codeblock intent handling

.gitignore

@@ -16,4 +16,3 @@ thumbs.db
 .env
 .eslintcache
 marktext.code-workspace
-**/*.NEW

.nvmrc

@@ -0,0 +1 @@
+16.15.1

src/muya/lib/contentState/backspaceCtrl.js

@@ -258,29 +258,42 @@ const backspaceCtrl = ContentState => {
       return this.singleRender(startBlock)
     }
 
-    // Fix: https://github.com/marktext/marktext/issues/2013
-    // Also fix the codeblock crashed when the code content is '\n' and press backspace.
     if (
       startBlock.functionType === 'codeContent' &&
       startBlock.key === endBlock.key &&
-      this.cursor.start.offset === this.cursor.end.offset &&
-      (/\n.$/.test(startBlock.text) || startBlock.text === '\n') &&
-      startBlock.text.length === this.cursor.start.offset
+      !(this.cursor.start.offset === 0 && this.cursor.end.offset === 0)
     ) {
       event.preventDefault()
       event.stopPropagation()
-
-      startBlock.text = /\n.$/.test(startBlock.text) ? startBlock.text.replace(/.$/, '') : ''
       const { key } = startBlock
-      const offset = startBlock.text.length
+      let offset
+      const startOffset = this.cursor.start.offset
+      const endOffset = this.cursor.end.offset
+      // Fix: https://github.com/marktext/marktext/issues/2013
+      // Also fix the codeblock crashed when the code content is '\n' and press backspace.
+      if (
+        startOffset === endOffset &&
+        (/\n.$/.test(startBlock.text) || startBlock.text === '\n') &&
+        startBlock.text.length === startOffset
+      ) {
+        startBlock.text = /\n.$/.test(startBlock.text) ? startBlock.text.slice(0, -1) : ''
+        offset = startBlock.text.length
+      } else {
+        // backspace at tabwidth within a codeblock if no text highlighted
+        // and cursor is after a tabWidth of whitespace
+        const regexUnindent = new RegExp(`\n.*(${String.fromCharCode(32).repeat(this.tabSize)})$`)
+        const shouldUnindent = regexUnindent.test(startBlock.text.substring(0, startOffset))
+        const backspaceSize = (shouldUnindent) ? this.tabSize : 1
+        offset = (startOffset === endOffset) ? startOffset - backspaceSize : startOffset
+        startBlock.text = startBlock.text.substring(0, offset) +
+          startBlock.text.substring(endOffset)
+      }
       this.cursor = {
         start: { key, offset },
         end: { key, offset }
       }
-
       return this.singleRender(startBlock)
     }
-
     // If select multiple paragraph or multiple characters in one paragraph, just let
     // inputCtrl to handle this case.
     if (start.key !== end.key || start.offset !== end.offset) {

src/muya/lib/contentState/enterCtrl.js

@@ -9,6 +9,10 @@ const checkAutoIndent = (text, offset) => {
   const pairStr = text.substring(offset - 1, offset + 1)
   return /^(\{\}|\[\]|\(\)|><)$/.test(pairStr)
 }
+const getCodeblockIndentSpace = text => {
+  const match = /\n([ \t]*).*$/.exec(text)
+  return match ? match[1] : ''
+}
 const getIndentSpace = text => {
   const match = /^(\s*)\S/.exec(text)
   return match ? match[1] : ''
@@ -271,7 +275,7 @@ const enterCtrl = ContentState => {
     ) {
       const { text, key } = block
       const autoIndent = checkAutoIndent(text, start.offset)
-      const indent = getIndentSpace(text)
+      const indent = getCodeblockIndentSpace(text.substring(1, start.offset))
       block.text = text.substring(0, start.offset) +
         '\n' +
         (autoIndent ? indent + ' '.repeat(this.tabSize) + '\n' : '') +

src/muya/lib/contentState/tabCtrl.js

@@ -189,7 +189,7 @@ const tabCtrl = ContentState => {
 
   ContentState.prototype.insertTab = function () {
     const tabSize = this.tabSize
-    const tabCharacter = String.fromCharCode(160).repeat(tabSize)
+    const tabCharacter = String.fromCharCode(32).repeat(tabSize)
     const { start, end } = this.cursor
     const startBlock = this.getBlock(start.key)
     const endBlock = this.getBlock(end.key)