#include "GxEPDDisplay.h"

#ifdef EXP_PIN_BACKLIGHT
  #include <PCA9557.h>
  extern PCA9557 expander;
#endif

#ifndef DISPLAY_ROTATION
  #define DISPLAY_ROTATION 0
#endif

#ifdef ESP32
  // E-ink and LoRa SHARE the same SPI bus (SCK=36, MOSI=33)
  // They MUST use the same SPI peripheral (HSPI) to avoid GPIO conflicts
  // Different chip selects allow both to coexist: E-ink CS=34, LoRa CS=3
  SPIClass displaySpi(HSPI);
#endif

bool GxEPDDisplay::begin() {
#ifdef ESP32
  // Initialize HSPI with shared pins
  // SCK=36, MISO=47 (for LoRa receive), MOSI=33, SS=34 (e-ink CS)
  displaySpi.begin(PIN_DISPLAY_SCLK, 47, PIN_DISPLAY_MOSI, PIN_DISPLAY_CS);
  
  // Tell GxEPD2 to use our SPI instance
  // Using slower speed (4MHz) for reliable e-ink communication
  display.epd2.selectSPI(displaySpi, SPISettings(4000000, MSBFIRST, SPI_MODE0));
#endif

  // Initialize with:
  // - 115200 baud for debug serial
  // - initial=true (do initial update)
  // - reset_duration=2 (ms)
  // - pulldown_rst_mode=false
  display.init(115200, true, 2, false);
  display.setRotation(DISPLAY_ROTATION);
  setTextSize(1);  // Default to size 1
  display.setPartialWindow(0, 0, display.width(), display.height());

  display.fillScreen(GxEPD_WHITE);
  display.display(true);
  
  #if DISP_BACKLIGHT
  digitalWrite(DISP_BACKLIGHT, LOW);
  pinMode(DISP_BACKLIGHT, OUTPUT);
  #endif
  
  _init = true;
  _isOn = true;  // Set display as "on" after initialization
  return true;
}

void GxEPDDisplay::turnOn() {
  if (!_init) begin();
#if defined(DISP_BACKLIGHT) && !defined(BACKLIGHT_BTN)
  digitalWrite(DISP_BACKLIGHT, HIGH);
#elif defined(EXP_PIN_BACKLIGHT) && !defined(BACKLIGHT_BTN)
  expander.digitalWrite(EXP_PIN_BACKLIGHT, HIGH);
#endif
  _isOn = true;
}

void GxEPDDisplay::turnOff() {
#if defined(DISP_BACKLIGHT) && !defined(BACKLIGHT_BTN)
  digitalWrite(DISP_BACKLIGHT, LOW);
#elif defined(EXP_PIN_BACKLIGHT) && !defined(BACKLIGHT_BTN)
  expander.digitalWrite(EXP_PIN_BACKLIGHT, LOW);
#endif
  _isOn = false;
}

void GxEPDDisplay::clear() {
  display.fillScreen(GxEPD_WHITE);
  display.setTextColor(GxEPD_BLACK);
  display_crc.reset();
}

void GxEPDDisplay::startFrame(Color bkg) {
  display.fillScreen(GxEPD_WHITE);
  display.setTextColor(_curr_color = GxEPD_BLACK);
  display_crc.reset();
}

void GxEPDDisplay::setTextSize(int sz) {
  display_crc.update<int>(sz);
  switch(sz) {
    case 0:  // Tiny - built-in 6x8 pixel font
      display.setFont(NULL);
      display.setTextSize(1);
      break;
    case 1:  // Small - use 9pt (was 9pt)
      display.setFont(&FreeSans9pt7b);
      break;
    case 2:  // Medium Bold - use 9pt bold instead of 12pt
      display.setFont(&FreeSans9pt7b);
      break;
    case 3:  // Large - use 12pt instead of 18pt
      display.setFont(&FreeSansBold12pt7b);
      break;
    default:
      display.setFont(&FreeSans9pt7b);
      break;
  }
}

void GxEPDDisplay::setColor(Color c) {
  display_crc.update<Color> (c);
  // colours need to be inverted for epaper displays
  if (c == DARK) {
    display.setTextColor(_curr_color = GxEPD_WHITE);
  } else {
    display.setTextColor(_curr_color = GxEPD_BLACK);
  }
}

void GxEPDDisplay::setCursor(int x, int y) {
  display_crc.update<int>(x);
  display_crc.update<int>(y);
  // Add extra offset (+5) to push text baseline down, preventing ascenders from overlapping elements above
  display.setCursor((x+offset_x)*scale_x, (y+offset_y+5)*scale_y);
}

void GxEPDDisplay::print(const char* str) {
  display_crc.update<char>(str, strlen(str));
  display.print(str);
}

void GxEPDDisplay::fillRect(int x, int y, int w, int h) {
  display_crc.update<int>(x);
  display_crc.update<int>(y);
  display_crc.update<int>(w);
  display_crc.update<int>(h);
  display.fillRect((x+offset_x)*scale_x, (y+offset_y)*scale_y, w*scale_x, h*scale_y, _curr_color);
}

void GxEPDDisplay::drawRect(int x, int y, int w, int h) {
  display_crc.update<int>(x);
  display_crc.update<int>(y);
  display_crc.update<int>(w);
  display_crc.update<int>(h);
  display.drawRect((x+offset_x)*scale_x, (y+offset_y)*scale_y, w*scale_x, h*scale_y, _curr_color);
}

void GxEPDDisplay::drawXbm(int x, int y, const uint8_t* bits, int w, int h) {
  display_crc.update<int>(x);
  display_crc.update<int>(y);
  display_crc.update<int>(w);
  display_crc.update<int>(h);
  display_crc.update<uint8_t>(bits, w * h / 8);
  // Calculate the base position in display coordinates (with offset applied)
  uint16_t startX = (x + offset_x) * scale_x;
  uint16_t startY = (y + offset_y) * scale_y;
  
  // Width in bytes for bitmap processing
  uint16_t widthInBytes = (w + 7) / 8;
  
  // Process the bitmap row by row
  for (uint16_t by = 0; by < h; by++) {
    // Calculate the target y-coordinates for this logical row
    int y1 = startY + (int)(by * scale_y);
    int y2 = startY + (int)((by + 1) * scale_y);
    int block_h = y2 - y1;
    
    // Scan across the row bit by bit
    for (uint16_t bx = 0; bx < w; bx++) {
      // Calculate the target x-coordinates for this logical column
      int x1 = startX + (int)(bx * scale_x);
      int x2 = startX + (int)((bx + 1) * scale_x);
      int block_w = x2 - x1;
      
      // Get the current bit
      uint16_t byteOffset = (by * widthInBytes) + (bx / 8);
      uint8_t bitMask = 0x80 >> (bx & 7);
      bool bitSet = pgm_read_byte(bits + byteOffset) & bitMask;
      
      // If the bit is set, draw a block of pixels
      if (bitSet) {
        // Draw the block as a filled rectangle
        display.fillRect(x1, y1, block_w, block_h, _curr_color);
      }
    }
  }
}

uint16_t GxEPDDisplay::getTextWidth(const char* str) {
  int16_t x1, y1;
  uint16_t w, h;
  display.getTextBounds(str, 0, 0, &x1, &y1, &w, &h);
  return ceil((w + 1) / scale_x);
}

void GxEPDDisplay::endFrame() {
  uint32_t crc = display_crc.finalize();
  if (crc != last_display_crc_value) {
    display.display(true);  // Partial refresh
    last_display_crc_value = crc;
  }
}