#include "MdReaderActivity.h"

#include <FontCacheManager.h>
#include <GfxRenderer.h>
#include <HalStorage.h>
#include <I18n.h>
#include <Serialization.h>
#include <Utf8.h>

#include <algorithm>
#include <functional>
#include <numeric>

#include "CrossPointSettings.h"
#include "CrossPointState.h"
#include "MappedInputManager.h"
#include "MdReaderTocSelectionActivity.h"
#include "ReaderUtils.h"
#include "RecentBooksStore.h"
#include "components/UITheme.h"
#include "fontIds.h"

namespace {
constexpr size_t CHUNK_SIZE = 8 * 1024;
constexpr size_t MAX_LINE_LENGTH = 64 * 1024;
constexpr unsigned long HEADING_SKIP_MS = 700;
constexpr uint32_t CACHE_MAGIC = 0x4D4B4449;  // "MKDI"
constexpr uint8_t CACHE_VERSION = 3;          // Bumped: nested list indent + task checkboxes

static std::string flattenHeadingText(const MdParser::ParsedLine& parsed) {
  std::string result;
  for (const auto& span : parsed.spans) {
    result += span.text;
  }
  return result;
}
}  // namespace

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

  if (!txt) {
    return;
  }

  ReaderUtils::applyOrientation(renderer, SETTINGS.orientation);

  txt->setupCacheDir();

  auto filePath = txt->getPath();
  auto fileName = filePath.substr(filePath.rfind('/') + 1);
  APP_STATE.openEpubPath = filePath;
  APP_STATE.saveToFile();
  RECENT_BOOKS.addBook(filePath, fileName, "", "", "");

  requestUpdate();
}

void MdReaderActivity::assignHeadingPageNumbers() {
  if (pageOffsets.empty()) {
    return;
  }
  for (auto& heading : headings) {
    const auto it = std::upper_bound(pageOffsets.begin(), pageOffsets.end(), heading.offset);
    heading.pageIndex = static_cast<int>((it == pageOffsets.begin()) ? 0 : (it - pageOffsets.begin() - 1));
  }
}

int MdReaderActivity::getHeadingIndexForOffset(size_t offset) const {
  if (headings.empty()) {
    return -1;
  }
  int index = -1;
  for (int i = 0; i < static_cast<int>(headings.size()); i++) {
    if (headings[i].offset <= offset) {
      index = i;
    } else {
      break;
    }
  }
  return index;
}

void MdReaderActivity::jumpToHeading(bool next) {
  if (headings.empty() || pageOffsets.empty()) {
    return;
  }

  const size_t currentOffset = (currentPage >= 0 && currentPage < totalPages) ? pageOffsets[currentPage] : 0;
  int headingIndex = getHeadingIndexForOffset(currentOffset);

  if (headingIndex < 0) {
    headingIndex = next ? 0 : static_cast<int>(headings.size()) - 1;
  } else {
    headingIndex += next ? 1 : -1;
  }

  if (headingIndex < 0) {
    headingIndex = 0;
  } else if (headingIndex >= static_cast<int>(headings.size())) {
    headingIndex = static_cast<int>(headings.size()) - 1;
  }

  const size_t headingOffset = headings[headingIndex].offset;
  const auto it = std::upper_bound(pageOffsets.begin(), pageOffsets.end(), headingOffset);
  if (it == pageOffsets.begin()) {
    currentPage = 0;
  } else {
    currentPage = static_cast<int>(it - pageOffsets.begin() - 1);
  }
  currentHeadingIndex = headingIndex;
  requestUpdate();
}

void MdReaderActivity::scanHeadings() {
  headings.clear();
  if (!txt) {
    return;
  }

  const size_t fileSize = txt->getFileSize();
  if (fileSize == 0) {
    return;
  }

  std::string pending;
  size_t pendingOffset = 0;
  bool hasPending = false;
  bool inCodeBlock = false;

  pageBuffer.resize(CHUNK_SIZE + 1);
  size_t offset = 0;

  while (offset < fileSize) {
    const size_t toRead = std::min(CHUNK_SIZE, fileSize - offset);
    if (!txt->readContent(pageBuffer.data(), offset, toRead)) {
      return;
    }
    pageBuffer[toRead] = '\0';

