package cmd

import (
	"io"
	"text/template"

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

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

var fishTpl = template.Must(template.New("fish").Funcs(tplFuncs).Parse(`
set -l progName {{ .RootCmd.Name }}
set -l commands {{- range .RootCmd.Subcommands }} {{ .Name }}{{ end }}

{{- /* Option template */ -}}
{{ define "opt" }}
complete -c $progName
{{- if ne .Opt.ShortName "" }} -s {{ .Opt.ShortName }} {{ end -}}
{{- if ne .Opt.Name "" }} -l {{ .Opt.Name }} {{ end -}} 
{{- if .Cond }} -n "{{ .Cond }}" {{ end -}}
-d '{{ .Opt.Description }}'
{{- end }}

{{- /* Command template */ -}}
{{ define "cmd" }}
{{ $parentVarPrefix := "" -}}
{{- $varPrefix := join .Cmd.Name "_" -}}
{{- if .VarPrefix -}}
{{- $varPrefix = join .VarPrefix $varPrefix -}}
{{- $parentVarPrefix = .VarPrefix -}}
{{- end -}}

{{ $parentCond := "" }}
{{- $cond := join "__fish_seen_subcommand_from " .Cmd.Name }}
{{- if .Prefix -}}
{{- $cond = join .Prefix $cond -}}
{{- $parentCond = .Prefix -}}
{{- end -}}

set -l {{ $varPrefix }}commands {{- range .Cmd.Subcommands }} {{ .Name }}{{ end }}
complete -f -c $progName -n "{{ $parentCond }}not __fish_seen_subcommand_from ${{ $parentVarPrefix }}commands" -a {{ .Cmd.Name }} -d "{{ .Cmd.ShortDescription }}"

{{- range .Cmd.Opts }}
{{- template "opt" (map "Opt" . "Cond" $cond) -}}
{{ end -}}

{{ $cmdName := .Cmd.Name }}
{{- range .Cmd.Subcommands }}
{{- template "cmd" (map "Cmd" . "Prefix" (join $cond "; ") "VarPrefix" $varPrefix) -}}
{{ end -}}
{{ end }}

{{- /* Top-level commands */ -}}
{{ range .RootCmd.Subcommands }}
{{- template "cmd" (map "Cmd" .) -}}
{{ end }}

{{- /* Root command options */ -}}
{{ range .RootCmd.Opts }}
{{- template "opt" (map "Opt" . "Cond" "not __fish_seen_subcommand_from $commands") -}}
{{ end }}

{{- /* Global options */ -}}
{{ range .GlobalOpts }}
{{- template "opt" (map "Opt" .) -}}
{{ end }}
`))