#include "EpubReaderActivity.h"

#include <Epub/Page.h>
#include <FsHelpers.h>
#include <GfxRenderer.h>
#include <SDCardManager.h>

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <utility>
#include <vector>

#include "CrossPointSettings.h"
#include "CrossPointState.h"
#include "EpubReaderChapterSelectionActivity.h"
#include "MappedInputManager.h"
#include "ScreenComponents.h"
#include "fontIds.h"

namespace {
// pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
constexpr unsigned long skipChapterMs = 700;
constexpr unsigned long goHomeMs = 1000;
constexpr int statusBarMargin = 19;
constexpr const char* readingStatsFilePath = "/ReadingStats.csv";

std::string formatMinutes(const float minutes) {
  if (minutes <= 0.0f) {
    return "";
  }

  const int totalMinutes = static_cast<int>(std::floor(minutes));
  return std::to_string(totalMinutes) + "m";
}
}  // namespace

void EpubReaderActivity::taskTrampoline(void* param) {
  auto* self = static_cast<EpubReaderActivity*>(param);
  self->displayTaskLoop();
}

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

  if (!epub) {
    return;
  }

  // Configure screen orientation based on settings
  switch (SETTINGS.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;
  }

  renderingMutex = xSemaphoreCreateMutex();

  epub->setupCacheDir();

  FsFile f;
  if (SdMan.openFileForRead("ERS", epub->getCachePath() + "/progress.bin", f)) {
    uint8_t data[4];
    if (f.read(data, 4) == 4) {
      currentSpineIndex = data[0] + (data[1] << 8);
      nextPageNumber = data[2] + (data[3] << 8);
      Serial.printf("[%lu] [ERS] Loaded cache: %d, %d\n", millis(), currentSpineIndex, nextPageNumber);
    }
    f.close();
  }

  loadReadingStats();
  lastPageInteractionMs = millis();
  // 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;
      Serial.printf("[%lu] [ERS] Opened for first time, navigating to text reference at index %d\n", millis(),
                    textSpineIndex);
    }
  }

  // Save current epub as last opened epub
  APP_STATE.openEpubPath = epub->getPath();
  APP_STATE.saveToFile();

  // Trigger first update
  updateRequired = true;

  xTaskCreate(&EpubReaderActivity::taskTrampoline, "EpubReaderActivityTask",
              8192,               // Stack size
              this,               // Parameters
              1,                  // Priority
              &displayTaskHandle  // Task handle
  );
}

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

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

  // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
  xSemaphoreTake(renderingMutex, portMAX_DELAY);
  if (displayTaskHandle) {
    vTaskDelete(displayTaskHandle);
    displayTaskHandle = nullptr;
  }
  vSemaphoreDelete(renderingMutex);
  renderingMutex = nullptr;
  section.reset();
  epub.reset();
}

void EpubReaderActivity::loop() {
  // Pass input responsibility to sub activity if exists
  if (subActivity) {
    subActivity->loop();
    return;
  }

  // Enter chapter selection activity
  if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
    recordReadingTimeDelta();
    // Don't start activity transition while rendering
    xSemaphoreTake(renderingMutex, portMAX_DELAY);
    exitActivity();
    enterNewActivity(new EpubReaderChapterSelectionActivity(
        this->renderer, this->mappedInput, epub, currentSpineIndex,
        [this] {
          exitActivity();
          updateRequired = true;
        },
        [this](const int newSpineIndex) {
          if (currentSpineIndex != newSpineIndex) {
            currentSpineIndex = newSpineIndex;
            nextPageNumber = 0;
            section.reset();
          }
          exitActivity();
          updateRequired = true;
        }));
    xSemaphoreGive(renderingMutex);
  }

  // Long press BACK (1s+) goes directly to home
  if (mappedInput.isPressed(MappedInputManager::Button::Back) && mappedInput.getHeldTime() >= goHomeMs) {
    recordReadingTimeDelta();
    onGoHome();
    return;
  }

  // Short press BACK goes to file selection
  if (mappedInput.wasReleased(MappedInputManager::Button::Back) && mappedInput.getHeldTime() < goHomeMs) {
    recordReadingTimeDelta();
    onGoBack();
    return;
  }

  const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
                            mappedInput.wasReleased(MappedInputManager::Button::Left);
  const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
                            mappedInput.wasReleased(MappedInputManager::Button::Right);

  if (!prevReleased && !nextReleased) {
    return;
  }

  recordReadingTimeDelta();

