#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.h"
#include "esp_log.h"
#include "nvs_flash.h"

#include "lwip/err.h"
#include "lwip/sys.h"
#include "lwip/ip_addr.h"
#include "lwip/netif.h"
#include "lwip/sockets.h"
#include "lwip/dhcp.h"

/* WiFi credentials */
#define EXAMPLE_ESP_WIFI_SSID "UCLA_WEB"
#define EXAMPLE_ESP_WIFI_PASS ""  // Empty password for the open WiFi
#define EXAMPLE_ESP_MAXIMUM_RETRY  5  // You can adjust the maximum retries if needed

/* Static IP Configuration */
#define EXAMPLE_STATIC_IP   "192.168.1.100"
#define EXAMPLE_NETMASK     "255.255.255.0"
#define EXAMPLE_GATEWAY     "192.168.1.1"

/* Event group for signaling connection events */
static EventGroupHandle_t s_wifi_event_group;

/* Define bits for connected and failed states */
#define WIFI_CONNECTED_BIT BIT0
#define WIFI_FAIL_BIT      BIT1

static const char *TAG = "wifi station";

static int s_retry_num = 0;

/* Function to configure static IP */
static void configure_static_ip(esp_netif_t *netif) {
    esp_netif_dhcpc_stop(netif);  // Stop DHCP client
    esp_netif_ip_info_t ip_info;

    ip4addr_aton(EXAMPLE_STATIC_IP, &ip_info.ip);
    ip4addr_aton(EXAMPLE_NETMASK, &ip_info.netmask);
    ip4addr_aton(EXAMPLE_GATEWAY, &ip_info.gw);

    ESP_ERROR_CHECK(esp_netif_set_ip_info(netif, &ip_info));
    ESP_LOGI(TAG, "Static IP configured: " IPSTR, IP2STR(&ip_info.ip));
}

/* Event handler to handle WiFi events */
static void event_handler(void* arg, esp_event_base_t event_base,
                                int32_t event_id, void* event_data)
{
    if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
        esp_wifi_connect();  // Attempt to connect to the network
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        if (s_retry_num < EXAMPLE_ESP_MAXIMUM_RETRY) {
            esp_wifi_connect();  // Retry connection
            s_retry_num++;
            ESP_LOGI(TAG, "Retrying to connect to the AP");
        } else {
            xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);  // Set fail bit if max retries are reached
        }
        ESP_LOGI(TAG,"Connection to AP failed");
    } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
        ip_event_got_ip_t* event = (ip_event_got_ip_t*) event_data;
        ESP_LOGI(TAG, "Got IP address: " IPSTR, IP2STR(&event->ip_info.ip));  // Log IP address when obtained
        s_retry_num = 0;  // Reset retry count
        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);  // Set connected bit
    }
}

/* WiFi initialization for station mode */
void wifi_init_sta(void)
{
    s_wifi_event_group = xEventGroupCreate();  // Create an event group for connection status

    ESP_ERROR_CHECK(esp_netif_init());  // Initialize network interface
    ESP_ERROR_CHECK(esp_event_loop_create_default());  // Initialize default event loop
    
    esp_netif_t *netif = esp_netif_create_default_wifi_sta();  // Create WiFi station interface

    configure_static_ip(netif);  // Set static IP

    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();  // Initialize WiFi configuration
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));  // Initialize WiFi driver

    esp_event_handler_instance_t instance_any_id;
    esp_event_handler_instance_t instance_got_ip;
    ESP_ERROR_CHECK(esp_event_handler_instance_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL, &instance_any_id));  // Register event handler for WiFi events
    ESP_ERROR_CHECK(esp_event_handler_instance_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, &instance_got_ip));  // Register event handler for IP event

    wifi_config_t wifi_config = {
        .sta = {
            .ssid = EXAMPLE_ESP_WIFI_SSID,  // SSID of the network
            .password = EXAMPLE_ESP_WIFI_PASS,  // Password of the network (empty for open network)
            .threshold.authmode = WIFI_AUTH_OPEN,  // Open authentication mode for open WiFi
        },
    };
    
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));  // Set WiFi mode to station (client)
    ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));  // Set WiFi configuration
    ESP_ERROR_CHECK(esp_wifi_start());  // Start WiFi

    ESP_LOGI(TAG, "WiFi initialization completed.");

    /* Wait for either successful connection (WIFI_CONNECTED_BIT) or failure (WIFI_FAIL_BIT) */
    EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group, WIFI_CONNECTED_BIT | WIFI_FAIL_BIT, pdFALSE, pdFALSE, portMAX_DELAY);

    if (bits & WIFI_CONNECTED_BIT) {
        ESP_LOGI(TAG, "Successfully connected to SSID: %s", EXAMPLE_ESP_WIFI_SSID);
    } else if (bits & WIFI_FAIL_BIT) {
        ESP_LOGI(TAG, "Failed to connect to SSID: %s", EXAMPLE_ESP_WIFI_SSID);
    } else {
        ESP_LOGE(TAG, "Unexpected event occurred.");
    }
}

void app_main(void)
{
    // Initialize NVS (non-volatile storage)
    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());  // Erase NVS if necessary
        ret = nvs_flash_init();  // Re-initialize NVS
    }
    ESP_ERROR_CHECK(ret);

    ESP_LOGI(TAG, "Starting WiFi Station Mode");
    wifi_init_sta();  // Initialize and connect to WiFi
}