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

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

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

    $completions = @(switch ($command) {
        'bat' {
            [CompletionResult]::new('-l', 'l', [CompletionResultType]::ParameterName, 'Set the language for syntax highlighting.')
            [CompletionResult]::new('--language', 'language', [CompletionResultType]::ParameterName, 'Set the language for syntax highlighting.')
            [CompletionResult]::new('-H', 'H', [CompletionResultType]::ParameterName, 'Highlight lines N through M.')
            [CompletionResult]::new('--highlight-line', 'highlight-line', [CompletionResultType]::ParameterName, 'Highlight lines N through M.')
            [CompletionResult]::new('--file-name', 'file-name', [CompletionResultType]::ParameterName, 'Specify the name to display for a file.')
            [CompletionResult]::new('--diff-context', 'diff-context', [CompletionResultType]::ParameterName, 'diff-context')
            [CompletionResult]::new('--tabs', 'tabs', [CompletionResultType]::ParameterName, 'Set the tab width to T spaces.')
            [CompletionResult]::new('--wrap', 'wrap', [CompletionResultType]::ParameterName, 'Specify the text-wrapping mode (*auto*, never, character).')
            [CompletionResult]::new('--terminal-width', 'terminal-width', [CompletionResultType]::ParameterName, 'Explicitly set the width of the terminal instead of determining it automatically. If prefixed with ''+'' or ''-'', the value will be treated as an offset to the actual terminal width. See also: ''--wrap''.')
            [CompletionResult]::new('--color', 'color', [CompletionResultType]::ParameterName, 'When to use colors (*auto*, never, always).')
            [CompletionResult]::new('--italic-text', 'italic-text', [CompletionResultType]::ParameterName, 'Use italics in output (always, *never*)')
            [CompletionResult]::new('--decorations', 'decorations', [CompletionResultType]::ParameterName, 'When to show the decorations (*auto*, never, always).')
            [CompletionResult]::new('--paging', 'paging', [CompletionResultType]::ParameterName, 'Specify when to use the pager, or use `-P` to disable (*auto*, never, always).')
            [CompletionResult]::new('--pager', 'pager', [CompletionResultType]::ParameterName, 'Determine which pager to use.')
            [CompletionResult]::new('-m', 'm', [CompletionResultType]::ParameterName, 'Use the specified syntax for files matching the glob pattern (''*.cpp:C++'').')
            [CompletionResult]::new('--map-syntax', 'map-syntax', [CompletionResultType]::ParameterName, 'Use the specified syntax for files matching the glob pattern (''*.cpp:C++'').')
            [CompletionResult]::new('--theme', 'theme', [CompletionResultType]::ParameterName, 'Set the color theme for syntax highlighting.')
            [CompletionResult]::new('--style', 'style', [CompletionResultType]::ParameterName, 'Comma-separated list of style elements to display (*default*, auto, full, plain, changes, header, header-filename, header-filesize, grid, rule, numbers, snip).')
            [CompletionResult]::new('-r', 'r', [CompletionResultType]::ParameterName, 'Only print the lines from N to M.')
            [CompletionResult]::new('--line-range', 'line-range', [CompletionResultType]::ParameterName, 'Only print the lines from N to M.')
            [CompletionResult]::new('-A', 'A', [CompletionResultType]::ParameterName, 'Show non-printable characters (space, tab, newline, ..).')
            [CompletionResult]::new('--show-all', 'show-all', [CompletionResultType]::ParameterName, 'Show non-printable characters (space, tab, newline, ..).')
            [CompletionResult]::new('-p', 'p', [CompletionResultType]::ParameterName, 'Show plain style (alias for ''--style=plain'').')
            [CompletionResult]::new('--plain', 'plain', [CompletionResultType]::ParameterName, 'Show plain style (alias for ''--style=plain'').')
            [CompletionResult]::new('-d', 'd', [CompletionResultType]::ParameterName, 'Only show lines that have been added/removed/modified.')
            [CompletionResult]::new('--diff', 'diff', [CompletionResultType]::ParameterName, 'Only show lines that have been added/removed/modified.')
            [CompletionResult]::new('-n', 'n', [CompletionResultType]::ParameterName, 'Show line numbers (alias for ''--style=numbers'').')
