#ifndef ST7567_H
#define ST7567_H

#include "esp_err.h"
#include "driver/i2c_master.h"

// Display dimensions
#define ST7567_WIDTH  128
#define ST7567_HEIGHT 64
#define ST7567_PAGES  (ST7567_HEIGHT / 8)

// Default I2C 7-bit address for most ST7567 breakout boards (some use 0x3F)
#define ST7567_I2C_ADDR_DEFAULT 0x3F

// ST7567 command set
#define ST7567_CMD_DISPLAY_OFF       0xAE
#define ST7567_CMD_DISPLAY_ON        0xAF
#define ST7567_CMD_START_LINE        0x40  // OR with 0-63
#define ST7567_CMD_PAGE_ADDR         0xB0  // OR with 0-8
#define ST7567_CMD_COL_ADDR_HIGH     0x10  // OR with high nibble
#define ST7567_CMD_COL_ADDR_LOW      0x00  // OR with low nibble
#define ST7567_CMD_ADC_NORMAL        0xA0  // column addr 0 = SEG0
#define ST7567_CMD_ADC_REVERSE       0xA1  // column addr 131 = SEG0
#define ST7567_CMD_ALL_PIXEL_NORMAL  0xA4
#define ST7567_CMD_ALL_PIXEL_ON      0xA5
#define ST7567_CMD_DISPLAY_NORMAL    0xA6
#define ST7567_CMD_DISPLAY_INVERSE   0xA7
#define ST7567_CMD_BIAS_1_9          0xA2
#define ST7567_CMD_BIAS_1_7          0xA3
#define ST7567_CMD_RESET             0xE2
#define ST7567_CMD_COM_NORMAL        0xC0
#define ST7567_CMD_COM_REVERSE       0xC8
#define ST7567_CMD_POWER_CTRL        0x28  // OR with 0-7 (booster/regulator/follower bits)
#define ST7567_CMD_RESISTOR_RATIO    0x20  // OR with 0-7
#define ST7567_CMD_CONTRAST_MODE     0x81  // followed by a second byte, 0-63
#define ST7567_CMD_STATIC_INDICATOR_OFF 0xAC
#define ST7567_CMD_NOP               0xE3

// Configuration structure
typedef struct {
    i2c_master_bus_handle_t i2c_bus;  // already-initialized I2C bus
    uint16_t i2c_addr;                // 7-bit device address, 0 = use ST7567_I2C_ADDR_DEFAULT
    uint32_t i2c_clock_speed_hz;      // 0 = use 400kHz default
    uint8_t contrast;                 // 0-63, 0 = use a sane default (0x20)
} st7567_config_t;

// Handle for ST7567 device
typedef struct {
    i2c_master_dev_handle_t i2c_dev;
    uint8_t framebuffer[ST7567_WIDTH * ST7567_PAGES];
} st7567_device_t;

/**
 * @brief Initialize ST7567 display
 *
 * @param config Configuration structure
 * @param device Pointer to store device state (framebuffer etc, caller-owned)
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_init(const st7567_config_t *config, st7567_device_t *device);

/**
 * @brief Send a single command byte to the ST7567
 *
 * @param dev Device handle
 * @param cmd Command byte
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_send_cmd(const st7567_device_t *dev, uint8_t cmd);

/**
 * @brief Send a data buffer to the ST7567
 *
 * @param dev Device handle
 * @param data Pointer to data buffer
 * @param len Length of data buffer
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_send_data(const st7567_device_t *dev, const uint8_t *data, size_t len);

/**
 * @brief Clear the display (just wipe framebuffer, don't send any commands)
 *
 * @param dev Device handle
 */
void st7567_clear_buffer(st7567_device_t *dev);

/**
 * @brief Clear the display (both GDRAM and local framebuffer)
 *
 * @param dev Device handle
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_clear(st7567_device_t *dev);

/**
 * @brief Set contrast (electronic volume)
 *
 * @param dev Device handle
 * @param contrast 0-63
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_set_contrast(const st7567_device_t *dev, uint8_t contrast);

/**
 * @brief Push the local framebuffer contents to the display
 *
 * @param dev Device handle
 * @return esp_err_t ESP_OK on success
 */
esp_err_t st7567_update_screen(const st7567_device_t *dev);

/**
 * @brief Turn a pixel ON at given coordinates
 * @param dev Device handle
 * @param x x coordinate
 * @param y y coordinate
 */
void st7567_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
 */
void st7567_clear_pixel(void *dev, uint8_t x, uint8_t y);

#endif // ST7567_H