    size_t pos = 0;
    while (pos < toRead) {
      size_t lineEnd = pos;
      while (lineEnd < toRead && pageBuffer[lineEnd] != '\n') {
        lineEnd++;
      }

      const bool hasNewline = (lineEnd < toRead && pageBuffer[lineEnd] == '\n');
      const bool fileHasMore = (offset + toRead < fileSize);
      const size_t rawLen = lineEnd - pos;
      const bool hasCR = (rawLen > 0 && pageBuffer[pos + rawLen - 1] == '\r');
      const size_t displayLen = hasCR ? rawLen - 1 : rawLen;
      const size_t lineStartOffset = hasPending ? pendingOffset : (offset + pos);

      std::string rawLine;
      if (hasPending) {
        rawLine = std::move(pending);
        pending.clear();
        hasPending = false;
      }
      rawLine.append(reinterpret_cast<char*>(pageBuffer.data() + pos), displayLen);

      if (!hasNewline && fileHasMore) {
        if (!hasPending) {
          pendingOffset = lineStartOffset;
        }
        pending = std::move(rawLine);
        hasPending = true;
        break;
      }

      if (MdParser::isCodeFence(rawLine)) {
        inCodeBlock = !inCodeBlock;
      }
      const MdParser::ParsedLine parsed = MdParser::parseLine(rawLine, inCodeBlock);
      if (parsed.blockType == MdParser::BlockType::Header1 || parsed.blockType == MdParser::BlockType::Header2 ||
          parsed.blockType == MdParser::BlockType::Header3) {
        int level = 1;
        if (parsed.blockType == MdParser::BlockType::Header2) {
          level = 2;
        } else if (parsed.blockType == MdParser::BlockType::Header3) {
          level = 3;
        }
        headings.push_back({lineStartOffset, level, flattenHeadingText(parsed)});
      }

      pos = hasNewline ? lineEnd + 1 : lineEnd;
    }

    offset += toRead;
  }

  if (hasPending) {
    if (MdParser::isCodeFence(pending)) {
      inCodeBlock = !inCodeBlock;
    }
    const MdParser::ParsedLine parsed = MdParser::parseLine(pending, inCodeBlock);
    if (parsed.blockType == MdParser::BlockType::Header1 || parsed.blockType == MdParser::BlockType::Header2 ||
        parsed.blockType == MdParser::BlockType::Header3) {
      int level = 1;
      if (parsed.blockType == MdParser::BlockType::Header2) {
        level = 2;
      } else if (parsed.blockType == MdParser::BlockType::Header3) {
        level = 3;
      }
      headings.push_back({pendingOffset, level, flattenHeadingText(parsed)});
    }
  }
}

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

  renderer.setOrientation(GfxRenderer::Orientation::Portrait);

  pageOffsets.clear();
  pageCodeBlockState.clear();
  currentPageLines.clear();
  APP_STATE.readerActivityLoadCount = 0;
  APP_STATE.saveToFile();
  txt.reset();
}

void MdReaderActivity::loop() {
  if (mappedInput.isPressed(MappedInputManager::Button::Back) && mappedInput.getHeldTime() >= ReaderUtils::GO_HOME_MS) {
    activityManager.goToFileBrowser(txt ? txt->getPath() : "");
    return;
  }

  if (mappedInput.wasReleased(MappedInputManager::Button::Back) &&
      mappedInput.getHeldTime() < ReaderUtils::GO_HOME_MS) {
    onGoHome();
    return;
  }

  if (mappedInput.wasReleased(MappedInputManager::Button::Confirm) && !headings.empty()) {
    currentHeadingIndex = getHeadingIndexForOffset(pageOffsets[currentPage]);
    ReaderUtils::enforceExitFullRefresh(renderer);
    startActivityForResult(
        std::make_unique<MdReaderTocSelectionActivity>(renderer, mappedInput, headings, currentHeadingIndex),
        [this](const ActivityResult& result) {
          if (!result.isCancelled) {
            currentPage = std::get<PageResult>(result.data).page;
            currentHeadingIndex = getHeadingIndexForOffset(pageOffsets[currentPage]);
            requestUpdate();
          }
        });
    return;
  }

