functions/Read-EBMarkdown.ps1

function Read-EBMarkdown {
    <#
    .SYNOPSIS
        Reads a markdown file and converts it to a page to be built into an ebook
     
    .DESCRIPTION
        Reads a markdown file and converts it to a page to be built into an ebook
     
    .PARAMETER Path
        Path to the file to read.
     
    .EXAMPLE
        PS C:\> Get-ChildItem *.md | Read-EBMarkdown
 
        Reads and converts all markdown files in he current folder
    #>

    [CmdletBinding()]
    param (
        [parameter(ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
        [Alias('FullName')]
        [string[]]
        $Path
    )
    
    begin {
        function ConvertFrom-Markdown {
            [CmdletBinding()]
            param (
                [string]
                $Path,
                
                [int]
                $Index
            )
            
            $lines = Get-Content -Path $Path -Encoding UTF8
            $stringBuilder = New-SBStringBuilder -Name ebook
            
            $inBlock = $false
            $blockData = [pscustomobject]@{
                Attributes = @{ }
                Type       = $null
                Lines       = @()
                File       = $Path
            }
            $paragraph = @()
            $firstPar = $true
            
            foreach ($line in $lines) {
                #region Process Block Content
                if ($inBlock) {
                    if ($line -like '## <*') {
                        try { $firstPar = ConvertFrom-MdBlock -Type $blockData.Type -Lines $blockData.Lines -Attributes $blockData.Attributes -StringBuilder $stringBuilder }
                        catch { Stop-PSFFunction -Message 'Failed to convert block' -ErrorRecord $_ -Target $blockData -EnableException $true -Cmdlet $PSCmdlet }
                        $inBlock = $false
                    }
                    else { $blockData.Lines += $line }
                    
                    continue
                }
                #endregion Process Block Content
                
                # Handle Chapter Title
                if ($line -like '# *') {
                    $null = $stringBuilder.AppendLine("<h2>$($line -replace '^# ')</h2>")
                    continue
                }
                
                # Handle begin of a Block
                if ($line -like '## <*') {
                    $inBlock = $true
                    $blockData = New-Block -Line $line -Path $Path
                    continue
                }
                
                #region Process paragraph
                if ($line.Trim() -eq "") {
                    if (-not $paragraph) { continue }
                    
                    $class = 'text'
                    if ($firstPar) {
                        $class = 'firstpar'
                        $firstPar = $false
                    }
                    
                    $null = $stringBuilder.AppendLine("<p class=`"$class`">$(($paragraph -join " ") -replace '\*\*(.+?)\*\*', '<b>$1</b>' -replace '_(.+?)_', '<i>$1</i>')</p>")
                    $paragraph = @()
                    continue
                }
                
                $paragraph += $line
                #endregion Process paragraph
            }
            
            #region Ensure final paragraph is taken care of
            if ($paragraph) {
                $class = 'text'
                if ($firstPar) {
                    $class = 'firstpar'
                    $firstPar = $false
                }
                
                $null = $stringBuilder.AppendLine("<p class=`"$class`">$(($paragraph -join " ") -replace '\*\*(.+?)\*\*', '<b>$1</b>' -replace '_(.+?)_', '<i>$1</i>')</p>")
            }
            #endregion Ensure final paragraph is taken care of
            
            New-Object EbookBuilder.Page -Property @{
                Index = $Index
                Name  = (Get-Item -Path $Path).BaseName
                Content = Close-SBStringBuilder -Name ebook
                SourceName = $Path
                TimeCreated = Get-Date
                MetaData = @{ }
            }
        }
        
        function New-Block {
            [Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSUseShouldProcessForStateChangingFunctions', '')]
            [CmdletBinding()]
            param (
                [string]
                $Line,
                
                [string]
                $Path
            )
            
            $type = $Line -replace '## <(\w+).+$', '$1'
            $attributes = @{ }
            $entries = $Line | Select-String '(\w+)="(.+?)"' -AllMatches
            foreach ($match in $entries.Matches) {
                $attributes[$match.Groups[1].Value] = $match.Groups[2].Value
            }
            
            [pscustomobject]@{
                Attributes = $attributes
                Type       = $type
                Lines       = @()
                File       = $Path
            }
        }
        
        $Index = 1
    }
    process {
        foreach ($pathItem in $Path) {
            Write-PSFMessage -Message "Processing: $pathItem"
            ConvertFrom-Markdown -Path $pathItem -Index $Index
            $Index++
        }
    }
}