before) {
      const e = _pdfView && _pdfView.entries[n - 1];
      if (e) _pdfSearchMarkPage(e);
      if (searchMatchIndex < 0 && n >= from) { searchMatchIndex = before; _pdfShowMatch(before); }
    }
    if (n % 20 === 0) _pdfSearchCount();
  }
  st.done = true;
  if (searchMatchIndex < 0 && st.matches.length) { searchMatchIndex = 0; _pdfShowMatch(0); }
  _pdfSearchCount();
}

/** Marks of search [st] in page [e]'s text layer (none when no search is on). */
function _pdfSearchMarkPage(e) {
  if (!e.textDivs || !e.textInfo) return;
  if (e.marked) {
    for (const i of e.marked) if (e.textDivs[i]) e.textDivs[i].textContent = e.textInfo.items[i].str;
    e.marked = null;
  }
  const st = _pdfSearchState;
  if (!st) return;
  const {starts} = e.textInfo.string;
  const items = e.textInfo.items;
  // Per span, the pieces of it that match (one match can run over several spans).
  const pieces = new Map();
  st.matches.forEach((m, idx) => {
    if (m.page !== e.num) return;
    for (let i = 0; i < items.length; i++) {
      const s = starts[i], len = (items[i].str || '').length;
      if (s >= m.end) break;
      if (s + len <= m.start || !len) continue;
      if (!pieces.has(i)) pieces.set(i, []);
      pieces.get(i).push([Math.max(m.start, s) - s, Math.min(m.end, s + len) - s, idx]);
    }
  });
  e.marked = [];
  pieces.forEach((list, i) => {
    const div = e.textDivs[i];
    if (!div) return;
    const str = items[i].str;
    div.textContent = '';
    let at = 0;
    for (const [a, b, idx] of list) {
      if (a > at) div.appendChild(document.createTextNode(str.slice(at, a)));
      const mark = document.createElement('mark');
      mark.className = 'reader-search-match' + (idx === searchMatchIndex ? ' active' : '');
      mark.dataset.m = idx;
      mark.textContent = str.slice(a, b);
      div.appendChild(mark);
      at = b;
    }
    if (at < str.length) div.appendChild(document.createTextNode(str.slice(at)));
    e.marked.push(i);
  });
}

/** Go to match [idx]: its page, and (scrolling) the match itself into view. */
async function _pdfShowMatch(idx) {
  const st = _pdfSearchState;
  const m = st && st.matches[idx];
  if (!m) return;
  const gen = _pdfSearchGen;
  _pdfSearchCount();
  document.querySelectorAll('.pdf-text-layer mark.reader-search-match').forEach(mk => {
    mk.classList.toggle('active', +mk.dataset.m === idx);
  });
  const contentEl = $('reader-content');
  const shown = readerSettings.pdfPaginated ? pdfCurrentPage : (contentEl ? _pdfTopPage(contentEl) : 0);
  if (m.page !== shown || readerSettings.pdfPaginated) pdfGoToPage(m.page);
  if (readerSettings.pdfPaginated || !contentEl) return;
  // Scrolling: the page is drawn (and its text laid over it) once it's near the view.
  for (let t = 0; t < 50; t++) {
    if (gen !== _pdfSearchGen || searchMatchIndex !== idx) return;
    const mk = contentEl.querySelector(`#pdf-page-${m.page} mark[data-m="${idx}"]`);
    if (mk) {
      _suppressScrollJumpDetect();
      mk.scrollIntoView({block: 'center'});
      return;
    }
    await new Promise(r => setTimeout(r, 100));
  }
}

function _pdfSearchStop() {
  _pdfSearchGen++;
  _pdfSearchState = null;
  if (_pdfView) _pdfView.entries.forEach(e => { if (e.marked) _pdfSearchMarkPage(e); });
}

function readerSearchNext() {
  if (!searchMatches.length) return;
  searchMatchIndex = (searchMatchIndex + 1) % searchMatches.length;
  scrollToSearchMatch(searchMatchIndex);
}

function readerSearchPrev() {
  if (!searchMatches.length) return;
  searchMatchIndex = (searchMatchIndex - 1 + searchMatches.length) % searchMatches.length;
  scrollToSearchMatch(searchMatchIndex);
}