ESP-1ch-Gateway/lib/WiFiManager-development/examples/AutoConnect/AutoConnectWithFSParameters/AutoConnectWithFSParameters.ino

#include <FS.h>          // this needs to be first, or it all crashes and burns...
#include <WiFiManager.h> // https://github.com/tzapu/WiFiManager
#include <ArduinoJson.h> // https://github.com/bblanchon/ArduinoJson

#ifdef ESP32
  #include <SPIFFS.h>
#endif

//define your default values here, if there are different values in config.json, they are overwritten.
char mqtt_server[40];
char mqtt_port[6]  = "8080";
char api_token[32] = "YOUR_API_TOKEN";

//default custom static IP
char static_ip[16] = "10.0.1.56";
char static_gw[16] = "10.0.1.1";
char static_sn[16] = "255.255.255.0";

//flag for saving data
bool shouldSaveConfig = false;

//callback notifying us of the need to save config
void saveConfigCallback () {
  Serial.println("Should save config");
  shouldSaveConfig = true;
}

void setupSpiffs(){
  //clean FS, for testing
  // SPIFFS.format();

  //read configuration from FS json
  Serial.println("mounting FS...");

  if (SPIFFS.begin()) {
    Serial.println("mounted file system");
    if (SPIFFS.exists("/config.json")) {
      //file exists, reading and loading
      Serial.println("reading config file");
      File configFile = SPIFFS.open("/config.json", "r");
      if (configFile) {
        Serial.println("opened config file");
        size_t size = configFile.size();
        // Allocate a buffer to store contents of the file.
        std::unique_ptr<char[]> buf(new char[size]);

        configFile.readBytes(buf.get(), size);
        DynamicJsonBuffer jsonBuffer;
        JsonObject& json = jsonBuffer.parseObject(buf.get());
        json.printTo(Serial);
        if (json.success()) {
          Serial.println("\nparsed json");

          strcpy(mqtt_server, json["mqtt_server"]);
          strcpy(mqtt_port, json["mqtt_port"]);
          strcpy(api_token, json["api_token"]);

          // if(json["ip"]) {
          //   Serial.println("setting custom ip from config");
          //   strcpy(static_ip, json["ip"]);
          //   strcpy(static_gw, json["gateway"]);
          //   strcpy(static_sn, json["subnet"]);
          //   Serial.println(static_ip);
          // } else {
          //   Serial.println("no custom ip in config");
          // }

        } else {
          Serial.println("failed to load json config");
        }
      }
    }
  } else {
    Serial.println("failed to mount FS");
  }
  //end read
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println();

  setupSpiffs();

  // WiFiManager, Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wm;

  //set config save notify callback
  wm.setSaveConfigCallback(saveConfigCallback);

  // setup custom parameters
  // 
  // The extra parameters to be configured (can be either global or just in the setup)
  // After connecting, parameter.getValue() will get you the configured value
  // id/name placeholder/prompt default length
  WiFiManagerParameter custom_mqtt_server("server", "mqtt server", mqtt_server, 40);
  WiFiManagerParameter custom_mqtt_port("port", "mqtt port", mqtt_port, 6);
  WiFiManagerParameter custom_api_token("api", "api token", "", 32);

  //add all your parameters here
  wm.addParameter(&custom_mqtt_server);
  wm.addParameter(&custom_mqtt_port);
  wm.addParameter(&custom_api_token);

  // set static ip
  // IPAddress _ip,_gw,_sn;
  // _ip.fromString(static_ip);
  // _gw.fromString(static_gw);
  // _sn.fromString(static_sn);
  // wm.setSTAStaticIPConfig(_ip, _gw, _sn);

  //reset settings - wipe credentials for testing
  //wm.resetSettings();

  //automatically connect using saved credentials if they exist
  //If connection fails it starts an access point with the specified name
  //here  "AutoConnectAP" if empty will auto generate basedcon chipid, if password is blank it will be anonymous
  //and goes into a blocking loop awaiting configuration
  if (!wm.autoConnect("AutoConnectAP", "password")) {
    Serial.println("failed to connect and hit timeout");
    delay(3000);
    // if we still have not connected restart and try all over again
    ESP.restart();
    delay(5000);
  }

  // always start configportal for a little while
  // wm.setConfigPortalTimeout(60);
  // wm.startConfigPortal("AutoConnectAP","password");

  //if you get here you have connected to the WiFi
  Serial.println("connected...yeey :)");

  //read updated parameters
  strcpy(mqtt_server, custom_mqtt_server.getValue());
  strcpy(mqtt_port, custom_mqtt_port.getValue());
  strcpy(api_token, custom_api_token.getValue());

  //save the custom parameters to FS
  if (shouldSaveConfig) {
    Serial.println("saving config");
    DynamicJsonBuffer jsonBuffer;
    JsonObject& json = jsonBuffer.createObject();
    json["mqtt_server"] = mqtt_server;
    json["mqtt_port"]   = mqtt_port;
    json["api_token"]   = api_token;

    // json["ip"]          = WiFi.localIP().toString();
    // json["gateway"]     = WiFi.gatewayIP().toString();
    // json["subnet"]      = WiFi.subnetMask().toString();

    File configFile = SPIFFS.open("/config.json", "w");
    if (!configFile) {
      Serial.println("failed to open config file for writing");
    }

    json.prettyPrintTo(Serial);
    json.printTo(configFile);
    configFile.close();
    //end save
    shouldSaveConfig = false;
  }

  Serial.println("local ip");
  Serial.println(WiFi.localIP());
  Serial.println(WiFi.gatewayIP());
  Serial.println(WiFi.subnetMask());
}

void loop() {
  // put your main code here, to run repeatedly:


}