crosspoint-reader-mod/src/activities/reader/EpubReaderActivity.cpp

#include "EpubReaderActivity.h"

#include <Epub/Page.h>
#include <Epub/blocks/TextBlock.h>
#include <FsHelpers.h>
#include <GfxRenderer.h>
#include <HalStorage.h>
#include <I18n.h>
#include <Logging.h>

#include "CrossPointSettings.h"
#include "CrossPointState.h"
#include "EpubReaderChapterSelectionActivity.h"
#include "EpubReaderFootnotesActivity.h"
#include "EpubReaderPercentSelectionActivity.h"
#include "KOReaderCredentialStore.h"
#include "KOReaderSyncActivity.h"
#include "MappedInputManager.h"
#include "QrDisplayActivity.h"
#include "RecentBooksStore.h"
#include "components/UITheme.h"
#include "fontIds.h"
#include "util/ScreenshotUtil.h"

namespace {
// pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
constexpr unsigned long skipChapterMs = 700;
constexpr unsigned long goHomeMs = 1000;

int clampPercent(int percent) {
  if (percent < 0) {
    return 0;
  }
  if (percent > 100) {
    return 100;
  }
  return percent;
}

// Apply the logical reader orientation to the renderer.
// This centralizes orientation mapping so we don't duplicate switch logic elsewhere.
void applyReaderOrientation(GfxRenderer& renderer, const uint8_t orientation) {
  switch (orientation) {
    case CrossPointSettings::ORIENTATION::PORTRAIT:
      renderer.setOrientation(GfxRenderer::Orientation::Portrait);
      break;
    case CrossPointSettings::ORIENTATION::LANDSCAPE_CW:
      renderer.setOrientation(GfxRenderer::Orientation::LandscapeClockwise);
      break;
    case CrossPointSettings::ORIENTATION::INVERTED:
      renderer.setOrientation(GfxRenderer::Orientation::PortraitInverted);
      break;
    case CrossPointSettings::ORIENTATION::LANDSCAPE_CCW:
      renderer.setOrientation(GfxRenderer::Orientation::LandscapeCounterClockwise);
      break;
    default:
      break;
  }
}

}  // namespace

void EpubReaderActivity::onEnter() {
  Activity::onEnter();

  if (!epub) {
    return;
  }

  // Configure screen orientation based on settings
  // NOTE: This affects layout math and must be applied before any render calls.
  applyReaderOrientation(renderer, SETTINGS.orientation);

  epub->setupCacheDir();

  FsFile f;
  if (Storage.openFileForRead("ERS", epub->getCachePath() + "/progress.bin", f)) {
    uint8_t data[6];
    int dataSize = f.read(data, 6);
    if (dataSize == 4 || dataSize == 6) {
      currentSpineIndex = data[0] + (data[1] << 8);
      nextPageNumber = data[2] + (data[3] << 8);
      cachedSpineIndex = currentSpineIndex;
      LOG_DBG("ERS", "Loaded cache: %d, %d", currentSpineIndex, nextPageNumber);
    }
    if (dataSize == 6) {
      cachedChapterTotalPageCount = data[4] + (data[5] << 8);
    }
    f.close();
  }
  // We may want a better condition to detect if we are opening for the first time.
  // This will trigger if the book is re-opened at Chapter 0.
  if (currentSpineIndex == 0) {
    int textSpineIndex = epub->getSpineIndexForTextReference();
    if (textSpineIndex != 0) {
      currentSpineIndex = textSpineIndex;
      LOG_DBG("ERS", "Opened for first time, navigating to text reference at index %d", textSpineIndex);
    }
  }

  // Save current epub as last opened epub and add to recent books
  APP_STATE.openEpubPath = epub->getPath();
  APP_STATE.saveToFile();
  RECENT_BOOKS.addBook(epub->getPath(), epub->getTitle(), epub->getAuthor(), epub->getThumbBmpPath());

  // Trigger first update
  requestUpdate();
}

void EpubReaderActivity::onExit() {
  Activity::onExit();

