#include "PlaceholderCoverGenerator.h"

#include <EpdFont.h>
#include <HalStorage.h>
#include <Logging.h>
#include <Utf8.h>

#include <algorithm>
#include <cstring>
#include <vector>

// Include the UI fonts directly for self-contained placeholder rendering.
// These are 1-bit bitmap fonts compiled from Ubuntu TTF.
#include "builtinFonts/ubuntu_10_regular.h"
#include "builtinFonts/ubuntu_12_bold.h"

// Book icon bitmap (48x48 1-bit, generated by scripts/generate_book_icon.py)
#include "BookIcon.h"

namespace {

// BMP writing helpers (same format as JpegToBmpConverter)
inline void write16(Print& out, const uint16_t value) {
  out.write(value & 0xFF);
  out.write((value >> 8) & 0xFF);
}

inline void write32(Print& out, const uint32_t value) {
  out.write(value & 0xFF);
  out.write((value >> 8) & 0xFF);
  out.write((value >> 16) & 0xFF);
  out.write((value >> 24) & 0xFF);
}

inline void write32Signed(Print& out, const int32_t value) {
  out.write(value & 0xFF);
  out.write((value >> 8) & 0xFF);
  out.write((value >> 16) & 0xFF);
  out.write((value >> 24) & 0xFF);
}

void writeBmpHeader1bit(Print& bmpOut, const int width, const int height) {
  const int bytesPerRow = (width + 31) / 32 * 4;
  const int imageSize = bytesPerRow * height;
  const uint32_t fileSize = 62 + imageSize;

  // BMP File Header (14 bytes)
  bmpOut.write('B');
  bmpOut.write('M');
  write32(bmpOut, fileSize);
  write32(bmpOut, 0);   // Reserved
  write32(bmpOut, 62);  // Offset to pixel data

  // DIB Header (BITMAPINFOHEADER - 40 bytes)
  write32(bmpOut, 40);
  write32Signed(bmpOut, width);
  write32Signed(bmpOut, -height);  // Negative = top-down
  write16(bmpOut, 1);              // Color planes
  write16(bmpOut, 1);              // Bits per pixel
  write32(bmpOut, 0);              // BI_RGB
  write32(bmpOut, imageSize);
  write32(bmpOut, 2835);  // xPixelsPerMeter
  write32(bmpOut, 2835);  // yPixelsPerMeter
  write32(bmpOut, 2);     // colorsUsed
  write32(bmpOut, 2);     // colorsImportant

  // Palette: index 0 = black, index 1 = white
  const uint8_t palette[8] = {
      0x00, 0x00, 0x00, 0x00,  // Black
      0xFF, 0xFF, 0xFF, 0x00   // White
  };
  for (const uint8_t b : palette) {
    bmpOut.write(b);
  }
}

/// 1-bit pixel buffer that can render text, icons, and shapes, then write as BMP.
class PixelBuffer {
 public:
  PixelBuffer(int width, int height) : width(width), height(height) {
    bytesPerRow = (width + 31) / 32 * 4;
    bufferSize = bytesPerRow * height;
    buffer = static_cast<uint8_t*>(malloc(bufferSize));
    if (buffer) {
      memset(buffer, 0xFF, bufferSize);  // White background
    }
  }

  ~PixelBuffer() {
    if (buffer) {
      free(buffer);
    }
  }

  bool isValid() const { return buffer != nullptr; }

  /// Set a pixel to black.
  void setBlack(int x, int y) {
    if (x < 0 || x >= width || y < 0 || y >= height) return;
    const int byteIndex = y * bytesPerRow + x / 8;
    const uint8_t bitMask = 0x80 >> (x % 8);
    buffer[byteIndex] &= ~bitMask;
  }

  /// Set a scaled "pixel" (scale x scale block) to black.
  void setBlackScaled(int x, int y, int scale) {
    for (int dy = 0; dy < scale; dy++) {
      for (int dx = 0; dx < scale; dx++) {
        setBlack(x + dx, y + dy);
      }
    }
  }

  /// Draw a filled rectangle in black.
  void fillRect(int x, int y, int w, int h) {
    for (int row = y; row < y + h && row < height; row++) {
      for (int col = x; col < x + w && col < width; col++) {
        setBlack(col, row);
      }
    }
  }

  /// Draw a rectangular border in black.
  void drawBorder(int x, int y, int w, int h, int thickness) {
    fillRect(x, y, w, thickness);                  // Top
    fillRect(x, y + h - thickness, w, thickness);   // Bottom
    fillRect(x, y, thickness, h);                   // Left
    fillRect(x + w - thickness, y, thickness, h);   // Right
  }

