using namespace System.Management.Automation
using namespace System.Management.Automation.Language

Register-ArgumentCompleter -Native -CommandName 'utilbox' -ScriptBlock {
    param($wordToComplete, $commandAst, $cursorPosition)

    $commandElements = $commandAst.CommandElements
    $command = @(
        'utilbox'
        for ($i = 1; $i -lt $commandElements.Count; $i++) {
            $element = $commandElements[$i]
            if ($element -isnot [StringConstantExpressionAst] -or
                $element.StringConstantType -ne [StringConstantType]::BareWord -or
                $element.Value.StartsWith('-') -or
                $element.Value -eq $wordToComplete) {
                break
        }
        $element.Value
    }) -join ';'

    $completions = @(switch ($command) {
        'utilbox' {
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('bootstrap', 'bootstrap', [CompletionResultType]::ParameterValue, 'Install shitbox into the filesystem')
            [CompletionResult]::new('clear', 'clear', [CompletionResultType]::ParameterValue, 'clear the terminal''s screen')
            [CompletionResult]::new('mountpoint', 'mountpoint', [CompletionResultType]::ParameterValue, 'see if a directory or file is a mountpoint')
            [CompletionResult]::new('swaplabel', 'swaplabel', [CompletionResultType]::ParameterValue, 'set the label of a swap filesystem')
            [CompletionResult]::new('swapoff', 'swapoff', [CompletionResultType]::ParameterValue, 'disable devices and files for paging and swapping')
            [CompletionResult]::new('umount', 'umount', [CompletionResultType]::ParameterValue, 'unmount filesystems')
            [CompletionResult]::new('help', 'help', [CompletionResultType]::ParameterValue, 'Print this message or the help of the given subcommand(s)')
            break
        }
        'utilbox;bootstrap' {
            [CompletionResult]::new('-p', 'p', [CompletionResultType]::ParameterName, 'The directory path under which to install')
            [CompletionResult]::new('--prefix', 'prefix', [CompletionResultType]::ParameterName, 'The directory path under which to install')
            [CompletionResult]::new('-u', 'u', [CompletionResultType]::ParameterName, 'Use /usr')
            [CompletionResult]::new('--usr', 'usr', [CompletionResultType]::ParameterName, 'Use /usr')
            [CompletionResult]::new('-s', 's', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('--soft', 'soft', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('all', 'all', [CompletionResultType]::ParameterValue, 'Install everything')
            [CompletionResult]::new('links', 'links', [CompletionResultType]::ParameterValue, 'Install links for each applet')
            [CompletionResult]::new('manpages', 'manpages', [CompletionResultType]::ParameterValue, 'Install Unix man pages')
            [CompletionResult]::new('completions', 'completions', [CompletionResultType]::ParameterValue, 'Install shell completions')
            [CompletionResult]::new('help', 'help', [CompletionResultType]::ParameterValue, 'Print this message or the help of the given subcommand(s)')
            break
        }
        'utilbox;bootstrap;all' {
            [CompletionResult]::new('-s', 's', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('--soft', 'soft', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('-a', 'a', [CompletionResultType]::ParameterName, 'Install completions for all supported shells')
            [CompletionResult]::new('--all', 'all', [CompletionResultType]::ParameterName, 'Install completions for all supported shells')
            [CompletionResult]::new('-b', 'b', [CompletionResultType]::ParameterName, 'Bash shell completions')
            [CompletionResult]::new('--bash', 'bash', [CompletionResultType]::ParameterName, 'Bash shell completions')
            [CompletionResult]::new('-f', 'f', [CompletionResultType]::ParameterName, 'Fish shell completions')
            [CompletionResult]::new('--fish', 'fish', [CompletionResultType]::ParameterName, 'Fish shell completions')
            [CompletionResult]::new('-n', 'n', [CompletionResultType]::ParameterName, 'Nushell completions')
            [CompletionResult]::new('--nu', 'nu', [CompletionResultType]::ParameterName, 'Nushell completions')
            [CompletionResult]::new('-p', 'p', [CompletionResultType]::ParameterName, 'PowerShell completions')
            [CompletionResult]::new('--pwsh', 'pwsh', [CompletionResultType]::ParameterName, 'PowerShell completions')
            [CompletionResult]::new('-z', 'z', [CompletionResultType]::ParameterName, 'Zshell completions')
            [CompletionResult]::new('--zsh', 'zsh', [CompletionResultType]::ParameterName, 'Zshell completions')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;bootstrap;links' {
