const Trouter = require("trouter");

const onerror = (err, req, res) =>
  (res.statusCode = err.status || 500) && res.end(err.message);
const isResSent = (res) => res.finished || res.headersSent || res.writableEnded;
const mount = (fn) => (fn.routes ? fn.handle.bind(fn) : fn);

module.exports = function factory({
  onError = onerror,
  onNoMatch = onerror.bind(null, { status: 404, message: "not found" }),
  attachParams = false,
  disableResponseWait = false,
} = {}) {
  async function nc(req, res) {
    let finishP;
    if (!disableResponseWait && "once" in res)
      finishP = new Promise((resolve) => {
        res.once("finish", resolve);
        if (isResSent(res)) resolve();
      });
    nc.handle(req, res, (err, next) =>
      err
        ? onError(err, req, res, () => next())
        : !isResSent(res) && onNoMatch(req, res)
    );
    await finishP;
  }
  nc.routes = [];
  const _use = Trouter.prototype.use.bind(nc);
  const _find = Trouter.prototype.find.bind(nc);
  const _add = Trouter.prototype.add.bind(nc);
  function add(method, base, ...fns) {
    if (typeof base === "function") return add(method, "*", base, ...fns);
    _add(method, base, ...fns);
    return nc;
  }
  nc.use = function use(base, ...fns) {
    if (typeof base === "function") return this.use("/", base, ...fns);
    if (typeof base === "string" && base !== "/") {
      let slashAdded = false;
      fns.unshift((req, _, next) => {
        req.url = req.url.substring(base.length);
        if ((slashAdded = req.url[0] !== "/")) req.url = "/" + req.url;
        next();
      });
      fns.push(
        (req, _, next) =>
          (req.url = base + (slashAdded ? req.url.substring(1) : req.url)) &&
          next()
      );
    }

    _use(base, ...fns.map(mount));
    return nc;
  };
  nc.all = add.bind(nc, "");
  nc.get = add.bind(nc, "GET");
  nc.head = add.bind(nc, "HEAD");
  nc.post = add.bind(nc, "POST");
  nc.put = add.bind(nc, "PUT");
  nc.delete = add.bind(nc, "DELETE");
  nc.options = add.bind(nc, "OPTIONS");
  nc.trace = add.bind(nc, "TRACE");
  nc.patch = add.bind(nc, "PATCH");
  nc.run = function run(req, res) {
    return new Promise((resolve, reject) => {
      this.handle(req, res, (err) => (err ? reject(err) : resolve()));
    });
  };
  nc.handle = function handle(req, res, done) {
    const idx = req.url.indexOf("?");
    const { handlers, params } = _find(
      req.method,
      idx !== -1 ? req.url.substring(0, idx) : req.url
    );
    if (attachParams) req.params = params;
    let i = 0;
    const len = handlers.length;
    const loop = async (next) => handlers[i++](req, res, next);
    const next = (err) => {
      i < len && !err ? loop(next).catch(next) : done(err, next);
    };
    next();
  };
  return nc;
}