  /// Draw a horizontal line in black with configurable thickness.
  void drawHLine(int x, int y, int length, int thickness = 1) {
    fillRect(x, y, length, thickness);
  }

  /// Render a single glyph at (cursorX, baselineY) with integer scaling. Returns advance in X (scaled).
  int renderGlyph(const EpdFontData* font, uint32_t codepoint, int cursorX, int baselineY, int scale = 1) {
    const EpdFont fontObj(font);
    const EpdGlyph* glyph = fontObj.getGlyph(codepoint);
    if (!glyph) {
      glyph = fontObj.getGlyph(REPLACEMENT_GLYPH);
    }
    if (!glyph) {
      return 0;
    }

    const uint8_t* bitmap = &font->bitmap[glyph->dataOffset];
    const int glyphW = glyph->width;
    const int glyphH = glyph->height;

    for (int gy = 0; gy < glyphH; gy++) {
      const int screenY = baselineY - glyph->top * scale + gy * scale;
      for (int gx = 0; gx < glyphW; gx++) {
        const int pixelPos = gy * glyphW + gx;
        const int screenX = cursorX + glyph->left * scale + gx * scale;

        bool isSet = false;
        if (font->is2Bit) {
          const uint8_t byte = bitmap[pixelPos / 4];
          const uint8_t bitIndex = (3 - pixelPos % 4) * 2;
          const uint8_t val = 3 - ((byte >> bitIndex) & 0x3);
          isSet = (val < 3);
        } else {
          const uint8_t byte = bitmap[pixelPos / 8];
          const uint8_t bitIndex = 7 - (pixelPos % 8);
          isSet = ((byte >> bitIndex) & 1);
        }

        if (isSet) {
          setBlackScaled(screenX, screenY, scale);
        }
      }
    }

    return glyph->advanceX * scale;
  }

  /// Render a UTF-8 string at (x, y) where y is the top of the text line, with integer scaling.
  void drawText(const EpdFontData* font, int x, int y, const char* text, int scale = 1) {
    const int baselineY = y + font->ascender * scale;
    int cursorX = x;
    uint32_t cp;
    while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
      cursorX += renderGlyph(font, cp, cursorX, baselineY, scale);
    }
  }

  /// Draw a 1-bit icon bitmap (MSB first, 0=black, 1=white) with integer scaling.
  void drawIcon(const uint8_t* icon, int iconW, int iconH, int x, int y, int scale = 1) {
    const int bytesPerIconRow = iconW / 8;
    for (int iy = 0; iy < iconH; iy++) {
      for (int ix = 0; ix < iconW; ix++) {
        const int byteIdx = iy * bytesPerIconRow + ix / 8;
        const uint8_t bitMask = 0x80 >> (ix % 8);
        // In the icon data: 0 = black (drawn), 1 = white (skip)
        if (!(icon[byteIdx] & bitMask)) {
          const int sx = x + ix * scale;
          const int sy = y + iy * scale;
          setBlackScaled(sx, sy, scale);
        }
      }
    }
  }

  /// Write the pixel buffer to a file as a 1-bit BMP.
  bool writeBmp(Print& out) const {
    if (!buffer) return false;
    writeBmpHeader1bit(out, width, height);
    out.write(buffer, bufferSize);
    return true;
  }

  int getWidth() const { return width; }
  int getHeight() const { return height; }

 private:
  int width;
  int height;
  int bytesPerRow;
  size_t bufferSize;
  uint8_t* buffer;
};

/// Measure the width of a UTF-8 string in pixels (at 1x scale).
int measureTextWidth(const EpdFontData* font, const char* text) {
  const EpdFont fontObj(font);
  int w = 0, h = 0;
  fontObj.getTextDimensions(text, &w, &h);
  return w;
}

/// Get the advance width of a single character.
int getCharAdvance(const EpdFontData* font, uint32_t cp) {
  const EpdFont fontObj(font);
  const EpdGlyph* glyph = fontObj.getGlyph(cp);
  if (!glyph) return 0;
  return glyph->advanceX;
}

/// Split a string into words (splitting on spaces).
std::vector<std::string> splitWords(const std::string& text) {
  std::vector<std::string> words;
  std::string current;
  for (size_t i = 0; i < text.size(); i++) {
    if (text[i] == ' ') {
      if (!current.empty()) {
        words.push_back(current);
        current.clear();
      }
    } else {
      current += text[i];
    }
  }
  if (!current.empty()) {
    words.push_back(current);
  }
  return words;
}

