/*
ESP8266/ESP32 publish the RSSI as the WiFi signal strength to ThingSpeak channel.
This example is for explaining how to use the AutoConnect library.

In order to execute this example, the ThingSpeak account is needed. Sing up
for New User Account and create a New Channel via My Channels.
For details, please refer to the project page.
https://hieromon.github.io/AutoConnect/howtoembed.html#used-with-mqtt-as-a-client-application

This example is based on the environment as of March 20, 2018.
Copyright (c) 2018 Hieromon Ikasamo.
This software is released under the MIT License.
https://opensource.org/licenses/MIT
*/

#if defined(ARDUINO_ARCH_ESP8266)
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#define GET_CHIPID()  (ESP.getChipId())
#elif defined(ARDUINO_ARCH_ESP32)
#include <WiFi.h>
#include <SPIFFS.h>
#include <HTTPClient.h>
#define GET_CHIPID()  ((uint16_t)(ESP.getEfuseMac()>>32))
#endif
#include <PubSubClient.h>
#include <AutoConnect.h>

/*
  AC_USE_SPIFFS indicates SPIFFS or LittleFS as available file systems that
  will become the AUTOCONNECT_USE_SPIFFS identifier and is exported as showng
  the valid file system. After including AutoConnect.h, the Sketch can determine
  whether to use FS.h or LittleFS.h by AUTOCONNECT_USE_SPIFFS definition.
*/
#ifdef AUTOCONNECT_USE_SPIFFS
#include <FS.h>
FS& FlashFS = SPIFFS;
#else
#include <LittleFS.h>
FS& FlashFS = LittleFS;
#endif

#define PARAM_FILE      "/param.json"
#define AUX_SETTING_URI "/mqtt_setting"
#define AUX_SAVE_URI    "/mqtt_save"
#define AUX_CLEAR_URI   "/mqtt_clear"

// JSON definition of AutoConnectAux.
// Multiple AutoConnectAux can be defined in the JSON array.
// In this example, JSON is hard-coded to make it easier to understand
// the AutoConnectAux API. In practice, it will be an external content
// which separated from the sketch, as the mqtt_RSSI_FS example shows.
static const char AUX_mqtt_setting[] PROGMEM = R"raw(
[
  {
    "title": "MQTT Setting",
    "uri": "/mqtt_setting",
    "menu": true,
    "element": [
      {
        "name": "style",
        "type": "ACStyle",
        "value": "label+input,label+select{position:sticky;left:120px;width:230px!important;box-sizing:border-box;}"
      },
      {
        "name": "header",
        "type": "ACText",
        "value": "<h2>MQTT broker settings</h2>",
        "style": "text-align:center;color:#2f4f4f;padding:10px;"
      },
      {
        "name": "caption",
        "type": "ACText",
        "value": "Publishing the WiFi signal strength to MQTT channel. RSSI value of ESP8266 to the channel created on ThingSpeak",
        "style": "font-family:serif;color:#4682b4;"
      },
      {
        "name": "mqttserver",
        "type": "ACInput",
        "value": "",
        "label": "Server",
        "pattern": "^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$",
        "placeholder": "MQTT broker server"
      },
      {
        "name": "channelid",
        "type": "ACInput",
        "label": "Channel ID",
        "pattern": "^[0-9]{6}$"
      },
      {
        "name": "userkey",
        "type": "ACInput",
        "label": "User Key"
      },
      {
        "name": "apikey",
        "type": "ACInput",
        "label": "API Key"
      },
      {
        "name": "newline",
        "type": "ACElement",
        "value": "<hr>"
      },
      {
        "name": "uniqueid",
        "type": "ACCheckbox",
        "value": "unique",
        "label": "Use APID unique",
        "checked": false
      },
      {
        "name": "period",
        "type": "ACRadio",
        "value": [
          "30 sec.",
          "60 sec.",
          "180 sec."
        ],
        "label": "Update period",
        "arrange": "vertical",
        "checked": 1
      },
      {
        "name": "newline",
        "type": "ACElement",
        "value": "<hr>"
      },
      {
        "name": "hostname",
        "type": "ACInput",
        "value": "",
        "label": "ESP host name",
        "pattern": "^([a-zA-Z0-9]([a-zA-Z0-9-])*[a-zA-Z0-9]){1,24}$"
      },
      {
        "name": "save",
        "type": "ACSubmit",
        "value": "Save&amp;Start",
        "uri": "/mqtt_save"
      },
      {
        "name": "discard",
        "type": "ACSubmit",
        "value": "Discard",
        "uri": "/"
      }
    ]
  },
  {
    "title": "MQTT Setting",
    "uri": "/mqtt_save",
    "menu": false,
    "element": [
      {
        "name": "caption",
        "type": "ACText",
        "value": "<h4>Parameters saved as:</h4>",
        "style": "text-align:center;color:#2f4f4f;padding:10px;"
      },
      {
        "name": "parameters",
        "type": "ACText"
      },
      {
        "name": "clear",
        "type": "ACSubmit",
        "value": "Clear channel",
        "uri": "/mqtt_clear"
      }
    ]
  }
]
)raw";

