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

// ESP32-C3 + relay module + simulated bulb (white LED)
// Wokwi relay module default behavior is ACTIVE-LOW:
//   LOW  -> relay energized -> COM connected to NO
//   HIGH -> relay idle      -> COM connected to NC
//
// Hardware:
// - GPIO4 -> relay IN
// - GPIO3 -> pushbutton to GND (INPUT_PULLUP)
//
// Behavior:
// - Short button press toggles the bulb
// - Web UI shows current state and toggles the bulb
// - WiFi credentials can be provisioned from the web page and saved in NVS
// - A fallback AP is started for real hardware recovery provisioning

constexpr int RELAY_PIN = 4;
constexpr int BUTTON_PIN = 3;
constexpr int RELAY_ON = LOW;
constexpr int RELAY_OFF = HIGH;

//const char* DEFAULT_WOKWI_SSID = "RelayBulb";
const char* DEFAULT_WOKWI_SSID = "Wokwi-GUEST";
const char* DEFAULT_WOKWI_PASS = "";
const char* AP_SSID = "SONNYNET";
const char* AP_PASS = "sunnyairplane264";

constexpr unsigned long WIFI_TIMEOUT_MS = 12000;
constexpr unsigned long DEBOUNCE_MS = 50;

WebServer server(80);
Preferences prefs;

bool bulbOn = false;
bool apStarted = false;
String configuredSsid;
String configuredPass;

bool lastButtonReading = HIGH;
bool buttonState = HIGH;
unsigned long lastDebounceTime = 0;

String htmlEscape(const String& value) {
  String out = value;
  out.replace("&", "&amp;");
  out.replace("<", "&lt;");
  out.replace(">", "&gt;");
  out.replace("\"", "&quot;");
  out.replace("'", "&#39;");
  return out;
}

String jsonEscape(const String& value) {
  String out = value;
  out.replace("\\", "\\\\");
  out.replace("\"", "\\\"");
  out.replace("\n", "\\n");
  out.replace("\r", "\\r");
  out.replace("\t", "\\t");
  return out;
}

void setBulb(bool on) {
  bulbOn = on;
  digitalWrite(RELAY_PIN, on ? RELAY_ON : RELAY_OFF);
  Serial.printf("Bulb is now %s\n", bulbOn ? "ON" : "OFF");
}

void toggleBulb() {
  setBulb(!bulbOn);
}

void loadWifiConfig() {
  prefs.begin("wifi", false);
  configuredSsid = prefs.getString("ssid", "");
  configuredPass = prefs.getString("pass", "");
}

void saveWifiConfig(const String& ssid, const String& pass) {
  configuredSsid = ssid;
  configuredPass = pass;
  prefs.putString("ssid", configuredSsid);
  prefs.putString("pass", configuredPass);
}

void clearWifiConfig() {
  configuredSsid = "";
  configuredPass = "";
  prefs.remove("ssid");
  prefs.remove("pass");
}

bool connectToWifi(const String& ssid, const String& pass, unsigned long timeoutMs = WIFI_TIMEOUT_MS) {
  if (ssid.isEmpty()) {
    return false;
  }

  Serial.printf("Connecting to WiFi SSID '%s'", ssid.c_str());
  WiFi.mode(WIFI_AP_STA);
  WiFi.disconnect();
  delay(200);

  if (ssid == DEFAULT_WOKWI_SSID) {
    WiFi.begin(ssid.c_str(), pass.c_str(), 6);
  } else {
    WiFi.begin(ssid.c_str(), pass.c_str());
  }

  unsigned long start = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - start < timeoutMs) {
    delay(250);
    Serial.print('.');
  }
  Serial.println();

  if (WiFi.status() == WL_CONNECTED) {
    Serial.printf("WiFi connected. IP: %s\n", WiFi.localIP().toString().c_str());
    return true;
  }

  Serial.println("WiFi connection failed");
  return false;
}

void startProvisioningAp() {
  if (apStarted) {
    return;
  }

  WiFi.mode(WIFI_AP_STA);
  apStarted = WiFi.softAP(AP_SSID, AP_PASS);
  if (apStarted) {
    Serial.printf("Provisioning AP started: %s\n", AP_SSID);
    Serial.printf("Provisioning AP IP: %s\n", WiFi.softAPIP().toString().c_str());
  } else {
    Serial.println("Failed to start provisioning AP");
  }
}

