powerline: add shlvl

modules/cli/powerline.nix

@@ -22,7 +22,7 @@ in
       args = lib.mkOption {
         type = lib.types.listOf lib.types.str;
         default = [
-          "-modules=\${remote:+'user,host,'}nix-shell,git,jobs,cwd"
+          "-modules=\${remote:+'user,host,'}nix-shell,shlvl,git,jobs,cwd"
           "-git-assume-unchanged-size 0"
           "-theme ${theme}"
           "-path-aliases '~/git=~/git'"
@@ -38,7 +38,12 @@ in
   config = lib.mkIf cfg.enable {
 
     environment.systemPackages = [
-      (pkgs.powerline-go.overrideAttrs (old: { patches = [ ./bold.patch ]; }))
+      (pkgs.powerline-go.overrideAttrs (old: {
+        patches = [
+          ./bold.patch
+          ./shlvl.patch
+        ];
+      }))
     ];
 
     programs.bash.interactiveShellInit = ''

modules/cli/shlvl.patch

@@ -0,0 +1,52 @@
+From 9fd668e356c3b89601109d6f1f53e5843af00af4 Mon Sep 17 00:00:00 2001
+From: Sean Buckley <sean.bck@gmail.com>
+Date: Tue, 7 Dec 2021 16:18:40 -0500
+Subject: [PATCH] add segment-shlvl
+
+---
+ main.go          |  1 +
+ segment-shlvl.go | 23 +++++++++++++++++++++++
+ 2 files changed, 24 insertions(+)
+ create mode 100644 segment-shlvl.go
+
+diff --git a/main.go b/main.go
+index 02f4a4a..2bd111e 100644
+--- a/main.go
++++ b/main.go
+@@ -97,6 +97,7 @@ var modules = map[string]func(*powerline) []pwl.Segment{
+ 	"root":                segmentRoot,
+ 	"shell-var":           segmentShellVar,
+ 	"shenv":               segmentShEnv,
++	"shlvl":               segmentShlvl,
+ 	"ssh":                 segmentSSH,
+ 	"termtitle":           segmentTermTitle,
+ 	"terraform-workspace": segmentTerraformWorkspace,
+diff --git a/segment-shlvl.go b/segment-shlvl.go
+new file mode 100644
+index 0000000..d8bba7d
+--- /dev/null
++++ b/segment-shlvl.go
+@@ -0,0 +1,23 @@
++package main
++
++import (
++	pwl "github.com/justjanne/powerline-go/powerline"
++	"os"
++	"strconv"
++)
++
++func segmentShlvl(p *powerline) []pwl.Segment {
++
++	level, _ := os.LookupEnv("SHLVL")
++	leveli, err := strconv.Atoi(level)
++
++	if err != nil || leveli < 1 {
++		return []pwl.Segment{}
++	}
++	return []pwl.Segment{{
++		Name:       "shlvl",
++		Content:    "\uE7A2 " + level,
++		Foreground: 231,
++		Background: 55,
++	}}
++}