From ba90879ff0ea161098f8fd34bb46db64cd7fcda4 Mon Sep 17 00:00:00 2001
From: Evan Fiordeliso <evan.fiordeliso@gmail.com>
Date: Mon, 13 Nov 2023 18:37:37 -0500
Subject: [PATCH] Add powershell completions implementation

---
 completions_powershell.go | 65 +++++++++++++++++++++++++++++++++++++--
 tpl_funcs.go              |  5 +++
 2 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/completions_powershell.go b/completions_powershell.go
index 3c4cf4b..ea55e56 100644
--- a/completions_powershell.go
+++ b/completions_powershell.go
@@ -19,12 +19,71 @@ var powerShellTpl = template.Must(template.New("PowerShell").Funcs(tplFuncs).Par
 {{- $progName := $rootCmd.Name -}}
 {{- $varName := $rootCmd.Name | camel -}}
 
+{{- define "cmd" -}}
+{{- $progName := .ProgName -}}
+{{- if .Cmd.IsRoot }}
+{{- /**/}}            '{{ $progName }}' {
+{{- else }}
+{{- /**/}}            '{{ $progName }};{{ join (split .Cmd.CommandPath " ") ";" }}' {
+{{- end -}}
+{{- range .Cmd.Opts -}}
+{{ if ne .Name "" }}
+                [CompletionResult]::new('--{{ .Name }}', '{{ .Name }}', [CompletionResultType]::ParameterName, '{{ .Description }}')
+{{- end -}}
+{{- if ne .ShortName "" }}
+                [CompletionResult]::new('-{{ .ShortName }}', '{{ .ShortName }}', [CompletionResultType]::ParameterName, '{{ .Description }}')
+{{- end -}}
+{{- end }}
+{{- range .Cmd.Subcommands }}
+                [CompletionResult]::new('{{ .Name }}', '{{ .Name }}', [CompletionResultType]::ParameterValue, '{{ .ShortDescription }}')
+{{- end }}
+                break;
+            }
+{{- range .Cmd.Subcommands }}
+{{ template "cmd" (map "Cmd" . "ProgName" $progName) }}
+{{- end -}}
+{{- end -}}
+using namespace System.Management.Automation
+using namespace System.Management.Automation.Language
+
 [scriptblock]$__{{ $varName }}CompleterBlock = {
     param(
-        $WordToComplete,
-        $CommandAst,
-        $CursorPosition
+        $wordToComplete,
+        $commandAst,
+        $cursorPosition
     )
+
+    $commandElements
+    $command = @(
+        '{{ $progName }}'
+        for ($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) {
+{{ template "cmd" (map "Cmd" $rootCmd "ProgName" $progName) }}
+        }
+{{- range .GlobalOpts -}}
+{{- if ne .Name "" }}
+        [CompletionResult]::new('--{{ .Name }}', '{{ .Name }}', [CompletionResultType]::ParameterName, '{{ .Description }}')
+{{- end -}}
+{{- if ne .ShortName "" }}
+        [CompletionResult]::new('-{{ .ShortName }}', '{{ .ShortName }}', [CompletionResultType]::ParameterName, '{{ .Description }}')
+{{- end -}}
+{{- end -}}
+    )
+
+    $completions.Where{ $_.CompletionText -like "$wordToComplete*" } |
+        Sort-Object -Property ListItemText
 }
 
 Register-ArgumentCompleter -CommandName {{ $progName }} -ScriptBlock $__{{ $varName }}CompleterBlock
diff --git a/tpl_funcs.go b/tpl_funcs.go
index db95e70..ab29b83 100644
--- a/tpl_funcs.go
+++ b/tpl_funcs.go
@@ -11,6 +11,7 @@ import (
 var tplFuncs = template.FuncMap{
 	"map":       tplMap,
 	"cat":       tplCat,
+	"split":     tplSplit,
 	"join":      tplJoin,
 	"under":     tplUnder,
 	"varPrefix": tplVarPrefix,
@@ -41,6 +42,10 @@ func tplCat(strs ...string) string {
 	return strings.Join(strs, "")
 }
 
+func tplSplit(s string, sep string) []string {
+	return strings.Split(s, sep)
+}
+
 func tplJoin(strs []string, sep string) string {
 	return strings.Join(strs, sep)
 }