#include "display/eink_display_handler.h"
#include "display/constants.h"
#include "common/constants.h"
#include "esp_log.h"
#include "esp_heap_caps.h"
#include <cstring>

#define TAG "EInkDisplayHandler"
#define BUSY_ACTIVE_LEVEL   0  // BUSY pin is active low
#define BUSY_INACTIVE_LEVEL 1

EInkDisplayHandler::EInkDisplayHandler(EventGroupHandle_t system_event_group)
  : DisplayHandler(system_event_group) {
  _refresh_mutex = xSemaphoreCreateMutex();
  if (_refresh_mutex == nullptr) {
    ESP_LOGE(TAG, "Failed to create refresh mutex");
  }
}

EInkDisplayHandler::~EInkDisplayHandler() {
  if (_touch_task_handle != nullptr) {
    vTaskDelete(_touch_task_handle);
  }
  if (_lvgl_display != nullptr) {
    lvgl_port_remove_disp(_lvgl_display);
  }
  if (_lvgl_touch_indev != nullptr) {
    lvgl_port_remove_touch(_lvgl_touch_indev);
  }
  if (_framebuffer != nullptr) {
    heap_caps_free(_framebuffer);
  }
  if (_refresh_mutex != nullptr) {
    vSemaphoreDelete(_refresh_mutex);
  }
}

void EInkDisplayHandler::init() {
  ESP_LOGI(TAG, "Initializing E-Ink display handler...");

  // Initialize GPIO pins
  gpio_config_t io_conf = {};
  io_conf.pin_bit_mask = (1ULL << PIN_DC) | (1ULL << PIN_RST);
  io_conf.mode = GPIO_MODE_OUTPUT;
  io_conf.pull_up_en = GPIO_PULLUP_DISABLE;
  io_conf.pull_down_en = GPIO_PULLDOWN_DISABLE;
  io_conf.intr_type = GPIO_INTR_DISABLE;
  gpio_config(&io_conf);

  // Configure BUSY pin as input
  io_conf.pin_bit_mask = (1ULL << PIN_BUSY);
  io_conf.mode = GPIO_MODE_INPUT;
  io_conf.pull_up_en = GPIO_PULLUP_ENABLE;
  gpio_config(&io_conf);

  // Initialize SPI bus
  spi_bus_config_t buscfg = {};
  buscfg.mosi_io_num = 11;  // MOSI pin
  buscfg.miso_io_num = -1;  // No MISO for e-paper
  buscfg.sclk_io_num = 12;  // SCK pin
  buscfg.quadwp_io_num = -1;
  buscfg.quadhd_io_num = -1;
  buscfg.max_transfer_sz = DISPLAY_BUFFER_SIZE;

  esp_err_t ret = spi_bus_initialize(SPI2_HOST, &buscfg, SPI_DMA_CH_AUTO);
  if (ret != ESP_OK) {
    ESP_LOGE(TAG, "Failed to initialize SPI bus: %s", esp_err_to_name(ret));
    return;
  }

  // Add SPI device
  spi_device_interface_config_t devcfg = {};
  devcfg.clock_speed_hz = 10 * 1000 * 1000;  // 10 MHz (max for GDEY075T7)
  devcfg.mode = 0;  // SPI mode 0
  devcfg.spics_io_num = PIN_CS;
  devcfg.queue_size = 1;
  devcfg.pre_cb = nullptr;

  ret = spi_bus_add_device(SPI2_HOST, &devcfg, &_spi);
  if (ret != ESP_OK) {
    ESP_LOGE(TAG, "Failed to add SPI device: %s", esp_err_to_name(ret));
    return;
  }

  // Initialize base display and touch devices
  init_devices(false);  // Don't set ready bit yet

  // Allocate framebuffer - try PSRAM first, fallback to internal RAM
  _framebuffer = (uint8_t*)heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_SPIRAM);
  if (_framebuffer != nullptr) {
    _framebuffer_in_psram = true;
    ESP_LOGI(TAG, "Framebuffer allocated in PSRAM (%d bytes)", DISPLAY_BUFFER_SIZE);
  } else {
    ESP_LOGW(TAG, "PSRAM not available, allocating framebuffer in internal RAM");
    _framebuffer = (uint8_t*)heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_INTERNAL);
    _framebuffer_in_psram = false;
    if (_framebuffer == nullptr) {
      ESP_LOGE(TAG, "Failed to allocate framebuffer");
      return;
    }
    ESP_LOGI(TAG, "Framebuffer allocated in internal RAM (%d bytes)", DISPLAY_BUFFER_SIZE);
  }
  memset(_framebuffer, 0xFF, DISPLAY_BUFFER_SIZE);  // Initialize to white