String wifiStatusText() {
  switch (WiFi.status()) {
    case WL_CONNECTED:
      return "Connected";
    case WL_NO_SSID_AVAIL:
      return "SSID not available";
    case WL_CONNECT_FAILED:
      return "Connect failed";
    case WL_CONNECTION_LOST:
      return "Connection lost";
    case WL_DISCONNECTED:
    default:
      return "Disconnected";
  }
}

String networkSummary() {
  String staIp = WiFi.status() == WL_CONNECTED ? WiFi.localIP().toString() : String("-");
  String staSsid = WiFi.status() == WL_CONNECTED ? WiFi.SSID() : String("-");
  String apIp = apStarted ? WiFi.softAPIP().toString() : String("-");
  String apName = apStarted ? String(AP_SSID) : String("-");

  String summary;
  summary += "<ul>";
  summary += "<li><strong>Bulb state:</strong> <span id='bulbState'>" + String(bulbOn ? "ON" : "OFF") + "</span></li>";
  summary += "<li><strong>WiFi status:</strong> <span id='wifiStatus'>" + htmlEscape(wifiStatusText()) + "</span></li>";
  summary += "<li><strong>Connected SSID:</strong> <span id='connectedSsid'>" + htmlEscape(staSsid) + "</span></li>";
  summary += "<li><strong>STA IP:</strong> <span id='staIp'>" + htmlEscape(staIp) + "</span></li>";
  summary += "<li><strong>Provisioning AP:</strong> " + htmlEscape(apName) + "</li>";
  summary += "<li><strong>AP IP:</strong> " + htmlEscape(apIp) + "</li>";
  summary += "</ul>";
  return summary;
}

String buildPage() {
  String page;
  page.reserve(6000);
  page += F("<!doctype html><html><head><meta charset='utf-8'>");
  page += F("<meta name='viewport' content='width=device-width,initial-scale=1'>");
  page += F("<title>ESP32-C3 Relay Bulb</title>");
  page += F("<style>");
  page += F("body{font-family:Arial,sans-serif;max-width:760px;margin:24px auto;padding:0 16px;background:#f5f5f5;color:#222}");
  page += F(".card{background:#fff;border-radius:14px;padding:18px 20px;margin:16px 0;box-shadow:0 2px 10px rgba(0,0,0,.08)}");
  page += F("button,input{font-size:16px;padding:10px 12px;border-radius:10px;border:1px solid #bbb}");
  page += F("button{cursor:pointer}");
  page += F("input{width:100%;box-sizing:border-box;margin:6px 0 12px}");
  page += F(".row{display:flex;gap:12px;flex-wrap:wrap}");
  page += F(".row > *{flex:1}");
  page += F(".state{font-size:28px;font-weight:700;margin:8px 0 12px}");
  page += F(".hint{color:#555;font-size:14px}");
  page += F("code{background:#eee;padding:2px 6px;border-radius:6px}");
  page += F("</style></head><body>");
  page += F("<h1>ESP32-C3 Relay + Bulb</h1>");

  page += F("<div class='card'>");
  page += F("<h2>Bulb control</h2>");
  page += F("<div class='state' id='stateHero'>");
  page += (bulbOn ? "ON" : "OFF");
  page += F("</div>");
  page += F("<form method='POST' action='/toggle'><button type='submit'>Toggle bulb</button></form>");
  page += F("<p class='hint'>Physical button on GPIO3 also toggles the relay. In Wokwi you can press the green button or use keyboard shortcut <code>T</code>.</p>");
  page += networkSummary();
  page += F("</div>");

  page += F("<div class='card'>");
  page += F("<h2>WiFi provisioning</h2>");
  page += F("<form method='POST' action='/wifi'>");
  page += F("<label>SSID</label>");
  page += "<input name='ssid' value='" + htmlEscape(configuredSsid) + "' placeholder='Wokwi-GUEST'>";
  page += F("<label>Password</label>");
  page += "<input name='password' type='password' value='" + htmlEscape(configuredPass) + "' placeholder='leave empty for Wokwi-GUEST'>";
  page += F("<div class='row'><button type='submit'>Save and connect</button><button type='button' onclick=\"location.href='/wifi/default'\">Use Wokwi defaults</button></div>");
  page += F("</form>");
  page += F("<form method='POST' action='/wifi/clear' style='margin-top:12px'><button type='submit'>Clear saved WiFi</button></form>");
  page += F("<p class='hint'>For Wokwi simulation, the default SSID is <code>Wokwi-GUEST</code> with an empty password. For browser access to the ESP32 web server in Wokwi, run the Private IoT Gateway and open <code>http://localhost:9080/</code>.</p>");
  page += F("</div>");

