More readability improvements

generate-readme-toc.js

@@ -1,5 +1,15 @@
 import fs from 'fs/promises'
 
+const README_FILE = 'README.rst'
+const CONTENTS_HEADING = 'Contents'
+const CONTENTS_UNDERLINE = '--------'
+const TOC_INDENT_LEVELS = {
+  '-': 1,
+  '~': 2,
+  '^': 3,
+}
+const HEADING_UNDERLINE_REGEX = /^[-~^]+$/
+
 async function generateTableOfContents(content) {
   const lines = content.split('\n')
   const headings = []
@@ -10,68 +20,71 @@ async function generateTableOfContents(content) {
     const line = lines[i].trim()
     const nextLine = lines[i + 1]?.trim() || ''
 
-    if (line === 'Contents' && nextLine.startsWith('--------')) {
+    if (line === CONTENTS_HEADING && nextLine.startsWith(CONTENTS_UNDERLINE)) {
       contentsHeadingIndex = i
       parsingHeadings = true // Start parsing headings after the "Contents" section
       i++ // Skip the underline
       continue
     }
 
-    if (parsingHeadings && nextLine && nextLine.match(/^[-~^]+$/)) {
-      const level =
-        nextLine[0] === '-'
-          ? 1
-          : nextLine[0] === '~'
-            ? 2
-            : nextLine[0] === '^'
-              ? 3
-              : 0
+    if (
+      parsingHeadings &&
+      nextLine &&
+      nextLine.match(HEADING_UNDERLINE_REGEX)
+    ) {
+      const level = TOC_INDENT_LEVELS[nextLine[0]] || 0
+
       if (level > 0 && line) {
         headings.push({ text: line, level })
       }
-      i++ // Skip the underline
+
+      i++
     }
   }
 
   // Generate table of contents
-  const toc = [''] // Start with an empty line after the "Contents" section
+  const toc = ['']
   headings.forEach((heading) => {
     const indent = '  '.repeat(heading.level - 1)
+
     toc.push(`${indent}* \`${heading.text} <${heading.text}_>\`_`)
-    toc.push('') // Add a newline after each item
+    toc.push('')
   })
 
   return { toc, contentsHeadingIndex }
 }
 
+function findTocEndIndex(lines, startIndex) {
+  return lines.findIndex(
+    (line, index) =>
+      index > startIndex + 2 &&
+      !line.trim().startsWith('*') &&
+      line.trim() !== '',
+  )
+}
+
 async function updateReadme() {
   try {
-    const content = await fs.readFile('README.rst', 'utf8')
+    const content = await fs.readFile(README_FILE, 'utf8')
     const { toc, contentsHeadingIndex } = await generateTableOfContents(content)
 
     if (contentsHeadingIndex === -1) {
-      console.error('Contents heading not found in the README.')
-      process.exit(1)
+      throw new Error('Contents heading not found in the README.')
     }
 
     const lines = content.split('\n')
-    const tocTableEndIndex = lines.findIndex(
-      (line, index) =>
-        index > contentsHeadingIndex + 2 &&
-        !line.trim().startsWith('*') &&
-        line.trim() !== '',
-    )
+    const tocEndIndex = findTocEndIndex(lines, contentsHeadingIndex)
 
     const newContent = [
-      ...lines.slice(0, contentsHeadingIndex + 2), // Include readme content before "Contents" heading, the heading itself and its underline
+      ...lines.slice(0, contentsHeadingIndex + 2), // Include content before "Contents" heading, the heading itself and its underline
       ...toc,
-      ...lines.slice(tocTableEndIndex), // Include all content after the previous TOC
+      ...lines.slice(tocEndIndex),
     ].join('\n')
 
-    await fs.writeFile('README.rst', newContent)
-    console.log('Table of Contents has been updated in README.rst')
+    await fs.writeFile(README_FILE, newContent)
+    console.log(`Table of Contents has been updated in ${README_FILE}`)
   } catch (error) {
-    console.error('Error processing file:', error)
+    console.error('Error updating README:', error.message)
     process.exit(1)
   }
 }