window.onload = function() {
    if (document.body.contains(document.goSearch)) {
      document.goSearch.onsubmit = function() { return goSearchNow() };

      /*
      Source:
        - https://github.com/nextapps-de/flexsearch#index-documents-field-search
        - https://raw.githack.com/nextapps-de/flexsearch/master/demo/autocomplete.html
        - http://elasticlunr.com/
        - https://github.com/getzola/zola/blob/master/docs/static/search.js
        - https://github.com/aaranxu/adidoks/blob/main/static/js/search.js
      */
      (function(){
        function inputFocus(e) {

          if (e.keyCode === 191//forward slash
              && document.activeElement.tagName !== "INPUT"
              && document.activeElement.tagName !== "TEXTAREA") {
            e.preventDefault();
            searchinput.focus();
            suggestions.classList.remove('d-none');
          }

          if (e.keyCode === 27 ) {//escape
            searchinput.blur();
            suggestions.classList.add('d-none');
            closeAllLists();
          }

          const focusableSuggestions= suggestions.querySelectorAll('a');
          if (suggestions.classList.contains('d-none')
              || focusableSuggestions.length === 0) {
            return;
          }
          const focusable= [...focusableSuggestions];
          const index = focusable.indexOf(document.activeElement);

          let nextIndex = 0;

          if (e.keyCode === 38) {//up arrow
            e.preventDefault();
            nextIndex= index > 0 ? index-1 : 0;
            focusableSuggestions[nextIndex].focus();
          }
          else if (e.keyCode === 40) {//down arrow
            e.preventDefault();
            nextIndex= index+1 < focusable.length ? index+1 : index;
            focusableSuggestions[nextIndex].focus();
          }

        }

        var suggestions = document.getElementById("suggestions");
        var searchinput = document.getElementById("searchinput");
        document.addEventListener("keydown", inputFocus);
        document.addEventListener("click", function(event) {suggestions.contains(event.target) || suggestions.classList.add("d-none")});

        var lang = document.documentElement.getAttribute("lang");
        var langOnly = lang.substring(0, 2);
        var baseUrl = document.querySelector("meta[name='base']").getAttribute("content");
        if (baseUrl.slice(-1) == "/") {
            baseUrl = baseUrl.slice(0, -1);
        }

        var index;
        searchinput.addEventListener('input', show_results, true);
        suggestions.addEventListener('click', accept_suggestion, true);


        // in page results when press enter or click search icon from search box
        function closeSearchNow() {
            const main = document.querySelector("main");
            main.innerHTML = window.main
        }

        function goSearchNow() {
            const main = document.querySelector("main");
            if (!window.main) {
                window.main = main.innerHTML
            };
            var results = document.getElementById("suggestions");// suggestions div generated by search box

            var ResultsClone = results.cloneNode(true);// make a clone of the results, so that we can alter it
            ResultsClone.id = "results";// alter the id of our clone, so that we can apply different css style

            var headerDiv = document.createElement("div");// create a div element

            var headerContent = '<form name="closeSearch"><h2><button type="submit" title="Close Search"><i class="svgs x"></i></button> <i class="svgs search"></i> '.concat(document.getElementById("searchinput").value, "</h2></form>");// header to use at top of results page

            headerDiv.innerHTML = headerContent;// document element div (headerDiv), set the inner contents to our header html (headerContent)

            ResultsClone.insertBefore(headerDiv, ResultsClone.firstChild);//insert our header div at the top of the page

            main.innerHTML = ResultsClone.outerHTML;//display ResultsClone.outerHTML as the page
            results.innerHTML = "";// clear the suggestions div popup
            document.getElementById("searchinput").value = "";// clear the search input box
            document.body.contains(document.closeSearch) && (document.closeSearch.onsubmit = function() { closeSearchNow() })
            return false
        }

        /* Close search suggestion popup list */
        function closeAllLists(elmnt) {
            var suggestions = document.getElementById("suggestions");
            while (suggestions.firstChild) {
                suggestions.removeChild(suggestions.firstChild);
            }
        }



        async function show_results() {
          var initIndex = async function () {
            if (index === undefined) {
              index = fetch(baseUrl + '/search_index.' + langOnly + '.json')
                .then(
                  async function(response) {
                    return await elasticlunr.Index.load(await response.json());
                }
              );
            }
            let res = await index;
            return res;
          }
          var value = this.value.trim();
          var options = {
            bool: "OR",
            fields: {
              title: {boost: 2},
              body: {boost: 1},
            }
          };
          //var results = index.search(value, options);
          var results = (await initIndex()).search(value, options);

          var entry, childs = suggestions.childNodes;
          var i = 0, len = results.length;
          var items = value.split(/\s+/);
          suggestions.classList.remove('d-none');

          results.forEach(function(page) {
            if (page.doc.body !== '') {
              entry = document.createElement('div');

              entry.innerHTML = '<a href><span></span><span></span></a>';

              a = entry.querySelector('a'),
              t = entry.querySelector('span:first-child'),
              d = entry.querySelector('span:nth-child(2)');
              a.href = page.ref;
              t.textContent = page.doc.title;
              d.innerHTML = makeTeaser(page.doc.body, items);

              suggestions.appendChild(entry);
            }
          });

          while(childs.length > len){
              suggestions.removeChild(childs[i])
          }

        }

        function accept_suggestion(){

            while(suggestions.lastChild){

                suggestions.removeChild(suggestions.lastChild);
            }

            return false;
        }
        // Get the string bytes from binary
        function getByteByBinary(binaryCode) {
          // Binary system, starts with `0b` in ES6
          // Octal number system, starts with `0` in ES5 and starts with `0o` in ES6
          // Hexadecimal, starts with `0x` in both ES5 and ES6
          var byteLengthDatas = [0, 1, 2, 3, 4];
          var len = byteLengthDatas[Math.ceil(binaryCode.length / 8)];
          return len;
        }