  // 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;
    updateRequired = true;
    return;
  }

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

  if (skipChapter) {
    // We don't want to delete the section mid-render, so grab the semaphore
    xSemaphoreTake(renderingMutex, portMAX_DELAY);
    nextPageNumber = 0;
    currentSpineIndex = nextReleased ? currentSpineIndex + 1 : currentSpineIndex - 1;
    section.reset();
    xSemaphoreGive(renderingMutex);
    updateRequired = true;
    return;
  }

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

  if (prevReleased) {
    if (section->currentPage > 0) {
      section->currentPage--;
    } else {
      // We don't want to delete the section mid-render, so grab the semaphore
      xSemaphoreTake(renderingMutex, portMAX_DELAY);
      nextPageNumber = UINT16_MAX;
      currentSpineIndex--;
      section.reset();
      xSemaphoreGive(renderingMutex);
    }
    updateRequired = true;
  } else {
    if (section->currentPage < section->pageCount - 1) {
      section->currentPage++;
    } else {
      // We don't want to delete the section mid-render, so grab the semaphore
      xSemaphoreTake(renderingMutex, portMAX_DELAY);
      nextPageNumber = 0;
      currentSpineIndex++;
      section.reset();
      xSemaphoreGive(renderingMutex);
    }
    updateRequired = true;
  }
}

void EpubReaderActivity::displayTaskLoop() {
  while (true) {
    if (updateRequired) {
      updateRequired = false;
      xSemaphoreTake(renderingMutex, portMAX_DELAY);
      renderScreen();
      xSemaphoreGive(renderingMutex);
    }
    vTaskDelay(10 / portTICK_PERIOD_MS);
  }
}

// TODO: Failure handling
void EpubReaderActivity::renderScreen() {
  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, "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 += statusBarMargin;

  if (!section) {
    const auto filepath = epub->getSpineItem(currentSpineIndex).href;
    Serial.printf("[%lu] [ERS] Loading file: %s, index: %d\n", millis(), 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)) {
      Serial.printf("[%lu] [ERS] Cache not found, building...\n", millis());

      // Progress bar dimensions
      constexpr int barWidth = 200;
      constexpr int barHeight = 10;
      constexpr int boxMargin = 20;
      const int textWidth = renderer.getTextWidth(UI_12_FONT_ID, "Indexing...");
      const int boxWidthWithBar = (barWidth > textWidth ? barWidth : textWidth) + boxMargin * 2;
      const int boxWidthNoBar = textWidth + boxMargin * 2;
      const int boxHeightWithBar = renderer.getLineHeight(UI_12_FONT_ID) + barHeight + boxMargin * 3;
      const int boxHeightNoBar = renderer.getLineHeight(UI_12_FONT_ID) + boxMargin * 2;
      const int boxXWithBar = (renderer.getScreenWidth() - boxWidthWithBar) / 2;
      const int boxXNoBar = (renderer.getScreenWidth() - boxWidthNoBar) / 2;
      constexpr int boxY = 50;
      const int barX = boxXWithBar + (boxWidthWithBar - barWidth) / 2;
      const int barY = boxY + renderer.getLineHeight(UI_12_FONT_ID) + boxMargin * 2;

      // Always show "Indexing..." text first
      {
        renderer.fillRect(boxXNoBar, boxY, boxWidthNoBar, boxHeightNoBar, false);
        renderer.drawText(UI_12_FONT_ID, boxXNoBar + boxMargin, boxY + boxMargin, "Indexing...");
        renderer.drawRect(boxXNoBar + 5, boxY + 5, boxWidthNoBar - 10, boxHeightNoBar - 10);
        renderer.displayBuffer();
        pagesUntilFullRefresh = 0;
      }

      // Setup callback - only called for chapters >= 50KB, redraws with progress bar
      auto progressSetup = [this, boxXWithBar, boxWidthWithBar, boxHeightWithBar, barX, barY] {
        renderer.fillRect(boxXWithBar, boxY, boxWidthWithBar, boxHeightWithBar, false);
        renderer.drawText(UI_12_FONT_ID, boxXWithBar + boxMargin, boxY + boxMargin, "Indexing...");
        renderer.drawRect(boxXWithBar + 5, boxY + 5, boxWidthWithBar - 10, boxHeightWithBar - 10);
        renderer.drawRect(barX, barY, barWidth, barHeight);
        renderer.displayBuffer();
      };