  // Reset orientation back to portrait for the rest of the UI
  renderer.setOrientation(GfxRenderer::Orientation::Portrait);

  APP_STATE.readerActivityLoadCount = 0;
  APP_STATE.saveToFile();
  section.reset();
  epub.reset();
}

void EpubReaderActivity::loop() {
  if (!epub) {
    // Should never happen
    finish();
    return;
  }

  // Enter reader menu activity.
  if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
    const int currentPage = section ? section->currentPage + 1 : 0;
    const int totalPages = section ? section->pageCount : 0;
    float bookProgress = 0.0f;
    if (epub->getBookSize() > 0 && section && section->pageCount > 0) {
      const float chapterProgress = static_cast<float>(section->currentPage) / static_cast<float>(section->pageCount);
      bookProgress = epub->calculateProgress(currentSpineIndex, chapterProgress) * 100.0f;
    }
    const int bookProgressPercent = clampPercent(static_cast<int>(bookProgress + 0.5f));
    startActivityForResult(std::make_unique<EpubReaderMenuActivity>(
                               renderer, mappedInput, epub->getTitle(), currentPage, totalPages, bookProgressPercent,
                               SETTINGS.orientation, !currentPageFootnotes.empty()),
                           [this](const ActivityResult& result) {
                             // Always apply orientation change even if the menu was cancelled
                             const auto& menu = std::get<MenuResult>(result.data);
                             applyOrientation(menu.orientation);
                             if (!result.isCancelled) {
                               onReaderMenuConfirm(static_cast<EpubReaderMenuActivity::MenuAction>(menu.action));
                             }
                           });
  }

  // Long press BACK (1s+) goes to file selection
  if (mappedInput.isPressed(MappedInputManager::Button::Back) && mappedInput.getHeldTime() >= goHomeMs) {
    activityManager.goToMyLibrary(epub ? epub->getPath() : "");
    return;
  }

  // Short press BACK goes directly to home (or restores position if viewing footnote)
  if (mappedInput.wasReleased(MappedInputManager::Button::Back) && mappedInput.getHeldTime() < goHomeMs) {
    if (footnoteDepth > 0) {
      restoreSavedPosition();
      return;
    }
    onGoHome();
    return;
  }

  // When long-press chapter skip is disabled, turn pages on press instead of release.
  const bool usePressForPageTurn = !SETTINGS.longPressChapterSkip;
  const bool prevTriggered = usePressForPageTurn ? (mappedInput.wasPressed(MappedInputManager::Button::PageBack) ||
                                                    mappedInput.wasPressed(MappedInputManager::Button::Left))
                                                 : (mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
                                                    mappedInput.wasReleased(MappedInputManager::Button::Left));
  const bool powerPageTurn = SETTINGS.shortPwrBtn == CrossPointSettings::SHORT_PWRBTN::PAGE_TURN &&
                             mappedInput.wasReleased(MappedInputManager::Button::Power);
  const bool nextTriggered = usePressForPageTurn
                                 ? (mappedInput.wasPressed(MappedInputManager::Button::PageForward) || powerPageTurn ||
                                    mappedInput.wasPressed(MappedInputManager::Button::Right))
                                 : (mappedInput.wasReleased(MappedInputManager::Button::PageForward) || powerPageTurn ||
                                    mappedInput.wasReleased(MappedInputManager::Button::Right));

  if (!prevTriggered && !nextTriggered) {
    return;
  }

  // any botton press when at end of the book goes back to the last page
  if (currentSpineIndex > 0 && currentSpineIndex >= epub->getSpineItemsCount()) {
    currentSpineIndex = epub->getSpineItemsCount() - 1;
    nextPageNumber = UINT16_MAX;
    requestUpdate();
    return;
  }

  const bool skipChapter = SETTINGS.longPressChapterSkip && mappedInput.getHeldTime() > skipChapterMs;

  if (skipChapter) {
    // We don't want to delete the section mid-render, so grab the semaphore
    {
      RenderLock lock(*this);
      nextPageNumber = 0;
      currentSpineIndex = nextTriggered ? currentSpineIndex + 1 : currentSpineIndex - 1;
      section.reset();
    }
    requestUpdate();
    return;
  }