/// Word-wrap text into lines that fit within maxWidth pixels at the given scale.
std::vector<std::string> wrapText(const EpdFontData* font, const std::string& text, int maxWidth, int scale = 1) {
  std::vector<std::string> lines;
  const auto words = splitWords(text);
  if (words.empty()) return lines;

  const int spaceWidth = getCharAdvance(font, ' ') * scale;
  std::string currentLine;
  int currentWidth = 0;

  for (const auto& word : words) {
    const int wordWidth = measureTextWidth(font, word.c_str()) * scale;

    if (currentLine.empty()) {
      currentLine = word;
      currentWidth = wordWidth;
    } else if (currentWidth + spaceWidth + wordWidth <= maxWidth) {
      currentLine += " " + word;
      currentWidth += spaceWidth + wordWidth;
    } else {
      lines.push_back(currentLine);
      currentLine = word;
      currentWidth = wordWidth;
    }
  }

  if (!currentLine.empty()) {
    lines.push_back(currentLine);
  }

  return lines;
}

/// Truncate a string with "..." if it exceeds maxWidth pixels at the given scale.
std::string truncateText(const EpdFontData* font, const std::string& text, int maxWidth, int scale = 1) {
  if (measureTextWidth(font, text.c_str()) * scale <= maxWidth) {
    return text;
  }

  std::string truncated = text;
  const char* ellipsis = "...";
  const int ellipsisWidth = measureTextWidth(font, ellipsis) * scale;

  while (!truncated.empty()) {
    utf8RemoveLastChar(truncated);
    if (measureTextWidth(font, truncated.c_str()) * scale + ellipsisWidth <= maxWidth) {
      return truncated + ellipsis;
    }
  }

  return ellipsis;
}

}  // namespace

bool PlaceholderCoverGenerator::generate(const std::string& outputPath, const std::string& title,
                                         const std::string& author, int width, int height) {
  LOG_DBG("PHC", "Generating placeholder cover %dx%d: \"%s\" by \"%s\"", width, height, title.c_str(), author.c_str());

  const EpdFontData* titleFont = &ubuntu_12_bold;
  const EpdFontData* authorFont = &ubuntu_10_regular;

  PixelBuffer buf(width, height);
  if (!buf.isValid()) {
    LOG_ERR("PHC", "Failed to allocate %dx%d pixel buffer (%d bytes)", width, height,
            (width + 31) / 32 * 4 * height);
    return false;
  }

  // Proportional layout constants based on cover dimensions.
  // The device bezel covers ~2-3px on each edge, so we pad inward from the edge.
  const int edgePadding = std::max(3, width / 48);    // ~10px at 480w, ~3px at 136w
  const int borderWidth = std::max(2, width / 96);     // ~5px at 480w, ~2px at 136w
  const int innerPadding = std::max(4, width / 32);    // ~15px at 480w, ~4px at 136w

  // Text scaling: 2x for full-size covers, 1x for thumbnails
  const int titleScale = (height >= 600) ? 2 : 1;
  const int authorScale = (height >= 600) ? 2 : 1;  // Author also larger on full covers
  // Icon: 2x for full cover, 1x for medium thumb, skip for small
  const int iconScale = (height >= 600) ? 2 : (height >= 350 ? 1 : 0);

  // Draw border inset from edge
  buf.drawBorder(edgePadding, edgePadding, width - 2 * edgePadding, height - 2 * edgePadding, borderWidth);

  // Content area (inside border + inner padding)
  const int contentX = edgePadding + borderWidth + innerPadding;
  const int contentY = edgePadding + borderWidth + innerPadding;
  const int contentW = width - 2 * contentX;
  const int contentH = height - 2 * contentY;

  if (contentW <= 0 || contentH <= 0) {
    LOG_ERR("PHC", "Cover too small for content (%dx%d)", width, height);
    FsFile file;
    if (!Storage.openFileForWrite("PHC", outputPath, file)) {
      return false;
    }
    buf.writeBmp(file);
    file.close();
    return true;
  }

  // --- Layout zones ---
  // Title zone: top 2/3 of content area (icon + title)
  // Author zone: bottom 1/3 of content area
  const int titleZoneH = contentH * 2 / 3;
  const int authorZoneH = contentH - titleZoneH;
  const int authorZoneY = contentY + titleZoneH;

  // --- Separator line at the zone boundary ---
  const int separatorWidth = contentW / 3;
  const int separatorX = contentX + (contentW - separatorWidth) / 2;
  buf.drawHLine(separatorX, authorZoneY, separatorWidth);

  // --- Icon dimensions (needed for title text wrapping) ---
  const int iconW = (iconScale > 0) ? BOOK_ICON_WIDTH * iconScale : 0;
  const int iconGap = (iconScale > 0) ? std::max(8, width / 40) : 0;  // Gap between icon and title text
  const int titleTextW = contentW - iconW - iconGap;  // Title wraps in narrower area beside icon

