#include "DictionaryDefinitionActivity.h"

#include <GfxRenderer.h>

#include <algorithm>
#include <cctype>
#include <cstdlib>

#include "CrossPointSettings.h"
#include "MappedInputManager.h"
#include "components/UITheme.h"
#include "fontIds.h"

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

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

void DictionaryDefinitionActivity::onEnter() {
  Activity::onEnter();
  renderingMutex = xSemaphoreCreateMutex();
  wrapText();
  updateRequired = true;
  xTaskCreate(&DictionaryDefinitionActivity::taskTrampoline, "DictDefTask", 4096, this, 1, &displayTaskHandle);
}

void DictionaryDefinitionActivity::onExit() {
  Activity::onExit();
  xSemaphoreTake(renderingMutex, portMAX_DELAY);
  if (displayTaskHandle) {
    vTaskDelete(displayTaskHandle);
    displayTaskHandle = nullptr;
  }
  vSemaphoreDelete(renderingMutex);
  renderingMutex = nullptr;
}

// ---------------------------------------------------------------------------
// Check if a Unicode codepoint is likely renderable by the e-ink bitmap font.
// Keeps Latin text, combining marks, common punctuation, currency, and letterlike symbols.
// Skips IPA extensions, Greek, Cyrillic, Arabic, CJK, and other non-Latin scripts.
// ---------------------------------------------------------------------------
bool DictionaryDefinitionActivity::isRenderableCodepoint(uint32_t cp) {
  if (cp <= 0x024F) return true;                       // Basic Latin + Latin Extended-A/B
  if (cp >= 0x0300 && cp <= 0x036F) return true;       // Combining Diacritical Marks
  if (cp >= 0x2000 && cp <= 0x206F) return true;       // General Punctuation
  if (cp >= 0x20A0 && cp <= 0x20CF) return true;       // Currency Symbols
  if (cp >= 0x2100 && cp <= 0x214F) return true;       // Letterlike Symbols
  if (cp >= 0x2190 && cp <= 0x21FF) return true;       // Arrows
  return false;
}

// ---------------------------------------------------------------------------
// HTML entity decoder
// ---------------------------------------------------------------------------
std::string DictionaryDefinitionActivity::decodeEntity(const std::string& entity) {
  // Named entities
  if (entity == "amp") return "&";
  if (entity == "lt") return "<";
  if (entity == "gt") return ">";
  if (entity == "quot") return "\"";
  if (entity == "apos") return "'";
  if (entity == "nbsp" || entity == "thinsp" || entity == "ensp" || entity == "emsp") return " ";
  if (entity == "ndash") return "\xE2\x80\x93";  // U+2013
  if (entity == "mdash") return "\xE2\x80\x94";   // U+2014
  if (entity == "lsquo") return "\xE2\x80\x98";
  if (entity == "rsquo") return "\xE2\x80\x99";
  if (entity == "ldquo") return "\xE2\x80\x9C";
  if (entity == "rdquo") return "\xE2\x80\x9D";
  if (entity == "hellip") return "\xE2\x80\xA6";
  if (entity == "lrm" || entity == "rlm" || entity == "zwj" || entity == "zwnj") return "";

  // Numeric entities: &#123; or &#x1F;
  if (!entity.empty() && entity[0] == '#') {
    unsigned long cp = 0;
    if (entity.size() > 1 && (entity[1] == 'x' || entity[1] == 'X')) {
      cp = std::strtoul(entity.c_str() + 2, nullptr, 16);
    } else {
      cp = std::strtoul(entity.c_str() + 1, nullptr, 10);
    }
    if (cp > 0 && cp < 0x80) {
      return std::string(1, static_cast<char>(cp));
    }
    if (cp >= 0x80 && cp < 0x800) {
      char buf[3] = {static_cast<char>(0xC0 | (cp >> 6)), static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
      return std::string(buf, 2);
    }
    if (cp >= 0x800 && cp < 0x10000) {
      char buf[4] = {static_cast<char>(0xE0 | (cp >> 12)), static_cast<char>(0x80 | ((cp >> 6) & 0x3F)),
                     static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
      return std::string(buf, 3);
    }
    if (cp >= 0x10000 && cp < 0x110000) {
      char buf[5] = {static_cast<char>(0xF0 | (cp >> 18)), static_cast<char>(0x80 | ((cp >> 12) & 0x3F)),
                     static_cast<char>(0x80 | ((cp >> 6) & 0x3F)), static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
      return std::string(buf, 4);
    }
  }