            [CompletionResult]::new('--number', 'number', [CompletionResultType]::ParameterName, 'Show line numbers (alias for ''--style=numbers'').')
            [CompletionResult]::new('-f', 'f', [CompletionResultType]::ParameterName, 'f')
            [CompletionResult]::new('--force-colorization', 'force-colorization', [CompletionResultType]::ParameterName, 'force-colorization')
            [CompletionResult]::new('-P', 'P', [CompletionResultType]::ParameterName, 'Alias for ''--paging=never''')
            [CompletionResult]::new('--no-paging', 'no-paging', [CompletionResultType]::ParameterName, 'Alias for ''--paging=never''')
            [CompletionResult]::new('--list-themes', 'list-themes', [CompletionResultType]::ParameterName, 'Display all supported highlighting themes.')
            [CompletionResult]::new('-L', 'L', [CompletionResultType]::ParameterName, 'Display all supported languages.')
            [CompletionResult]::new('--list-languages', 'list-languages', [CompletionResultType]::ParameterName, 'Display all supported languages.')
            [CompletionResult]::new('-u', 'u', [CompletionResultType]::ParameterName, 'u')
            [CompletionResult]::new('--unbuffered', 'unbuffered', [CompletionResultType]::ParameterName, 'unbuffered')
            [CompletionResult]::new('--no-config', 'no-config', [CompletionResultType]::ParameterName, 'Do not use the configuration file')
            [CompletionResult]::new('--no-custom-assets', 'no-custom-assets', [CompletionResultType]::ParameterName, 'Do not load custom assets')
            [CompletionResult]::new('--config-file', 'config-file', [CompletionResultType]::ParameterName, 'Show path to the configuration file.')
            [CompletionResult]::new('--generate-config-file', 'generate-config-file', [CompletionResultType]::ParameterName, 'Generates a default configuration file.')
            [CompletionResult]::new('--config-dir', 'config-dir', [CompletionResultType]::ParameterName, 'Show bat''s configuration directory.')
            [CompletionResult]::new('--cache-dir', 'cache-dir', [CompletionResultType]::ParameterName, 'Show bat''s cache directory.')
            [CompletionResult]::new('--diagnostic', 'diagnostic', [CompletionResultType]::ParameterName, 'Show diagnostic information for bug reports.')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print this help message.')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print this help message.')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Show version information.')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Show version information.')
            [CompletionResult]::new('cache', 'cache', [CompletionResultType]::ParameterValue, 'Modify the syntax-definition and theme cache')
            break
        }
        'bat;cache' {
            [CompletionResult]::new('--source', 'source', [CompletionResultType]::ParameterName, 'Use a different directory to load syntaxes and themes from.')
            [CompletionResult]::new('--target', 'target', [CompletionResultType]::ParameterName, 'Use a different directory to store the cached syntax and theme set.')
            [CompletionResult]::new('-b', 'b', [CompletionResultType]::ParameterName, 'Initialize (or update) the syntax/theme cache.')
            [CompletionResult]::new('--build', 'build', [CompletionResultType]::ParameterName, 'Initialize (or update) the syntax/theme cache.')
            [CompletionResult]::new('-c', 'c', [CompletionResultType]::ParameterName, 'Remove the cached syntax definitions and themes.')
            [CompletionResult]::new('--clear', 'clear', [CompletionResultType]::ParameterName, 'Remove the cached syntax definitions and themes.')
            [CompletionResult]::new('--blank', 'blank', [CompletionResultType]::ParameterName, 'Create completely new syntax and theme sets (instead of appending to the default sets).')
            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Prints help information')
            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Prints help information')
            [CompletionResult]::new('-V', 'V', [CompletionResultType]::ParameterName, 'Prints version information')
            [CompletionResult]::new('--version', 'version', [CompletionResultType]::ParameterName, 'Prints version information')
            break
        }
    })

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