  auto [prevTriggered, nextTriggered] = ReaderUtils::detectPageTurn(mappedInput);
  if (!prevTriggered && !nextTriggered) {
    return;
  }

  const bool headingSkip = mappedInput.getHeldTime() > HEADING_SKIP_MS;
  if (headingSkip && !headings.empty()) {
    jumpToHeading(nextTriggered);
    return;
  }

  if (prevTriggered && currentPage > 0) {
    currentPage--;
    currentHeadingIndex = getHeadingIndexForOffset(pageOffsets[currentPage]);
    requestUpdate();
  } else if (nextTriggered) {
    if (currentPage < totalPages - 1) {
      currentPage++;
      currentHeadingIndex = getHeadingIndexForOffset(pageOffsets[currentPage]);
      requestUpdate();
    } else {
      onGoHome();
    }
  }
}

void MdReaderActivity::initializeReader() {
  if (initialized) {
    return;
  }

  cachedFontId = SETTINGS.getReaderFontId();
  cachedScreenMargin = SETTINGS.screenMargin;
  cachedParagraphAlignment = SETTINGS.paragraphAlignment;

  renderer.getOrientedViewableTRBL(&cachedOrientedMarginTop, &cachedOrientedMarginRight, &cachedOrientedMarginBottom,
                                   &cachedOrientedMarginLeft);
  cachedOrientedMarginTop += cachedScreenMargin;
  cachedOrientedMarginLeft += cachedScreenMargin;
  cachedOrientedMarginRight += cachedScreenMargin;
  cachedOrientedMarginBottom +=
      std::max(cachedScreenMargin, static_cast<uint8_t>(UITheme::getInstance().getStatusBarHeight()));

  viewportWidth = renderer.getScreenWidth() - cachedOrientedMarginLeft - cachedOrientedMarginRight;
  const int viewportHeight = renderer.getScreenHeight() - cachedOrientedMarginTop - cachedOrientedMarginBottom;
  const int lineHeight = renderer.getLineHeight(cachedFontId);

  pageBuffer.reserve(CHUNK_SIZE + 1);
  scanHeadings();

  linesPerPage = viewportHeight / lineHeight;
  if (linesPerPage < 1) linesPerPage = 1;

  LOG_DBG("MDR", "Viewport: %dx%d, lines per page: %d", viewportWidth, viewportHeight, linesPerPage);

  if (!loadPageIndexCache()) {
    buildPageIndex();
    savePageIndexCache();
  }
  assignHeadingPageNumbers();

  loadProgress();

  initialized = true;
}

int MdReaderActivity::measureSpans(const std::vector<MdParser::Span>& spans) const {
  return std::accumulate(spans.begin(), spans.end(), 0, [this](int acc, const MdParser::Span& span) {
    return acc + (span.text.empty() ? 0 : renderer.getTextAdvanceX(cachedFontId, span.text.c_str(), span.style));
  });
}

bool MdReaderActivity::wordWrapParsedLine(const MdParser::ParsedLine& parsed, int indent,
                                          std::vector<RenderedLine>& outLines, int maxLines, bool isCodeBlock) {
  const size_t startSize = outLines.size();

  if (parsed.spans.empty()) {
    RenderedLine rl;
    rl.indent = indent;
    rl.isHR = (parsed.blockType == MdParser::BlockType::HorizontalRule);
    outLines.push_back(std::move(rl));
    return true;
  }

  const int availableWidth = viewportWidth - indent;
  if (availableWidth <= 0) return true;

  // Build a flat list of all spans, prepending the list prefix if present.
  std::vector<MdParser::Span> allSpans;
  if (!parsed.listPrefix.empty()) {
    allSpans.push_back({parsed.listPrefix, EpdFontFamily::REGULAR});
  }
  allSpans.insert(allSpans.end(), parsed.spans.begin(), parsed.spans.end());

  const int listPrefixIndent =
      !parsed.listPrefix.empty()
          ? renderer.getTextAdvanceX(cachedFontId, parsed.listPrefix.c_str(), EpdFontFamily::REGULAR)
          : 0;

  // Check if everything fits on one line
  int totalWidth = measureSpans(allSpans);
  if (totalWidth <= availableWidth) {
    RenderedLine rl;
    rl.spans = std::move(allSpans);
    rl.indent = indent;
    rl.isCodeBlock = isCodeBlock;
    outLines.push_back(std::move(rl));
    return true;
  }