  return "";  // unknown entity — drop it
}

// ---------------------------------------------------------------------------
// HTML → TextAtom list
// ---------------------------------------------------------------------------
std::vector<DictionaryDefinitionActivity::TextAtom> DictionaryDefinitionActivity::parseHtml(const std::string& html) {
  std::vector<TextAtom> atoms;

  bool isBold = false;
  bool isItalic = false;
  bool inSvg = false;
  int svgDepth = 0;
  std::vector<ListState> listStack;
  std::string currentWord;

  auto currentStyle = [&]() -> EpdFontFamily::Style {
    if (isBold && isItalic) return EpdFontFamily::BOLD_ITALIC;
    if (isBold) return EpdFontFamily::BOLD;
    if (isItalic) return EpdFontFamily::ITALIC;
    return EpdFontFamily::REGULAR;
  };

  auto flushWord = [&]() {
    if (!currentWord.empty() && !inSvg) {
      atoms.push_back({currentWord, currentStyle(), false, 0});
      currentWord.clear();
    }
  };

  auto indentPx = [&]() -> int {
    // 15 pixels per nesting level (the first level has no extra indent)
    int depth = static_cast<int>(listStack.size());
    return (depth > 1) ? (depth - 1) * 15 : 0;
  };

  // Skip any leading non-HTML text (e.g. pronunciation guides like "/ˈsɪm.pəl/, /ˈsɪmpəl/")
  // that appears before the first tag in sametypesequence=h entries.
  size_t i = 0;
  {
    size_t firstTag = html.find('<');
    if (firstTag != std::string::npos) i = firstTag;
  }

  while (i < html.size()) {
    // ------- HTML tag -------
    if (html[i] == '<') {
      flushWord();

      size_t tagEnd = html.find('>', i);
      if (tagEnd == std::string::npos) break;

      std::string tagContent = html.substr(i + 1, tagEnd - i - 1);

      // Extract tag name: first token, lowercased, trailing '/' stripped.
      size_t space = tagContent.find(' ');
      std::string tagName = (space != std::string::npos) ? tagContent.substr(0, space) : tagContent;
      for (auto& c : tagName) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
      if (!tagName.empty() && tagName.back() == '/') tagName.pop_back();

      // --- SVG handling (skip all content inside <svg>…</svg>) ---
      if (tagName == "svg") {
        inSvg = true;
        svgDepth = 1;
      } else if (inSvg) {
        if (tagName == "svg") {
          svgDepth++;
        } else if (tagName == "/svg") {
          svgDepth--;
          if (svgDepth <= 0) inSvg = false;
        }
      }

      if (!inSvg) {
        // --- Inline style tags ---
        if (tagName == "b" || tagName == "strong") {
          isBold = true;
        } else if (tagName == "/b" || tagName == "/strong") {
          isBold = false;
        } else if (tagName == "i" || tagName == "em") {
          isItalic = true;
        } else if (tagName == "/i" || tagName == "/em") {
          isItalic = false;

          // --- Block-level tags → newlines ---
        } else if (tagName == "p" || tagName == "h1" || tagName == "h2" || tagName == "h3" || tagName == "h4") {
          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
          // Headings get bold style applied to following text
          if (tagName != "p") isBold = true;
        } else if (tagName == "/p" || tagName == "/h1" || tagName == "/h2" || tagName == "/h3" || tagName == "/h4") {
          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
          isBold = false;
        } else if (tagName == "br") {
          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});