  // No current section, attempt to rerender the book
  if (!section) {
    requestUpdate();
    return;
  }

  if (prevTriggered) {
    if (section->currentPage > 0) {
      section->currentPage--;
    } else if (currentSpineIndex > 0) {
      // We don't want to delete the section mid-render, so grab the semaphore
      {
        RenderLock lock(*this);
        nextPageNumber = UINT16_MAX;
        currentSpineIndex--;
        section.reset();
      }
    }
    requestUpdate();
  } else {
    if (section->currentPage < section->pageCount - 1) {
      section->currentPage++;
    } else {
      // We don't want to delete the section mid-render, so grab the semaphore
      {
        RenderLock lock(*this);
        nextPageNumber = 0;
        currentSpineIndex++;
        section.reset();
      }
    }
    requestUpdate();
  }
}

// Translate an absolute percent into a spine index plus a normalized position
// within that spine so we can jump after the section is loaded.
void EpubReaderActivity::jumpToPercent(int percent) {
  if (!epub) {
    return;
  }

  const size_t bookSize = epub->getBookSize();
  if (bookSize == 0) {
    return;
  }

  // Normalize input to 0-100 to avoid invalid jumps.
  percent = clampPercent(percent);

  // Convert percent into a byte-like absolute position across the spine sizes.
  // Use an overflow-safe computation: (bookSize / 100) * percent + (bookSize % 100) * percent / 100
  size_t targetSize =
      (bookSize / 100) * static_cast<size_t>(percent) + (bookSize % 100) * static_cast<size_t>(percent) / 100;
  if (percent >= 100) {
    // Ensure the final percent lands inside the last spine item.
    targetSize = bookSize - 1;
  }

  const int spineCount = epub->getSpineItemsCount();
  if (spineCount == 0) {
    return;
  }

  int targetSpineIndex = spineCount - 1;
  size_t prevCumulative = 0;

  for (int i = 0; i < spineCount; i++) {
    const size_t cumulative = epub->getCumulativeSpineItemSize(i);
    if (targetSize <= cumulative) {
      // Found the spine item containing the absolute position.
      targetSpineIndex = i;
      prevCumulative = (i > 0) ? epub->getCumulativeSpineItemSize(i - 1) : 0;
      break;
    }
  }

  const size_t cumulative = epub->getCumulativeSpineItemSize(targetSpineIndex);
  const size_t spineSize = (cumulative > prevCumulative) ? (cumulative - prevCumulative) : 0;
  // Store a normalized position within the spine so it can be applied once loaded.
  pendingSpineProgress =
      (spineSize == 0) ? 0.0f : static_cast<float>(targetSize - prevCumulative) / static_cast<float>(spineSize);
  if (pendingSpineProgress < 0.0f) {
    pendingSpineProgress = 0.0f;
  } else if (pendingSpineProgress > 1.0f) {
    pendingSpineProgress = 1.0f;
  }

  // Reset state so render() reloads and repositions on the target spine.
  {
    RenderLock lock(*this);
    currentSpineIndex = targetSpineIndex;
    nextPageNumber = 0;
    pendingPercentJump = true;
    section.reset();
  }
}

