// 2ef524a | https://github.com/jacobsoo/Decoder-JJEncode/blob/master/decoder.html

var JJdecode = {
    dst: '',
    out: function (c) {
        JJdecode.dst += c;
    },
    decode: function (txt) {
        //get string from src
        var t = txt;

        //clean it
        t.replace(/^\s+|\s+$/g, "");

        var startpos;
        var endpos;
        var gv;
        var gvl;

        if (t.indexOf("\"\'\\\"+\'+\",") == 0) //palindrome check
        {
            //locate jjcode
            startpos = t.indexOf('$$+"\\""+') + 8;
            endpos = t.indexOf('"\\"")())()');

            //get gv
            gv = t.substring((t.indexOf('"\'\\"+\'+",') + 9), t.indexOf("=~[]"));
            gvl = gv.length;
        } else {
            //get gv
            gv = t.substr(0, t.indexOf("="));
            gvl = gv.length;

            //locate jjcode
            startpos = t.indexOf('"\\""+') + 5;
            endpos = t.indexOf('"\\"")())()');
        }

        if (startpos == endpos) {
            throw new Error("No data !");
            return;
        }

        //start decoding
        var data = t.substring(startpos, endpos);

        //hex decode string
        var b = ["___+", "__$+", "_$_+", "_$$+", "$__+", "$_$+", "$$_+", "$$$+", "$___+", "$__$+", "$_$_+", "$_$$+", "$$__+", "$$_$+", "$$$_+", "$$$$+"];

        //lotu
        var str_l = "(![]+\"\")[" + gv + "._$_]+";
        var str_o = gv + "._$+";
        var str_t = gv + ".__+";
        var str_u = gv + "._+";

        //0123456789abcdef
        var str_hex = gv + ".";

        //s
        var str_s = '"';
        var gvsig = gv + ".";

        var str_quote = '\\\\\\"';
        var str_slash = '\\\\\\\\';

        var str_lower = "\\\\\"+";
        var str_upper = "\\\\\"+" + gv + "._+";

        var str_end = '"+'; //end of s loop

        while (data != "") {
            //l o t u
            if (0 == data.indexOf(str_l)) {
                data = data.substr(str_l.length);
                JJdecode.out("l");
                continue;
            } else if (0 == data.indexOf(str_o)) {
                data = data.substr(str_o.length);
                JJdecode.out("o");
                continue;
            } else if (0 == data.indexOf(str_t)) {
                data = data.substr(str_t.length);
                JJdecode.out("t");
                continue;
            } else if (0 == data.indexOf(str_u)) {
                data = data.substr(str_u.length);
                JJdecode.out("u");
                continue;
            }

            //0123456789abcdef
            if (0 == data.indexOf(str_hex)) {
                data = data.substr(str_hex.length);

                //check every element of hex decode string for a match
                var i = 0;
                for (i = 0; i < b.length; i++) {
                    if (0 == data.indexOf(b[i])) {
                        data = data.substr((b[i]).length);
                        JJdecode.out(i.toString(16));
                        break;
                    }
                }
                continue;
            }

            //start of s block
            if (0 == data.indexOf(str_s)) {
                data = data.substr(str_s.length);

                //check if "R
                if (0 == data.indexOf(str_upper)) // r4 n >= 128
                {
                    data = data.substr(str_upper.length); //skip sig

                    var ch_str = "";
                    for (j = 0; j < 2; j++) //shouldn't be more than 2 hex chars
                    {
                        //gv + "."+b[ c ]
                        if (0 == data.indexOf(gvsig)) {
                            data = data.substr(gvsig.length); //skip gvsig
                            for (k = 0; k < b.length; k++) //for every entry in b
                            {
                                if (0 == data.indexOf(b[k])) {
                                    data = data.substr(b[k].length);
                                    ch_str += k.toString(16) + "";
                                    break;
                                }
                            }
                        } else {
                            break; //done
                        }
                    }

