#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "driver/i2c.h"

// I2C definitions
#define I2C_MASTER_SCL_IO    22    // GPIO number for I2C master clock
#define I2C_MASTER_SDA_IO    21    // GPIO number for I2C master data
#define I2C_MASTER_NUM       I2C_NUM_0 // I2C port number for master dev
#define I2C_MASTER_TX_BUF_DISABLE   0   // I2C master doesn't need buffer
#define I2C_MASTER_RX_BUF_DISABLE   0   // I2C master doesn't need buffer
#define I2C_MASTER_FREQ_HZ    100000     // I2C master clock frequency

// LCD Address
#define LCD_ADDR              0x27   // I2C address of the LCD

// LCD Commands
#define LCD_CLEAR_DISPLAY     0x01   // Clear display command
#define LCD_RETURN_HOME       0x02   // Return home command
#define LCD_ENTRY_MODE_SET    0x04   // Entry mode set command
#define LCD_DISPLAY_CONTROL   0x08   // Display control command
#define LCD_CURSOR_SHIFT      0x10   // Cursor or display shift command
#define LCD_FUNCTION_SET      0x20   // Function set command
#define LCD_SET_CGRAM_ADDR    0x40   // Set CGRAM address command
#define LCD_SET_DDRAM_ADDR    0x80   // Set DDRAM address command

// Function prototypes
esp_err_t i2c_lcd_write_byte(uint8_t data, uint8_t cmd);
void i2c_lcd_init();
void i2c_lcd_clear();
void i2c_lcd_puts(const char *str);

void app_main(void)
{
    // Initialize I2C master
    i2c_config_t conf;
    conf.mode = I2C_MODE_MASTER;
    conf.sda_io_num = I2C_MASTER_SDA_IO;
    conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
    conf.scl_io_num = I2C_MASTER_SCL_IO;
    conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
    conf.master.clk_speed = I2C_MASTER_FREQ_HZ;
    i2c_param_config(I2C_MASTER_NUM, &conf);
    i2c_driver_install(I2C_MASTER_NUM, conf.mode, I2C_MASTER_RX_BUF_DISABLE, I2C_MASTER_TX_BUF_DISABLE, 0);

    // Initialize LCD
    i2c_lcd_init();

    // Display some text
    i2c_lcd_puts("Hello, ESP32!");
}

esp_err_t i2c_lcd_write_byte(uint8_t data, uint8_t cmd)
{
    i2c_cmd_handle_t cmd_handle = i2c_cmd_link_create();
    i2c_master_start(cmd_handle);
    i2c_master_write_byte(cmd_handle, LCD_ADDR << 1 | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(cmd_handle, data, true);
    i2c_master_stop(cmd_handle);
    esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_NUM, cmd_handle, 1000 / portTICK_PERIOD_MS);
    i2c_cmd_link_delete(cmd_handle);
    return ret;
}

void i2c_lcd_init()
{
    // Initialize LCD
    vTaskDelay(50 / portTICK_PERIOD_MS);
    i2c_lcd_write_byte(0x30, 0);
    vTaskDelay(5 / portTICK_PERIOD_MS);
    i2c_lcd_write_byte(0x30, 0);
    vTaskDelay(1 / portTICK_PERIOD_MS);
    i2c_lcd_write_byte(0x30, 0);
    vTaskDelay(1 / portTICK_PERIOD_MS);

    // Set 4-bit mode
    i2c_lcd_write_byte(0x20, 0);
    vTaskDelay(1 / portTICK_PERIOD_MS);

    // Initialize LCD in 4-bit mode
    i2c_lcd_write_byte(0x28, 0);  // Function set: 4-bit mode, 2 lines, 5x8 font
    i2c_lcd_write_byte(0x08, 0);  // Display off
    i2c_lcd_clear();               // Clear display
    i2c_lcd_write_byte(0x06, 0);  // Entry mode set: Increment cursor, no shift
    //i2c_lcd_write_byte(0x0C, 0);  // Display on, cursor off, blink off
}

void i2c_lcd_clear()
{
    i2c_lcd_write_byte(LCD_CLEAR_DISPLAY, 0);
    vTaskDelay(2 / portTICK_PERIOD_MS);
}

void i2c_lcd_puts(const char *str)
{
    while (*str)
    {
        i2c_lcd_write_byte(*str, 1);
        str++;
    }
}