#include <WiFi.h>
#include <WebServer.h>
#include <DNSServer.h>
#include <Preferences.h>

const byte DNS_PORT = 53;
DNSServer dnsServer;
WebServer server(80);
Preferences prefs;

IPAddress apIP(192,168,4,1);
const char* AP_SSID = "ESP32_Portal";

String wifi_ssid;
String wifi_pass;

void handleRoot() {
  server.send(200, "text/html", "WiFi Setup");
}

void handleSave() {
  wifi_ssid = server.arg("ssid");
  wifi_pass = server.arg("pass");

  // Save credentials
  prefs.begin("wifi", false);
  prefs.putString("ssid", wifi_ssid);
  prefs.putString("pass", wifi_pass);
  prefs.end();

  server.send(200, "text/html", "Saved. Connecting...");

  WiFi.softAPdisconnect(true);
  WiFi.mode(WIFI_STA);
  WiFi.begin(wifi_ssid.c_str(), wifi_pass.c_str());
}

void handleNotFound() {
  server.sendHeader("Location", "/", true);
  server.send(302, "text/plain", "");
}

void startPortal() {
  WiFi.mode(WIFI_AP);
  WiFi.softAP(AP_SSID);
  WiFi.softAPConfig(apIP, apIP, IPAddress(255,255,255,0));

  dnsServer.start(DNS_PORT, "*", apIP);

  server.on("/", handleRoot);
  server.on("/save", HTTP_POST, handleSave);
  server.onNotFound(handleNotFound);
  server.begin();
}

void connectWiFi() {
  prefs.begin("wifi", true);
  wifi_ssid = prefs.getString("ssid", "");
  wifi_pass = prefs.getString("pass", "");
  prefs.end();

  if (wifi_ssid == "") return;

  WiFi.mode(WIFI_STA);
  WiFi.begin(wifi_ssid.c_str(), wifi_pass.c_str());

  unsigned long start = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - start < 15000) {
    delay(500);
  }
}

void setup() {
  Serial.begin(115200);

  connectWiFi();

  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Starting captive portal");
    startPortal();
  } else {
    Serial.println("Connected to WiFi");
    Serial.println(WiFi.localIP());
  }
}

void loop() {
  dnsServer.processNextRequest();
  server.handleClient();
}