void EpubReaderActivity::onReaderMenuConfirm(EpubReaderMenuActivity::MenuAction action) {
  switch (action) {
    case EpubReaderMenuActivity::MenuAction::SELECT_CHAPTER: {
      const int spineIdx = currentSpineIndex;
      const std::string path = epub->getPath();
      startActivityForResult(
          std::make_unique<EpubReaderChapterSelectionActivity>(renderer, mappedInput, epub, path, spineIdx),
          [this](const ActivityResult& result) {
            if (!result.isCancelled && currentSpineIndex != std::get<ChapterResult>(result.data).spineIndex) {
              currentSpineIndex = std::get<ChapterResult>(result.data).spineIndex;
              nextPageNumber = 0;
              section.reset();
            }
          });
      break;
    }
    case EpubReaderMenuActivity::MenuAction::FOOTNOTES: {
      startActivityForResult(std::make_unique<EpubReaderFootnotesActivity>(renderer, mappedInput, currentPageFootnotes),
                             [this](const ActivityResult& result) {
                               if (!result.isCancelled) {
                                 const auto& footnoteResult = std::get<FootnoteResult>(result.data);
                                 navigateToHref(footnoteResult.href, true);
                               }
                               requestUpdate();
                             });
      break;
    }
    case EpubReaderMenuActivity::MenuAction::GO_TO_PERCENT: {
      float bookProgress = 0.0f;
      if (epub && epub->getBookSize() > 0 && section && section->pageCount > 0) {
        const float chapterProgress = static_cast<float>(section->currentPage) / static_cast<float>(section->pageCount);
        bookProgress = epub->calculateProgress(currentSpineIndex, chapterProgress) * 100.0f;
      }
      const int initialPercent = clampPercent(static_cast<int>(bookProgress + 0.5f));
      startActivityForResult(
          std::make_unique<EpubReaderPercentSelectionActivity>(renderer, mappedInput, initialPercent),
          [this](const ActivityResult& result) {
            if (!result.isCancelled) {
              jumpToPercent(std::get<PercentResult>(result.data).percent);
            }
          });
      break;
    }
    case EpubReaderMenuActivity::MenuAction::DISPLAY_QR: {
      if (section && section->currentPage >= 0 && section->currentPage < section->pageCount) {
        auto p = section->loadPageFromSectionFile();
        if (p) {
          std::string fullText;
          for (const auto& el : p->elements) {
            if (el->getTag() == TAG_PageLine) {
              const auto& line = static_cast<const PageLine&>(*el);
              if (line.getBlock()) {
                const auto& words = line.getBlock()->getWords();
                for (const auto& w : words) {
                  if (!fullText.empty()) fullText += " ";
                  fullText += w;
                }
              }
            }
          }
          if (!fullText.empty()) {
            startActivityForResult(std::make_unique<QrDisplayActivity>(renderer, mappedInput, fullText),
                                   [this](const ActivityResult& result) {});
            break;
          }
        }
      }
      // If no text or page loading failed, just close menu
      requestUpdate();
      break;
    }
    case EpubReaderMenuActivity::MenuAction::GO_HOME: {
      onGoHome();
      return;
    }
    case EpubReaderMenuActivity::MenuAction::DELETE_CACHE: {
      {
        RenderLock lock(*this);
        if (epub && section) {
          uint16_t backupSpine = currentSpineIndex;
          uint16_t backupPage = section->currentPage;
          uint16_t backupPageCount = section->pageCount;
          section.reset();
          epub->clearCache();
          epub->setupCacheDir();
          saveProgress(backupSpine, backupPage, backupPageCount);
        }
      }
      onGoHome();
      return;
    }
    case EpubReaderMenuActivity::MenuAction::SCREENSHOT: {
      {
        RenderLock lock(*this);
        pendingScreenshot = true;
      }
      requestUpdate();
      break;
    }
    case EpubReaderMenuActivity::MenuAction::SYNC: {
      if (KOREADER_STORE.hasCredentials()) {
        const int currentPage = section ? section->currentPage : 0;
        const int totalPages = section ? section->pageCount : 0;
        startActivityForResult(
            std::make_unique<KOReaderSyncActivity>(renderer, mappedInput, epub, epub->getPath(), currentSpineIndex,
                                                   currentPage, totalPages),
            [this](const ActivityResult& result) {
              if (!result.isCancelled) {
                const auto& sync = std::get<SyncResult>(result.data);
                if (currentSpineIndex != sync.spineIndex || (section && section->currentPage != sync.page)) {
                  currentSpineIndex = sync.spineIndex;
                  nextPageNumber = sync.page;
                  section.reset();
                }
              }
            });
      }
      break;
    }
  }
}

void EpubReaderActivity::applyOrientation(const uint8_t orientation) {
  // No-op if the selected orientation matches current settings.
  if (SETTINGS.orientation == orientation) {
    return;
  }

