#ifndef OLED_DISPLAY_H
#define OLED_DISPLAY_H

#include <stdint.h>
#include <stdbool.h>
#include "driver/gpio.h"
#include "driver/i2c.h"
#include "esp_err.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Hardware Specifications for ABrobot ESP32-C3 0.42" OLED */
#define OLED_I2C_PORT           I2C_NUM_0
#define OLED_I2C_ADDR           0x3C
#define OLED_PIN_SDA            GPIO_NUM_5
#define OLED_PIN_SCL            GPIO_NUM_6
#define OLED_I2C_FREQ_HZ        400000

/* Display Resolution */
#define OLED_WIDTH              72
#define OLED_HEIGHT             40
#define OLED_PAGES              5   /* (40 / 8) */
#define OLED_BUFFER_SIZE        (OLED_WIDTH * OLED_PAGES)

/* Controller Column Offset (SSD1306/SH1106 internal RAM mapping) */
#ifndef OLED_COLUMN_OFFSET
#define OLED_COLUMN_OFFSET      28  /* Common offset is 28 (or 26-30 depending on batch) */
#endif

/* Color modes */
#define OLED_COLOR_BLACK        0
#define OLED_COLOR_WHITE        1
#define OLED_COLOR_INVERT       2

/**
 * @brief Initialize I2C driver and SSD1306/SH1106 OLED display.
 * 
 * @param sda GPIO number for SDA (default: GPIO_NUM_5)
 * @param scl GPIO number for SCL (default: GPIO_NUM_6)
 * @param col_offset Internal column offset (default: OLED_COLUMN_OFFSET)
 * @return esp_err_t ESP_OK on success
 */
esp_err_t oled_init(gpio_num_t sda, gpio_num_t scl, uint8_t col_offset);

/**
 * @brief Clear the frame buffer (all black).
 */
void oled_clear(void);

/**
 * @brief Fill the entire frame buffer (all white).
 */
void oled_fill(void);

/**
 * @brief Push the frame buffer to the OLED display over I2C.
 * 
 * @return esp_err_t ESP_OK on success
 */
esp_err_t oled_update(void);

/**
 * @brief Set display contrast.
 * 
 * @param contrast Value 0 to 255
 * @return esp_err_t ESP_OK on success
 */
esp_err_t oled_set_contrast(uint8_t contrast);

/**
 * @brief Invert the display colors in hardware.
 * 
 * @param invert true for inverted, false for normal
 * @return esp_err_t ESP_OK on success
 */
esp_err_t oled_invert(bool invert);

/**
 * @brief Draw a single pixel in the frame buffer.
 * 
 * @param x X coordinate (0 to 71)
 * @param y Y coordinate (0 to 39)
 * @param color OLED_COLOR_BLACK, OLED_COLOR_WHITE, or OLED_COLOR_INVERT
 */
void oled_draw_pixel(int16_t x, int16_t y, uint8_t color);

/**
 * @brief Draw a line using Bresenham's algorithm.
 */
void oled_draw_line(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint8_t color);

/**
 * @brief Draw an unfilled rectangle.
 */
void oled_draw_rect(int16_t x, int16_t y, int16_t w, int16_t h, uint8_t color);

/**
 * @brief Draw a filled rectangle.
 */
void oled_fill_rect(int16_t x, int16_t y, int16_t w, int16_t h, uint8_t color);

/**
 * @brief Draw a single character using the 5x7 font.
 * 
 * @param x X position (top-left)
 * @param y Y position (top-left)
 * @param c ASCII character
 * @param color OLED_COLOR_WHITE or OLED_COLOR_BLACK
 */
void oled_draw_char(int16_t x, int16_t y, char c, uint8_t color);

/**
 * @brief Draw a text string using the 5x7 font.
 * 
 * @param x X position (top-left)
 * @param y Y position (top-left)
 * @param str Null-terminated string
 * @param color OLED_COLOR_WHITE or OLED_COLOR_BLACK
 */
void oled_draw_string(int16_t x, int16_t y, const char *str, uint8_t color);

#ifdef __cplusplus
}
#endif

#endif // OLED_DISPLAY_H