#include <SecurityManager.h>

SecurityManager::SecurityManager(AsyncWebServer* server, FS* fs) : SettingsPersistence(fs, SECURITY_SETTINGS_FILE) {
  server->on(USERS_PATH, HTTP_GET, std::bind(&SecurityManager::fetchUsers, this, std::placeholders::_1));
}

SecurityManager::~SecurityManager() {}

void SecurityManager::readFromJsonObject(JsonObject& root) {
  // secret  
  _jwtSecret = root["jwt_secret"] | DEFAULT_JWT_SECRET;

  // roles
  _roles.clear();
  if (root["roles"].is<JsonArray>()) {
    JsonArray roles = root["roles"];
    for (JsonVariant role : roles) {
      _roles.push_back(role.as<String>());
    }
  }

  // users
  _users.clear();
  if (root["users"].is<JsonArray>()) {
    JsonArray users = root["users"];
    for (JsonVariant user : users) {
      String username =  user["username"];
      String password = user["password"];
      String role = user["role"];
      _users.push_back(User(username, password, role));
    }
  }
}

void SecurityManager::writeToJsonObject(JsonObject& root) {
  // secret
  root["jwt_secret"] = _jwtSecret;

  // roles
  JsonArray roles = root.createNestedArray("roles");
  for (String _role : _roles) {
    roles.add(_role);
  }

  // users
  JsonArray users = root.createNestedArray("users");
  for (User _user : _users) {
    JsonObject user = users.createNestedObject();
    user["username"] = _user.getUsername();
    user["password"] = _user.getPassword();
    user["role"] = _user.getRole();
  }
}

void SecurityManager::fetchUsers(AsyncWebServerRequest *request) {
  AsyncJsonResponse * response = new AsyncJsonResponse(MAX_USERS_SIZE);
  JsonObject jsonObject = response->getRoot();  
  writeToJsonObject(jsonObject);
  response->setLength();
  request->send(response);
}

void SecurityManager::begin() {
  // read config
  readFromFS();

  // configure secret
  jwtHandler.setSecret(_jwtSecret);
}

Authentication SecurityManager::authenticateRequest(AsyncWebServerRequest *request) {
  AsyncWebHeader* authorizationHeader = request->getHeader(AUTHORIZATION_HEADER);
  if (authorizationHeader) {
    String value = authorizationHeader->value();
    value.startsWith(AUTHORIZATION_HEADER_PREFIX);
    value = value.substring(AUTHORIZATION_HEADER_PREFIX_LEN);
    return authenticateJWT(value);
  }  
  return Authentication();
}

Authentication SecurityManager::authenticateJWT(String jwt) {
  DynamicJsonDocument payloadDocument(MAX_JWT_SIZE);
  jwtHandler.parseJWT(jwt, payloadDocument);
  if (payloadDocument.is<JsonObject>()) {
    JsonObject parsedPayload = payloadDocument.as<JsonObject>();
    String username = parsedPayload["username"];
    for (User _user : _users) {
      if (_user.getUsername() == username && validatePayload(parsedPayload, &_user)){
        return Authentication(_user);
      }
    }
  }
  return Authentication();
}

Authentication SecurityManager::authenticate(String username, String password) {
  for (User _user : _users) {
    if (_user.getUsername() == username && _user.getPassword() == password){
      return Authentication(_user);
    }
  }
  return Authentication();
}

inline void populateJWTPayload(JsonObject &payload, User *user) {
  payload["username"] = user->getUsername();
  payload["role"] = user->getRole();
}

boolean SecurityManager::validatePayload(JsonObject &parsedPayload, User *user) {
  DynamicJsonDocument _jsonDocument(MAX_JWT_SIZE);      
  JsonObject payload = _jsonDocument.to<JsonObject>();
  populateJWTPayload(payload, user);
  return payload == parsedPayload;
}

String SecurityManager::generateJWT(User *user) {
  DynamicJsonDocument _jsonDocument(MAX_JWT_SIZE);      
  JsonObject payload = _jsonDocument.to<JsonObject>();
  populateJWTPayload(payload, user);
  return jwtHandler.buildJWT(payload);
}