const ScanManager = () => {

    function portsList(ports) {
        const portsExp = ports.split(",");
        let portsArr = [];
        for (s of portsExp) {
            if (s.includes("-")) {
                const r = s.split("-")
                const r0 = parseInt(r[0], 10);
                const r1 = parseInt(r[1], 10) + 1;
                for (let i = r0; i < r1; i++) {
                    portsArr.push(i);
                }
            } else {
                portsArr.push(s);

            }
        }
        return portsArr;
    };

    //https://stackoverflow.com/questions/12303989/cartesian-product-of-multiple-arrays-in-javascript
    const f = (a, b) => [].concat(...a.map(d => b.map(e => [].concat(d, e))));
    const cartesian = (a, b, ...c) => (b ? cartesian(f(a, b), ...c) : a);

    function ipAddressList(ipAddressSpec) {
        const targetExp = ipAddressSpec.split(",");
        let final = [];

        for (s of targetExp) {
            // Do we have a cname
            // TKTK implement better check.
            if (s.match(/[a-z]/i)) {
                final.push(s);
                continue;
            };

            const arr = s.split(".")
            let j = 0
            let temp = [
                [],
                [],
                [],
                []
            ];
            for (a of arr) {
                if (a.includes("-")) {
                    const r = a.split("-")
                    const r0 = parseInt(r[0], 10);
                    const r1 = parseInt(r[1], 10) + 1;
                    for (let i = r0; i < r1; i++) {
                        temp[j].push(i);
                    }

                } else {
                    temp[j].push(a);

                }
                j += 1;
            }
            let final_temp = cartesian(temp[0], temp[1], temp[2], temp[3])
            for (s of final_temp) {
                final.push(s.join("."))
            }
        }
        return final;
    }
    let workerList = [];
    let results = [];
    let index = 0;
    let workerCount = window.navigator.hardwareConcurrency || 4;
    let messageReceived = 0;
    let targetTimeoutErrors = {};
    let doneRescan = false;
    let timeOut = 300;

    return {
        run(ipAddressSpec, portSpec, resultFn, completedFn) {
            let addresses = ipAddressList(ipAddressSpec);
            let portsArr = portsList(portSpec);
            let targets = cartesian(addresses, portsArr);

            for (let i = 0; i < workerCount; i++) {
                let worker = new Worker('scan.js');
                workerList.push(worker);
            }

            function checkScanDone(lastResult) {
                if (lastResult != null) {
                    resultFn(lastResult);
                };

                if (index === targets.length && messageReceived === targets.length) {
                    const targetSizeBeforeChange = targets.length

                    if (doneRescan === false) {
                        doneRescan = true;
                        timeOut = 3000;

                        for (let target in targetTimeoutErrors) {
                            // if not all scanned ports for a given host timed out 
                            // (e.g. fetch error instead), then we should rescan.
                            // Works if we scan two ports per host (one closed and one open)
                            if (targetTimeoutErrors[target].count < portsArr.length) {
                                targetTimeoutErrors[target].rescanports.forEach(port => {
                                    targets.push([target, port]);
                                })
                            };
                        };

                        if (targetSizeBeforeChange === targets.length) {
                            results.sort(function (a, b) {
                                return (b.duration - a.duration);
                            });
                            completedFn(results);
                            return true;

                        } else {
                            console.log(`Rescanning targets with larger timeout: ${targets.slice(index)}`);
                            return false;

                        }
                    } else {
                        results.sort(function (a, b) {
                            return (b.duration - a.duration);
                        });
                        completedFn(results);
                        return true;
                    }
                } else {
                    return false;

                }
            }

            for (let w of workerList) {
                w.onmessage = function (msg) {
                    let lastResult = null;
                    if (msg.data.error === false) {
                        results.push(msg.data);
                        lastResult = msg.data;
                    } else if (msg.data.errorReason === 'timeout') {
                        if (msg.data.target.address in targetTimeoutErrors) {
                            targetTimeoutErrors[msg.data.target.address].count += 1;
                            targetTimeoutErrors[msg.data.target.address]
                                .rescanports.push(msg.data.target.port);
                        } else {
                            targetTimeoutErrors[msg.data.target.address] = {
                                count: 1,
                                rescanports: [msg.data.target.port]
                            };;
                        };
                    };

                    messageReceived++;

