var specificity = require('route-order')();
var slash = require('express-slash');

function OKServer(options) {
  if (!(this instanceof OKServer)) return new OKServer(options);
  options = options || {};
  if (!options.express)
    throw new Error('No Express provided to OKServer');
  if (!options.app)
    throw new Error('No Express app provided to OKServer')
  if (!options.views)
    throw new Error('No views provided to OKServer');
  var views = options.views;
  var express = options.express;
  var app = this._app = options.app;
  var router = express.Router({
    strict: app.get('strict routing')
  });
  Object.keys(views)
    // Sort such that more general routes are matched last
    .sort(specificity)
    // Add the views
    .forEach(function(route) {
      var view = views[route];
      var mount = view.mount;
      if (!mount)
        throw Error('View doesn\'t specify a mount point');
      var handler = view.middleware();
      if (!handler)
        throw new Error('View doesn\'t provide middleware');
      router[mount](route, handler);
    });
  app.use(router);
  app.use(slash());

  /**
   * Create a handler which redirect all requests to
   * the same route with a trailing slash appended
   */
  function redirect(routeNoSlash) {
    return function(req, res) {
      res.redirect(301, routeNoSlash + '/');
    }
  }
}

OKServer.prototype.listen = function listen(port) {
  this._app.listen(port || 1337);
  return this;
};

module.exports = OKServer;