// ==UserScript==
// @name            Arca base64 autodecoder
// @name:ko         아카라이브 Base64 자동 디코더
// @version         1.17
// @author          Laria
// @match           https://arca.live/b/*/*
// @description     Arca.live Base64 auto decoder
// @description:ko  아카라이브 Base64 자동 복호화 스크립트
// @icon            https://www.google.com/s2/favicons?sz=64&domain=arca.live
// @license         MIT
// @encoding        utf-8
// @run-at          document-end
// @supportURL      https://greasyfork.org/ko/scripts/482577-arca-base64-autodecoder
// @namespace       https://greasyfork.org/users/1235854
// @downloadURL none
// ==/UserScript==

/*
 * == Change log ==
 * 1.0 - Release
 * 1.1 - Invalid character update (replace -> replaceAll)
 * 1.11 - Improved show multiple links
 * 1.12 - Show Single links Bugfix
 * 1.13 - Bugfix 1.12
 * 1.14 - Base64 add padding func
 * 1.15 - Add annotation, display improvements
 * 1.16 - Display improved - CSS applied
 * 1.17 - var safe, max_iter defined (~7, def:3)
*/

const version = '1.16R';

//max attempt decode depth, defalut depth : 3
//Caution! browser performance impact..
var max_iter = 3


//base64 encoded(http:/*, https:/*) string prefix
const regArr = [
    /(aHR0cDovL|aHR0cHM6Ly)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 1 time
    /(YUhSMGNEb3ZM|YUhSMGNITTZMe)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 2 time
    /(WVVoU01HTkViM1pN|WVVoU01HTklUVFpNZ)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 3 time
    /(V1ZWb1UwMUhUa1ZpTTFwT|V1ZWb1UwMUhUa2xVVkZwTl)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 4 time
    /(VjFaV2IxVXdNVWhVYTFacFRURndU|VjFaV2IxVXdNVWhVYTJ4VlZrWndUb)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 5 time
    /(VmpGYVYySXhWWGROVldoVllURmFjRlJVUm5kV|VmpGYVYySXhWWGROVldoVllUSjRWbFpyV25kVW)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 6 time
    /(Vm1wR1lWWXlTWGhXV0dST1ZsZG9WbGxVUm1GalJsSlZVbTVrV|Vm1wR1lWWXlTWGhXV0dST1ZsZG9WbGxVU2pSV2JGcHlWMjVrVl)(\w|=|\+|\/)*(?=[^\+=\w\/])/g, //encoding 7 time
];
//auto optimization
max_iter = max_iter > regArr.length ? regArr.length : max_iter;
//regex prefix - drag
const regInvalid = /[^\w\+\/=]/;

//auto add padding - add '=' padding in base64 encoded string
function base64AddPadding(str) {
    return str + Array((4 - str.length % 4) % 4 + 1).join('=');
}

//base64 decode
var Base64 = {
    _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
    decode : function (input) {
        var output = "";
        var chr1, chr2, chr3;
        var enc1, enc2, enc3, enc4;
        var i = 0;

        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

        while (i < input.length) {
            enc1 = this._keyStr.indexOf(input.charAt(i++));
            enc2 = this._keyStr.indexOf(input.charAt(i++));
            enc3 = this._keyStr.indexOf(input.charAt(i++));
            enc4 = this._keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            //last bits
            output = output + String.fromCharCode(chr1);
            if (enc3 != 64) { //=
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) { //==
                output = output + String.fromCharCode(chr3);
            }
        }

        output = Base64._utf8_decode(output);
        return output;
    },
    // private method for UTF-8 decoding
    _utf8_decode : function (utftext) {
        var string = "";
        var i = 0;
        var c = 0;
        var c1 = 0;
        var c2 = 0;
        var c3 = 0;

        while ( i < utftext.length ) {
            c = utftext.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            }
            else if((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i+1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            }
            else {
                c2 = utftext.charCodeAt(i+1);
                c3 = utftext.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }
        }
        return string;
    }
};

var hindex = 0; //total decode count

//drag function comparison
var lastSelected = document;
var lastSelectedTime = Date.now();

