#ifndef ST7920_H
#define ST7920_H

#include "esp_err.h"
#include "driver/spi_master.h"

// Display dimensions
#define ST7920_WIDTH  128
#define ST7920_HEIGHT 64

// SPI commands for ST7920
#define ST7920_CMD_BASIC_FUNC       0x30  // Basic instruction set
#define ST7920_CMD_EXTENDED_FUNC    0x34  // Extended instruction set
#define ST7920_CMD_DISPLAY_ON       0x0C  // Display ON
#define ST7920_CMD_DISPLAY_OFF      0x08  // Display OFF
#define ST7920_CMD_CLEAR            0x01  // Clear display
#define ST7920_CMD_ENTRY_MODE       0x06  // Entry mode
#define ST7920_CMD_HOME             0x02  // Return home
#define ST7920_CMD_GRAPHIC_ON       0x36  // Extended + Graphic mode ON
#define ST7920_CMD_SET_GRAPHIC_ADDR 0x80  // Set GDRAM address

// Configuration structure
typedef struct {
    spi_host_device_t spi_host;
    int pin_cs;
    int pin_bl;
    int spi_clock_speed_hz;
} st7920_config_t;

// Handle for ST7920 device
typedef struct {
    spi_device_handle_t spi;
    int pin_cs;
    int pin_bl;
    uint8_t framebuffer[ST7920_WIDTH * ST7920_HEIGHT / 8];
} st7920_device_t;

/**
 * @brief Initialize ST7920 display
 * 
 * @param config Configuration structure
 * @param out_dev Pointer to store device handle
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7920_init(const st7920_config_t *config, st7920_device_t *device);

/**
 * @brief Send command to ST7920
 * 
 * @param dev Device handle
 * @param cmd Command byte
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7920_send_cmd(const st7920_device_t *dev, uint8_t cmd);

/**
 * @brief Send data to ST7920
 * 
 * @param dev Device handle
 * @param data Data byte
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7920_send_data(const st7920_device_t *dev, uint8_t data);

/**
 * @brief Clear the display
 * 
 * @param dev Device handle
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7920_clear(void *p);

/**
 * @brief Set backlight on or off
 *
 * @param dev Device handle
 * @param backlight Backlight enabled
 */
esp_err_t st7920_set_backlight(const st7920_device_t *dev, bool backlight);

/**
 * @brief Update the entire display with framebuffer contents
 * 
 * @param dev Device handle
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7920_update_screen(const void *dev);

/**
 * @brief Turn a pixel ON at given coordinates
 * @param dev Device handle
 * @param x x coordinate
 * @param y y coordinate
 */
esp_err_t st7920_draw_pixel(void *dev, uint8_t x, uint8_t y);

/**
 * @brief Turn a pixel OFF at given coordinates
 * @param dev Device handle
 * @param x x coordinate
 * @param y y coordinate
 */
esp_err_t st7920_clear_pixel(void *dev, uint8_t x, uint8_t y);

#endif // ST7920_H