  // --- Prepare title text (wraps within the area to the right of the icon) ---
  const std::string displayTitle = title.empty() ? "Untitled" : title;
  auto titleLines = wrapText(titleFont, displayTitle, titleTextW, titleScale);

  constexpr int MAX_TITLE_LINES = 5;
  if (static_cast<int>(titleLines.size()) > MAX_TITLE_LINES) {
    titleLines.resize(MAX_TITLE_LINES);
    titleLines.back() = truncateText(titleFont, titleLines.back(), titleTextW, titleScale);
  }

  // --- Prepare author text (multi-line, max 3 lines) ---
  std::vector<std::string> authorLines;
  if (!author.empty()) {
    authorLines = wrapText(authorFont, author, contentW, authorScale);
    constexpr int MAX_AUTHOR_LINES = 3;
    if (static_cast<int>(authorLines.size()) > MAX_AUTHOR_LINES) {
      authorLines.resize(MAX_AUTHOR_LINES);
      authorLines.back() = truncateText(authorFont, authorLines.back(), contentW, authorScale);
    }
  }

  // --- Calculate title zone layout (icon LEFT of title) ---
  // Tighter line spacing so 2-3 title lines fit within the icon height
  const int titleLineH = titleFont->advanceY * titleScale * 3 / 4;
  const int iconH = (iconScale > 0) ? BOOK_ICON_HEIGHT * iconScale : 0;
  const int numTitleLines = static_cast<int>(titleLines.size());
  // Visual height: distance from top of first line to bottom of last line's glyphs.
  // Use ascender (not full advanceY) for the last line since trailing line-gap isn't visible.
  const int titleVisualH = (numTitleLines > 0)
                               ? (numTitleLines - 1) * titleLineH + titleFont->ascender * titleScale
                               : 0;
  const int titleBlockH = std::max(iconH, titleVisualH);  // Taller of icon or text

  int titleStartY = contentY + (titleZoneH - titleBlockH) / 2;
  if (titleStartY < contentY) {
    titleStartY = contentY;
  }

  // If title fits within icon height, center it vertically against the icon.
  // Otherwise top-align so extra lines overflow below.
  const int iconY = titleStartY;
  const int titleTextY = (iconH > 0 && titleVisualH <= iconH)
                             ? titleStartY + (iconH - titleVisualH) / 2
                             : titleStartY;

  // --- Horizontal centering: measure the widest title line, then center icon+gap+text block ---
  int maxTitleLineW = 0;
  for (const auto& line : titleLines) {
    const int w = measureTextWidth(titleFont, line.c_str()) * titleScale;
    if (w > maxTitleLineW) maxTitleLineW = w;
  }
  const int titleBlockW = iconW + iconGap + maxTitleLineW;
  const int titleBlockX = contentX + (contentW - titleBlockW) / 2;

  // --- Draw icon ---
  if (iconScale > 0) {
    buf.drawIcon(BookIcon, BOOK_ICON_WIDTH, BOOK_ICON_HEIGHT, titleBlockX, iconY, iconScale);
  }

  // --- Draw title lines (to the right of the icon) ---
  const int titleTextX = titleBlockX + iconW + iconGap;
  int currentY = titleTextY;
  for (const auto& line : titleLines) {
    buf.drawText(titleFont, titleTextX, currentY, line.c_str(), titleScale);
    currentY += titleLineH;
  }

  // --- Draw author lines (centered vertically in bottom 1/3, centered horizontally) ---
  if (!authorLines.empty()) {
    const int authorLineH = authorFont->advanceY * authorScale;
    const int authorBlockH = static_cast<int>(authorLines.size()) * authorLineH;
    int authorStartY = authorZoneY + (authorZoneH - authorBlockH) / 2;
    if (authorStartY < authorZoneY + 4) {
      authorStartY = authorZoneY + 4;  // Small gap below separator
    }

    for (const auto& line : authorLines) {
      const int lineWidth = measureTextWidth(authorFont, line.c_str()) * authorScale;
      const int lineX = contentX + (contentW - lineWidth) / 2;
      buf.drawText(authorFont, lineX, authorStartY, line.c_str(), authorScale);
      authorStartY += authorLineH;
    }
  }

  // --- Write to file ---
  FsFile file;
  if (!Storage.openFileForWrite("PHC", outputPath, file)) {
    LOG_ERR("PHC", "Failed to open output file: %s", outputPath.c_str());
    return false;
  }

  const bool success = buf.writeBmp(file);
  file.close();

  if (success) {
    LOG_DBG("PHC", "Placeholder cover written to %s", outputPath.c_str());
  } else {
    LOG_ERR("PHC", "Failed to write placeholder BMP");
    Storage.remove(outputPath.c_str());
  }

  return success;
}