  // Create LVGL display driver
  lvgl_port_display_cfg_t disp_cfg = {};

  disp_cfg.io_handle = nullptr;
  disp_cfg.panel_handle = nullptr;
  disp_cfg.buffer_size = DISPLAY_WIDTH * 40;  // 40 lines buffer
  disp_cfg.double_buffer = false;
  disp_cfg.hres = DISPLAY_WIDTH;
  disp_cfg.vres = DISPLAY_HEIGHT;
  disp_cfg.monochrome = true;

  disp_cfg.rotation.swap_xy = false;
  disp_cfg.rotation.mirror_x = false;
  disp_cfg.rotation.mirror_y = false;

  disp_cfg.flags.buff_dma = _framebuffer_in_psram ? false : true;
  disp_cfg.flags.buff_spiram = _framebuffer_in_psram;
  disp_cfg.flags.swap_bytes = false;
  disp_cfg.flags.full_refresh = false;
  disp_cfg.flags.direct_mode = false;

  _lvgl_display = lvgl_port_add_disp(&disp_cfg);
  if (_lvgl_display == nullptr) {
    ESP_LOGE(TAG, "Failed to create LVGL display");
    return;
  }

  // Set custom flush callback
  lv_display_set_flush_cb(_lvgl_display, _lvgl_flush_cb);
  lv_display_set_user_data(_lvgl_display, this);

  ESP_LOGI(TAG, "LVGL display registered");

  // Register GT911 touch input with LVGL
  const lvgl_port_touch_cfg_t touch_cfg = {
    .disp = _lvgl_display,
    .handle = get_touch_handle(),
    .scale = {}, // Default scaling
  };

  _lvgl_touch_indev = lvgl_port_add_touch(&touch_cfg);
  if (_lvgl_touch_indev == nullptr) {
    ESP_LOGE(TAG, "Failed to register LVGL touch input");
    return;
  }

  // Override touch read callback to check BUSY pin
  lv_indev_set_read_cb(_lvgl_touch_indev, _lvgl_touch_read_cb);
  lv_indev_set_user_data(_lvgl_touch_indev, this);

  ESP_LOGI(TAG, "LVGL touch input registered");

  // Perform initial full refresh to clear display
  ESP_LOGI(TAG, "Performing initial display clear...");
  _perform_full_refresh(_framebuffer);

  // Set display ready bits
  xEventGroupSetBits(_system_event_group, DISPLAY_READY_BIT | TOUCH_CALIBRATED_BIT);
  ESP_LOGI(TAG, "E-Ink display handler initialized successfully");
}

void EInkDisplayHandler::start_touch_task() {
  // Note: With lvgl_port_add_touch, the ESP-IDF LVGL port handles touch reading internally
  // We don't need a separate touch task unless we want custom processing
  ESP_LOGI(TAG, "Touch input handled by LVGL port");
}

void EInkDisplayHandler::request_full_refresh() {
  if (xSemaphoreTake(_refresh_mutex, pdMS_TO_TICKS(100)) == pdTRUE) {
    _force_full_refresh = true;
    _partial_refresh_count = 0;
    xSemaphoreGive(_refresh_mutex);
    ESP_LOGI(TAG, "Full refresh requested");
  }
}

bool EInkDisplayHandler::is_busy() const {
  return gpio_get_level(PIN_BUSY) == BUSY_ACTIVE_LEVEL;  // BUSY is active LOW
}

void EInkDisplayHandler::_lvgl_flush_cb(lv_display_t* disp, const lv_area_t* area, uint8_t* px_map) {
  EInkDisplayHandler* handler = static_cast<EInkDisplayHandler*>(lv_display_get_user_data(disp));
  if (handler == nullptr) {
    ESP_LOGE(TAG, "Invalid handler in flush callback");
    lv_display_flush_ready(disp);
    return;
  }

  // Check if display is busy
  if (handler->is_busy()) {
    ESP_LOGW(TAG, "Display busy, skipping flush");
    lv_display_flush_ready(disp);
    return;
  }