  // Word-wrap across spans
  const int continuationIndent = indent + listPrefixIndent;
  RenderedLine currentLine;
  currentLine.indent = indent;
  currentLine.isCodeBlock = isCodeBlock;
  int currentWidth = 0;
  bool fullyConsumed = true;

  for (size_t si = 0; si < allSpans.size(); si++) {
    const auto& span = allSpans[si];
    if (span.text.empty()) continue;

    int spanWidth = renderer.getTextAdvanceX(cachedFontId, span.text.c_str(), span.style);

    if (currentWidth + spanWidth <= availableWidth) {
      currentLine.spans.push_back(span);
      currentWidth += spanWidth;
      continue;
    }

    // Need to break within this span
    std::string remaining = span.text;
    auto style = span.style;

    while (!remaining.empty()) {
      // Check line limit (using lines added, not total size)
      if (static_cast<int>(outLines.size() - startSize) >= maxLines) {
        fullyConsumed = false;
        goto done;
      }

      int remWidth = renderer.getTextAdvanceX(cachedFontId, remaining.c_str(), style);

      if (currentWidth + remWidth <= availableWidth) {
        currentLine.spans.push_back({remaining, style});
        currentWidth += remWidth;
        remaining.clear();
        break;
      }

      size_t breakPos = remaining.size();

      while (breakPos > 0 && renderer.getTextAdvanceX(cachedFontId, remaining.substr(0, breakPos).c_str(), style) >
                                 availableWidth - currentWidth) {
        size_t spacePos = remaining.rfind(' ', breakPos - 1);
        if (spacePos != std::string::npos && spacePos > 0) {
          breakPos = spacePos;
        } else {
          breakPos--;
          while (breakPos > 0 && (remaining[breakPos] & 0xC0) == 0x80) {
            breakPos--;
          }
        }
      }

      if (breakPos == 0) {
        if (currentLine.spans.empty()) {
          breakPos = 1;
          while (breakPos < remaining.size() && (remaining[breakPos] & 0xC0) == 0x80) {
            breakPos++;
          }
        } else {
          outLines.push_back(std::move(currentLine));
          currentLine = RenderedLine();
          currentLine.indent = continuationIndent;
          currentLine.isCodeBlock = isCodeBlock;
          currentWidth = 0;
          continue;
        }
      }

      currentLine.spans.push_back({remaining.substr(0, breakPos), style});
      outLines.push_back(std::move(currentLine));
      currentLine = RenderedLine();
      currentLine.indent = continuationIndent;
      currentLine.isCodeBlock = isCodeBlock;
      currentWidth = 0;

      size_t skip = breakPos;
      if (skip < remaining.size() && remaining[skip] == ' ') {
        skip++;
      }
      remaining = remaining.substr(skip);
    }
  }

done:
  if (!currentLine.spans.empty()) {
    outLines.push_back(std::move(currentLine));
  }
  return fullyConsumed;
}

bool MdReaderActivity::loadPageAtOffset(size_t offset, bool startInCodeBlock, std::vector<RenderedLine>& outLines,
                                        size_t& nextOffset, bool& endInCodeBlock) {
  outLines.clear();
  endInCodeBlock = startInCodeBlock;
  const size_t fileSize = txt->getFileSize();

  if (offset >= fileSize) {
    return false;
  }

  size_t bufferSize = std::min(CHUNK_SIZE, fileSize - offset);
  pageBuffer.resize(bufferSize + 1);
  if (!txt->readContent(pageBuffer.data(), offset, bufferSize)) {
    return false;
  }
  pageBuffer[bufferSize] = '\0';

  bool inCodeBlock = startInCodeBlock;
  size_t pos = 0;

  while (pos < bufferSize && static_cast<int>(outLines.size()) < linesPerPage) {
    // Find end of line and extend the read buffer if we are at chunk boundary.
    size_t lineEnd = pos;
    while (lineEnd < bufferSize && pageBuffer[lineEnd] != '\n') {
      lineEnd++;
    }