            [CompletionResult]::new('-s', 's', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('--soft', 'soft', [CompletionResultType]::ParameterName, 'Install soft links instead of hardlinks')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;bootstrap;manpages' {
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;bootstrap;completions' {
            [CompletionResult]::new('-a', 'a', [CompletionResultType]::ParameterName, 'Install completions for all supported shells')
            [CompletionResult]::new('--all', 'all', [CompletionResultType]::ParameterName, 'Install completions for all supported shells')
            [CompletionResult]::new('-b', 'b', [CompletionResultType]::ParameterName, 'Bash shell completions')
            [CompletionResult]::new('--bash', 'bash', [CompletionResultType]::ParameterName, 'Bash shell completions')
            [CompletionResult]::new('-f', 'f', [CompletionResultType]::ParameterName, 'Fish shell completions')
            [CompletionResult]::new('--fish', 'fish', [CompletionResultType]::ParameterName, 'Fish shell completions')
            [CompletionResult]::new('-n', 'n', [CompletionResultType]::ParameterName, 'Nushell completions')
            [CompletionResult]::new('--nu', 'nu', [CompletionResultType]::ParameterName, 'Nushell completions')
            [CompletionResult]::new('-p', 'p', [CompletionResultType]::ParameterName, 'PowerShell completions')
            [CompletionResult]::new('--pwsh', 'pwsh', [CompletionResultType]::ParameterName, 'PowerShell completions')
            [CompletionResult]::new('-z', 'z', [CompletionResultType]::ParameterName, 'Zshell completions')
            [CompletionResult]::new('--zsh', 'zsh', [CompletionResultType]::ParameterName, 'Zshell completions')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;bootstrap;help' {
            [CompletionResult]::new('all', 'all', [CompletionResultType]::ParameterValue, 'Install everything')
            [CompletionResult]::new('links', 'links', [CompletionResultType]::ParameterValue, 'Install links for each applet')
            [CompletionResult]::new('manpages', 'manpages', [CompletionResultType]::ParameterValue, 'Install Unix man pages')
            [CompletionResult]::new('completions', 'completions', [CompletionResultType]::ParameterValue, 'Install shell completions')
            [CompletionResult]::new('help', 'help', [CompletionResultType]::ParameterValue, 'Print this message or the help of the given subcommand(s)')
            break
        }
        'utilbox;bootstrap;help;all' {
            break
        }
        'utilbox;bootstrap;help;links' {
            break
        }
        'utilbox;bootstrap;help;manpages' {
            break
        }
        'utilbox;bootstrap;help;completions' {
            break
        }
        'utilbox;bootstrap;help;help' {
            break
        }
        'utilbox;clear' {
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;mountpoint' {
            [CompletionResult]::new('-d', 'd', [CompletionResultType]::ParameterName, 'Show the major/minor numbers of the device that is mounted on the given directory.')
            [CompletionResult]::new('--fs-devno', 'fs-devno', [CompletionResultType]::ParameterName, 'Show the major/minor numbers of the device that is mounted on the given directory.')
            [CompletionResult]::new('-x', 'x', [CompletionResultType]::ParameterName, 'Show the major/minor numbers of the given blockdevice on standard output.')
            [CompletionResult]::new('--devno', 'devno', [CompletionResultType]::ParameterName, 'Show the major/minor numbers of the given blockdevice on standard output.')
            [CompletionResult]::new('-q', 'q', [CompletionResultType]::ParameterName, 'Be quiet - don’t print anything.')
            [CompletionResult]::new('--quiet', 'quiet', [CompletionResultType]::ParameterName, 'Be quiet - don’t print anything.')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;swaplabel' {
            [CompletionResult]::new('-L', 'L', [CompletionResultType]::ParameterName, 'set the label')
            [CompletionResult]::new('-l', 'l', [CompletionResultType]::ParameterName, 'set the label')
            [CompletionResult]::new('--label', 'label', [CompletionResultType]::ParameterName, 'set the label')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;swapoff' {
            [CompletionResult]::new('-a', 'a', [CompletionResultType]::ParameterName, 'Disable swapping on all known swap devices and files as found in /etc/fstab.')
            [CompletionResult]::new('--all', 'all', [CompletionResultType]::ParameterName, 'Disable swapping on all known swap devices and files as found in /etc/fstab.')
