// Minimal code example to connect to WiFi.

#include <string.h>
#include "minimal_wifi.h"
#include "sdkconfig.h"
#include "esp_event.h"
#include "esp_wifi.h"
#include "esp_wifi_default.h"
#include "esp_log.h"
#include "esp_netif.h"
#include "driver/gpio.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "lwip/err.h"
#include "lwip/sys.h"

#define CONFIG_EXAMPLE_WIFI_SSID "Tufts_Wireless"
#define CONFIG_EXAMPLE_WIFI_PASSWORD ""

// Scan mode, either `WIFI_FAST_SCAN` or `WIFI_ALL_CHANNEL_SCAN`
#define EXAMPLE_WIFI_SCAN_METHOD WIFI_FAST_SCAN

// Sorting for AP scan, either `WIFI_CONNECT_AP_BY_SIGNAL` or `..._BY_SECURITY`
#define EXAMPLE_WIFI_CONNECT_AP_SORT_METHOD WIFI_CONNECT_AP_BY_SIGNAL

// Lower limits of what to accept in the scan
#define CONFIG_EXAMPLE_WIFI_SCAN_RSSI_THRESHOLD -100
// https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/network/esp_wifi.html#_CPPv416wifi_auth_mode_t
#define EXAMPLE_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_OPEN

#define NR_OF_IP_ADDRESSES_TO_WAIT_FOR 1

static SemaphoreHandle_t s_semph_get_ip_addrs;
static esp_netif_t *s_example_esp_netif = NULL;

static const char *TAG = "wifi_connect";

static esp_netif_t *wifi_start(void);
static void wifi_stop(void);

/**
 * @brief Checks the netif description if it contains specified prefix.
 * All netifs created withing common connect component are prefixed with the module TAG,
 * so it returns true if the specified netif is owned by this module
 */
static bool is_our_netif(const char *prefix, esp_netif_t *netif)
{
    return strncmp(prefix, esp_netif_get_desc(netif), strlen(prefix) - 1) == 0;
}

static esp_ip4_addr_t s_ip_addr;

static void on_got_ip(void *arg, esp_event_base_t event_base,
                      int32_t event_id, void *event_data)
{
    ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
    if (!is_our_netif(TAG, event->esp_netif)) {
        ESP_LOGW(TAG, "Got IPv4 from another interface \"%s\": ignored", esp_netif_get_desc(event->esp_netif));
        return;
    }
    ESP_LOGI(TAG, "Got IPv4 event: Interface \"%s\" address: " IPSTR, esp_netif_get_desc(event->esp_netif), IP2STR(&event->ip_info.ip));
    memcpy(&s_ip_addr, &event->ip_info.ip, sizeof(s_ip_addr));
    xSemaphoreGive(s_semph_get_ip_addrs);
}

esp_err_t example_connect(void)
{
    // If the semaphore is already initialized, something has gone horribly wrong
    if (s_semph_get_ip_addrs != NULL) {
        return ESP_ERR_INVALID_STATE;
    }
    s_semph_get_ip_addrs = xSemaphoreCreateCounting(NR_OF_IP_ADDRESSES_TO_WAIT_FOR, 0);

    wifi_start();
    ESP_ERROR_CHECK(esp_register_shutdown_handler(&wifi_stop));
    ESP_LOGI(TAG, "Waiting for IP(s)");
    for (int i = 0; i < NR_OF_IP_ADDRESSES_TO_WAIT_FOR; ++i) {
        xSemaphoreTake(s_semph_get_ip_addrs, portMAX_DELAY);
    }
    // iterate over active interfaces, and print out IPs of "our" netifs
    esp_netif_t *netif = NULL;
    esp_netif_ip_info_t ip;
    for (int i = 0; i < esp_netif_get_nr_of_ifs(); ++i) {
        netif = esp_netif_next(netif);
        if (is_our_netif(TAG, netif)) {
            ESP_LOGI(TAG, "Connected to %s", esp_netif_get_desc(netif));
            ESP_ERROR_CHECK(esp_netif_get_ip_info(netif, &ip));