  page += F("<script>");
  page += F("async function refreshState(){try{const r=await fetch('/state');const s=await r.json();document.getElementById('bulbState').textContent=s.bulbOn?'ON':'OFF';document.getElementById('stateHero').textContent=s.bulbOn?'ON':'OFF';document.getElementById('wifiStatus').textContent=s.wifiStatus;document.getElementById('connectedSsid').textContent=s.connectedSsid;document.getElementById('staIp').textContent=s.staIp;}catch(e){}}setInterval(refreshState,1000);refreshState();");
  page += F("</script>");
  page += F("</body></html>");
  return page;
}

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

void handleToggle() {
  toggleBulb();
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleState() {
  String staIp = WiFi.status() == WL_CONNECTED ? WiFi.localIP().toString() : String("-");
  String connectedSsid = WiFi.status() == WL_CONNECTED ? WiFi.SSID() : String("-");
  String json = "{";
  json += "\"bulbOn\":" + String(bulbOn ? "true" : "false");
  json += ",\"wifiStatus\":\"" + jsonEscape(wifiStatusText()) + "\"";
  json += ",\"connectedSsid\":\"" + jsonEscape(connectedSsid) + "\"";
  json += ",\"staIp\":\"" + jsonEscape(staIp) + "\"";
  json += "}";
  server.send(200, "application/json", json);
}

void handleWifiSave() {
  String ssid = server.arg("ssid");
  String password = server.arg("password");
  ssid.trim();

  if (ssid.isEmpty()) {
    server.send(400, "text/plain", "SSID cannot be empty");
    return;
  }

  saveWifiConfig(ssid, password);
  bool connected = connectToWifi(configuredSsid, configuredPass);

  if (!connected) {
    startProvisioningAp();
  }

  server.sendHeader("Location", "/");
  server.send(303);
}

void handleWifiDefault() {
  saveWifiConfig(DEFAULT_WOKWI_SSID, DEFAULT_WOKWI_PASS);
  connectToWifi(configuredSsid, configuredPass);
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleWifiClear() {
  clearWifiConfig();
  WiFi.disconnect();
  startProvisioningAp();
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleNotFound() {
  server.send(404, "text/plain", "Not found");
}

void setupServer() {
  server.on("/", HTTP_GET, handleRoot);
  server.on("/toggle", HTTP_GET, handleToggle);
  server.on("/toggle", HTTP_POST, handleToggle);
  server.on("/state", HTTP_GET, handleState);
  server.on("/wifi", HTTP_POST, handleWifiSave);
  server.on("/wifi/default", HTTP_GET, handleWifiDefault);
  server.on("/wifi/clear", HTTP_POST, handleWifiClear);
  server.onNotFound(handleNotFound);
  server.begin();
  Serial.println("HTTP server started on port 80");
}

void handleButton() {
  bool reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonReading) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > DEBOUNCE_MS) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) {
        toggleBulb();
      }
    }
  }

  lastButtonReading = reading;
}

void setup() {
  Serial.begin(115200);
  delay(300);
  Serial.println("\nESP32-C3 relay + bulb + button + web UI starting...");

  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  setBulb(false);

  loadWifiConfig();
  startProvisioningAp();

  bool connected = false;
  if (!configuredSsid.isEmpty()) {
    connected = connectToWifi(configuredSsid, configuredPass);
  }

  if (!connected) {
    saveWifiConfig(DEFAULT_WOKWI_SSID, DEFAULT_WOKWI_PASS);
    connected = connectToWifi(configuredSsid, configuredPass);
  }

  if (!connected) {
    Serial.println("Running with provisioning AP only");
  }

  setupServer();

  Serial.println("Open the web UI:");
  if (WiFi.status() == WL_CONNECTED) {
    Serial.printf("- Device IP: http://%s/\n", WiFi.localIP().toString().c_str());
    Serial.println("- In Wokwi with Private IoT Gateway: http://localhost:9080/");
  }
  if (apStarted) {
    Serial.printf("- Provisioning AP IP: http://%s/\n", WiFi.softAPIP().toString().c_str());
  }
}

void loop() {
  handleButton();
  server.handleClient();
  delay(5);
}