            [CompletionResult]::new('-v', 'v', [CompletionResultType]::ParameterName, 'output a diagnostic for every file processed')
            [CompletionResult]::new('--verbose', 'verbose', [CompletionResultType]::ParameterName, 'output a diagnostic for every file processed')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;umount' {
            [CompletionResult]::new('-t', 't', [CompletionResultType]::ParameterName, 'Indicate that the actions should only be taken on filesystems of the specified type.')
            [CompletionResult]::new('--types', 'types', [CompletionResultType]::ParameterName, 'Indicate that the actions should only be taken on filesystems of the specified type.')
            [CompletionResult]::new('-a', 'a', [CompletionResultType]::ParameterName, 'All of the file systems described in /proc/mounts are unmounted. The proc filesystem is not unmounted.')
            [CompletionResult]::new('--all', 'all', [CompletionResultType]::ParameterName, 'All of the file systems described in /proc/mounts are unmounted. The proc filesystem is not unmounted.')
            [CompletionResult]::new('-f', 'f', [CompletionResultType]::ParameterName, 'Force an unmount (in case of an unreachable NFS system).')
            [CompletionResult]::new('--force', 'force', [CompletionResultType]::ParameterName, 'Force an unmount (in case of an unreachable NFS system).')
            [CompletionResult]::new('-l', 'l', [CompletionResultType]::ParameterName, 'Lazy unmount. Detach the filesystem from the fs hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore.')
            [CompletionResult]::new('--lazy', 'lazy', [CompletionResultType]::ParameterName, 'Lazy unmount. Detach the filesystem from the fs hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore.')
            [CompletionResult]::new('-n', 'n', [CompletionResultType]::ParameterName, 'Unmount without writing in /etc/mtab. This is the default action. This flag exists only for historical compatability.')
            [CompletionResult]::new('-v', 'v', [CompletionResultType]::ParameterName, 'output a diagnostic for every file processed')
            [CompletionResult]::new('--verbose', 'verbose', [CompletionResultType]::ParameterName, 'output a diagnostic for every file processed')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help (see more with ''--help'')')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Print version')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Print version')
            break
        }
        'utilbox;help' {
            [CompletionResult]::new('bootstrap', 'bootstrap', [CompletionResultType]::ParameterValue, 'Install shitbox into the filesystem')
            [CompletionResult]::new('clear', 'clear', [CompletionResultType]::ParameterValue, 'clear the terminal''s screen')
            [CompletionResult]::new('mountpoint', 'mountpoint', [CompletionResultType]::ParameterValue, 'see if a directory or file is a mountpoint')
            [CompletionResult]::new('swaplabel', 'swaplabel', [CompletionResultType]::ParameterValue, 'set the label of a swap filesystem')
            [CompletionResult]::new('swapoff', 'swapoff', [CompletionResultType]::ParameterValue, 'disable devices and files for paging and swapping')
            [CompletionResult]::new('umount', 'umount', [CompletionResultType]::ParameterValue, 'unmount filesystems')
            [CompletionResult]::new('help', 'help', [CompletionResultType]::ParameterValue, 'Print this message or the help of the given subcommand(s)')
            break
        }
        'utilbox;help;bootstrap' {
            [CompletionResult]::new('all', 'all', [CompletionResultType]::ParameterValue, 'Install everything')
            [CompletionResult]::new('links', 'links', [CompletionResultType]::ParameterValue, 'Install links for each applet')
            [CompletionResult]::new('manpages', 'manpages', [CompletionResultType]::ParameterValue, 'Install Unix man pages')
            [CompletionResult]::new('completions', 'completions', [CompletionResultType]::ParameterValue, 'Install shell completions')
            break
        }
        'utilbox;help;bootstrap;all' {
            break
        }
        'utilbox;help;bootstrap;links' {
            break
        }
        'utilbox;help;bootstrap;manpages' {
            break
        }
        'utilbox;help;bootstrap;completions' {
            break
        }
        'utilbox;help;clear' {
            break
        }
        'utilbox;help;mountpoint' {
            break
        }
        'utilbox;help;swaplabel' {
            break
        }
        'utilbox;help;swapoff' {
            break
        }
        'utilbox;help;umount' {
            break
        }
        'utilbox;help;help' {
            break
        }
    })

    $completions.Where{ $_.CompletionText -like "$wordToComplete*" } |
        Sort-Object -Property ListItemText
}