        // Get the string bytes from hexadecimal
        function getByteByHex(hexCode) {
          return getByteByBinary(parseInt(hexCode, 16).toString(2));
        }
        // Get substring by bytes
        // If using JavaScript inline substring method, it will return error codes
        // Source: https://www.52pojie.cn/thread-1059814-1-1.html
        function substringByByte(str, maxLength) {
          var result = "";
          var flag = false;
          var len = 0;
          var length = 0;
          var length2 = 0;
          for (var i = 0; i < str.length; i++) {
            var code = str.codePointAt(i).toString(16);
            if (code.length > 4) {
              i++;
              if ((i + 1) < str.length) {
                flag = str.codePointAt(i + 1).toString(16) == "200d";
              }
            }
            if (flag) {
              len += getByteByHex(code);
              if (i == str.length - 1) {
                length += len;
                if (length <= maxLength) {
                  result += str.substr(length2, i - length2 + 1);
                } else {
                  break
                }
              }
            } else {
              if (len != 0) {
                length += len;
                length += getByteByHex(code);
                if (length <= maxLength) {
                  result += str.substr(length2, i - length2 + 1);
                  length2 = i + 1;
                } else {
                  break
                }
                len = 0;
                continue;
              }
              length += getByteByHex(code);
              if (length <= maxLength) {
                if (code.length <= 4) {
                  result += str[i]
                } else {
                  result += str[i - 1] + str[i]
                }
                length2 = i + 1;
              } else {
                break
              }
            }
          }
          return result;
        }
        /* Taken from mdbook
        // The strategy is as follows:
        // First, assign a value to each word in the document:
        //  Words that correspond to search terms (stemmer aware): 40
        //  Normal words: 2
        //  First word in a sentence: 8
        // Then use a sliding window with a constant number of words and count the
        // sum of the values of the words within the window. Then use the window that got the
        // maximum sum. If there are multiple maximas, then get the last one.
        // Enclose the terms in <b>.
        */
        function makeTeaser(body, terms) {
          var TERM_WEIGHT = 40;
          var NORMAL_WORD_WEIGHT = 2;
          var FIRST_WORD_WEIGHT = 8;
          var TEASER_MAX_WORDS = 30;

          var stemmedTerms = terms.map(function (w) {
            return elasticlunr.stemmer(w.toLowerCase());
          });
          var termFound = false;
          var index = 0;
          var weighted = []; // contains elements of ["word", weight, index_in_document]

          // split in sentences, then words
          var sentences = body.toLowerCase().split(". ");
          for (var i in sentences) {
            var words = sentences[i].split(/[\s\n]/);
            var value = FIRST_WORD_WEIGHT;
            for (var j in words) {

              var word = words[j];

              if (word.length > 0) {
                for (var k in stemmedTerms) {
                  if (elasticlunr.stemmer(word).startsWith(stemmedTerms[k])) {
                    value = TERM_WEIGHT;
                    termFound = true;
                  }
                }
                weighted.push([word, value, index]);
                value = NORMAL_WORD_WEIGHT;
              }

              index += word.length;
              index += 1;  // ' ' or '.' if last word in sentence
            }

            index += 1;  // because we split at a two-char boundary '. '
          }

          if (weighted.length === 0) {
            if (body.length !== undefined && body.length > TEASER_MAX_WORDS * 10) {
              return body.substring(0, TEASER_MAX_WORDS * 10) + '...';
            } else {
              return body;
            }
          }

          var windowWeights = [];
          var windowSize = Math.min(weighted.length, TEASER_MAX_WORDS);
          // We add a window with all the weights first
          var curSum = 0;
          for (var i = 0; i < windowSize; i++) {
            curSum += weighted[i][1];
          }
          windowWeights.push(curSum);

          for (var i = 0; i < weighted.length - windowSize; i++) {
            curSum -= weighted[i][1];
            curSum += weighted[i + windowSize][1];
            windowWeights.push(curSum);
          }

          // If we didn't find the term, just pick the first window
          var maxSumIndex = 0;
          if (termFound) {
            var maxFound = 0;
            // backwards
            for (var i = windowWeights.length - 1; i >= 0; i--) {
              if (windowWeights[i] > maxFound) {
                maxFound = windowWeights[i];
                maxSumIndex = i;
              }
            }
          }

          var teaser = [];
          var startIndex = weighted[maxSumIndex][2];
          for (var i = maxSumIndex; i < maxSumIndex + windowSize; i++) {
            var word = weighted[i];
            if (startIndex < word[2]) {
              // missing text from index to start of `word`
              teaser.push(body.substring(startIndex, word[2]));
              startIndex = word[2];
            }

            // add <em/> around search terms
            if (word[1] === TERM_WEIGHT) {
              teaser.push("<b>");
            }

            startIndex = word[2] + word[0].length;
            // Check the string is ascii characters or not
            var re = /^[\x00-\xff]+$/
            if (word[1] !== TERM_WEIGHT && word[0].length >= 12 && !re.test(word[0])) {
              // If the string's length is too long, it maybe a Chinese/Japance/Korean article
              // if using substring method directly, it may occur error codes on emoji chars
              var strBefor = body.substring(word[2], startIndex);
              var strAfter = substringByByte(strBefor, 12);
              teaser.push(strAfter);
            } else {
              teaser.push(body.substring(word[2], startIndex));
            }

            if (word[1] === TERM_WEIGHT) {
              teaser.push("</b>");
            }
          }
          teaser.push("…");
          return teaser.join("");
        }
        document.goSearch.onsubmit = function() { return goSearchNow() };
      }());
    }
};
