✨ Add script to correct markdown headers

- resolves brianary#72

Author: brianary

Repair-MarkdownHeaders.ps1

@@ -0,0 +1,121 @@
+<#
+.SYNOPSIS
+Updates markdown content to replace level 1 & 2 ATX headers to Setext headers.
+
+.FUNCTIONALITY
+Markdown
+
+.INPUTS
+System.String containing markdown code to update.
+
+.OUTPUTS
+System.String containing updated markdown code.
+
+.LINK
+https://webcoder.info/markdown-headers.html
+
+.EXAMPLE
+Repair-MarkdownHeaders.ps1 -Path readme.md -Style SetextWithAtx
+
+Updates the file with the specified header style.
+
+.EXAMPLE
+$content = $markdown |Repair-MarkdownHeaders.ps1 -Style Atx
+
+Returns markdown code that uses ATX headers.
+#>
+
+#Requires -Version 7
+[CmdletBinding()][OutputType([string],ParameterSetName='InputObject')] Param(
+# Markdown file to update.
+[Parameter(ParameterSetName='Path',Position=0,Mandatory=$true)][string] $Path,
+# The text encoding to use when converting text to binary data.
+[Parameter(ParameterSetName='Path',Position=1)]
+[ValidateSet('ascii','utf16','utf16BE','utf32','utf32BE','utf7','utf8')]
+[string] $Encoding = 'utf8',
+# Markdown content to update.
+[Parameter(ParameterSetName='InputObject',ValueFromPipeline=$true)][string] $InputObject,
+# The style of headers to use.
+[ValidateSet('Atx', 'AtxClosed', 'SetextWithAtx')]
+[string] $Style = 'SetextWithAtx',
+# The line endings to use.
+[ValidatePattern('\A\r?\n\z')][string] $NewLine = [Environment]::NewLine
+)
+Begin
+{
+    filter Repair-Atx
+    {
+        [CmdletBinding()] Param(
+        [Parameter(ValueFromPipeline=$true)][string] $InputObject
+        )
+        $md = ConvertFrom-Markdown -InputObject $InputObject
+        $value = switch($md.Tokens)
+        {
+            {$_.Span.Length -eq 0} {}
+            {$_ -is [Markdig.Syntax.HeadingBlock] -and $_.IsSetext}
+            {
+                $headertext = $InputObject.Substring($_.Span.Start, $_.Span.Length).TrimEnd(($_.Level -eq 1 ? '=' : '-')).Trim()
+                "$(New-Object string '#',$_.Level) $headertext"
+            }
+            default {$InputObject.Substring($_.Span.Start, $_.Span.Length).Trim()}
+        }
+        return $value -join "$NewLine$NewLine"
+    }
+
+    filter Repair-AtxClosed
+    {
+        [CmdletBinding()] Param(
+        [Parameter(ValueFromPipeline=$true)][string] $InputObject
+        )
+        $md = ConvertFrom-Markdown -InputObject $InputObject
+        $value = switch($md.Tokens)
+        {
+            {$_.Span.Length -eq 0} {}
+            {$_ -is [Markdig.Syntax.HeadingBlock] -and $_.IsSetext}
+            {
+                $headertext = $InputObject.Substring($_.Span.Start, $_.Span.Length).TrimEnd(($_.Level -eq 1 ? '=' : '-')).Trim()
+                $atx = (New-Object string '#',$_.Level)
+                "$atx $headertext $atx"
+            }
+            {$_ -is [Markdig.Syntax.HeadingBlock] -and !$_.IsSetext}
+            {
+                $headertext = $InputObject.Substring($_.Span.Start, $_.Span.Length).TrimStart($_.HeaderChar).Trim()
+                $atx = (New-Object string '#',$_.Level)
+                "$atx $headertext $atx"
+            }
+            default {$InputObject.Substring($_.Span.Start, $_.Span.Length).Trim()}
+        }
+        return $value -join "$NewLine$NewLine"
+    }
+
+    filter Repair-SetextWithAtx
+    {
+        [CmdletBinding()] Param(
+        [Parameter(ValueFromPipeline=$true)][string] $InputObject
+        )
+        $md = ConvertFrom-Markdown -InputObject $InputObject
+        $value = switch($md.Tokens)
+        {
+            {$_.Span.Length -eq 0} {}
+            {$_ -is [Markdig.Syntax.HeadingBlock] -and $_.Level -lt 3 -and !$_.IsSetext}
+            {
+                $headertext = $InputObject.Substring($_.Span.Start, $_.Span.Length).TrimStart($_.HeaderChar).Trim()
+                "$headertext$NewLine$(New-Object string ($_.Level -eq 1 ? '=' : '-'),$headertext.Length)"
+            }
+            default {$InputObject.Substring($_.Span.Start, $_.Span.Length).Trim()}
+        }
+        return $value -join "$NewLine$NewLine"
+    }
+}
+Process
+{
+    switch($PSCmdlet.ParameterSetName)
+    {
+        InputObject {return $InputObject |& "Repair-$Style"}
+        Path
+        {
+            $content = Get-Content $Path -Raw
+            $content |& "Repair-$Style" |Out-File $Path $Encoding
+        }
+    }
+}

test/data/rehead.md

@@ -0,0 +1,36 @@
+# *Test* `code` [link](to.md)
+
+A test of heading conversion.
+
+## .
+
+Dot!
+
+```ps1
+# comment
+Get-PSDrive env
+```
+
+Alpha
+-----
+
+### Eh
+
+1. A
+2. B
+3. C
+
+### Bee ###
+
+🐝
+
+### Sea #########################################
+
+🌊
+
+## Test 🗝️ Key
+
+```bash
+# output
+echo OK
+```