From 0ebb0c58103c4e095f4ca29ef4ca1ff91c37c28f Mon Sep 17 00:00:00 2001
From: Mimi <1119186082@qq.com>
Date: Wed, 29 Jul 2020 17:05:45 +0800
Subject: [PATCH] Optimize local search (#64)

* Highlight search keywords

* Sort search results by the number of keywords included
---
 layout/_partials/search/localsearch.njk       |   2 +-
 scripts/helpers/next-config.js                |  16 +-
 .../components/third-party/search.styl        |  13 +-
 source/js/local-search.js                     | 343 ++++++++++--------
 4 files changed, 211 insertions(+), 163 deletions(-)

diff --git a/layout/_partials/search/localsearch.njk b/layout/_partials/search/localsearch.njk
index df81e95..26931e6 100644
--- a/layout/_partials/search/localsearch.njk
+++ b/layout/_partials/search/localsearch.njk
@@ -3,7 +3,7 @@
     <i class="fa fa-search"></i>
   </span>
   <div class="search-input-container">
-    <input autocomplete="off" autocapitalize="off"
+    <input autocomplete="off" autocapitalize="off" maxlength="80"
            placeholder="{{ __('search.placeholder') }}" spellcheck="false"
            type="search" class="search-input">
   </div>
diff --git a/scripts/helpers/next-config.js b/scripts/helpers/next-config.js
index cef8bea..89d5b9a 100644
--- a/scripts/helpers/next-config.js
+++ b/scripts/helpers/next-config.js
@@ -9,7 +9,6 @@ const { parse } = require('url');
  */
 hexo.extend.helper.register('next_config', function() {
   const { config, theme, next_version } = this;
-  config.algolia = config.algolia || {};
   const exportConfig = {
     hostname  : parse(config.url).hostname || config.url,
     root      : config.root,
@@ -24,19 +23,22 @@ hexo.extend.helper.register('next_config', function() {
     lazyload  : theme.lazyload,
     pangu     : theme.pangu,
     comments  : theme.comments,
-    algolia   : {
+    motion    : theme.motion,
+    prism     : config.prismjs.enable && !config.prismjs.preprocess
+  };
+  if (theme.algolia_search && theme.algolia_search.enable) {
+    config.algolia = config.algolia || {};
+    exportConfig.algolia = {
       appID    : config.algolia.applicationID,
       apiKey   : config.algolia.apiKey,
       indexName: config.algolia.indexName,
       hits     : theme.algolia_search.hits,
       labels   : theme.algolia_search.labels
-    },
-    localsearch: theme.local_search,
-    motion     : theme.motion,
-    prism      : config.prismjs.enable && !config.prismjs.preprocess
-  };
+    };
+  }
   if (config.search) {
     exportConfig.path = config.search.path;
+    exportConfig.localsearch = theme.local_search;
   }
   return `<script class="hexo-configurations">
     var NexT = window.NexT || {};
diff --git a/source/css/_common/components/third-party/search.styl b/source/css/_common/components/third-party/search.styl
index ff75552..0673cbb 100644
--- a/source/css/_common/components/third-party/search.styl
+++ b/source/css/_common/components/third-party/search.styl
@@ -154,12 +154,6 @@ if (hexo-config('local_search.enable')) {
       font-weight: bold;
     }
 
-    .search-keyword {
-      border-bottom: 1px dashed $red;
-      color: $red;
-      font-weight: bold;
-    }
-
     #search-result {
       display: flex;
       height: calc(100% - 55px);
@@ -172,4 +166,11 @@ if (hexo-config('local_search.enable')) {
       margin: auto;
     }
   }
+
+  mark.search-keyword {
+    background: transparent;
+    border-bottom: 1px dashed $red;
+    color: $red;
+    font-weight: bold;
+  }
 }
diff --git a/source/js/local-search.js b/source/js/local-search.js
index 5e5ae15..cb0efde 100644
--- a/source/js/local-search.js
+++ b/source/js/local-search.js
@@ -1,52 +1,56 @@
 /* global CONFIG */
 