    while (lineEnd == bufferSize && offset + bufferSize < fileSize && bufferSize < MAX_LINE_LENGTH) {
      size_t extra = std::min(CHUNK_SIZE, fileSize - offset - bufferSize);
      if (bufferSize + extra > MAX_LINE_LENGTH) {
        extra = MAX_LINE_LENGTH - bufferSize;
      }
      if (extra == 0) {
        break;
      }

      pageBuffer.resize(bufferSize + extra + 1);
      if (!txt->readContent(pageBuffer.data() + bufferSize, offset + bufferSize, extra)) {
        return false;
      }
      bufferSize += extra;
      pageBuffer[bufferSize] = '\0';

      while (lineEnd < bufferSize && pageBuffer[lineEnd] != '\n') {
        lineEnd++;
      }
    }

    const bool isAtBufferEnd = (lineEnd == bufferSize);
    const bool isEOF = (offset + bufferSize >= fileSize);
    const bool lineComplete = (lineEnd < bufferSize) || isEOF || (isAtBufferEnd && bufferSize >= MAX_LINE_LENGTH);
    if (!lineComplete && !outLines.empty()) {
      // Incomplete line at chunk boundary and we already have content — stop here
      break;
    }

    size_t lineContentLen = lineEnd - pos;
    bool hasCR = (lineContentLen > 0 && pageBuffer[pos + lineContentLen - 1] == '\r');
    size_t displayLen = hasCR ? lineContentLen - 1 : lineContentLen;

    std::string rawLine(reinterpret_cast<char*>(pageBuffer.data() + pos), displayLen);

    // Check for code fence toggle
    bool wasFence = false;
    if (MdParser::isCodeFence(rawLine)) {
      inCodeBlock = !inCodeBlock;
      wasFence = true;
    }

    // Parse the markdown line
    MdParser::ParsedLine parsed;
    if (wasFence) {
      // Fence lines produce no visible output
      parsed.blockType = MdParser::BlockType::CodeBlock;
    } else {
      parsed = MdParser::parseLine(rawLine, inCodeBlock);
    }

    // Determine indent (base + nesting level)
    int indent = 0;
    switch (parsed.blockType) {
      case MdParser::BlockType::UnorderedList:
      case MdParser::BlockType::OrderedList:
        indent = LIST_INDENT + parsed.indentLevel * LIST_INDENT;
        break;
      case MdParser::BlockType::Blockquote:
        indent = BLOCKQUOTE_INDENT;
        break;
      case MdParser::BlockType::CodeBlock:
        if (!wasFence) indent = CODE_INDENT;
        break;
      default:
        break;
    }

    // Word-wrap and add to output (skip fence lines)
    if (!wasFence) {
      size_t linesBefore = outLines.size();
      int remainingLines = linesPerPage - static_cast<int>(outLines.size());
      bool fullyConsumed = wordWrapParsedLine(parsed, indent, outLines, remainingLines,
                                              parsed.blockType == MdParser::BlockType::CodeBlock);

      if (!fullyConsumed) {
        if (linesBefore > 0) {
          // Page was partially filled — rollback this line and save it for next page
          outLines.resize(linesBefore);
          // Don't advance pos — next page re-processes this source line
        } else {
          // First line on page is longer than a full page — accept truncation, advance past it
          pos = lineComplete ? lineEnd + 1 : lineEnd;
        }
        break;
      }
    }

    // Advance past the newline (only if source line was fully consumed)
    pos = lineEnd + 1;
  }

  // Ensure progress
  if (pos == 0 && !outLines.empty()) {
    pos = 1;
  }

  nextOffset = offset + pos;
  if (nextOffset > fileSize) {
    nextOffset = fileSize;
  }

  endInCodeBlock = inCodeBlock;
  return !outLines.empty();
}

void MdReaderActivity::buildPageIndex() {
  pageOffsets.clear();
  pageCodeBlockState.clear();

  const size_t fileSize = txt->getFileSize();
  if (fileSize == 0) {
    totalPages = 0;
    LOG_DBG("MDR", "Empty markdown file, no pages");
    return;
  }

  pageOffsets.push_back(0);
  pageCodeBlockState.push_back(0);

  size_t offset = 0;
  bool inCodeBlock = false;

  LOG_DBG("MDR", "Building page index for %zu bytes...", fileSize);