//create link each components
function createLink(src, index, url, depth) {
  //n번째 링크 (base64 깊이: 0) [ ABCDEF= ]
  return '<a href="' + url + '" title="' + url + ' (새 창으로 열기)" target="_blank" rel="external nofollow noopener noreferrer">' + index.toString() + '번째 링크 (base64 깊이: ' + depth.toString() + ')</a> [ <span style="font-size: 87.5%;color: rgb(71 188 115);">' + src.toString() + '</span> ]';
}

//decode & generate
function replacerGen(numIter) {
  return function(source) {
      try {
        rstring = ""; //return msg
        console.log('\n' + (hindex+1).toString() + '번째 인코딩된 링크: ' + source.toString()); //source

        //decode
        var converted = Base64.decode(base64AddPadding(source));
        //attempt to decode nested base64 encoded string
        for(var i=0; i<numIter; i++) {
            converted = Base64.decode(base64AddPadding(converted));
        }
        hindex++;

        //remove invalid string - �
        converted = decodeURI(encodeURI(converted).replaceAll('%00', ''));
        console.log(hindex.toString() + '번째 디코딩 완료: ' + converted.toString()); //converted

        //split by new line
        converted = converted.split(/\r?\n/);
        //single component
        if (converted.length == 2 && converted[converted.length-1] == '') {
          rstring += createLink(source, hindex, converted[0], numIter+1);
        //multiple component
        } else if (converted.length > 1) {
          rstring += '[ <span style="font-size: 87.5%;color: rgb(71 188 115);">' + source.toString() + '</span> ]';
          nindex = 1;
          converted.forEach(function(j) {
            if (j != '') {
              rstring += '<br>' + createLink('링크 자동 분할 : ' + nindex.toString() + '번째', hindex, j, numIter+1);
              hindex++;
              nindex++;
            }
          });
          //apply last components
          hindex--;
          nindex--;

          rstring = '<span style="color: rgb(232 62 140);"><b><i>분할된 링크 총 ' + nindex.toString() + '개</i></b></span> ' + rstring;
        } else rstring += createLink(source, hindex, converted, numIter+1);
        return rstring;
    } catch(e) {
        console.warn('\n에러 발생: ' + e);
        console.warn('base64 변환 실패: ' + source.toString());
    }
    return '<span style="color: rgb(255 0 0);">[ base64 변환 실패: ' + source.toString() + '</span> ]';
  };
}

//user drag event
//function disabled
function selClicked(event) {
  var sel = document.getSelection().toString();
  if (!sel.match(regInvalid) && sel.length >= 10 && lastSelectedTime + 200 < Date.now()) {
    try {
      var converted = decodeURI(encodeURI(Base64.decode(base64AddPadding(sel))).replaceAll('%00', ''));
      this.innerHTML = this.innerHTML.replace(sel, converted);
      this.removeEventListener('click', selClicked);
    } catch (e) {
      return;
    } finally {
    }
  }
}

//main
(function() {
  'use strict';

  console.log('Arca.live Base64 오토 디코더 V' + version + '\n디코딩 준비');
  //article
  var article = document.getElementsByClassName("article-content")[0];
  for(var i=0; i<max_iter; i++) {
    article.innerHTML = article.innerHTML.replaceAll(regArr[i], replacerGen(i));
  }

  //comment
  var comments = document.getElementsByClassName("list-area");
  if(comments.length != 0) {
    for(var j=0; j<max_iter; j++) {
      comments[0].innerHTML = comments[0].innerHTML.replaceAll(regArr[j], replacerGen(j));
    }
  }

  /*
  //user drag
  document.addEventListener('selectionchange', function() {
    var sel = document.getSelection().anchorNode;
    if(sel) {
      sel = sel.parentElement;
      if(sel != lastSelected) {
        lastSelected.removeEventListener('click', selClicked);
        sel.addEventListener('click', selClicked);
        lastSelected = sel;
        lastSelectedTime = Date.now();
      }
    }
  })
  */

  console.log('총 ' + hindex.toString() + '개 디코딩 작업 완료');
})();