 document.addEventListener('DOMContentLoaded', () => {
+  if (!CONFIG.path) {
+    console.warn('`hexo-generator-searchdb` plugin is not installed!');
+    return;
+  }
   // Popup Window
   let isfetched = false;
   let datas;
-  let isXml = true;
-  // Search DB path
-  let searchPath = CONFIG.path;
-  if (searchPath.length === 0) {
-    searchPath = 'search.xml';
-  } else if (searchPath.endsWith('json')) {
-    isXml = false;
-  }
   const input = document.querySelector('.search-input');
-  const resultContent = document.getElementById('search-result');
 
-  const getIndexByWord = (word, text, caseSensitive) => {
-    if (CONFIG.localsearch.unescape) {
-      const div = document.createElement('div');
-      div.innerText = word;
-      word = div.innerHTML;
-    }
-    const wordLen = word.length;
-    if (wordLen === 0) return [];
-    let startPosition = 0;
-    let position = [];
+  const getIndexByWord = (words, text, caseSensitive = false) => {
     const index = [];
-    if (!caseSensitive) {
-      text = text.toLowerCase();
-      word = word.toLowerCase();
-    }
-    while ((position = text.indexOf(word, startPosition)) > -1) {
-      index.push({ position, word });
-      startPosition = position + wordLen;
-    }
-    return index;
+    const included = new Set();
+    words.forEach(word => {
+      if (CONFIG.localsearch.unescape) {
+        const div = document.createElement('div');
+        div.innerText = word;
+        word = div.innerHTML;
+      }
+      const wordLen = word.length;
+      if (wordLen === 0) return;
+      let startPosition = 0;
+      let position = -1;
+      if (!caseSensitive) {
+        text = text.toLowerCase();
+        word = word.toLowerCase();
+      }
+      while ((position = text.indexOf(word, startPosition)) > -1) {
+        index.push({ position, word });
+        included.add(word);
+        startPosition = position + wordLen;
+      }
+    });
+    // Sort index by position of keyword
+    index.sort((left, right) => {
+      if (left.position !== right.position) {
+        return left.position - right.position;
+      }
+      return right.word.length - left.word.length;
+    });
+    return [index, included];
   };
 
   // Merge hits into slices
-  const mergeIntoSlice = (start, end, index, searchText) => {
-    let item = index[index.length - 1];
+  const mergeIntoSlice = (start, end, index) => {
+    let item = index[0];
     let { position, word } = item;
     const hits = [];
-    let searchTextCountInSlice = 0;
+    const count = new Set();
     while (position + word.length <= end && index.length !== 0) {
-      if (word === searchText) {
-        searchTextCountInSlice++;
-      }
+      count.add(word);
       hits.push({
         position,
         length: word.length
@@ -54,13 +58,13 @@ document.addEventListener('DOMContentLoaded', () => {
       const wordEnd = position + word.length;
 
       // Move to next position of hit
-      index.pop();
+      index.shift();
       while (index.length !== 0) {
-        item = index[index.length - 1];
+        item = index[0];
         position = item.position;
         word = item.word;
         if (wordEnd > position) {
-          index.pop();
+          index.shift();
         } else {
           break;
         }
@@ -70,136 +74,114 @@ document.addEventListener('DOMContentLoaded', () => {
       hits,
       start,
       end,
-      searchTextCount: searchTextCountInSlice
+      count: count.size
     };
   };
 