  GUI.drawPopup(renderer, tr(STR_INDEXING));

  while (offset < fileSize) {
    std::vector<RenderedLine> tempLines;
    size_t nextOffset = offset;
    bool nextCodeBlock = inCodeBlock;

    if (!loadPageAtOffset(offset, inCodeBlock, tempLines, nextOffset, nextCodeBlock)) {
      break;
    }

    if (nextOffset <= offset) {
      break;
    }

    offset = nextOffset;
    inCodeBlock = nextCodeBlock;

    if (offset < fileSize) {
      pageOffsets.push_back(offset);
      pageCodeBlockState.push_back(inCodeBlock ? 1 : 0);
    }

    if (pageOffsets.size() % 20 == 0) {
      vTaskDelay(1);
    }
  }

  totalPages = pageOffsets.size();
  LOG_DBG("MDR", "Built page index: %d pages", totalPages);
}

void MdReaderActivity::render(RenderLock&&) {
  if (!txt) {
    return;
  }

  if (!initialized) {
    initializeReader();
  }

  if (pageOffsets.empty()) {
    renderer.clearScreen();
    renderer.drawCenteredText(UI_12_FONT_ID, 300, tr(STR_EMPTY_FILE), true, EpdFontFamily::BOLD);
    renderer.displayBuffer();
    return;
  }

  if (currentPage < 0) currentPage = 0;
  if (currentPage >= totalPages) currentPage = totalPages - 1;

  // Load current page
  size_t offset = pageOffsets[currentPage];
  bool startCodeBlock =
      (currentPage < static_cast<int>(pageCodeBlockState.size())) ? pageCodeBlockState[currentPage] : false;
  size_t nextOffset;
  bool endCodeBlock;
  currentPageLines.clear();
  loadPageAtOffset(offset, startCodeBlock, currentPageLines, nextOffset, endCodeBlock);

  renderer.clearScreen();
  renderPage();

  saveProgress();
}

void MdReaderActivity::renderPage() {
  const int lineHeight = renderer.getLineHeight(cachedFontId);

  std::function<void()> renderLines = [&]() {
    int y = cachedOrientedMarginTop;
    for (const auto& line : currentPageLines) {
      if (line.isHR) {
        // Draw horizontal rule as a thin line
        int hrY = y + lineHeight / 2;
        renderer.drawLine(cachedOrientedMarginLeft + line.indent, hrY, cachedOrientedMarginLeft + viewportWidth, hrY);
        y += lineHeight;
      } else {
        if (line.isCodeBlock) {
          const int barX = cachedOrientedMarginLeft + std::max(line.indent - 6, 0);
          renderer.drawLine(barX, y + 2, barX, y + lineHeight - 2);
        }
        if (!line.spans.empty()) {
          int x = cachedOrientedMarginLeft + line.indent;

          // Apply text alignment for non-indented lines
          if (line.indent == 0) {
            int contentWidth = viewportWidth;
            switch (cachedParagraphAlignment) {
              case CrossPointSettings::CENTER_ALIGN: {
                x = cachedOrientedMarginLeft + (contentWidth - measureSpans(line.spans)) / 2;
                break;
              }
              case CrossPointSettings::RIGHT_ALIGN: {
                x = cachedOrientedMarginLeft + contentWidth - measureSpans(line.spans);
                break;
              }
              default:
                break;
            }
          }

          // Render each span
          for (const auto& span : line.spans) {
            if (!span.text.empty()) {
              renderer.drawText(cachedFontId, x, y, span.text.c_str(), true, span.style);
              x += renderer.getTextAdvanceX(cachedFontId, span.text.c_str(), span.style);
            }
          }
        }
        y += lineHeight;
      }
    }
  };

  // Font prewarm: scan pass accumulates text, then prewarm, then real render
  auto* fcm = renderer.getFontCacheManager();
  auto scope = fcm->createPrewarmScope();
  renderLines();
  scope.endScanAndPrewarm();

  // BW rendering
  renderLines();
  renderStatusBar();

