const config = require('./config');

function createJsonSender(ws) {
  return (data) => {
    if (ws.readyState === 1) {
      ws.send(JSON.stringify(data));
    }
  };
}

function createClientHandlers(ws, sendJson) {
  let authenticated = false;
  let login = null;

  function getLogin() { return login; }

  function handleAuth(userLogin) {
    authenticated = true;
    login = userLogin;
    console.log(`Authenticated: ${login}`);
    sendJson({ type: 'auth_result', success: true });
    return { type: 'system', text: `${login} joined the chat` };
  }

  function handleAuthFail(reason) {
    sendJson({ type: 'auth_result', success: false, reason });
  }

  function wrapHandler(handler) {
    return (raw) => {
      let parsed;
      try {
        parsed = JSON.parse(raw.toString());
      } catch {
        sendJson({ type: 'error', message: 'Invalid JSON' });
        return null;
      }

      if (!authenticated) {
        if (parsed.type === 'auth') {
          return handler({ type: 'auth', login: parsed.login, password: parsed.password });
        }
        sendJson({ type: 'error', message: 'Authenticate first' });
        return null;
      }

      return handler(parsed);
    };
  }

  return { getLogin, handleAuth, handleAuthFail, wrapHandler };
}

function formatSizeEstimate(base64Length) {
  return Math.ceil((base64Length * 3) / 4);
}

function validateFile(parsed) {
  if (!parsed.filename || !parsed.mime || !parsed.data) {
    return 'Invalid file message';
  }
  const size = formatSizeEstimate(parsed.data.length);
  if (size > config.maxFileSize) {
    return `File too large (max ${config.maxFileSize / 1024 / 1024} MB)`;
  }
  return null;
}

function broadcast(server, message, excludeWs) {
  const json = JSON.stringify(message);
  server.clients.forEach(client => {
    if (client !== excludeWs && client.readyState === 1) {
      client.send(json);
    }
  });
}

module.exports = { createJsonSender, createClientHandlers, validateFile, broadcast };