   // Highlight title and content
-  const highlightKeyword = (text, slice) => {
+  const highlightKeyword = (val, slice) => {
     let result = '';
-    let prevEnd = slice.start;
-    slice.hits.forEach(hit => {
-      result += text.substring(prevEnd, hit.position);
-      const end = hit.position + hit.length;
-      result += `<b class="search-keyword">${text.substring(hit.position, end)}</b>`;
-      prevEnd = end;
-    });
-    result += text.substring(prevEnd, slice.end);
+    let index = slice.start;
+    for (const { position, length } of slice.hits) {
+      result += val.substring(index, position);
+      index = position + length;
+      result += `<mark class="search-keyword">${val.substr(position, length)}</mark>`;
+    }
+    result += val.substring(index, slice.end);
     return result;
   };
 
+  const getResultItems = keywords => {
+    const resultItems = [];
+    datas.forEach(({ title, content, url }) => {
+      // The number of different keywords included in the article.
+      const [indexOfTitle, keysOfTitle] = getIndexByWord(keywords, title);
+      const [indexOfContent, keysOfContent] = getIndexByWord(keywords, content);
+      const includedCount = new Set([...keysOfTitle, ...keysOfContent]).size;
+
+      // Show search results
+      const hitCount = indexOfTitle.length + indexOfContent.length;
+      if (hitCount === 0) return;
+
+      const slicesOfTitle = [];
+      if (indexOfTitle.length !== 0) {
+        slicesOfTitle.push(mergeIntoSlice(0, title.length, indexOfTitle));
+      }
+
+      let slicesOfContent = [];
+      while (indexOfContent.length !== 0) {
+        const item = indexOfContent[0];
+        const { position } = item;
+        // Cut out 100 characters. The maxlength of .search-input is 80.
+        const start = Math.max(0, position - 20);
+        const end = Math.min(content.length, position + 80);
+        slicesOfContent.push(mergeIntoSlice(start, end, indexOfContent));
+      }
+
+      // Sort slices in content by included keywords' count and hits' count
+      slicesOfContent.sort((left, right) => {
+        if (left.count !== right.count) {
+          return right.count - left.count;
+        } else if (left.hits.length !== right.hits.length) {
+          return right.hits.length - left.hits.length;
+        }
+        return left.start - right.start;
+      });
+
+      // Select top N slices in content
+      const upperBound = parseInt(CONFIG.localsearch.top_n_per_article, 10);
+      if (upperBound >= 0) {
+        slicesOfContent = slicesOfContent.slice(0, upperBound);
+      }
+
+      let resultItem = '';
+
+      url = new URL(url, location.origin);
+      url.searchParams.append('highlight', keywords.join(' '));
+
+      if (slicesOfTitle.length !== 0) {
+        resultItem += `<li><a href="${url.href}" class="search-result-title">${highlightKeyword(title, slicesOfTitle[0])}</a>`;
+      } else {
+        resultItem += `<li><a href="${url.href}" class="search-result-title">${title}</a>`;
+      }
+
+      slicesOfContent.forEach(slice => {
+        resultItem += `<a href="${url.href}"><p class="search-result">${highlightKeyword(content, slice)}...</p></a>`;
+      });
+
+      resultItem += '</li>';
+      resultItems.push({
+        item: resultItem,
+        id  : resultItems.length,
+        hitCount,
+        includedCount
+      });
+    });
+    return resultItems;
+  };
+
   const inputEventFunction = () => {
     if (!isfetched) return;
     const searchText = input.value.trim().toLowerCase();
     const keywords = searchText.split(/[-\s]+/);
-    if (keywords.length > 1) {
-      keywords.push(searchText);
-    }
-    const resultItems = [];
+    const resultContent = document.getElementById('search-result');
+    let resultItems = [];
     if (searchText.length > 0) {
       // Perform local searching
-      datas.forEach(({ title, content, url }) => {
-        const titleInLowerCase = title.toLowerCase();
-        const contentInLowerCase = content.toLowerCase();
-        let indexOfTitle = [];
-        let indexOfContent = [];
-        let searchTextCount = 0;
-        keywords.forEach(keyword => {
-          indexOfTitle = indexOfTitle.concat(getIndexByWord(keyword, titleInLowerCase, false));
-          indexOfContent = indexOfContent.concat(getIndexByWord(keyword, contentInLowerCase, false));
-        });
-
-        // Show search results