                    JJdecode.out(String.fromCharCode(parseInt(ch_str, 16)));
                    continue;
                } else if (0 == data.indexOf(str_lower)) //r3 check if "R // n < 128
                {
                    data = data.substr(str_lower.length); //skip sig

                    var ch_str = "";
                    var ch_lotux = ""
                    var temp = "";
                    var b_checkR1 = 0;
                    for (j = 0; j < 3; j++) //shouldn't be more than 3 octal chars
                    {

                        if (j > 1) //lotu check
                        {
                            if (0 == data.indexOf(str_l)) {
                                data = data.substr(str_l.length);
                                ch_lotux = "l";
                                break;
                            } else if (0 == data.indexOf(str_o)) {
                                data = data.substr(str_o.length);
                                ch_lotux = "o";
                                break;
                            } else if (0 == data.indexOf(str_t)) {
                                data = data.substr(str_t.length);
                                ch_lotux = "t";
                                break;
                            } else if (0 == data.indexOf(str_u)) {
                                data = data.substr(str_u.length);
                                ch_lotux = "u";
                                break;
                            }
                        }

                        //gv + "."+b[ c ]
                        if (0 == data.indexOf(gvsig)) {
                            temp = data.substr(gvsig.length);
                            for (k = 0; k < 8; k++) //for every entry in b octal
                            {
                                if (0 == temp.indexOf(b[k])) {
                                    if (parseInt(ch_str + k + "", 8) > 128) {
                                        b_checkR1 = 1;
                                        break;
                                    }

                                    ch_str += k + "";
                                    data = data.substr(gvsig.length); //skip gvsig
                                    data = data.substr(b[k].length);
                                    break;
                                }
                            }

                            if (1 == b_checkR1) {
                                if (0 == data.indexOf(str_hex)) //0123456789abcdef
                                {
                                    data = data.substr(str_hex.length);

                                    //check every element of hex decode string for a match
                                    var i = 0;
                                    for (i = 0; i < b.length; i++) {
                                        if (0 == data.indexOf(b[i])) {
                                            data = data.substr((b[i]).length);
                                            ch_lotux = i.toString(16);
                                            break;
                                        }
                                    }

                                    break;
                                }
                            }
                        } else {
                            break; //done
                        }
                    }
                    JJdecode.out(String.fromCharCode(parseInt(ch_str, 8)) + ch_lotux);
                    continue; //step out of the while loop
                } else //"S ----> "SR or "S+
                {

                    // if there is, loop s until R 0r +
                    // if there is no matching s block, throw error

                    var match = 0;
                    var n;
                    //searching for mathcing pure s block
                    while (true) {
                        n = data.charCodeAt(0);
                        if (0 == data.indexOf(str_quote)) {
                            data = data.substr(str_quote.length);
                            JJdecode.out('"');
                            match += 1;
                            continue;
                        } else if (0 == data.indexOf(str_slash)) {
                            data = data.substr(str_slash.length);
                            JJdecode.out('\\');
                            match += 1;
                            continue;
                        } else if (0 == data.indexOf(str_end)) //reached end off S block ? +
                        {
                            if (match == 0) {
                                throw new Error("+ no match S block: " + data);
                                return;
                            }
                            data = data.substr(str_end.length);

                            break; //step out of the while loop
                        } else if (0 == data.indexOf(str_upper)) //r4 reached end off S block ? - check if "R n >= 128
                        {
                            if (match == 0) {
                                throw new Error("no match S block n>128: " + data);
                                return;
                            }

                            data = data.substr(str_upper.length); //skip sig

                            var ch_str = "";
                            var ch_lotux = "";
                            for (j = 0; j < 10; j++) //shouldn't be more than 10 hex chars
                            {

