// https://github.com/ben-bradley/ping-lite/blob/master/ping-lite.js
// Fixed on Windows
const net = require("net");
const spawn = require("child_process").spawn;
const events = require("events");
const fs = require("fs");
const util = require("./util-server");

module.exports = Ping;

/**
 * Constructor for ping class
 * @param {string} host Host to ping
 * @param {object} [options] Options for the ping command
 * @param {array|string} [options.args] - Arguments to pass to the ping command
 */
function Ping(host, options) {
    if (!host) {
        throw new Error("You must specify a host to ping!");
    }

    this._host = host;
    this._options = options = (options || {});

    events.EventEmitter.call(this);

    const timeout = 10;

    if (util.WIN) {
        this._bin = "c:/windows/system32/ping.exe";
        this._args = (options.args) ? options.args : [ "-n", "1", "-w", timeout * 1000, host ];
        this._regmatch = /[><=]([0-9.]+?)ms/;

    } else if (util.LIN) {
        this._bin = "/bin/ping";

        const defaultArgs = [ "-n", "-w", timeout, "-c", "1", host ];

        if (net.isIPv6(host) || options.ipv6) {
            defaultArgs.unshift("-6");
        }

        this._args = (options.args) ? options.args : defaultArgs;
        this._regmatch = /=([0-9.]+?) ms/;

    } else if (util.MAC) {

        if (net.isIPv6(host) || options.ipv6) {
            this._bin = "/sbin/ping6";
        } else {
            this._bin = "/sbin/ping";
        }

        this._args = (options.args) ? options.args : [ "-n", "-t", timeout, "-c", "1", host ];
        this._regmatch = /=([0-9.]+?) ms/;

    } else if (util.BSD) {
        this._bin = "/sbin/ping";

        const defaultArgs = [ "-n", "-t", timeout, "-c", "1", host ];

        if (net.isIPv6(host) || options.ipv6) {
            defaultArgs.unshift("-6");
        }

        this._args = (options.args) ? options.args : defaultArgs;
        this._regmatch = /=([0-9.]+?) ms/;

    } else {
        throw new Error("Could not detect your ping binary.");
    }

    if (!fs.existsSync(this._bin)) {
        throw new Error("Could not detect " + this._bin + " on your system");
    }

    this._i = 0;

    return this;
}

Ping.prototype.__proto__ = events.EventEmitter.prototype;

/**
 * Callback for send
 * @callback pingCB
 * @param {any} err Any error encountered
 * @param {number} ms Ping time in ms
 */

/**
 * Send a ping
 * @param {pingCB} callback Callback to call with results
 */
Ping.prototype.send = function (callback) {
    let self = this;
    callback = callback || function (err, ms) {
        if (err) {
            return self.emit("error", err);
        }
        return self.emit("result", ms);
    };

    let _ended;
    let _exited;
    let _errored;

    this._ping = spawn(this._bin, this._args, { windowsHide: true }); // spawn the binary

    this._ping.on("error", function (err) { // handle binary errors
        _errored = true;
        callback(err);
    });

    this._ping.stdout.on("data", function (data) { // log stdout
        if (util.WIN) {
            data = convertOutput(data);
        }
        this._stdout = (this._stdout || "") + data;
    });

    this._ping.stdout.on("end", function () {
        _ended = true;
        if (_exited && !_errored) {
            onEnd.call(self._ping);
        }
    });

    this._ping.stderr.on("data", function (data) { // log stderr
        if (util.WIN) {
            data = convertOutput(data);
        }
        this._stderr = (this._stderr || "") + data;
    });

    this._ping.on("exit", function (code) { // handle complete
        _exited = true;
        if (_ended && !_errored) {
            onEnd.call(self._ping);
        }
    });

    /**
     * @param {Function} callback
     *
     * Generated by Trelent
     */
    function onEnd() {
        let stdout = this.stdout._stdout;
        let stderr = this.stderr._stderr;
        let ms;

        if (stderr) {
            return callback(new Error(stderr));
        }

        if (!stdout) {
            return callback(new Error("No stdout detected"));
        }

        ms = stdout.match(self._regmatch); // parse out the ##ms response
        ms = (ms && ms[1]) ? Number(ms[1]) : ms;

        callback(null, ms, stdout);
    }
};

/**
 * Ping every interval
 * @param {pingCB} callback Callback to call with results
 */
Ping.prototype.start = function (callback) {
    let self = this;
    this._i = setInterval(function () {
        self.send(callback);
    }, (self._options.interval || 5000));
    self.send(callback);
};

/** Stop sending pings */
Ping.prototype.stop = function () {
    clearInterval(this._i);
};

/**
 * Try to convert to UTF-8 for Windows, as the ping's output on Windows is not UTF-8 and could be in other languages
 * Thank @pemassi
 * https://github.com/louislam/uptime-kuma/issues/570#issuecomment-941984094
 * @param {any} data
 * @returns {string}
 */
function convertOutput(data) {
    if (util.WIN) {
        if (data) {
            return util.convertToUTF8(data);
        }
    }
    return data;
}