  ReaderUtils::displayWithRefreshCycle(renderer, pagesUntilFullRefresh);

  if (SETTINGS.textAntiAliasing) {
    ReaderUtils::renderAntiAliased(renderer, [&]() { renderLines(); });
  }
}

void MdReaderActivity::renderStatusBar() const {
  const float progress = totalPages > 0 ? (currentPage + 1) * 100.0f / totalPages : 0;
  std::string title;
  if (SETTINGS.statusBarTitle != CrossPointSettings::STATUS_BAR_TITLE::HIDE_TITLE) {
    title = txt->getTitle();
  }
  GUI.drawStatusBar(renderer, progress, currentPage + 1, totalPages, title);
}

void MdReaderActivity::saveProgress() const {
  FsFile f;
  if (Storage.openFileForWrite("MDR", txt->getCachePath() + "/progress.bin", f)) {
    // 7-byte format matching TxtReaderActivity: page(2 bytes LE) + file offset(4 bytes LE) + overallPercent(1 byte)
    const size_t offset =
        (currentPage >= 0 && currentPage < static_cast<int>(pageOffsets.size())) ? pageOffsets[currentPage] : 0;
    uint8_t data[7];
    data[0] = currentPage & 0xFF;
    data[1] = (currentPage >> 8) & 0xFF;
    data[2] = offset & 0xFF;
    data[3] = (offset >> 8) & 0xFF;
    data[4] = (offset >> 16) & 0xFF;
    data[5] = (offset >> 24) & 0xFF;
    data[6] = ReaderUtils::pageProgressPercentByte(currentPage, totalPages);
    f.write(data, 7);
    f.close();
  }
}

void MdReaderActivity::loadProgress() {
  FsFile f;
  if (Storage.openFileForRead("MDR", txt->getCachePath() + "/progress.bin", f)) {
    uint8_t data[7];
    const int dataSize = f.read(data, 7);
    f.close();
    if (dataSize >= 4) {
      // Page sits in bytes 0-1 in both the old 4-byte uint32 format and the new 7-byte format
      // (page counts stay well under 65536, so the upper bytes were always zero).
      int loadedPage = data[0] + (data[1] << 8);
      if (totalPages == 0) {
        currentPage = 0;
      } else if (loadedPage >= totalPages) {
        currentPage = totalPages - 1;
      } else {
        currentPage = loadedPage;
      }
      LOG_DBG("MDR", "Loaded progress: page %d/%d", currentPage, totalPages);
    }
  }
}

bool MdReaderActivity::loadPageIndexCache() {
  std::string cachePath = txt->getCachePath() + "/index.bin";
  FsFile f;
  if (!Storage.openFileForRead("MDR", cachePath, f)) {
    LOG_DBG("MDR", "No page index cache found");
    return false;
  }

  uint32_t magic;
  serialization::readPod(f, magic);
  if (magic != CACHE_MAGIC) {
    LOG_DBG("MDR", "Cache magic mismatch, rebuilding");
    return false;
  }

  uint8_t version;
  serialization::readPod(f, version);
  if (version != CACHE_VERSION) {
    LOG_DBG("MDR", "Cache version mismatch (%d != %d), rebuilding", version, CACHE_VERSION);
    return false;
  }

  uint32_t fileSize;
  serialization::readPod(f, fileSize);
  if (fileSize != txt->getFileSize()) {
    LOG_DBG("MDR", "Cache file size mismatch, rebuilding");
    return false;
  }

  int32_t cachedWidth;
  serialization::readPod(f, cachedWidth);
  if (cachedWidth != viewportWidth) {
    LOG_DBG("MDR", "Cache viewport width mismatch, rebuilding");
    return false;
  }

  int32_t cachedLines;
  serialization::readPod(f, cachedLines);
  if (cachedLines != linesPerPage) {
    LOG_DBG("MDR", "Cache lines per page mismatch, rebuilding");
    return false;
  }

  int32_t fontId;
  serialization::readPod(f, fontId);
  if (fontId != cachedFontId) {
    LOG_DBG("MDR", "Cache font ID mismatch, rebuilding");
    return false;
  }

  int32_t margin;
  serialization::readPod(f, margin);
  if (margin != cachedScreenMargin) {
    LOG_DBG("MDR", "Cache screen margin mismatch, rebuilding");
    return false;
  }

  uint8_t alignment;
  serialization::readPod(f, alignment);
  if (alignment != cachedParagraphAlignment) {
    LOG_DBG("MDR", "Cache paragraph alignment mismatch, rebuilding");
    return false;
  }

