#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_event_loop.h"
#include "esp_log.h"
#include "nvs_flash.h"

#include "lwip/err.h"
#include "lwip/sys.h"

#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
#define EXAMPLE_ESP_MAXIMUM_RETRY  CONFIG_ESP_MAXIMUM_RETRY

static EventGroupHandle_t s_wifi_event_group;
const int WIFI_CONNECTED_BIT = BIT0;
static const char *TAG = "wifi station";
static int s_retry_num = 0;


static void check_status()
{
	EventBits_t uxBits;
	uxBits = xEventGroupGetBits(s_wifi_event_group);
	if(uxBits & WIFI_CONNECTED_BIT)
	{
		printf ("wifi connected\n"); 
	}
	
	else if (!(uxBits & WIFI_CONNECTED_BIT))
	{
		printf ("wifi disconnected\n"); 
	}
	
}

static esp_err_t event_handler(void *ctx, system_event_t *event)
{
    switch(event->event_id) 
	{
    case SYSTEM_EVENT_STA_START:
        esp_wifi_connect();
        break;
    case SYSTEM_EVENT_STA_GOT_IP:
        ESP_LOGI(TAG, "got ip:%s",
                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
        s_retry_num = 0;
        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
		
		check_status(); // To update the wifi status
        break;
		
    case SYSTEM_EVENT_STA_DISCONNECTED:
    {
		esp_wifi_connect();
		xEventGroupClearBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
		
		check_status(); // To update the wifi status
		break;		 
    }
    default:
        break;
    }
    return ESP_OK;
}

void wifi_init_sta()
{
    s_wifi_event_group = xEventGroupCreate();

    tcpip_adapter_init();
    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL) );

    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
    wifi_config_t wifi_config = {
        .sta = {
            .ssid = EXAMPLE_ESP_WIFI_SSID,
            .password = EXAMPLE_ESP_WIFI_PASS
        },
    };

    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
    ESP_ERROR_CHECK(esp_wifi_start() );

    ESP_LOGI(TAG, "wifi_init_sta finished.");
    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
}

void app_main()
{
    //Initialize NVS
    esp_err_t ret = nvs_flash_init();
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
      ESP_ERROR_CHECK(nvs_flash_erase());
      ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK(ret);
    
    ESP_LOGI(TAG, "ESP_WIFI_MODE_STA");
    wifi_init_sta();
}