      // Progress callback to update progress bar
      auto progressCallback = [this, barX, barY, barWidth, barHeight](int progress) {
        const int fillWidth = (barWidth - 2) * progress / 100;
        renderer.fillRect(barX + 1, barY + 1, fillWidth, barHeight - 2, true);
        renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
      };

      if (!section->createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                      SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                      viewportHeight, progressSetup, progressCallback)) {
        Serial.printf("[%lu] [ERS] Failed to persist page data to SD\n", millis());
        section.reset();
        return;
      }
    } else {
      Serial.printf("[%lu] [ERS] Cache found, skipping build...\n", millis());
    }

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

  renderer.clearScreen();

  if (section->pageCount == 0) {
    Serial.printf("[%lu] [ERS] No pages to render\n", millis());
    renderer.drawCenteredText(UI_12_FONT_ID, 300, "Empty chapter", true, EpdFontFamily::BOLD);
    renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
    renderer.displayBuffer();
    return;
  }

  if (section->currentPage < 0 || section->currentPage >= section->pageCount) {
    Serial.printf("[%lu] [ERS] Page out of bounds: %d (max %d)\n", millis(), section->currentPage, section->pageCount);
    renderer.drawCenteredText(UI_12_FONT_ID, 300, "Out of bounds", true, EpdFontFamily::BOLD);
    renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
    renderer.displayBuffer();
    return;
  }

  {
    auto p = section->loadPageFromSectionFile();
    if (!p) {
      Serial.printf("[%lu] [ERS] Failed to load page from SD - clearing section cache\n", millis());
      section->clearCache();
      section.reset();
      return renderScreen();
    }
    const auto start = millis();
    renderContents(std::move(p), orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
    Serial.printf("[%lu] [ERS] Rendered page in %dms\n", millis(), millis() - start);
  }

  FsFile f;
  if (SdMan.openFileForWrite("ERS", epub->getCachePath() + "/progress.bin", f)) {
    uint8_t data[4];
    data[0] = currentSpineIndex & 0xFF;
    data[1] = (currentSpineIndex >> 8) & 0xFF;
    data[2] = section->currentPage & 0xFF;
    data[3] = (section->currentPage >> 8) & 0xFF;
    f.write(data, 4);
    f.close();
  }
}

void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int orientedMarginTop,
                                        const int orientedMarginRight, const int orientedMarginBottom,
                                        const int orientedMarginLeft) {
  page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
  renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
  if (pagesUntilFullRefresh <= 1) {
    renderer.displayBuffer(EInkDisplay::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::recordReadingTimeDelta() {
  if (!epub) {
    return;
  }

  const unsigned long now = millis();
  const unsigned long deltaMs = now - lastPageInteractionMs;
  lastPageInteractionMs = now;

  const unsigned long sleepTimeoutMs = SETTINGS.getSleepTimeoutMs();
  if (deltaMs < 1000 || deltaMs > sleepTimeoutMs) {
    return;  // ignore very short taps and anything longer than the sleep timeout
  }

  currentBookSeconds += static_cast<uint32_t>(deltaMs / 1000);  // whole seconds only
  persistReadingStats();
}

void EpubReaderActivity::loadReadingStats() {
  currentBookSeconds = 0;

  FsFile f;
  if (!SdMan.openFileForRead("ERS", readingStatsFilePath, f)) {
    return;  // No stats file yet
  }

  const size_t fileSize = f.size();
  if (fileSize == 0) {
    f.close();
    return;
  }

  std::string content;
  content.resize(fileSize);
  const auto bytesRead = f.read(reinterpret_cast<uint8_t*>(&content[0]), fileSize);
  f.close();
  if (bytesRead != fileSize) {
    return;
  }

  size_t pos = 0;
  while (pos < content.size()) {
    const size_t eol = content.find('\n', pos);
    const size_t lineEnd = (eol == std::string::npos) ? content.size() : eol;
    const auto line = content.substr(pos, lineEnd - pos);

    const auto comma = line.find(',');
    if (comma != std::string::npos) {
      const auto path = line.substr(0, comma);
      if (path == epub->getPath()) {
        currentBookSeconds = static_cast<uint32_t>(strtoul(line.c_str() + comma + 1, nullptr, 10));
        break;
      }
    }

    if (eol == std::string::npos) {
      break;
    }
    pos = eol + 1;
  }
}

void EpubReaderActivity::persistReadingStats() const {
  if (!epub) {
    return;
  }

  std::vector<std::pair<std::string, uint32_t>> rows;