                    if (checkScanDone(lastResult) === false) {

                        if (index < targets.length) {
                            let target = {
                                "address": targets[index][0],
                                "port": targets[index][1]
                            };
                            w.postMessage({ targetdata: target, timeout: timeOut });
                            index++;
                        }
                    }
                }
            }

            for (let w of workerList) {
                if (index < targets.length) {
                    let target = {
                        "address": targets[index][0],
                        "port": targets[index][1]
                    };
                    w.postMessage({ targetdata: target, timeout: timeOut });
                    index++;
                } else {
                    break;
                }
            }
        },
        shutDown() {
            for (let w of workerList) {
                w.terminate();
            }
        }
    }
}

function getLocalIpAddress() {
    const p = new Promise((resolve, reject) => {
        if (!(typeof (RTCPeerConnection) === "function")) {
            reject(new Error('WebRTC is not supported'));
            return;
        };
        const rtc = new RTCPeerConnection({
            iceServers: []
        });
        const timer = setTimeout(() => reject(new Error("Promise timed out")), 1000);
        rtc.onicecandidate = e => {
            if (e.candidate) {
                clearTimeout(timer),
                    resolve(e.candidate.candidate.split(" ", 5)[4]);
            };
        };
        if (!(typeof (rtc.createDataChannel) === "function")) {
            reject(new Error('createDataChannel is not supported'));
            return;
        };
        rtc.createDataChannel('');
        rtc.createOffer().then(d => rtc.setLocalDescription(d), e => reject(e));
    })
    return p;
};

//  Obtain external IP address to exploit weak end system model in consumer/small business routers
async function getMyExternalIpAddress() {
    const response = await fetch("/clientinfo");
    const json = await response.json();
    return json.IPAddress;
}