-        if (indexOfTitle.length > 0 || indexOfContent.length > 0) {
-          const hitCount = indexOfTitle.length + indexOfContent.length;
-          // Sort index by position of keyword
-          [indexOfTitle, indexOfContent].forEach(index => {
-            index.sort((itemLeft, itemRight) => {
-              if (itemRight.position !== itemLeft.position) {
-                return itemRight.position - itemLeft.position;
-              }
-              return itemLeft.word.length - itemRight.word.length;
-            });
-          });
-
-          const slicesOfTitle = [];
-          if (indexOfTitle.length !== 0) {
-            const tmp = mergeIntoSlice(0, title.length, indexOfTitle, searchText);
-            searchTextCount += tmp.searchTextCountInSlice;
-            slicesOfTitle.push(tmp);
-          }
-
-          let slicesOfContent = [];
-          while (indexOfContent.length !== 0) {
-            const item = indexOfContent[indexOfContent.length - 1];
-            const { position, word } = item;
-            // Cut out 100 characters
-            let start = position - 20;
-            let end = position + 80;
-            if (start < 0) {
-              start = 0;
-            }
-            if (end < position + word.length) {
-              end = position + word.length;
-            }
-            if (end > content.length) {
-              end = content.length;
-            }
-            const tmp = mergeIntoSlice(start, end, indexOfContent, searchText);
-            searchTextCount += tmp.searchTextCountInSlice;
-            slicesOfContent.push(tmp);
-          }
-
-          // Sort slices in content by search text's count and hits' count
-          slicesOfContent.sort((sliceLeft, sliceRight) => {
-            if (sliceLeft.searchTextCount !== sliceRight.searchTextCount) {
-              return sliceRight.searchTextCount - sliceLeft.searchTextCount;
-            } else if (sliceLeft.hits.length !== sliceRight.hits.length) {
-              return sliceRight.hits.length - sliceLeft.hits.length;
-            }
-            return sliceLeft.start - sliceRight.start;
-          });
-
-          // Select top N slices in content
-          const upperBound = parseInt(CONFIG.localsearch.top_n_per_article, 10);
-          if (upperBound >= 0) {
-            slicesOfContent = slicesOfContent.slice(0, upperBound);
-          }
-
-          let resultItem = '';
-
-          if (slicesOfTitle.length !== 0) {
-            resultItem += `<li><a href="${url}" class="search-result-title">${highlightKeyword(title, slicesOfTitle[0])}</a>`;
-          } else {
-            resultItem += `<li><a href="${url}" class="search-result-title">${title}</a>`;
-          }
-
-          slicesOfContent.forEach(slice => {
-            resultItem += `<a href="${url}"><p class="search-result">${highlightKeyword(content, slice)}...</p></a>`;
-          });
-
-          resultItem += '</li>';
-          resultItems.push({
-            item: resultItem,
-            id  : resultItems.length,
-            hitCount,
-            searchTextCount
-          });
-        }
-      });
+      resultItems = getResultItems(keywords);
     }
     if (keywords.length === 1 && keywords[0] === '') {
       resultContent.innerHTML = '<div id="no-result"><i class="fa fa-search fa-5x"></i></div>';
     } else if (resultItems.length === 0) {
       resultContent.innerHTML = '<div id="no-result"><i class="far fa-frown fa-5x"></i></div>';
     } else {
-      resultItems.sort((resultLeft, resultRight) => {
-        if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
-          return resultRight.searchTextCount - resultLeft.searchTextCount;
-        } else if (resultLeft.hitCount !== resultRight.hitCount) {
-          return resultRight.hitCount - resultLeft.hitCount;
+      resultItems.sort((left, right) => {
+        if (left.includedCount !== right.includedCount) {
+          return right.includedCount - left.includedCount;
+        } else if (left.hitCount !== right.hitCount) {
+          return right.hitCount - left.hitCount;
         }
-        return resultRight.id - resultLeft.id;
+        return right.id - left.id;
       });
       resultContent.innerHTML = `<ul class="search-result-list">${resultItems.map(result => result.item).join('')}</ul>`;
       window.pjax && window.pjax.refresh(resultContent);
@@ -207,7 +189,10 @@ document.addEventListener('DOMContentLoaded', () => {
   };
 