  FsFile f;
  if (SdMan.openFileForRead("ERS", readingStatsFilePath, f)) {
    const size_t fileSize = f.size();
    if (fileSize > 0) {
      std::string content;
      content.resize(fileSize);
      const auto bytesRead = f.read(reinterpret_cast<uint8_t*>(&content[0]), fileSize);
      if (bytesRead == fileSize) {
        size_t pos = 0;
        while (pos < content.size()) {
          const size_t eol = content.find('\n', pos);
          const size_t lineEnd = (eol == std::string::npos) ? content.size() : eol;
          const auto line = content.substr(pos, lineEnd - pos);

          const auto comma = line.find(',');
          if (comma != std::string::npos) {
            const auto path = line.substr(0, comma);
            const uint32_t seconds = static_cast<uint32_t>(strtoul(line.c_str() + comma + 1, nullptr, 10));
            rows.emplace_back(path, seconds);
          }

          if (eol == std::string::npos) {
            break;
          }
          pos = eol + 1;
        }
      }
    }
    f.close();
  }

  const auto existing = std::find_if(rows.begin(), rows.end(), [this](const std::pair<std::string, uint32_t>& row) {
    return row.first == epub->getPath();
  });

  if (existing != rows.end()) {
    existing->second = currentBookSeconds;
  } else {
    rows.emplace_back(epub->getPath(), currentBookSeconds);
  }

  if (!SdMan.openFileForWrite("ERS", readingStatsFilePath, f)) {
    return;
  }

  for (const auto& row : rows) {
    const std::string line = row.first + "," + std::to_string(row.second) + "\n";
    f.write(reinterpret_cast<const uint8_t*>(line.c_str()), line.size());
  }
  f.close();
}

void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const int orientedMarginBottom,
                                         const int orientedMarginLeft) const {
  // determine visible status bar elements
  const bool showProgress = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
  const bool showBattery = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::NO_PROGRESS ||
                           SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
  const bool showChapterTitle = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::NO_PROGRESS ||
                                SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;

  // Position status bar near the bottom of the logical screen, regardless of orientation
  const auto screenHeight = renderer.getScreenHeight();
  const auto textY = screenHeight - orientedMarginBottom - 4;
  int progressTextWidth = 0;

  if (showProgress) {
    // Calculate progress in book
    const float sectionChapterProg = static_cast<float>(section->currentPage) / section->pageCount;
    const uint8_t bookProgress = epub->calculateProgress(currentSpineIndex, sectionChapterProg);

    // Right aligned text for progress counter
    const std::string progress = std::to_string(section->currentPage + 1) + "/" + std::to_string(section->pageCount) +
                                 "  " + std::to_string(bookProgress) + "%";
    progressTextWidth = renderer.getTextWidth(SMALL_FONT_ID, progress.c_str());
    renderer.drawText(SMALL_FONT_ID, renderer.getScreenWidth() - orientedMarginRight - progressTextWidth, textY,
                      progress.c_str());
  }

  if (showBattery) {
    ScreenComponents::drawBattery(renderer, orientedMarginLeft + 1, textY);
  }

  if (showChapterTitle) {
    // Centered chatper title text
    // Page width minus existing content with 30px padding on each side
    const int titleMarginLeft = 50 + 30 + orientedMarginLeft;  // 50px for battery
    const int titleMarginRight = progressTextWidth + 30 + orientedMarginRight;
    const int availableTextWidth = renderer.getScreenWidth() - titleMarginLeft - titleMarginRight;
    const int tocIndex = epub->getTocIndexForSpineIndex(currentSpineIndex);

    std::string title;
    int titleWidth;
    if (tocIndex == -1) {
      title = "Unnamed";
      titleWidth = renderer.getTextWidth(SMALL_FONT_ID, "Unnamed");
    } else {
      const auto tocItem = epub->getTocItem(tocIndex);
      title = tocItem.title;
      titleWidth = renderer.getTextWidth(SMALL_FONT_ID, title.c_str());
      while (titleWidth > availableTextWidth && title.length() > 11) {
        title.replace(title.length() - 8, 8, "...");
        titleWidth = renderer.getTextWidth(SMALL_FONT_ID, title.c_str());
      }
    }

    renderer.drawText(SMALL_FONT_ID, titleMarginLeft + (availableTextWidth - titleWidth) / 2, textY, title.c_str());
  }
}