          // --- Separator between definition entries ---
        } else if (tagName == "/html") {
          atoms.push_back({"", EpdFontFamily::REGULAR, true, 0});
          atoms.push_back({"", EpdFontFamily::REGULAR, true, 0});  // extra blank line
          isBold = false;
          isItalic = false;
          // Skip any raw text between </html> and the next tag — this is where
          // pronunciation guides (e.g. /ˈsɪmpəl/, /ksɛpt/) live in this dictionary.
          size_t nextTag = html.find('<', tagEnd + 1);
          i = (nextTag != std::string::npos) ? nextTag : html.size();
          continue;

          // --- Lists ---
        } else if (tagName == "ol") {
          bool alpha = tagContent.find("lower-alpha") != std::string::npos;
          listStack.push_back({0, alpha});
        } else if (tagName == "ul") {
          listStack.push_back({0, false});
        } else if (tagName == "/ol" || tagName == "/ul") {
          if (!listStack.empty()) listStack.pop_back();
        } else if (tagName == "li") {
          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
          if (!listStack.empty()) {
            auto& ls = listStack.back();
            ls.counter++;
            std::string marker;
            if (ls.isAlpha && ls.counter >= 1 && ls.counter <= 26) {
              marker = std::string(1, static_cast<char>('a' + ls.counter - 1)) + ". ";
            } else if (ls.isAlpha) {
              marker = std::to_string(ls.counter) + ". ";
            } else {
              marker = std::to_string(ls.counter) + ". ";
            }
            atoms.push_back({marker, EpdFontFamily::REGULAR, false, 0});
          } else {
            // Unordered list or bare <li>
            atoms.push_back({"\xE2\x80\xA2 ", EpdFontFamily::REGULAR, false, 0});
          }
        }
        // All other tags (span, div, code, sup, sub, table, etc.) are silently ignored;
        // their text content will still be emitted.
      }

      i = tagEnd + 1;
      continue;
    }

    // Skip content inside SVG
    if (inSvg) {
      i++;
      continue;
    }

    // ------- HTML entity -------
    if (html[i] == '&') {
      size_t semicolon = html.find(';', i);
      if (semicolon != std::string::npos && semicolon - i < 16) {
        std::string entity = html.substr(i + 1, semicolon - i - 1);
        std::string decoded = decodeEntity(entity);
        if (!decoded.empty()) {
          // Treat decoded chars like normal text (could be space etc.)
          for (char dc : decoded) {
            if (dc == ' ') {
              flushWord();
            } else {
              currentWord += dc;
            }
          }
        }
        i = semicolon + 1;
        continue;
      }
      // Not a valid entity — emit '&' literally
      currentWord += '&';
      i++;
      continue;
    }

    // ------- IPA pronunciation (skip /…/ and […] containing non-ASCII) -------
    if (html[i] == '/' || html[i] == '[') {
      char closeDelim = (html[i] == '/') ? '/' : ']';
      size_t end = html.find(closeDelim, i + 1);
      if (end != std::string::npos && end - i < 80) {
        bool hasNonAscii = false;
        for (size_t j = i + 1; j < end; j++) {
          if (static_cast<unsigned char>(html[j]) > 127) {
            hasNonAscii = true;
            break;
          }
        }
        if (hasNonAscii) {
          flushWord();
          i = end + 1;  // skip entire IPA section including delimiters
          continue;
        }
      }
      // Not IPA — fall through to treat as regular character
    }

    // ------- Whitespace -------
    if (html[i] == ' ' || html[i] == '\t' || html[i] == '\n' || html[i] == '\r') {
      flushWord();
      i++;
      continue;
    }

