Now we will develop a program for our smart home project:

1. Create a project called smarthome. Our main program is the smarthome.c file.

First, we will declare our libraries for this project:

#include <esp_wifi.h>
#include <esp_event_loop.h>
#include <esp_log.h>
#include <esp_system.h>
#include <nvs_flash.h>
#include <sys/param.h>

#include <esp_http_server.h>

2. We will then define our logger title and GPIO for our LED:

static const char *TAG="APP";
#define LED1 12

3. Next, we will develop a HTTP POST request handler via the httpd_uri_t struct. We define the /led request with HTTP_POST for the request method. In addition, we pass the led_post_handle() function into the request handler as follows:

httpd_uri_t led_post = {
    .uri = "/led",
    .method = HTTP_POST,
    .handler = led_post_handler,
    .user_ctx = NULL
};

4. Now we implement our led_post_handler() function. This function reads the HTTP request message. Then, check whether the request body has a value of 1 or 0 in the HTTP request body. If the request body consists of value 1, we turn on the LED by calling the gpio_set_level() function:

esp_err_t led_post_handler(httpd_req_t *req)
{
    char buf[100];
    int ret, remaining = req->content_len;

    while (remaining > 0) {
        buf[0] = '';
        if ((ret = httpd_req_recv(req, &buf, 1)) <= 0) {
            if (ret == HTTPD_SOCK_ERR_TIMEOUT) {
                httpd_resp_send_408(req);
            }
            return ESP_FAIL;
        }
        buf[ret] = '';
        ESP_LOGI(TAG, "Recv HTTP => %s", buf);
        if (buf[0] == '1') {
            ESP_LOGI(TAG, "====================================");
            ESP_LOGI(TAG, ">>> Turn on LED");
            gpio_set_level(LED1, 1);
            httpd_resp_send_chunk(req, "Turn on LED", ret);
            
        }
        else
        if (buf[0] == '0') {
            ESP_LOGI(TAG, "====================================");
            ESP_LOGI(TAG, ">>> Turn off LED");
            gpio_set_level(LED1, 0);
            httpd_resp_send_chunk(req, "Turn off LED", ret);
        }
        else {
            ESP_LOGI(TAG, "====================================");
            ESP_LOGI(TAG, ">>> Unknow command"); 
            httpd_resp_send_chunk(req, "Unknow command", ret); 
        }
        remaining -= ret;
       
    }

    // End response
    httpd_resp_send_chunk(req, NULL, 0);
    return ESP_OK;
}

5. Next, we will develop a web server in the ESP32 board.