package cmd

import (
	"io"
	"text/template"

	"go.fifitido.net/cmd/opt"
)

func WritePowerShellCompletions(out io.Writer, rootCmd *Command) error {
	return powerShellTpl.Execute(out, map[string]any{
		"RootCmd":    rootCmd,
		"GlobalOpts": opt.Globals(),
	})
}

var powerShellTpl = template.Must(template.New("PowerShell").Funcs(tplFuncs).Parse(`
{{- $rootCmd := .RootCmd -}}
{{- $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
    )

    $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
`))