   const fetchData = () => {
-    fetch(CONFIG.root + searchPath)
+    // Search DB path
+    const searchPath = CONFIG.root + CONFIG.path;
+    const isXml = !CONFIG.path.endsWith('json');
+    fetch(searchPath)
       .then(response => response.text())
       .then(res => {
         // Get the contents from search data
@@ -227,11 +212,68 @@ document.addEventListener('DOMContentLoaded', () => {
           return data;
         });
         // Remove loading animation
-        document.getElementById('no-result').innerHTML = '<i class="fa fa-search fa-5x"></i>';
         inputEventFunction();
       });
   };
 
+  /**
+   * This function returns the parsed url parameters of the
+   * current request. Multiple values per key are supported,
+   * it will always return arrays of strings for the value parts.
+   */
+  const getQueryParameters = () => {
+    const s = location.search;
+    const parts = s.substr(s.indexOf('?') + 1).split('&');
+    const result = {};
+    for (const part of parts) {
+      const [key, value] = part.split('=', 2);
+      if (key in result) {
+        result[key].push(value);
+      } else {
+        result[key] = [value];
+      }
+    }
+    return result;
+  };
+
+  // Highlight by wrapping node in mark elements with the given class name
+  const highlightText = (node, slice, className) => {
+    const val = node.nodeValue;
+    let index = slice.start;
+    const children = [];
+    for (const { position, length } of slice.hits) {
+      const text = document.createTextNode(val.substring(index, position));
+      index = position + length;
+      const mark = document.createElement('mark');
+      mark.className = className;
+      mark.appendChild(document.createTextNode(val.substr(position, length)));
+      children.push(text, mark);
+    }
+    node.nodeValue = val.substring(index, slice.end);
+    children.forEach(element => {
+      node.parentNode.insertBefore(element, node);
+    });
+  };
+
+  // Highlight the search words provided in the url in the text
+  const highlightSearchWords = () => {
+    const params = getQueryParameters();
+    const keywords = params.highlight ? params.highlight[0].split(/\+/).map(decodeURIComponent) : [];
+    const body = document.querySelector('.post-body');
+    if (!keywords.length || !body) return;
+    const walk = document.createTreeWalker(body, NodeFilter.SHOW_TEXT, null, false);
+    const allNodes = [];
+    while (walk.nextNode()) {
+      if (!walk.currentNode.parentNode.matches('button, select, textarea')) allNodes.push(walk.currentNode);
+    }
+    allNodes.forEach(node => {
+      const [indexOfNode] = getIndexByWord(keywords, node.nodeValue);
+      if (!indexOfNode.length) return;
+      const slice = mergeIntoSlice(0, node.nodeValue.length, indexOfNode);
+      highlightText(node, slice, 'search-keyword');
+    });
+  };
+
   if (CONFIG.localsearch.preload) {
     fetchData();
   }
@@ -268,7 +310,10 @@ document.addEventListener('DOMContentLoaded', () => {
     }
   });
   document.querySelector('.popup-btn-close').addEventListener('click', onPopupClose);
-  document.addEventListener('pjax:success', onPopupClose);
+  document.addEventListener('pjax:success', () => {
+    highlightSearchWords();
+    onPopupClose();
+  });
   window.addEventListener('keyup', event => {
     if (event.key === 'Escape') {
       onPopupClose();