// Adjusting WebServer class with between ESP8266 and ESP32.
#if defined(ARDUINO_ARCH_ESP8266)
typedef ESP8266WebServer  WiFiWebServer;
#elif defined(ARDUINO_ARCH_ESP32)
typedef WebServer WiFiWebServer;
#endif

AutoConnect  portal;
AutoConnectConfig config;
WiFiClient   wifiClient;
PubSubClient mqttClient(wifiClient);
String  serverName;
String  channelId;
String  userKey;
String  apiKey;
String  apid;
String  hostName;
bool  uniqueid;
unsigned int  updateInterval = 0;
unsigned long lastPub = 0;

#define MQTT_USER_ID  "anyone"

bool mqttConnect() {
  static const char alphanum[] = "0123456789"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz";  // For random generation of client ID.
  char    clientId[9];

  uint8_t retry = 3;
  while (!mqttClient.connected()) {
    if (serverName.length() <= 0)
      break;

    mqttClient.setServer(serverName.c_str(), 1883);
    Serial.println(String("Attempting MQTT broker:") + serverName);

    for (uint8_t i = 0; i < 8; i++) {
      clientId[i] = alphanum[random(62)];
    }
    clientId[8] = '\0';

    if (mqttClient.connect(clientId, MQTT_USER_ID, userKey.c_str())) {
      Serial.println("Established:" + String(clientId));
      return true;
    }
    else {
      Serial.println("Connection failed:" + String(mqttClient.state()));
      if (!--retry)
        break;
      delay(3000);
    }
  }
  return false;
}

void mqttPublish(String msg) {
  String path = String("channels/") + channelId + String("/publish/") + apiKey;
  mqttClient.publish(path.c_str(), msg.c_str());
}

int getStrength(uint8_t points) {
  uint8_t sc = points;
  long    rssi = 0;

  while (sc--) {
    rssi += WiFi.RSSI();
    delay(20);
  }
  return points ? static_cast<int>(rssi / points) : 0;
}

void getParams(AutoConnectAux& aux) {
  serverName = aux["mqttserver"].value;
  serverName.trim();
  channelId = aux["channelid"].value;
  channelId.trim();
  userKey = aux["userkey"].value;
  userKey.trim();
  apiKey = aux["apikey"].value;
  apiKey.trim();
  AutoConnectRadio& period = aux["period"].as<AutoConnectRadio>();
  updateInterval = period.value().substring(0, 2).toInt() * 1000;
  uniqueid = aux["uniqueid"].as<AutoConnectCheckbox>().checked;
  hostName = aux["hostname"].value;
  hostName.trim();
}

// Load parameters saved with  saveParams from SPIFFS into the
// elements defined in /mqtt_setting JSON.
String loadParams(AutoConnectAux& aux, PageArgument& args) {
  (void)(args);
  File param = FlashFS.open(PARAM_FILE, "r");
  if (param) {
    if (aux.loadElement(param)) {
      getParams(aux);
      Serial.println(PARAM_FILE " loaded");
    }
    else
      Serial.println(PARAM_FILE " failed to load");
    param.close();
  }
  else {
    Serial.println(PARAM_FILE " open failed");
#ifdef ARDUINO_ARCH_ESP32
    Serial.println("If you get error as 'SPIFFS: mount failed, -10025', Please modify with 'SPIFFS.begin(true)'.");
#endif
  }
  return String("");
}

// Save the value of each element entered by '/mqtt_setting' to the
// parameter file. The saveParams as below is a callback function of
// /mqtt_save. When invoking this handler, the input value of each
// element is already stored in '/mqtt_setting'.
// In Sketch, you can output to stream its elements specified by name.
String saveParams(AutoConnectAux& aux, PageArgument& args) {
  // The 'where()' function returns the AutoConnectAux that caused
  // the transition to this page.
  AutoConnectAux&   mqtt_setting = *portal.aux(portal.where());
  getParams(mqtt_setting);
  AutoConnectInput& mqttserver = mqtt_setting["mqttserver"].as<AutoConnectInput>();

