const _ = require('lodash');
const crypto = global.yoho.crypto;

function urlJoin(a, b) {
    if (_.endsWith(a, '/') && _.startsWith(b, '/')) {
        return a + b.substring(1, b.length);
    } else if (!_.endsWith(a, '/') && !_.startsWith(b, '/')) {
        return a + '/' + b;
    } else {
        return a + b;
    }
}

function _encode(str) {
    return encodeURIComponent(crypto.encryption(null, str));
}

const encode = _.memoize(_encode);

function getRouter(req) {
    let route = req.route ? req.route.path : '';
    let appPath = req.app.mountpath;

    if (_.isArray(route) && route.length > 0) {
        route = route[0];
    }

    let key = urlJoin(appPath, route.toString()); // route may be a regexp

    if (key) {
        return encode(key);
    }

    return '';
}

module.exports.md = function(req, res, next) {
    function onRender() {
        res.locals._router = getRouter(req);
    }

    res.on('beforeRender', onRender);
    next();
};

module.exports.getRouter = getRouter;