    // ------- Regular character (with non-renderable character filter) -------
    {
      unsigned char byte = static_cast<unsigned char>(html[i]);
      if (byte < 0x80) {
        // ASCII — always renderable
        currentWord += html[i];
        i++;
      } else {
        // Multi-byte UTF-8: decode codepoint and check if renderable
        int seqLen = 1;
        uint32_t cp = 0;
        if ((byte & 0xE0) == 0xC0) {
          seqLen = 2;
          cp = byte & 0x1F;
        } else if ((byte & 0xF0) == 0xE0) {
          seqLen = 3;
          cp = byte & 0x0F;
        } else if ((byte & 0xF8) == 0xF0) {
          seqLen = 4;
          cp = byte & 0x07;
        } else {
          i++;
          continue;
        }  // invalid start byte

        if (i + static_cast<size_t>(seqLen) > html.size()) {
          i++;
          continue;
        }

        bool valid = true;
        for (int j = 1; j < seqLen; j++) {
          unsigned char cb = static_cast<unsigned char>(html[i + j]);
          if ((cb & 0xC0) != 0x80) {
            valid = false;
            break;
          }
          cp = (cp << 6) | (cb & 0x3F);
        }

        if (valid && isRenderableCodepoint(cp)) {
          for (int j = 0; j < seqLen; j++) {
            currentWord += html[i + j];
          }
        }
        // else: silently skip non-renderable character

        i += valid ? seqLen : 1;
      }
    }
  }

  flushWord();
  return atoms;
}

// ---------------------------------------------------------------------------
// Word-wrap the parsed HTML atoms into positioned line segments
// ---------------------------------------------------------------------------
void DictionaryDefinitionActivity::wrapText() {
  wrappedLines.clear();

  const bool landscape = orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||
                         orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW;
  const int screenWidth = renderer.getScreenWidth();
  const int lineHeight = renderer.getLineHeight(readerFontId);
  const int sidePadding = landscape ? 50 : 20;
  constexpr int topArea = 50;
  constexpr int bottomArea = 50;
  const int maxWidth = screenWidth - 2 * sidePadding;
  const int spaceWidth = renderer.getSpaceWidth(readerFontId);

  linesPerPage = (renderer.getScreenHeight() - topArea - bottomArea) / lineHeight;
  if (linesPerPage < 1) linesPerPage = 1;

  auto atoms = parseHtml(definition);

  std::vector<Segment> currentLine;
  int currentX = 0;
  int baseIndent = 0;  // indent for continuation lines within the same block

  for (const auto& atom : atoms) {
    // ---- Newline directive ----
    if (atom.isNewline) {
      // Collapse multiple consecutive blank lines
      if (currentLine.empty() && !wrappedLines.empty() && wrappedLines.back().empty()) {
        // Already have a blank line; update indent but don't push another
        baseIndent = atom.indent;
        currentX = baseIndent;
        continue;
      }
      wrappedLines.push_back(std::move(currentLine));
      currentLine.clear();
      baseIndent = atom.indent;
      currentX = baseIndent;
      continue;
    }

    // ---- Text word ----
    int wordWidth = renderer.getTextWidth(readerFontId, atom.text.c_str(), atom.style);
    int gap = (currentX > baseIndent) ? spaceWidth : 0;

    // Wrap if this word won't fit
    if (currentX + gap + wordWidth > maxWidth && currentX > baseIndent) {
      wrappedLines.push_back(std::move(currentLine));
      currentLine.clear();
      currentX = baseIndent;
      gap = 0;
    }

    int16_t x = static_cast<int16_t>(currentX + gap);
    currentLine.push_back({atom.text, x, atom.style});
    currentX = x + wordWidth;
  }

  // Flush last line
  if (!currentLine.empty()) {
    wrappedLines.push_back(std::move(currentLine));
  }

  totalPages = (static_cast<int>(wrappedLines.size()) + linesPerPage - 1) / linesPerPage;
  if (totalPages < 1) totalPages = 1;
}

void DictionaryDefinitionActivity::loop() {
  const bool prevPage = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
                        mappedInput.wasReleased(MappedInputManager::Button::Left);
  const bool nextPage = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
                        mappedInput.wasReleased(MappedInputManager::Button::Right);

  if (prevPage && currentPage > 0) {
    currentPage--;
    updateRequired = true;
  }

  if (nextPage && currentPage < totalPages - 1) {
    currentPage++;
    updateRequired = true;
  }

  if (mappedInput.wasReleased(MappedInputManager::Button::Back) ||
      mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
    onBack();
    return;
  }
}

void DictionaryDefinitionActivity::renderScreen() {
  renderer.clearScreen();

  const bool landscape = orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||
                         orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW;
  const int sidePadding = landscape ? 50 : 20;
  constexpr int titleY = 10;
  const int lineHeight = renderer.getLineHeight(readerFontId);
  constexpr int bodyStartY = 50;

