/**
 * @file main.c
 * @brief ESP32-S3 CSI Node — ADR-018 compliant firmware.
 *
 * Initializes NVS, WiFi STA mode, CSI collection, and UDP streaming.
 * CSI frames are serialized in ADR-018 binary format and sent to the
 * aggregator over UDP.
 */

#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 "sdkconfig.h"

#include "csi_collector.h"
#include "stream_sender.h"
#include "nvs_config.h"

static const char *TAG = "main";

/* Runtime configuration (loaded from NVS or Kconfig defaults). */
static nvs_config_t s_cfg;

/* Event group bits */
#define WIFI_CONNECTED_BIT BIT0
#define WIFI_FAIL_BIT      BIT1

static EventGroupHandle_t s_wifi_event_group;
static int s_retry_num = 0;
#define MAX_RETRY 10

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();
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        if (s_retry_num < MAX_RETRY) {
            esp_wifi_connect();
            s_retry_num++;
            ESP_LOGI(TAG, "Retrying WiFi connection (%d/%d)", s_retry_num, MAX_RETRY);
        } else {
            xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
        }
    } 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: " IPSTR, IP2STR(&event->ip_info.ip));
        s_retry_num = 0;
        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
    }
}

static void wifi_init_sta(void)
{
    s_wifi_event_group = xEventGroupCreate();

    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());
    esp_netif_create_default_wifi_sta();

    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));

    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));
    ESP_ERROR_CHECK(esp_event_handler_instance_register(
        IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, &instance_got_ip));

    wifi_config_t wifi_config = {
        .sta = {
            .threshold.authmode = WIFI_AUTH_WPA2_PSK,
        },
    };

    /* Copy runtime SSID/password from NVS config */
    strncpy((char *)wifi_config.sta.ssid, s_cfg.wifi_ssid, sizeof(wifi_config.sta.ssid) - 1);
    strncpy((char *)wifi_config.sta.password, s_cfg.wifi_password, sizeof(wifi_config.sta.password) - 1);

    /* If password is empty, use open auth */
    if (strlen((char *)wifi_config.sta.password) == 0) {
        wifi_config.sta.threshold.authmode = WIFI_AUTH_OPEN;
    }

    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_LOGI(TAG, "WiFi STA initialized, connecting to SSID: %s", s_cfg.wifi_ssid);

    /* Wait for connection */
    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, "Connected to WiFi");
    } else if (bits & WIFI_FAIL_BIT) {
        ESP_LOGE(TAG, "Failed to connect to WiFi after %d retries", MAX_RETRY);
    }
}

void app_main(void)
{
    /* 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);

    /* Load runtime config (NVS overrides Kconfig defaults) */
    nvs_config_load(&s_cfg);

    ESP_LOGI(TAG, "ESP32-S3 CSI Node (ADR-018) — Node ID: %d", s_cfg.node_id);

    /* Initialize WiFi STA */
    wifi_init_sta();

    /* Initialize UDP sender with runtime target */
    if (stream_sender_init_with(s_cfg.target_ip, s_cfg.target_port) != 0) {
        ESP_LOGE(TAG, "Failed to initialize UDP sender");
        return;
    }

    /* Initialize CSI collection */
    csi_collector_init();

    ESP_LOGI(TAG, "CSI streaming active → %s:%d",
             s_cfg.target_ip, s_cfg.target_port);

    /* Main loop — keep alive */
    while (1) {
        vTaskDelay(pdMS_TO_TICKS(10000));
    }
}