var koa = require('koa');
var userauth = require('koa-userauth');
var session = require('koa-generic-session');

var app = new koa();
app.keys = ['i m secret'];

app.use(session());
app.use(userauth({
  match: '/user',
  // auth system login url
  loginURLFormatter: function (url) {
    return 'http://login.demo.com/login?redirect=' + url;
  },
  // login callback and getUser info handler
  getUser: async ctx => {
    var token = this.query.token;
    // get user
    return user;
  }
}));

/**
 * User auth middleware.
 *
 * @param {Object} [options]
 *  - {String|Regex|Function(pathname, ctx)} match, detect which url need to check user auth.
 *      `''` empty string meaning match all, @see `path-match` package.
 *  - {String|Regex|Function(pathname, ctx)} ignore, detect which url no need to check user auth.
 *      If `match` exists, this argument will be ignored.
 *  - {Function(url, rootPath, ctx)} loginURLFormatter, format the login url.
 *  - {String} [rootPath], custom app url root path, default is '/'.
 *  - {String} [loginPath], default is '/login'.
 *  - {String} [loginCallbackPath], default is `options.loginPath + '/callback'`.
 *  - {String} [logoutPath], default is '/logout'.
 *  - {String} [userField], logined user field name on `this.session`, default is 'user', `this.session.user`.
 *  - {Async Function (ctx)} getUser, get user function, must get user info with `req`.
 *  - {Async Function (ctx, user)} [loginCallback], you can handle user login logic here,return [user, redirectUrl]
 *  - {Function(ctx)} [loginCheck], return true meaning logined. default is `true`.
 *  - {Async Function (ctx, user)} [logoutCallback], you can handle user logout logic here.return redirectUrl
 *  - {Function(ctx)} [getRedirectTarget], customize how to get the redirect target after login
 * @return {Async Function (next)} userauth middleware
 * @public
 */