'use strict';

const { canonicalizeAltaOrigin } = require('./url-policy');

const MAX_COOKIE_LENGTH = 4096;

function sessionError(code, message) {
  const error = new Error(message);
  error.code = code;
  return error;
}

function validateCookie(cookie) {
  if (
    typeof cookie !== 'string' ||
    cookie.length === 0 ||
    cookie.length > MAX_COOKIE_LENGTH ||
    /[;\r\n\0]/.test(cookie)
  ) {
    throw sessionError('INVALID_SESSION_COOKIE', 'Invalid Alta session cookie');
  }
  return cookie;
}

class SessionStore {
  #origin = null;
  #cookie = null;
  #disposed = false;

  establish(deploymentOrigin, cookie) {
    if (this.#disposed) {
      throw sessionError('SESSION_STORE_DISPOSED', 'Alta session store is disposed');
    }

    // Validate the complete replacement before dropping the current session.
    const nextOrigin = canonicalizeAltaOrigin(deploymentOrigin);
    const nextCookie = validateCookie(cookie);
    this.#origin = nextOrigin;
    this.#cookie = nextCookie;
    return this.describe();
  }

  setSession(deploymentOrigin, cookie) {
    return this.establish(deploymentOrigin, cookie);
  }

  requireSession() {
    if (this.#disposed || this.#origin === null || this.#cookie === null) {
      throw sessionError('NO_ALTA_SESSION', 'No active Alta session');
    }
    return Object.freeze({ origin: this.#origin, cookie: this.#cookie });
  }

  describe() {
    return Object.freeze({
      connected: !this.#disposed && this.#origin !== null && this.#cookie !== null,
      origin: !this.#disposed ? this.#origin : null,
    });
  }

  clear() {
    this.#cookie = null;
    this.#origin = null;
  }

  dispose() {
    this.clear();
    this.#disposed = true;
  }
}

function createSessionStore() {
  return new SessionStore();
}

module.exports = {
  MAX_COOKIE_LENGTH,
  SessionStore,
  createSessionStore,
  validateCookie,
};