#ifndef PANEL_DEVICE_H
#define PANEL_DEVICE_H

#include <esp_lcd_panel_dev.h>
#include <esp_lcd_panel_ops.h>
#include <esp_lcd_panel_io.h>
#include <esp_log.h>

#include <display/lv_display.h>

#include "i2c.h"

// LVGL reserves 2x4 bytes in the buffer to be used as a palette.
// This additional space must be added to the IPanelDevice::buf_size_.
#define LVGL_PALETTE_SIZE      8
#define LVGL_TICK_PERIOD_MS    5
#define LVGL_TASK_STACK_SIZE   (4 * 1024)
#define LVGL_TASK_PRIORITY     2

#define LCD_H_RES              128
#define LCD_V_RES              64

/**
 * Encapsulates vendor specific ESP LCD panel initialization logic.
 * This pure virtual interface can be inherited from for using new LCD devices.
 * See SSD1306 as an example to implement IPanelDevice for NT35510 or ST7789.
 *
 * At this time only I2C is supported.
 * Classes that inherit from this interface should likely be marked final.
 */
class IPanelDevice {
public:
  /**
   * Construct an IPanelDevice.
   *
   * @param i2c I2C object. Eventually this will mature to IProtocol or similar.
   * @param config I2C configuration for this device.
   * @param height Height of the device screen in pixels.
   * @param width Width of the device screen in pixels.
   */
  explicit IPanelDevice(I2C &i2c,
                        esp_lcd_panel_io_i2c_config_t config,
                        int width,
                        int height) :
      IPanelDevice(i2c, config, width, height,
                   width * height / 8 + LVGL_PALETTE_SIZE) { }

  /**
   * Construct an IPanelDevice.
   *
   * @param i2c I2C object. Eventually this will mature to IProtocol or similar.
   * @param config I2C configuration for this device.
   * @param height Height of the device screen in pixels.
   * @param width Width of the device screen in pixels.
   * @param draw_buf_size Size of the draw buffer for this device.
   */
  explicit IPanelDevice(I2C &i2c,
                        esp_lcd_panel_io_i2c_config_t io_config,
                        int width,
                        int height,
                        size_t draw_buf_size) :
      width_(width),
      height_(height),
      rst_num_(i2c.rst_num_),
      lv_buf_size_(draw_buf_size),
      esp_io_config_(io_config) { }

  virtual ~IPanelDevice() = default;

  //
  // PUBLIC METHODS

  /**
   * Create an LVGL display using the width and height of this device.
   *
   * @return Handle to the created LVGL display.
   */
  [[nodiscard]] lv_display_t *create_display() const
  {
    auto display = lv_display_create(width_, height_);
    assert(display);
    return display;
  }

  /**
   * Create an ESP LCD panel IO handle.
   *
   * @return The created ESP LCD panel IO handle.
   */
  [[nodiscard]] esp_lcd_panel_io_handle_t create_io_handle()
  {
    ESP_LOGI(TAG, "Creating panel IO handle");
    esp_lcd_panel_io_handle_t handle = nullptr;
    ESP_ERROR_CHECK(
        esp_lcd_new_panel_io_i2c(I2C::get(), &esp_io_config_, &handle));
    return handle;
  }

  /**
   * Create and initialize an ESP panel handle.
   * IPanelDevice implementors must initialize the panel within init_panel.
   *
   * @param config ESP LCD panel configuration.
   * @param io ESP LCD panel IO handle.
   * @param [out] panel ESP LCD panel handle output pointer location.
   */
  void create_panel(esp_lcd_panel_dev_config_t &config,
                    esp_lcd_panel_io_handle_t io,
                    esp_lcd_panel_handle_t &panel)
  {
    // If the passed handle is already allocated, delete it.
    if (panel != nullptr) {
      ESP_LOGI(TAG, "Removing unused panel");
      esp_lcd_panel_del(panel);
    }

    ESP_LOGI(TAG, "Install SSD1306 panel driver");
    // Call pure virtual method responsible for initializing the panel handle.
    init_panel(config, io, panel);
  }

  /**
   * Retrieve the device specific vendor configuration structure.
   *
   * @return Address of vendor configuration structure.
   * @sa SSD1306::vendor_config
   */
  virtual void *vendor_config() = 0;