  // Title: the word in bold (UI font)
  renderer.drawText(UI_12_FONT_ID, sidePadding, titleY, headword.c_str(), true, EpdFontFamily::BOLD);

  // Separator line
  renderer.drawLine(sidePadding, 40, renderer.getScreenWidth() - sidePadding, 40);

  // Body: styled definition lines
  int startLine = currentPage * linesPerPage;
  for (int i = 0; i < linesPerPage && (startLine + i) < static_cast<int>(wrappedLines.size()); i++) {
    int y = bodyStartY + i * lineHeight;
    const auto& line = wrappedLines[startLine + i];
    for (const auto& seg : line) {
      renderer.drawText(readerFontId, sidePadding + seg.x, y, seg.text.c_str(), true, seg.style);
    }
  }

  // Pagination indicator (bottom right)
  if (totalPages > 1) {
    std::string pageInfo = std::to_string(currentPage + 1) + "/" + std::to_string(totalPages);
    int textWidth = renderer.getTextWidth(SMALL_FONT_ID, pageInfo.c_str());
    renderer.drawText(SMALL_FONT_ID, renderer.getScreenWidth() - sidePadding - textWidth,
                      renderer.getScreenHeight() - 50, pageInfo.c_str());
  }

  // Button hints (bottom face buttons — hide Confirm stub like Home Screen)
  const auto labels = mappedInput.mapLabels("\xC2\xAB Back", "", "\xC2\xAB Page", "Page \xC2\xBB");
  GUI.drawButtonHints(renderer, labels.btn1, labels.btn2, labels.btn3, labels.btn4);

  // Side button hints (drawn in portrait coordinates for correct placement)
  {
    const auto origOrientation = renderer.getOrientation();
    renderer.setOrientation(GfxRenderer::Orientation::Portrait);
    const int portW = renderer.getScreenWidth();

    constexpr int sideButtonWidth = 30;
    constexpr int sideButtonHeight = 78;
    constexpr int sideButtonGap = 5;
    constexpr int sideTopY = 345;
    constexpr int cornerRadius = 6;
    const int sideX = portW - sideButtonWidth;
    const int sideButtonY[2] = {sideTopY, sideTopY + sideButtonHeight + sideButtonGap};
    const char* sideLabels[2] = {"\xC2\xAB Page", "Page \xC2\xBB"};
    const bool useCCW = (orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW);

    for (int i = 0; i < 2; i++) {
      renderer.fillRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, false);
      renderer.drawRoundedRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, 1, cornerRadius, true, false,
                               true, false, true);

      const std::string truncated = renderer.truncatedText(SMALL_FONT_ID, sideLabels[i], sideButtonHeight);
      const int tw = renderer.getTextWidth(SMALL_FONT_ID, truncated.c_str());

      if (useCCW) {
        renderer.drawTextRotated90CCW(SMALL_FONT_ID, sideX,
                                      sideButtonY[i] + (sideButtonHeight - tw) / 2, truncated.c_str());
      } else {
        renderer.drawTextRotated90CW(SMALL_FONT_ID, sideX,
                                     sideButtonY[i] + (sideButtonHeight + tw) / 2, truncated.c_str());
      }
    }

    renderer.setOrientation(origOrientation);
  }

  // Use half refresh when entering the screen for cleaner transition; fast refresh for page turns.
  renderer.displayBuffer(firstRender ? HalDisplay::HALF_REFRESH : HalDisplay::FAST_REFRESH);
  firstRender = false;
}