  uint32_t numPages;
  serialization::readPod(f, numPages);

  pageOffsets.clear();
  // Sanity check: reject corrupt cache with absurd page count
  if (numPages == 0 || numPages > 100000) {
    LOG_DBG("MDR", "Cache page count out of range (%u), rebuilding", numPages);
    return false;
  }

  pageOffsets.reserve(numPages);
  pageCodeBlockState.clear();
  pageCodeBlockState.reserve(numPages);

  for (uint32_t i = 0; i < numPages; i++) {
    uint32_t pageOffset;
    serialization::readPod(f, pageOffset);
    uint8_t codeState;
    serialization::readPod(f, codeState);
    pageOffsets.push_back(pageOffset);
    pageCodeBlockState.push_back(codeState);
  }

  totalPages = pageOffsets.size();
  LOG_DBG("MDR", "Loaded page index cache: %d pages", totalPages);
  return true;
}

void MdReaderActivity::savePageIndexCache() const {
  std::string cachePath = txt->getCachePath() + "/index.bin";
  FsFile f;
  if (!Storage.openFileForWrite("MDR", cachePath, f)) {
    LOG_ERR("MDR", "Failed to save page index cache");
    return;
  }

  serialization::writePod(f, CACHE_MAGIC);
  serialization::writePod(f, CACHE_VERSION);
  serialization::writePod(f, static_cast<uint32_t>(txt->getFileSize()));
  serialization::writePod(f, static_cast<int32_t>(viewportWidth));
  serialization::writePod(f, static_cast<int32_t>(linesPerPage));
  serialization::writePod(f, static_cast<int32_t>(cachedFontId));
  serialization::writePod(f, static_cast<int32_t>(cachedScreenMargin));
  serialization::writePod(f, cachedParagraphAlignment);
  serialization::writePod(f, static_cast<uint32_t>(pageOffsets.size()));

  for (size_t i = 0; i < pageOffsets.size(); i++) {
    serialization::writePod(f, static_cast<uint32_t>(pageOffsets[i]));
    serialization::writePod(f, pageCodeBlockState[i]);
  }

  LOG_DBG("MDR", "Saved page index cache: %d pages", totalPages);
}

void MdReaderActivity::onButtonAction(const CrossPointSettings::BUTTON_ACTION action) {
  using BA = CrossPointSettings::BUTTON_ACTION;
  auto clampPage = [this]() {
    if (totalPages == 0) {
      currentPage = 0;
      return;
    }
    if (currentPage < 0) currentPage = 0;
    if (currentPage >= totalPages) currentPage = totalPages - 1;
  };
  switch (action) {
    case BA::BTN_PAGE_FORWARD:
      if (currentPage < totalPages - 1) {
        currentPage++;
        currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
        requestUpdate();
      }
      break;
    case BA::BTN_PAGE_BACK:
      if (currentPage > 0) {
        currentPage--;
        currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
        requestUpdate();
      }
      break;
    case BA::BTN_PAGE_FORWARD_10:
      currentPage += 10;
      clampPage();
      currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
      requestUpdate();
      break;
    case BA::BTN_PAGE_BACK_10:
      currentPage -= 10;
      clampPage();
      currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
      requestUpdate();
      break;
    case BA::BTN_NEXT_SECTION:
      jumpToHeading(true);
      break;
    case BA::BTN_PREV_SECTION:
      jumpToHeading(false);
      break;
    case BA::BTN_OPEN_TOC:
      if (!headings.empty()) {
        currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
        startActivityForResult(
            std::make_unique<MdReaderTocSelectionActivity>(renderer, mappedInput, headings, currentHeadingIndex),
            [this](const ActivityResult& result) {
              if (!result.isCancelled) {
                currentPage = std::get<PageResult>(result.data).page;
                currentHeadingIndex = pageOffsets.empty() ? -1 : getHeadingIndexForOffset(pageOffsets[currentPage]);
                requestUpdate();
              }
            });
      }
      break;
    case BA::BTN_EXIT_READER:
      ReaderUtils::enforceExitFullRefresh(renderer);
      finish();
      break;
    default:
      break;
  }
}