  // The entered value is owned by AutoConnectAux of /mqtt_setting.
  // To retrieve the elements of /mqtt_setting, it is necessary to get
  // the AutoConnectAux object of /mqtt_setting.
  File param = FlashFS.open(PARAM_FILE, "w");
  mqtt_setting.saveElement(param, { "mqttserver", "channelid", "userkey", "apikey", "uniqueid", "period", "hostname" });
  param.close();

  // Echo back saved parameters to AutoConnectAux page.
  AutoConnectText&  echo = aux["parameters"].as<AutoConnectText>();
  echo.value = "Server: " + serverName;
  echo.value += mqttserver.isValid() ? String(" (OK)") : String(" (ERR)");
  echo.value += "<br>Channel ID: " + channelId + "<br>";
  echo.value += "User Key: " + userKey + "<br>";
  echo.value += "API Key: " + apiKey + "<br>";
  echo.value += "Update period: " + String(updateInterval / 1000) + " sec.<br>";
  echo.value += "Use APID unique: " + String(uniqueid == true ? "true" : "false") + "<br>";
  echo.value += "ESP host name: " + hostName + "<br>";

  return String("");
}

void handleRoot() {
  String  content =
    "<html>"
    "<head>"
    "<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">"
    "</head>"
    "<body>"
    "<iframe width=\"450\" height=\"260\" style=\"transform:scale(0.79);-o-transform:scale(0.79);-webkit-transform:scale(0.79);-moz-transform:scale(0.79);-ms-transform:scale(0.79);transform-origin:0 0;-o-transform-origin:0 0;-webkit-transform-origin:0 0;-moz-transform-origin:0 0;-ms-transform-origin:0 0;border: 1px solid #cccccc;\" src=\"https://thingspeak.com/channels/454951/charts/1?bgcolor=%23ffffff&color=%23d62020&dynamic=true&type=line\"></iframe>"
    "<p style=\"padding-top:5px;text-align:center\">" AUTOCONNECT_LINK(COG_24) "</p>"
    "</body>"
    "</html>";

  WiFiWebServer&  webServer = portal.host();
  webServer.send(200, "text/html", content);
}

// Clear channel using ThingSpeak's API.
void handleClearChannel() {
  HTTPClient  httpClient;
  WiFiClient  client;
  String  endpoint = serverName;
  endpoint.replace("mqtt", "api");
  String  delUrl = "http://" + endpoint + "/channels/" + channelId + "/feeds.json?api_key=" + userKey;

  Serial.print("DELETE " + delUrl);
  if (httpClient.begin(client, delUrl)) {
    Serial.print(":");
    int resCode = httpClient.sendRequest("DELETE");
    String  res = httpClient.getString();
    httpClient.end();
    Serial.println(String(resCode) + "," + res);
  }
  else
    Serial.println(" failed");

  // Returns the redirect response.
  WiFiWebServer&  webServer = portal.host();
  webServer.sendHeader("Location", String("http://") + webServer.client().localIP().toString() + String("/"));
  webServer.send(302, "text/plain", "");
  webServer.client().flush();
  webServer.client().stop();
}

void setup() {
  delay(1000);
  Serial.begin(115200);
  Serial.println();
  FlashFS.begin();

  if (portal.load(FPSTR(AUX_mqtt_setting))) {
    AutoConnectAux& mqtt_setting = *portal.aux(AUX_SETTING_URI);
    PageArgument  args;
    loadParams(mqtt_setting, args);
    if (uniqueid) {
      config.apid = String("ESP") + "-" + String(GET_CHIPID(), HEX);
      Serial.println("apid set to " + config.apid);
    }
    if (hostName.length()) {
      config.hostName = hostName;
      Serial.println("hostname set to " + config.hostName);
    }
    config.homeUri = "/";
    portal.config(config);

    portal.on(AUX_SETTING_URI, loadParams);
    portal.on(AUX_SAVE_URI, saveParams);
  }
  else
    Serial.println("load error");

  Serial.print("WiFi ");
  if (portal.begin()) {
    config.bootUri = AC_ONBOOTURI_HOME;
    Serial.println("connected:" + WiFi.SSID());
    Serial.println("IP:" + WiFi.localIP().toString());
  }
  else {
    Serial.println("connection failed:" + String(WiFi.status()));
    Serial.println("Needs WiFi connection to start publishing messages");
  }

  WiFiWebServer&  webServer = portal.host();
  webServer.on("/", handleRoot);
  webServer.on(AUX_CLEAR_URI, handleClearChannel);
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    // MQTT publish control
    if (updateInterval > 0) {
      if (millis() - lastPub > updateInterval) {
        if (!mqttClient.connected()) {
          mqttConnect();
        }
        String item = String("field1=") + String(getStrength(7));
        mqttPublish(item);
        mqttClient.loop();
        lastPub = millis();
      }
    }
  }
  portal.handleClient();
}