From dda8485d57bc59bd4781ea43cf1dc200351afebe Mon Sep 17 00:00:00 2001
From: Martin Fischer <martin@push-f.com>
Date: Thu, 12 Dec 2024 08:31:51 +0100
Subject: enable SSH host-specific terminal background colors

---
 nixos/parts/graphical.nix   | 12 ++++++++++++
 user/zsh/zshrc-graphical.sh | 11 +++++++++++
 2 files changed, 23 insertions(+)

diff --git a/nixos/parts/graphical.nix b/nixos/parts/graphical.nix
index 990cd9e..8c340fc 100644
--- a/nixos/parts/graphical.nix
+++ b/nixos/parts/graphical.nix
@@ -18,6 +18,18 @@
     brightnessctl
     wl-clipboard # for wl-copy and wl-paste
 
+    # When I ssh into a server my terminal changes to a host-specific background color via
+    # a LocalCommand configured in ~/.ssh/config and a ZSH function to reset the color on exit.
+    (writeShellScriptBin "set-bg" ''
+      #!/usr/bin/env bash
+      rgb_with_slashes=$(echo "$1" | sed -r 's,(..)(..),\1/\2/,')
+      echo -en "\033]11;rgb:$rgb_with_slashes\007"
+    '')
+    (writeShellScriptBin "reset-bg" ''
+      #!/usr/bin/env bash
+      echo -en "\033]111\007"
+    '')
+
     # graphical tools
     imv
     mpv
diff --git a/user/zsh/zshrc-graphical.sh b/user/zsh/zshrc-graphical.sh
index d60c15a..678448e 100644
--- a/user/zsh/zshrc-graphical.sh
+++ b/user/zsh/zshrc-graphical.sh
@@ -1,5 +1,16 @@
 # This file is sourced by .zshrc if parts/graphical.nix was imported.
 
+function ssh() {
+    # In my ~/.ssh/config I configure host-specific background colors, for example:
+    #
+    #     Host forest
+    #     LocalCommand set-bg 003300
+    #
+    # Since SSH doesn't provide a way of running a command on exit, this shell
+    # function takes care of resetting the background color on exit.
+    command ssh "$@"; reset-bg
+}
+
 if [ $TERM = foot ]; then
     # Enable spawning of new terminal instances in the current working directory
     function osc7-pwd() {
-- 
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