                                if (j > 1) //lotu check
                                {
                                    if (0 == data.indexOf(str_l)) {
                                        data = data.substr(str_l.length);
                                        ch_lotux = "l";
                                        break;
                                    } else if (0 == data.indexOf(str_o)) {
                                        data = data.substr(str_o.length);
                                        ch_lotux = "o";
                                        break;
                                    } else if (0 == data.indexOf(str_t)) {
                                        data = data.substr(str_t.length);
                                        ch_lotux = "t";
                                        break;
                                    } else if (0 == data.indexOf(str_u)) {
                                        data = data.substr(str_u.length);
                                        ch_lotux = "u";
                                        break;
                                    }
                                }

                                //gv + "."+b[ c ]
                                if (0 == data.indexOf(gvsig)) {
                                    data = data.substr(gvsig.length); //skip gvsig
                                    for (k = 0; k < b.length; k++) //for every entry in b
                                    {
                                        if (0 == data.indexOf(b[k])) {
                                            data = data.substr(b[k].length);
                                            ch_str += k.toString(16) + "";
                                            break;
                                        }
                                    }
                                } else {
                                    break; //done
                                }
                            }

                            JJdecode.out(String.fromCharCode(parseInt(ch_str, 16)));
                            break; //step out of the while loop
                        } else if (0 == data.indexOf(str_lower)) //r3 check if "R // n < 128
                        {
                            if (match == 0) {
                                throw new Error("no match S block n<128: " + data);
                                return;
                            }

                            data = data.substr(str_lower.length); //skip sig

                            var ch_str = "";
                            var ch_lotux = ""
                            var temp = "";
                            var b_checkR1 = 0;
                            for (j = 0; j < 3; j++) //shouldn't be more than 3 octal chars
                            {

                                if (j > 1) //lotu check
                                {
                                    if (0 == data.indexOf(str_l)) {
                                        data = data.substr(str_l.length);
                                        ch_lotux = "l";
                                        break;
                                    } else if (0 == data.indexOf(str_o)) {
                                        data = data.substr(str_o.length);
                                        ch_lotux = "o";
                                        break;
                                    } else if (0 == data.indexOf(str_t)) {
                                        data = data.substr(str_t.length);
                                        ch_lotux = "t";
                                        break;
                                    } else if (0 == data.indexOf(str_u)) {
                                        data = data.substr(str_u.length);
                                        ch_lotux = "u";
                                        break;
                                    }
                                }

                                //gv + "."+b[ c ]
                                if (0 == data.indexOf(gvsig)) {
                                    temp = data.substr(gvsig.length);
                                    for (k = 0; k < 8; k++) //for every entry in b octal
                                    {
                                        if (0 == temp.indexOf(b[k])) {
                                            if (parseInt(ch_str + k + "", 8) > 128) {
                                                b_checkR1 = 1;
                                                break;
                                            }

                                            ch_str += k + "";
                                            data = data.substr(gvsig.length); //skip gvsig
                                            data = data.substr(b[k].length);
                                            break;
                                        }
                                    }

                                    if (1 == b_checkR1) {
                                        if (0 == data.indexOf(str_hex)) //0123456789abcdef
                                        {
                                            data = data.substr(str_hex.length);

                                            //check every element of hex decode string for a match
                                            var i = 0;
                                            for (i = 0; i < b.length; i++) {
                                                if (0 == data.indexOf(b[i])) {
                                                    data = data.substr((b[i]).length);
                                                    ch_lotux = i.toString(16);
                                                    break;
                                                }
                                            }
                                        }
                                    }
                                } else {
                                    break; //done
                                }
                            }
                            JJdecode.out(String.fromCharCode(parseInt(ch_str, 8)) + ch_lotux);
                            break; //step out of the while loop
                        } else if ((0x21 <= n && n <= 0x2f) || (0x3A <= n && n <= 0x40) || (0x5b <= n && n <= 0x60) || (0x7b <= n && n <= 0x7f)) {
                            JJdecode.out(data.charAt(0));
                            data = data.substr(1);
                            match += 1;
                        }

                    }
                    continue;
                }
            }

            throw new Error("no match : " + data);
            break;
        }

        return JJdecode.dst;
    }
};