  // Preserve current reading position so we can restore after reflow.
  {
    RenderLock lock(*this);
    if (section) {
      cachedSpineIndex = currentSpineIndex;
      cachedChapterTotalPageCount = section->pageCount;
      nextPageNumber = section->currentPage;
    }

    // Persist the selection so the reader keeps the new orientation on next launch.
    SETTINGS.orientation = orientation;
    SETTINGS.saveToFile();

    // Update renderer orientation to match the new logical coordinate system.
    applyReaderOrientation(renderer, SETTINGS.orientation);

    // Reset section to force re-layout in the new orientation.
    section.reset();
  }
}

// TODO: Failure handling
void EpubReaderActivity::render(RenderLock&& lock) {
  if (!epub) {
    return;
  }

  // edge case handling for sub-zero spine index
  if (currentSpineIndex < 0) {
    currentSpineIndex = 0;
  }
  // based bounds of book, show end of book screen
  if (currentSpineIndex > epub->getSpineItemsCount()) {
    currentSpineIndex = epub->getSpineItemsCount();
  }

  // Show end of book screen
  if (currentSpineIndex == epub->getSpineItemsCount()) {
    renderer.clearScreen();
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_END_OF_BOOK), true, EpdFontFamily::BOLD);
    renderer.displayBuffer();
    return;
  }

  // Apply screen viewable areas and additional padding
  int orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft;
  renderer.getOrientedViewableTRBL(&orientedMarginTop, &orientedMarginRight, &orientedMarginBottom,
                                   &orientedMarginLeft);
  orientedMarginTop += SETTINGS.screenMargin;
  orientedMarginLeft += SETTINGS.screenMargin;
  orientedMarginRight += SETTINGS.screenMargin;
  orientedMarginBottom +=
      std::max(SETTINGS.screenMargin, static_cast<uint8_t>(UITheme::getInstance().getStatusBarHeight()));

  if (!section) {
    const auto filepath = epub->getSpineItem(currentSpineIndex).href;
    LOG_DBG("ERS", "Loading file: %s, index: %d", filepath.c_str(), currentSpineIndex);
    section = std::unique_ptr<Section>(new Section(epub, currentSpineIndex, renderer));

    const uint16_t viewportWidth = renderer.getScreenWidth() - orientedMarginLeft - orientedMarginRight;
    const uint16_t viewportHeight = renderer.getScreenHeight() - orientedMarginTop - orientedMarginBottom;

    if (!section->loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                  SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                  viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle)) {
      LOG_DBG("ERS", "Cache not found, building...");

      const auto popupFn = [this]() { GUI.drawPopup(renderer, tr(STR_INDEXING)); };

      if (!section->createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                      SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                      viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle, popupFn)) {
        LOG_ERR("ERS", "Failed to persist page data to SD");
        section.reset();
        return;
      }
    } else {
      LOG_DBG("ERS", "Cache found, skipping build...");
    }

    if (nextPageNumber == UINT16_MAX) {
      section->currentPage = section->pageCount - 1;
    } else {
      section->currentPage = nextPageNumber;
    }

    // handles changes in reader settings and reset to approximate position based on cached progress
    if (cachedChapterTotalPageCount > 0) {
      // only goes to relative position if spine index matches cached value
      if (currentSpineIndex == cachedSpineIndex && section->pageCount != cachedChapterTotalPageCount) {
        float progress = static_cast<float>(section->currentPage) / static_cast<float>(cachedChapterTotalPageCount);
        int newPage = static_cast<int>(progress * section->pageCount);
        section->currentPage = newPage;
      }
      cachedChapterTotalPageCount = 0;  // resets to 0 to prevent reading cached progress again
    }

