From 7a729db684f4bc54f8376aeee242511a1cb06aaf Mon Sep 17 00:00:00 2001
From: Niraj Acharya <nirajacharyacode@gmail.com>
Date: Thu, 29 Feb 2024 16:50:08 +0545
Subject: [PATCH] adding collapsible table of content

---
 src/components/detail/ContentSidebar.vue | 29 +--------
 src/components/detail/TOC.vue            | 81 ++++++++++++++++++++++++
 src/helpers/markdown.js                  | 44 ++++++++++++-
 3 files changed, 124 insertions(+), 30 deletions(-)
 create mode 100644 src/components/detail/TOC.vue

diff --git a/src/components/detail/ContentSidebar.vue b/src/components/detail/ContentSidebar.vue
index d6b2fb9..2791447 100644
--- a/src/components/detail/ContentSidebar.vue
+++ b/src/components/detail/ContentSidebar.vue
@@ -2,14 +2,7 @@
   <div class="blog-content-sidebar">
     <div class="toc">
       <div class="title sharp-border">Table of content</div>
-      <div v-for="(item, index) in toc"
-        :key="index"
-        class="toc--item"
-        @click="scrollToHeading(item.id)"
-      >
-        <mdi-menu-right class="mdi-circle" />
-        {{ item.text }}
-      </div>
+      <TOC :toc='toc' :hidden="false"/>
     </div>
     <br>
     <div class="title sharp-border">Tags</div>
@@ -28,6 +21,7 @@
 </template>
 <script setup>
 import { defineProps } from "vue"
+import TOC from "./TOC.vue"
 
 defineProps({
   toc: {
@@ -42,25 +36,6 @@ defineProps({
   }
 })
 
-const scrollToHeading = (headingId) => {
-  const xpath = `//*[@id="${headingId}"]`
-  const heading = document.evaluate(
-    xpath,
-    document,
-    null,
-    XPathResult.FIRST_ORDERED_NODE_TYPE,
-    null
-  ).singleNodeValue
-  if (heading) {
-    const position = heading.getBoundingClientRect()
-    // scrolls to 100px above element
-    window.scrollTo({
-      left: position.left,
-      top: position.top + window.scrollY - 100,
-      behavior: "smooth"
-    })
-  }
-}
 </script>
 <style lang="scss">
 .blog-content-sidebar {
diff --git a/src/components/detail/TOC.vue b/src/components/detail/TOC.vue
new file mode 100644
index 0000000..da01565
--- /dev/null
+++ b/src/components/detail/TOC.vue
@@ -0,0 +1,81 @@
+<template>
+  <div>
+    <div
+      v-for="item in toc"
+      :key="item.id"
+      :style="{
+        'padding-left': item.val * 0.2 + 'em',
+        display: hidden ? 'none' : 'block',
+      }"
+      @click="scrollToHeading(item.id, $event)"
+    >
+      <mdi-menu-right class="mdi-circle" @click="hideNested($event)" />
+      {{ item.title }}
+      <TOC v-if="isArray(item.node)" :toc="item.node" :hidden="hidden" />
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { defineProps } from "vue"
+
+// TODO: hide with prop insted of -> hideNested
+
+defineProps({
+  toc: {
+    type: Array
+  },
+  hidden: {
+    type: Boolean
+  }
+})
+
+const isArray = (c) => {
+  return Array.isArray(c)
+}
+
+const scrollToHeading = (headingId, e) => {
+  e.stopPropagation()
+  const xpath = `//*[@id="${headingId}"]`
+  const heading = document.evaluate(
+    xpath,
+    document,
+    null,
+    XPathResult.FIRST_ORDERED_NODE_TYPE,
+    null
+  ).singleNodeValue
+  if (heading) {
+    const position = heading.getBoundingClientRect()
+    window.scrollTo({
+      left: position.left,
+      top: position.top + window.scrollY - 100,
+      behavior: "smooth"
+    })
+  }
+}
+
+const hideNested = (e) => {
+  e.preventDefault()
+  e.stopPropagation()
+  e = e.target
+  while (e.tagName !== "DIV") {
+    e = e.parentElement
+  }
+  e.childNodes.forEach((element) => {
+    if (element.tagName === "DIV") {
+      if (element.classList.length === 0) {
+        element.style.display = "none"
+        element.classList.add("hide")
+      } else {
+        element.style.display = "block"
+        element.classList.remove("hide")
+      }
+    }
+  })
+}
+</script>
+<style scoped>
+.hide {
+  display: none;
+}
+</style>
diff --git a/src/helpers/markdown.js b/src/helpers/markdown.js
index 71f6f8c..8012369 100644
--- a/src/helpers/markdown.js
+++ b/src/helpers/markdown.js
@@ -84,12 +84,50 @@ export const getTableOfContent = (source) => {
   const tokens = marked.lexer(source)
   // remove the first 2 tokens to avoid meta information
   // and then return every tokens that is of header type
-  const headers = tokens.slice(2).filter(token => token.type === "heading" && token.depth <= 4)
-  headers.forEach(header => {
+  const hg = []
+  const headers = tokens
+    .slice(2)
+    .filter((token) => token.type === "heading")// && token.depth <= 4)
+  headers.forEach((header) => {
     const html = marked.parser([header])
     const doc = new DOMParser().parseFromString(html, "text/xml")
     header.id = doc.firstChild.id
     header.text = doc.firstChild.textContent
+    hg.push(new Graph(header.depth, header.text, header.id, null))
   })
-  return headers
+  const stack = [hg[0]]
+  const ans = []
+  hg.forEach((h) => {
+    if (h.val === stack[0].val) {
+      ans.push(h)
+      stack.push(h)
+    } else if (h.val > stack[stack.length - 1].val) {
+      stack[stack.length - 1].addNode(h)
+      stack.push(h)
+    } else if (h.val < stack[stack.length - 1].val) {
+      while (!(h.val > stack[stack.length - 1].val)) {
+        stack.splice(stack.length - 1, 1)
+      }
+      stack[stack.length - 1].addNode(h)
+      stack.push(h)
+    } else {
+      stack.splice(stack.length - 1, 1)
+      stack[stack.length - 1].addNode(h)
+      stack.push(h)
+    }
+  })
+  return ans
+}
+
+class Graph {
+  constructor (val, title, id) {
+    this.val = val
+    this.title = title
+    this.id = id
+    this.node = []
+  }
+
+  addNode (node) {
+    this.node.push(node)
+  }
 }