/*
 * decaffeinate suggestions:
 * DS102: Remove unnecessary code created because of implicit returns
 * DS103: Rewrite code to no longer use __guard__
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
const os = require("os");
const yn = require("yn");

const STACKDRIVER_LOGGING = yn(process.env['STACKDRIVER_LOGGING']);

module.exports.monitor = logger => (function(req, res, next) {
    const Metrics = require("./index");
    const startTime = process.hrtime();
    const {
        end
    } = res;
    res.end = function() {
        let info;
        end.apply(this, arguments);
        const responseTime = process.hrtime(startTime);
        const responseTimeMs = Math.round((responseTime[0] * 1000) + (responseTime[1] / 1000000));
        const requestSize = parseInt(req.headers["content-length"], 10);
        if ((req.route != null ? req.route.path : undefined) != null) {
            const routePath = req.route.path.toString().replace(/\//g, '_').replace(/\:/g, '').slice(1);
            Metrics.timing("http_request", responseTimeMs, null, {method:req.method, status_code: res.statusCode, path:routePath});
            if (requestSize) {
                Metrics.summary("http_request_size_bytes", requestSize, {method:req.method, status_code: res.statusCode, path:routePath});
            }
        }
        const remoteIp = req.ip || __guard__(req.socket != null ? req.socket.socket : undefined, x => x.remoteAddress) || (req.socket != null ? req.socket.remoteAddress : undefined);
        const reqUrl = req.originalUrl || req.url;
        const referrer = req.headers['referer'] || req.headers['referrer'];
        if (STACKDRIVER_LOGGING) {
            info = {
                httpRequest: {
                    requestMethod: req.method,
                    requestUrl: reqUrl,
                    requestSize,
                    status: res.statusCode,
                    responseSize: res.getHeader("content-length"),
                    userAgent: req.headers["user-agent"],
                    remoteIp,
                    referer: referrer,
                    latency: {
                        seconds: responseTime[0],
                        nanos: responseTime[1]
                    },
                    protocol: req.protocol
                }
            };
        } else {
            info = {
                req: {
                    url: reqUrl,
                    method: req.method,
                    referrer,
                    "remote-addr": remoteIp,
                    "user-agent": req.headers["user-agent"],
                    "content-length": req.headers["content-length"]
                },
                res: {
                    "content-length": res.getHeader("content-length"),
                    statusCode: res.statusCode
                },
                "response-time": responseTimeMs
            };
        }
        return logger.info(info, "%s %s", req.method, reqUrl);
    };
    return next();
});

function __guard__(value, transform) {
  return (typeof value !== 'undefined' && value !== null) ? transform(value) : undefined;
}