  // Wait for any ongoing refresh to complete
  handler->_wait_for_busy();

  bool perform_full_refresh = false;

  if (xSemaphoreTake(handler->_refresh_mutex, pdMS_TO_TICKS(100)) == pdTRUE) {
    // Check if full refresh is needed
    if (handler->_force_full_refresh) {
      perform_full_refresh = true;
      handler->_force_full_refresh = false;
      handler->_partial_refresh_count = 0;
    } else {
      handler->_partial_refresh_count++;
      if (handler->_partial_refresh_count >= PARTIAL_REFRESH_THRESHOLD) {
        perform_full_refresh = true;
        handler->_partial_refresh_count = 0;
      }
    }
    xSemaphoreGive(handler->_refresh_mutex);
  }

  // Copy LVGL buffer to framebuffer
  // For 1-bit mode, LVGL provides data in packed format (8 pixels per byte)
  int32_t w = lv_area_get_width(area);
  int32_t h = lv_area_get_height(area);

  ESP_LOGI(TAG, "Flushing area: x=%d, y=%d, w=%d, h=%d, full_refresh=%d",
    area->x1, area->y1, w, h, perform_full_refresh);

  // For simplicity with e-paper, we'll do full frame updates
  // Copy the entire buffer
  for (int32_t y = 0; y < h; y++) {
    int32_t fb_y = area->y1 + y;
    if (fb_y >= DISPLAY_HEIGHT) break;

    for (int32_t x = 0; x < w; x += 8) {
      int32_t fb_x = area->x1 + x;
      if (fb_x >= DISPLAY_WIDTH) break;

      // Calculate byte position in framebuffer (row-major, 1-bit packed)
      size_t fb_byte_idx = (fb_y * DISPLAY_WIDTH + fb_x) / 8;
      size_t px_byte_idx = (y * w + x) / 8;

      if (fb_byte_idx < DISPLAY_BUFFER_SIZE && px_byte_idx < (w * h / 8)) {
        handler->_framebuffer[fb_byte_idx] = px_map[px_byte_idx];
      }
    }
  }

  // Perform refresh
  if (perform_full_refresh) {
    ESP_LOGI(TAG, "Performing full refresh...");
    handler->_perform_full_refresh(handler->_framebuffer);
  } else {
    ESP_LOGI(TAG, "Performing partial refresh...");
    handler->_perform_partial_refresh(handler->_framebuffer);
  }

  lv_display_flush_ready(disp);
}

void EInkDisplayHandler::_lvgl_touch_read_cb(lv_indev_t* indev, lv_indev_data_t* data) {
  EInkDisplayHandler* handler = static_cast<EInkDisplayHandler*>(lv_indev_get_user_data(indev));

  // Disable touch input during display refresh (BUSY)
  if (handler->is_busy()) {
    data->state = LV_INDEV_STATE_RELEASED;
    data->continue_reading = false;
    return;
  }

  esp_lcd_touch_handle_t tp_handle = handler->get_touch_handle();
  if (tp_handle == nullptr) {
    data->state = LV_INDEV_STATE_RELEASED;
    return;
  }


  // Read touch data from GT911
  esp_err_t ret = esp_lcd_touch_read_data(tp_handle);
  if (ret == ESP_OK) {
    uint8_t touch_cnt = 0;
    // Get touch data using new API
    esp_lcd_touch_point_data_t point_data[1];
    esp_lcd_touch_get_data(tp_handle, point_data, &touch_cnt, 1);

    if (touch_cnt > 0) {
      data->point.x = point_data[0].x;
      data->point.y = point_data[0].y;
      data->state = LV_INDEV_STATE_PRESSED;
    } else {
      data->state = LV_INDEV_STATE_RELEASED;
    }
  } else {
    data->state = LV_INDEV_STATE_RELEASED;
  }

  data->continue_reading = false;
}

void EInkDisplayHandler::_perform_full_refresh(const uint8_t* framebuffer) {
  ESP_LOGI(TAG, "Starting full refresh (3 seconds)...");

  _wait_for_busy();

