fix1252/1251 to UTF8 encoding for idv3tags

convertIDv3tags.ps1

# .description: "This script reads the ID3 tags of MP3 files in a directory, corrects the encoding from WINDOWS-1251 (incorrectly displayed as WINDOWS-1252) to UTF-8, and saves the corrected tags back to the files."
# .prerequisites: "To run this script, you must first obtain TagLibSharp.dll. This can be done by downloading it from https://nuget.org/packages/TagLibSharp/2.3.0 or by compiling the sources available at https://github.com/mono/taglib-sharp."
# .how_to_use: "Execute this script in the directory containing the MP3 files you wish to correct. Ensure TagLibSharp.dll is accessible to the script, adjusting the library loading path as necessary."
# You can optionally pass args as -AllArtists, -AllAlbum, -AllPicture, -AllComment to set the appropriate meta properties for a group of files
param(
    # assign $null by default
    [string]$AllArtist = $null,
    [string]$AllAlbum = $null,
    [string]$AllPicture = $null,
    [string]$AllComment = $null

)


Add-Type -Path ".\TagLibSharp.dll"


# Register the code page provider to ensure Windows-1251 is available
# Check if running in PowerShell Core (version 6 and above)
if ($PSVersionTable.PSEdition -eq 'Core') {
    # Register the code page provider to ensure Windows-1251 is available
    [System.Text.Encoding]::RegisterProvider([System.Text.CodePagesEncodingProvider]::Instance)
}
else {
    # obtain binary package from https://nuget.info/packages/System.Text.Encoding.CodePages/ (netstandard 2.0)
    Add-Type -Path ".\System.Text.Encoding.CodePages.dll"
    [System.Text.Encoding]::RegisterProvider([System.Text.CodePagesEncodingProvider]::Instance)
}

function Test-NeedsEncodingCorrection {
    param (
        [string]$text
    )

    # Define the allowed Cyrillic range and additional allowed characters
    $cyrillicRangeStart = [int][char]'А'  # U+0410
    $cyrillicRangeEnd = [int][char]'я'    #p U+044F
    $additionalAllowedChars = @('!', '=', '-', '+', '~', ' ', ',', '.', '\', '(', ')', "'", '"') + ('0'..'9') | ForEach-Object { [int][char]$_ }
    # Convert text to array of Unicode code points

    # Add uppercase Latin alphabet (A-Z) lowercase Latin alphabet (a-z) and 0-9
    $latinLowercase = [char[]]'QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm1234567890' | ForEach-Object { [int][char]$_ }
    $additionalAllowedChars += $latinLowercase

    $codePoints = $text.ToCharArray() | ForEach-Object { [int]$_ }
    $needsCorrection = $false
    # Check each character against the allowed range
    foreach ($codePoint in $codePoints) {
        $isAllowed = ($codePoint -ge $cyrillicRangeStart -and $codePoint -le $cyrillicRangeEnd) -or $additionalAllowedChars -contains $codePoint
        # Write-Host "CodePoint: $codePoint IsAllowed: $isAllowed" uncommnet for debug purposes
        if (-not $isAllowed) {
            $needsCorrection = $true
            break
        }
    }

    # If all characters are within the allowed range, return false
    return $needsCorrection
}



# Define the directory containing the MP3 files
$directoryPath = (Get-Location).Path

# Get all MP3 files in the directory
$mp3Files = Get-ChildItem -Path $directoryPath -Filter *.mp3

foreach ($file in $mp3Files) {
    # Use TagLib# to read the MP3 file
    $mp3 = [TagLib.File]::Create($file.FullName)

    # display progress current file number of total files
    # move cursor back to start of line and print normally it could be as a breeze
    Write-Host $file.Name, "of total:", $mp3Files.Count, "`r"  -NoNewline
    # Read existing tags
    $title = $mp3.Tag.Title
 
    $album = $mp3.Tag.Album

    

    # Assuming the incorrect encoding is Windows-1251, and we need to convert to UTF-8
    # This step might need adjustments based on the actual encoding issues

    # Correct encoding conversion logic
    if (-not [string]::IsNullOrWhiteSpace($title) -and (Test-NeedsEncodingCorrection -text $title)) {
        $bytesTitle = [System.Text.Encoding]::GetEncoding(1252).GetBytes($title)
        $titleCorrected = [System.Text.Encoding]::GetEncoding(1251).GetString($bytesTitle)
    }
    else {
        $bytesTitle = $null #  
        $titleCorrected = $title
        
    }
    

   
    if ($AllComment -ne $null -and $AllComment -ne '') {
        $commentCorrected = $AllComment
    }
    else {
        if (-not [string]::IsNullOrWhiteSpace($mp3.Tag.Comment) -and (Test-NeedsEncodingCorrection -text ($mp3.Tag.Comment)) ) {
            $commentCorrected = [System.Text.Encoding]::GetEncoding(1251).GetString([System.Text.Encoding]::GetEncoding(1252).GetBytes($mp3.Tag.Comment))
        }
        else {
            $commentCorrected = $mp3.Tag.Comment
        }
    }
    
    if ($AllArtist -ne $null -and $AllArtist -ne '') {
        $artistCorrected = $AllArtist
    }
    else {
        $performers = $mp3.Tag.Performers -join ", "
        if (-not [string]::IsNullOrWhiteSpace($performers) -and (Test-NeedsEncodingCorrection -text $performers)) {
            $artistCorrected = [System.Text.Encoding]::GetEncoding(1251).GetString([System.Text.Encoding]::GetEncoding(1252).GetBytes($performers))
        }
        else {
            $artistCorrected = $performers # No conversion needed or performers is empty
        }
    }
    
    if ($AllAlbum -ne $null -and $AllAlbum -ne '') {
        $albumCorrected = $AllAlbum
    }
    else {
        $album = $mp3.Tag.Album
        if (-not [string]::IsNullOrWhiteSpace($album) -and (Test-NeedsEncodingCorrection -text $album)) {
            $albumCorrected = [System.Text.Encoding]::GetEncoding(1251).GetString([System.Text.Encoding]::GetEncoding(1252).GetBytes($album))
        }
        else {
            $albumCorrected = $album # No conversion needed or album is empty
        }
    }
   
    # test if $AllPicture contains valid path to image file and if it does, add it to the mp3 file
    if (-not [string]::IsNullOrWhiteSpace($AllPicture) -and (Test-Path $AllPicture -PathType Leaf)) {
        $mp3.Tag.Pictures = [TagLib.Picture]::CreateFromPath($AllPicture)
    }

    # Update tags with corrected values
    $mp3.Tag.Title = $titleCorrected
    $mp3.Tag.Performers = $artistCorrected -split ", "
    $mp3.Tag.Album = $albumCorrected
    $mp3.Tag.Comment = $commentCorrected

    # Save the changes
    $mp3.Save()

    # Dispose the MP3 object to free resources
    $mp3.Dispose()
}