    if (pendingPercentJump && section->pageCount > 0) {
      // Apply the pending percent jump now that we know the new section's page count.
      int newPage = static_cast<int>(pendingSpineProgress * static_cast<float>(section->pageCount));
      if (newPage >= section->pageCount) {
        newPage = section->pageCount - 1;
      }
      section->currentPage = newPage;
      pendingPercentJump = false;
    }
  }

  renderer.clearScreen();

  if (section->pageCount == 0) {
    LOG_DBG("ERS", "No pages to render");
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_EMPTY_CHAPTER), true, EpdFontFamily::BOLD);
    renderStatusBar();
    renderer.displayBuffer();
    return;
  }

  if (section->currentPage < 0 || section->currentPage >= section->pageCount) {
    LOG_DBG("ERS", "Page out of bounds: %d (max %d)", section->currentPage, section->pageCount);
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_OUT_OF_BOUNDS), true, EpdFontFamily::BOLD);
    renderStatusBar();
    renderer.displayBuffer();
    return;
  }

  {
    auto p = section->loadPageFromSectionFile();
    if (!p) {
      LOG_ERR("ERS", "Failed to load page from SD - clearing section cache");
      section->clearCache();
      section.reset();
      requestUpdate();  // Try again after clearing cache
      // TODO: prevent infinite loop if the page keeps failing to load for some reason
      return;
    }

    // Collect footnotes from the loaded page
    currentPageFootnotes = std::move(p->footnotes);

    const auto start = millis();
    renderContents(std::move(p), orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
    LOG_DBG("ERS", "Rendered page in %dms", millis() - start);
    renderer.clearFontCache();
  }
  saveProgress(currentSpineIndex, section->currentPage, section->pageCount);

  if (pendingScreenshot) {
    pendingScreenshot = false;
    ScreenshotUtil::takeScreenshot(renderer);
  }
}

void EpubReaderActivity::saveProgress(int spineIndex, int currentPage, int pageCount) {
  FsFile f;
  if (Storage.openFileForWrite("ERS", epub->getCachePath() + "/progress.bin", f)) {
    uint8_t data[6];
    data[0] = currentSpineIndex & 0xFF;
    data[1] = (currentSpineIndex >> 8) & 0xFF;
    data[2] = currentPage & 0xFF;
    data[3] = (currentPage >> 8) & 0xFF;
    data[4] = pageCount & 0xFF;
    data[5] = (pageCount >> 8) & 0xFF;
    f.write(data, 6);
    f.close();
    LOG_DBG("ERS", "Progress saved: Chapter %d, Page %d", spineIndex, currentPage);
  } else {
    LOG_ERR("ERS", "Could not save progress!");
  }
}
void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int orientedMarginTop,
                                        const int orientedMarginRight, const int orientedMarginBottom,
                                        const int orientedMarginLeft) {
  // Force special handling for pages with images when anti-aliasing is on
  bool imagePageWithAA = page->hasImages() && SETTINGS.textAntiAliasing;

  page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
  renderStatusBar();
  if (imagePageWithAA) {
    // Double FAST_REFRESH with selective image blanking (pablohc's technique):
    // HALF_REFRESH sets particles too firmly for the grayscale LUT to adjust.
    // Instead, blank only the image area and do two fast refreshes.
    // Step 1: Display page with image area blanked (text appears, image area white)
    // Step 2: Re-render with images and display again (images appear clean)
    int16_t imgX, imgY, imgW, imgH;
    if (page->getImageBoundingBox(imgX, imgY, imgW, imgH)) {
      renderer.fillRect(imgX + orientedMarginLeft, imgY + orientedMarginTop, imgW, imgH, false);
      renderer.displayBuffer(HalDisplay::FAST_REFRESH);

      // Re-render page content to restore images into the blanked area
      page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
      renderStatusBar();
      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
    } else {
      renderer.displayBuffer(HalDisplay::HALF_REFRESH);
    }
    // Double FAST_REFRESH handles ghosting for image pages; don't count toward full refresh cadence
  } else if (pagesUntilFullRefresh <= 1) {
    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
    pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
  } else {
    renderer.displayBuffer();
    pagesUntilFullRefresh--;
  }