  // Step 1: Write old data (0x10) - typically all zeros for full refresh
  epd_write_cmd(0x10);

  xSemaphoreTake(_spi_mutex, portMAX_DELAY);
  gpio_set_level(PIN_DC, 1);  // Data mode

  for (size_t i = 0; i < DISPLAY_BUFFER_SIZE; i++) {
    spi_transaction_t t = {};
    t.length = 8;
    uint8_t byte = 0x00;  // Old data (cleared screen)
    t.tx_buffer = &byte;
    spi_device_polling_transmit(_spi, &t);
  }
  xSemaphoreGive(_spi_mutex);

  // Step 2: Write new data (0x13) with data inversion
  epd_write_cmd(0x13);

  xSemaphoreTake(_spi_mutex, portMAX_DELAY);
  gpio_set_level(PIN_DC, 1);  // Data mode

  for (size_t i = 0; i < DISPLAY_BUFFER_SIZE; i++) {
    spi_transaction_t t = {};
    t.length = 8;
    uint8_t byte = ~framebuffer[i];  // Invert data per manufacturer spec
    t.tx_buffer = &byte;
    spi_device_polling_transmit(_spi, &t);
  }
  xSemaphoreGive(_spi_mutex);

  // Step 3: Trigger display refresh (DRF)
  epd_write_cmd(0x12);
  vTaskDelay(pdMS_TO_TICKS(10));

  // Wait for refresh to complete
  _wait_for_busy();

  ESP_LOGI(TAG, "Full refresh complete");
}

void EInkDisplayHandler::_perform_partial_refresh(const uint8_t* framebuffer) {
  ESP_LOGI(TAG, "Starting partial refresh (0.3 seconds)...");

  _wait_for_busy();

  // Step 1: Configure VCOM for partial refresh
  const uint8_t vcom_data[] = { 0xA9, 0x07 };
  epd_write_cmd_with_data(0x50, vcom_data, 2);

  // Step 2: Enter partial refresh mode
  epd_write_cmd(0x91);

  // Step 3: Define partial window (full screen for now)
  // Format: 0x90 + 9 bytes (x_start_H, x_start_L, x_end_H, x_end_L, y_start_H, y_start_L, y_end_H, y_end_L, 0x01)
  // For full screen: x=0 to 799 (0x031F), y=0 to 479 (0x01DF)
  const uint8_t window_data[] = {
    0x00, 0x00,  // x_start = 0
    0x03, 0x1F,  // x_end = 799 (0x31F)
    0x00, 0x00,  // y_start = 0
    0x01, 0xDF,  // y_end = 479 (0x1DF)
    0x01         // PT_SCAN
  };
  epd_write_cmd_with_data(0x90, window_data, 9);

  // Step 4: Write new data with inversion (0x13 command)
  epd_write_cmd(0x13);

  xSemaphoreTake(_spi_mutex, portMAX_DELAY);
  gpio_set_level(PIN_DC, 1);  // Data mode

  for (size_t i = 0; i < DISPLAY_BUFFER_SIZE; i++) {
    spi_transaction_t t = {};
    t.length = 8;
    uint8_t byte = ~framebuffer[i];  // Invert data per manufacturer spec
    t.tx_buffer = &byte;
    spi_device_polling_transmit(_spi, &t);
  }
  xSemaphoreGive(_spi_mutex);

  // Step 5: Trigger partial display refresh (DRF)
  epd_write_cmd(0x12);
  vTaskDelay(pdMS_TO_TICKS(10));

  // Wait for refresh to complete
  _wait_for_busy();

  // Step 6: Exit partial refresh mode
  epd_write_cmd(0x92);

  ESP_LOGI(TAG, "Partial refresh complete");
}

void EInkDisplayHandler::_wait_for_busy() {
  ESP_LOGI(TAG, "Waiting for display ready (BUSY pin)...");
  int timeout = 0;
  while (gpio_get_level(PIN_BUSY) == BUSY_INACTIVE_LEVEL) {  // 0=BUSY, 1=FREE
    vTaskDelay(pdMS_TO_TICKS(100));
    timeout++;
    if (timeout > 50) {  // 5 second timeout
      ESP_LOGW(TAG, "Display BUSY timeout!");
      break;
    }
  }
  ESP_LOGI(TAG, "Display ready");
}

void EInkDisplayHandler::_convert_buffer_to_epaper(const uint8_t* lvgl_buf, uint8_t* epd_buf, size_t size) {
  // LVGL 1-bit format is already compatible with e-paper
  // Just copy directly
  memcpy(epd_buf, lvgl_buf, size);
}