//const ports = "1,3-4,6-7,9,13,17,19-26,30,32-33,37,42-43,49,53,70,79-85,88-90,99-100,106,109-111,113,119,125,135,139,143-144,146,161,163,179,199,211-212,222,254-256,259,264,280,301,306,311,340,366,389,406-407,416-417,425,427,443-445,458,464-465,481,497,500,512-515,524,541,543-545,548,554-555,563,587,593,616-617,625,631,636,646,648,666-668,683,687,691,700,705,711,714,720,722,726,749,765,777,783,787,800-801,808,843,873,880,888,898,900-903,911-912,981,987,990,992-993,995,999-1002,1007,1009-1011,1021-1100,1102,1104-1108,1110-1114,1117,1119,1121-1124,1126,1130-1132,1137-1138,1141,1145,1147-1149,1151-1152,1154,1163-1166,1169,1174-1175,1183,1185-1187,1192,1198-1199,1201,1213,1216-1218,1233-1234,1236,1244,1247-1248,1259,1271-1272,1277,1287,1296,1300-1301,1309-1311,1322,1328,1334,1352,1417,1433-1434,1443,1455,1461,1494,1500-1501,1503,1521,1524,1533,1556,1580,1583,1594,1600,1641,1658,1666,1687-1688,1700,1717-1721,1723,1755,1761,1782-1783,1801,1805,1812,1839-1840,1862-1864,1875,1900,1914,1935,1947,1971-1972,1974,1984,1998-2010,2013,2020-2022,2030,2033-2035,2038,2040-2043,2045-2049,2065,2068,2099-2100,2103,2105-2107,2111,2119,2121,2126,2135,2144,2160-2161,2170,2179,2190-2191,2196,2200,2222,2251,2260,2288,2301,2323,2366,2381-2383,2393-2394,2399,2401,2492,2500,2522,2525,2557,2601-2602,2604-2605,2607-2608,2638,2701-2702,2710,2717-2718,2725,2800,2809,2811,2869,2875,2909-2910,2920,2967-2968,2998,3000-3001,3003,3005-3007,3011,3013,3017,3030-3031,3052,3071,3077,3128,3168,3211,3221,3260-3261,3268-3269,3283,3300-3301,3306,3322-3325,3333,3351,3367,3369-3372,3389-3390,3404,3476,3493,3517,3527,3546,3551,3580,3659,3689-3690,3703,3737,3766,3784,3800-3801,3809,3814,3826-3828,3851,3869,3871,3878,3880,3889,3905,3914,3918,3920,3945,3971,3986,3995,3998,4000-4006,4045,4111,4125-4126,4129,4224,4242,4279,4321,4343,4443-4446,4449,4550,4567,4662,4848,4899-4900,4998,5000-5004,5009,5030,5033,5050-5051,5054,5060-5061,5080,5087,5100-5102,5120,5190,5200,5214,5221-5222,5225-5226,5269,5280,5298,5357,5405,5414,5431-5432,5440,5500,5510,5544,5550,5555,5560,5566,5631,5633,5666,5678-5679,5718,5730,5800-5802,5810-5811,5815,5822,5825,5850,5859,5862,5877,5900-5904,5906-5907,5910-5911,5915,5922,5925,5950,5952,5959-5963,5987-5989,5998-6007,6009,6025,6059,6100-6101,6106,6112,6123,6129,6156,6346,6389,6502,6510,6543,6547,6565-6567,6580,6646,6666-6669,6689,6692,6699,6779,6788-6789,6792,6839,6881,6901,6969,7000-7002,7004,7007,7019,7025,7070,7100,7103,7106,7200-7201,7402,7435,7443,7496,7512,7625,7627,7676,7741,7777-7778,7800,7911,7920-7921,7937-7938,7999-8002,8007-8011,8021-8022,8031,8042,8045,8080-8090,8093,8099-8100,8180-8181,8192-8194,8200,8222,8254,8290-8292,8300,8333,8383,8400,8402,8443,8500,8600,8649,8651-8652,8654,8701,8800,8873,8888,8899,8994,9000-9003,9009-9011,9040,9050,9071,9080-9081,9090-9091,9099-9103,9110-9111,9200,9207,9220,9290,9415,9418,9485,9500,9502-9503,9535,9575,9593-9595,9618,9666,9876-9878,9898,9900,9917,9929,9943-9944,9968,9998-10004,10009-10010,10012,10024-10025,10082,10180,10215,10243,10566,10616-10617,10621,10626,10628-10629,10778,11110-11111,11967,12000,12174,12265,12345,13456,13722,13782-13783,14000,14238,14441-14442,15000,15002-15004,15660,15742,16000-16001,16012,16016,16018,16080,16113,16992-16993,17877,17988,18040,18101,18988,19101,19283,19315,19350,19780,19801,19842,20000,20005,20031,20221-20222,20828,21571,22939,23502,24444,24800,25734-25735,26214,27000,27352-27353,27355-27356,27715,28201,30000,30718,30951,31038,31337,32768-32785,33354,33899,34571-34573,35500,38292,40193,40911,41511,42510,44176,44442-44443,44501,45100,48080,49152-49161,49163,49165,49167,49175-49176,49400,49999-50003,50006,50300,50389,50500,50636,50800,51103,51493,52673,52822,52848,52869,54045,54328,55055-55056,55555,55600,56737-56738,57294,57797,58080,60020,60443,61532,61900,62078,63331,64623,64680,65000,65129,65389"

function resultFn(result) {
    console.log(result);
    document.getElementById("results").innerHTML += JSON.stringify(result, null, 4) + "<br/>";
}

function doneFn(results) {
    document.getElementById("results").innerHTML += "Done.<br/>";
    setTimeout(function () {
        sm.shutDown();
    }, 3000);

}

function scan() {
    sm = ScanManager();
    const addrSpec = document.getElementById("ipaddressspec").value;
    const portSpec = document.getElementById("portspec").value;
    sm.run(addrSpec, portSpec, resultFn, doneFn);
}

async function getMyIpAddressesThenScan() {
    sm = ScanManager();
    let addrSpec = `127.0.0.1,0.0.0.0,`;
    const portSpec = document.getElementById("portspec").value;
    let externalAddress = await getMyExternalIpAddress();
    addrSpec = `${addrSpec}${externalAddress},`;

    getLocalIpAddress()
        .then(address => {
            const range = `${address.split('.', 3).join('.')}.1-254`;
            addrSpec = `${addrSpec}${range}`;
            document.getElementById("ipaddressspec").value = addrSpec;
            sm.run(addrSpec, portSpec, resultFn, doneFn);
        },
            e => {
                console.log(e);
                addrSpec = `${addrSpec}192.168.1.1-255`;
                document.getElementById("ipaddressspec").value = addrSpec;
                sm.run(addrSpec, portSpec, resultFn, doneFn);

            })
}