// ==UserScript==
// @name            Arca base64 autodecoder
// @name:ko         아카라이브 Base64 자동 디코더
// @version         1.18
// @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
// @grant           GM.setValue
// @grant           GM.getValue
// @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)
 * 1.18 - auto update check, log system
*/

//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
];
//limit max_iter
max_iter = max_iter > regArr.length ? regArr.length : max_iter;
//regex prefix - drag
const regInvalid = /[^\w\+\/=]/;

//update chk
var upd_chk = true;

//info param
const sc_name = '['+GM.info.script.name+']';
const sc_name_upd = '['+GM.info.script.name+'-UPD]';
const sc_ver = GM.info.script.version;

//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'+sc_name,'No.',(hindex+1).toString(),'encoded link:\n', 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(sc_name,'No.',hindex.toString(),'decode completed:\n',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--;
        console.log(sc_name,'No.',hindex.toString(),'- splitted total :', nindex.toString());
        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('\n'+sc_name,'error occured during decoding:', e);
      console.warn(sc_name,'base64 decode fail:', 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 {
      console.log(sc_name,'live match - ' + sel.toString());
      var converted = decodeURI(encodeURI(Base64.decode(base64AddPadding(sel))).replaceAll('%00', ''));
      console.log(sc_name,'converted - ' + converted.toString());
      this.innerHTML = this.innerHTML.replace(sel, converted);
    } catch (e) {
      return;
    } finally {
      this.removeEventListener('click', selClicked);
    }
  }
}

//update check
function checkForUpdate(){
  if (!upd_chk) {
    console.log(sc_name_upd,'updchk skipped.');
    return;
  }
  const tar_sc = 'https://update.greasyfork.org/scripts/482577/Arca%20base64%20autodecoder.user.js';
  fetch(tar_sc)
  .then(response => response.text())
  .then(data => {
    //extract version from greaskyfork script
    const match = data.match(/@version\s+(\d+\.\d+)/);
    if (match) {
      const tar_version = parseFloat(match[1]);
      const cur_version = parseFloat(sc_ver);
      //new version detected
      if (tar_version > cur_version) {
        console.log(sc_name_upd,'new version available. ('+cur_version+' -> '+tar_version+')');
        //y/n dialog
        if (window.confirm(sc_name+'\n새로운 버전이 감지되었습니다. 업데이트를 권장합니다.\n( 기존버전 : '+cur_version+', 새로운 버전 : '+tar_version+' )\n\n취소를 누르면 앞으로 업데이트 확인 알림을 띄우지 않습니다.')) {
          console.log(sc_name_upd,'opening source url..');
          window.location.replace(tar_sc);
        } else {
          GM.setValue('chkupd', false);
          console.log(sc_name_upd,'updchk disabled.');
          window.alert(sc_name+'\n앞으로 업데이트 확인 알림을 띄우지 않습니다.');
        }
      } else {
        console.log(sc_name_upd,'latest version detected.');
      }
    } else {
      console.error(sc_name_upd,'unable to extract version..');
    }
  })
  .catch(error => {
    upd_chk = false;
    console.error(sc_name_upd,'link unreachable.. -', error);
  });
  upd_chk = false;
}

//main
(async () => {
  'use strict';

  //chk browser env
  if(((navigator.language || navigator.userLanguage) != 'ko-KR')) console.warn('Warning! this script support only korean language..');

  console.log(sc_name,'V',sc_ver,'ready');

  //get extension env
  if(GM.info.scriptWillUpdate) {
    //get env
    upd_chk = await GM.getValue('chkupd', true);

    //chk update
    await checkForUpdate();
  }

  //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
  console.log('USR-Drag enabled.');
  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(sc_name,'total',hindex.toString(),'decode task completed.');
})();