  // Save bw buffer to reset buffer state after grayscale data sync
  renderer.storeBwBuffer();

  // grayscale rendering
  // TODO: Only do this if font supports it
  if (SETTINGS.textAntiAliasing) {
    renderer.clearScreen(0x00);
    renderer.setRenderMode(GfxRenderer::GRAYSCALE_LSB);
    page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
    renderer.copyGrayscaleLsbBuffers();

    // Render and copy to MSB buffer
    renderer.clearScreen(0x00);
    renderer.setRenderMode(GfxRenderer::GRAYSCALE_MSB);
    page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
    renderer.copyGrayscaleMsbBuffers();

    // display grayscale part
    renderer.displayGrayBuffer();
    renderer.setRenderMode(GfxRenderer::BW);
  }

  // restore the bw data
  renderer.restoreBwBuffer();
}

void EpubReaderActivity::renderStatusBar() const {
  // Calculate progress in book
  const int currentPage = section->currentPage + 1;
  const float pageCount = section->pageCount;
  const float sectionChapterProg = (pageCount > 0) ? (static_cast<float>(currentPage) / pageCount) : 0;
  const float bookProgress = epub->calculateProgress(currentSpineIndex, sectionChapterProg) * 100;

  const int tocIndex = epub->getTocIndexForSpineIndex(currentSpineIndex);
  std::string title;

  if (SETTINGS.statusBarTitle == CrossPointSettings::STATUS_BAR_TITLE::CHAPTER_TITLE) {
    if (tocIndex == -1) {
      title = tr(STR_UNNAMED);
    } else {
      const auto tocItem = epub->getTocItem(tocIndex);
      title = tocItem.title;
    }
  } else if (SETTINGS.statusBarTitle == CrossPointSettings::STATUS_BAR_TITLE::BOOK_TITLE) {
    title = epub->getTitle();
  } else {
    title = "";
  }

  GUI.drawStatusBar(renderer, bookProgress, currentPage, pageCount, title);
}

void EpubReaderActivity::navigateToHref(const std::string& hrefStr, const bool savePosition) {
  if (!epub) return;

  // Push current position onto saved stack
  if (savePosition && section && footnoteDepth < MAX_FOOTNOTE_DEPTH) {
    savedPositions[footnoteDepth] = {currentSpineIndex, section->currentPage};
    footnoteDepth++;
    LOG_DBG("ERS", "Saved position [%d]: spine %d, page %d", footnoteDepth, currentSpineIndex, section->currentPage);
  }

  // Check for same-file anchor reference (#anchor only)
  bool sameFile = !hrefStr.empty() && hrefStr[0] == '#';

  int targetSpineIndex;
  if (sameFile) {
    // Same file — navigate to page 0 of current spine item
    targetSpineIndex = currentSpineIndex;
  } else {
    targetSpineIndex = epub->resolveHrefToSpineIndex(hrefStr);
  }

  if (targetSpineIndex < 0) {
    LOG_DBG("ERS", "Could not resolve href: %s", hrefStr.c_str());
    if (savePosition && footnoteDepth > 0) footnoteDepth--;  // undo push
    return;
  }

  {
    RenderLock lock(*this);
    currentSpineIndex = targetSpineIndex;
    nextPageNumber = 0;
    section.reset();
  }
  requestUpdate();
  LOG_DBG("ERS", "Navigated to spine %d for href: %s", targetSpineIndex, hrefStr.c_str());
}

void EpubReaderActivity::restoreSavedPosition() {
  if (footnoteDepth <= 0) return;
  footnoteDepth--;
  const auto& pos = savedPositions[footnoteDepth];
  LOG_DBG("ERS", "Restoring position [%d]: spine %d, page %d", footnoteDepth, pos.spineIndex, pos.pageNumber);

  {
    RenderLock lock(*this);
    currentSpineIndex = pos.spineIndex;
    nextPageNumber = pos.pageNumber;
    section.reset();
  }
  requestUpdate();
}