#include "esp_event_base.h"
#include "esp_log.h"
#include "mqtt_client.h"

#include <stdint.h>
#include <string.h>

static const char *TAG = "mqtt"; // Logs are coming from this mqtt module

static uint32_t MQTT_CONNECTED = 0;
static int s_retry_num = 0;

#define MQTT_TOPIC "/topic/test"
#define MQTT_BROKER "mqtt://192.168.178.53:1883"
#define MAX_RETRY 5

esp_mqtt_client_handle_t mqtt_connect();

static void mqtt_event_handler(void *handler_args, esp_event_base_t base,
                               int32_t event_id, void *event_data)
{
  if (event_id == MQTT_EVENT_CONNECTED) {
    ESP_LOGI(TAG, "Connected to MQTT broker.");
    MQTT_CONNECTED = 1;
  }

  if (event_id == MQTT_EVENT_PUBLISHED) {
    // Cast event which is void to a specific type provided by ESP-IDF
    // Then dereference and get `msg_id` field
    esp_mqtt_event_handle_t event = (esp_mqtt_event_handle_t)event_data;
    ESP_LOGI(TAG, "Message published succesfully, msg_id: %d", (*event).msg_id);
  }

  if (event_id == MQTT_EVENT_DISCONNECTED) {
    MQTT_CONNECTED = 0;
    ESP_LOGI(TAG, "Disconnected from MQTT broker. Attempting to reconnect.");
    if (s_retry_num < MAX_RETRY) {
      mqtt_connect();
      s_retry_num++;
      ESP_LOGI(TAG, "Retrying MQTT connection.");
    } else {
      ESP_LOGI(TAG, "Could not connect to MQTT broker. Giving up.");
    }
  }
}

esp_mqtt_client_handle_t mqtt_connect()
{
  ESP_LOGI(TAG, "Attempting to connect to MQTT broker %s", MQTT_BROKER);
  esp_mqtt_client_config_t mqtt_config = {.broker.address.uri = MQTT_BROKER};
  esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_config);
  esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler,
                                 client);
  esp_mqtt_client_start(client);
  return client;
}

void mqtt_publish(esp_mqtt_client_handle_t client, const char *payload)
{
  if (MQTT_CONNECTED) {
    ESP_LOGI(TAG, "Publishing payload %s to topic %s", payload, MQTT_TOPIC);
    esp_mqtt_client_publish(client, MQTT_TOPIC, payload, strlen(payload), 0, 0);
  } else {
    ESP_LOGI(TAG, "Could not publish to MQTT topic %s. Not connected to broker",
             MQTT_TOPIC);
  }
}

// https://github.com/ESP32Tutorials/esp32-mqtt-pub-sub-esp-idf/blob/main/main/app_main.c