  //
  // PUBLIC MEMBERS

  /// Width of the device screen in pixels.
  int32_t width_;

  /// Height of the device screen in pixels.
  int32_t height_;

  /// RST GPIO pin number.
  int rst_num_;

  /// LVGL draw buffer size for the device.
  size_t lv_buf_size_;

  /// ESP LCD panel IO configuration.
  esp_lcd_panel_io_i2c_config_t esp_io_config_;

  /**
   * Registers LVGL draw buffers for this display.
   *
   * An implementation of the interface can optionally override this method to
   * provide custom LVGL callbacks and display configurations.
   *
   * @param display_handle LVGL display handle to use for rendering.
   * @param io_handle IO handle for the ESP LCD panel.
   */
  virtual void register_draw_buffer(lv_display_t *display_handle,
                                    esp_lcd_panel_io_handle_t io_handle);

  /**
   * Registers LVGL ticker timer callback for rendering this display.
   *
   * An implementation of the interface can optionally override this method to
   * provide custom LVGL callbacks and tick configurations.
   */
  virtual void register_lvgl_tick_timer();

private:

  //
  // PRIVATE METHODS

  /**
    * Initializes the ESP panel using vendor specific APIs and configurations.
    * This method should implement any setup logic specific to the device.
    *
    * @param config ESP LCD panel configuration.
    * @param io ESP LCD panel IO handle.
    * @param [out] panel ESP LCD panel handle output pointer location.
    */
  virtual void init_panel(esp_lcd_panel_dev_config_t &config,
                          esp_lcd_panel_io_handle_t io,
                          esp_lcd_panel_handle_t &panel) = 0;

  //
  // PRIVATE STATIC METHODS

/**
 * The callback invoked when panel IO finishes transferring color data.
 * This signals that the panel is ready to flush image data to the display.
 *
 * @param panel LCD panel IO handles.
 * @param data Panel IO event data, fed by driver.
 * @param user_ctx User data, passed from `esp_lcd_panel_io_xxx_config_t`.
 * @return Whether a high priority task has been waken up by this function.
 * @sa SSD1306::SSD1306 for setting user_ctx data passed to the callback.
 * @sa register_rendering_data for overriding this callback.
 */
  static bool lvgl_flush_ready_cb(esp_lcd_panel_io_handle_t panel,
                                  esp_lcd_panel_io_event_data_t *data,
                                  void *user_ctx);

  /**
   * The callback invoked for flushing the rendered image to the display.
   *
   * `px_map` contains the rendered image as raw pixel map and it should be
   *  copied to `area` on the display.
   *
   * @param display LVGL display handle to use for rendering.
   * @param area Area of the display being flushed.
   * @param px_map Rendered image data for writing to the display area.
   * @sa register_rendering_data for overriding this callback.
   */
  static void lvgl_flush_cb(lv_display_t *display,
                            const lv_area_t *area,
                            uint8_t *px_map);

  /**
   * Callback invoked for every period of the timer.
   *
   * This callback _must_ call lv_tick_inc to inform LVGL how much time has
   * elapsed since the last period of the timer.
   *
   * @param data User data passed to the callback.
   * @sa register_lvgl_tick_timer for setting user data and the tick period of
   *        the timer, or overriding this callback entirely.
   */
  static void lvgl_increase_tick_cb(void *data);

  /**
   * FreeRTOS task callback invoked for handling LVGL events or updating the UI.
   *
   * This function is intentionally an endless loop and should never return.
   * LVGL initialization logic can optionally be added before entering the loop.
   * Input logic can optionally be handled within the loop.
   *
   * This callback _must_ call lv_timer_handler to handle LVGL periodic timers.
   *
   * @param data User data passed to the callback.
   * @sa register_lvgl_tick_timer for overriding this callback.
   */
  [[noreturn]] static void lvgl_port_task(void *data);

  /**
   * Draw buffer for this panel device.
   * For LV_COLOR_FORMAT_I1 we need an extra buffer to hold the converted data.
   */
  static uint8_t oled_buffer_[LCD_H_RES * LCD_V_RES / 8];

  //
  // PRIVATE MEMBERS

  /// LVGL draw buffer associated with this Display's lv_display_t.
  void *lv_buf_;

  /// Tag used for ESP logging.
  constexpr static const char *TAG = "IPanelDevice";
};

#endif // PANEL_DEVICE_H