Added completions for PowerShell

completions/dog.ps1

@@ -0,0 +1,90 @@
+# Note: This works for both Windows PowerShell 5.1 and also PowerShell 7 (Core).
+# But beware that in Windows PowerShell 5.1, it has issues with completing args if they start with '-'.
+# For more information about the bug, see: https://github.com/PowerShell/PowerShell/issues/2912
+# In PowerShell 7+, it should work correctly.
+Register-ArgumentCompleter -Native -CommandName 'dog' -ScriptBlock {
+    param($wordToComplete, $commandAst, $cursorPosition)
+
+    [string]$argsString = $commandAst.ToString()
+
+    # skip the "dog", split the args afterwards as array
+    [string[]]$argsArray = $argsString.Split([char[]]@(' ', '=')) | Select-Object -Skip 1
+    if ($argsArray -eq $null) { $argsArray = @() }
+
+    # detect if starting a new arg (aka ending with space and asking for a completion)
+    [bool]$isNewArg = $cursorPosition -gt $argsString.Length
+    if ($isNewArg) {
+        # if writing a new arg, add empty arg so that current and previous would be shifted
+        $argsArray += ''
+    }
+
+    # get current arg (empty if starting new)
+    [string]$currentArg = $argsArray[-1]
+    if ([string]::IsNullOrEmpty($currentArg)) {
+        $currentArg = ''
+    }
+
+    # get previous arg
+    [string]$previousArg = $argsArray[-2]
+    if ([string]::IsNullOrEmpty($previousArg)) {
+        $previousArg = ''
+    }
+
+    [string[]]$dnsTypeValues = @('A', 'AAAA', 'CAA', 'CNAME', 'HINFO', 'MX', 'NS', 'PTR', 'SOA', 'SRV', 'TXT')
+
+    [string[]]$completions = @()
+    [bool]$isOptionValue = $argsString.EndsWith('=')
+
+    # complete option value
+    switch -Regex ($previousArg) {
+        '^(-q|--query)'       { $isOptionValue = $true }
+        '^(-t|--type)'        { $isOptionValue = $true; $completions += $dnsTypeValues }
+        '^(-n|--nameserver)'  { $isOptionValue = $true }
+        '^(--class)'          { $isOptionValue = $true; $completions += @('IN', 'CH', 'HS') }
+        '^(--edns)'           { $isOptionValue = $true; $completions += @('disable', 'hide', 'show') }
+        '^(--txid)'           { $isOptionValue = $true }
+        '^(-Z)'               { $isOptionValue = $true; $completions += @('aa', 'ad', 'bufsize=', 'cd') }
+        '^(--color|--colour)' { $isOptionValue = $true; $completions += @('always', 'automatic', 'never') }
+    }
+
+    # detect whether to complete option value
+    if ($isOptionValue) {
+        if (!$isNewArg) {
+            # if using =, complete including the option name and =
+            $completions = $completions | ForEach-Object { "$previousArg=$_" }
+        }
+    } 
+    else {
+        # if not completing option value, offer DNS type values first
+        $completions += $dnsTypeValues
+
+        # complete option name
+        [string[]]$allOptions = @(
+            '-q', '--query',
+            '-t', '--type',
+            '-n', '--nameserver',
+            '--class',
+            '--edns',
+            '--txid',
+            '-Z',
+            '-U', '--udp',
+            '-T', '--tcp',
+            '-S', '--tls',
+            '-H', '--https',
+            '-1', '--short',
+            '-J', '--json',
+            '--color', '--colour',
+            '--seconds',
+            '--time',
+            '-?', '--help',
+            '-v', '--version'
+        ) | Sort-Object
+
+        $completions += $allOptions
+    }
+
+    if ($completions.Count -gt 0) {
+        # narrow down completions by like* matching
+        return $completions -like "$currentArg*"
+    }
+}