            ESP_LOGI(TAG, "- IPv4 address: " IPSTR, IP2STR(&ip.ip));
        }
    }
    return ESP_OK;
}

esp_err_t example_disconnect(void)
{
    if (s_semph_get_ip_addrs == NULL) {
        return ESP_ERR_INVALID_STATE;
    }
    vSemaphoreDelete(s_semph_get_ip_addrs);
    s_semph_get_ip_addrs = NULL;
    wifi_stop();
    ESP_ERROR_CHECK(esp_unregister_shutdown_handler(&wifi_stop));
    return ESP_OK;
}

static void on_wifi_disconnect(void *arg, esp_event_base_t event_base,
                               int32_t event_id, void *event_data)
{
    ESP_LOGI(TAG, "Wi-Fi disconnected, trying to reconnect...");
    esp_err_t err = esp_wifi_connect();
    if (err == ESP_ERR_WIFI_NOT_STARTED) {
        return;
    }
    ESP_ERROR_CHECK(err);
}

static esp_netif_t *wifi_start(void)
{
    char *desc;
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));

    esp_netif_inherent_config_t esp_netif_config = ESP_NETIF_INHERENT_DEFAULT_WIFI_STA();
    // Prefix the interface description with the module TAG
    // Warning: the interface desc is used in tests to capture actual connection details (IP, gw, mask)
    asprintf(&desc, "%s: %s", TAG, esp_netif_config.if_desc);
    esp_netif_config.if_desc = desc;
    esp_netif_config.route_prio = 128;
    esp_netif_t *netif = esp_netif_create_wifi(WIFI_IF_STA, &esp_netif_config);
    free(desc);
    esp_wifi_set_default_wifi_sta_handlers();

    ESP_ERROR_CHECK(esp_event_handler_register(WIFI_EVENT, WIFI_EVENT_STA_DISCONNECTED, &on_wifi_disconnect, NULL));
    ESP_ERROR_CHECK(esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &on_got_ip, NULL));
    ESP_ERROR_CHECK(esp_wifi_set_storage(WIFI_STORAGE_RAM));
    wifi_config_t wifi_config = {
        .sta = {
            .ssid = CONFIG_EXAMPLE_WIFI_SSID,
            .password = CONFIG_EXAMPLE_WIFI_PASSWORD,
            .scan_method = EXAMPLE_WIFI_SCAN_METHOD,
            .sort_method = EXAMPLE_WIFI_CONNECT_AP_SORT_METHOD,
            .threshold.rssi = CONFIG_EXAMPLE_WIFI_SCAN_RSSI_THRESHOLD,
            .threshold.authmode = EXAMPLE_WIFI_SCAN_AUTH_MODE_THRESHOLD,
        },
    };
    ESP_LOGI(TAG, "Connecting to %s...", wifi_config.sta.ssid);
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
    ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
    ESP_ERROR_CHECK(esp_wifi_start());
    esp_wifi_connect();
    return netif;
}

static void wifi_stop(void)
{
    esp_netif_t *wifi_netif = get_example_netif_from_desc("sta");
    ESP_ERROR_CHECK(esp_event_handler_unregister(WIFI_EVENT, WIFI_EVENT_STA_DISCONNECTED, &on_wifi_disconnect));
    ESP_ERROR_CHECK(esp_event_handler_unregister(IP_EVENT, IP_EVENT_STA_GOT_IP, &on_got_ip));
    esp_err_t err = esp_wifi_stop();
    if (err == ESP_ERR_WIFI_NOT_INIT) {
        return;
    }
    ESP_ERROR_CHECK(err);
    ESP_ERROR_CHECK(esp_wifi_deinit());
    ESP_ERROR_CHECK(esp_wifi_clear_default_wifi_driver_and_handlers(wifi_netif));
    esp_netif_destroy(wifi_netif);
    s_example_esp_netif = NULL;
}

/*
esp_netif_t *get_example_netif(void)
{
    return s_example_esp_netif;
}
*/

esp_netif_t *get_example_netif_from_desc(const char *desc)
{
    esp_netif_t *netif = NULL;
    char *expected_desc;
    asprintf(&expected_desc, "%s: %s", TAG, desc);
    while ((netif = esp_netif_next(netif)) != NULL) {
        if (strcmp(esp_netif_get_desc(netif), expected_desc) == 0) {
            free(expected_desc);
            return netif;
        }
    }
    free(expected_desc);
    return netif;
}