add tmux plugin: prefix_highlight

.tmux.conf

@@ -33,7 +33,6 @@ set -g mouse-select-pane on
 set -g mouse-resize-pane
 set -g mouse-select-window on
 
-
 ##########################################
 ### Styling
 ##########################################
@@ -54,7 +53,7 @@ set -g status-fg colour137
 set -g status-attr dim
 set -g status-left ''
 set -g status-left-length 20
-set -g status-right "#[fg=colour233,bg=colour245,bold] #(tmux-mem-cpu-load -g 5 --interval 1) %H:%M:%S "
+set -g status-right "#{prefix_highlight} #[fg=colour233,bg=colour245,bold] #(tmux-mem-cpu-load -g 5 --interval 1) %H:%M:%S "
 set -g status-right-length 60
 
 # messaging
@@ -138,3 +137,14 @@ bind-key C-b last-window
 
 # special settings for MacOS
 if-shell 'test "$(uname)" = "Darwin"' 'source ~/.tmux-osx.conf'
+
+##########################################
+### Plugins
+##########################################
+
+# prefix_highlight (https://github.com/tmux-plugins/tmux-prefix-highlight)
+run-shell ~/.tmux/prefix_highlight.tmux
+set -g @prefix_highlight_fg 'white' # default is 'colour231'
+set -g @prefix_highlight_bg 'blue'  # default is 'colour04'
+set -g @prefix_highlight_show_copy_mode 'on'
+set -g @prefix_highlight_copy_mode_attr 'fg=black,bg=yellow,bold' # default is 'fg=default,bg=yellow'

.tmux/prefix_highlight.tmux

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+
+set -e
+
+# Place holder for status left/right
+place_holder="\#{prefix_highlight}"
+
+# Possible configurations
+fg_color_config='@prefix_highlight_fg'
+bg_color_config='@prefix_highlight_bg'
+show_copy_config='@prefix_highlight_show_copy_mode'
+copy_attr_config='@prefix_highlight_copy_mode_attr'
+
+# Defaults
+default_fg='colour231'
+default_bg='colour04'
+default_copy_attr='fg=default,bg=yellow'
+
+tmux_option() {
+    local -r value=$(tmux show-option -gqv "$1")
+    local -r default="$2"
+
+    if [ ! -z "$value" ]; then
+        echo "$value"
+    else
+        echo "$default"
+    fi
+}
+
+highlight() {
+    local -r \
+        status="$1" \
+        prefix="$2" \
+        prefix_highlight="$3" \
+        show_copy_mode="$4" \
+        copy_highlight="$5"
+
+    local -r status_value="$(tmux_option "$status")"
+
+    if [[ "on" = "$show_copy_mode" ]]; then
+        local -r fallback="${copy_highlight}#{?pane_in_mode,Copy,}"
+    else
+        local -r fallback=""
+    fi
+
+    local -r highlight_on_prefix="${prefix_highlight}#{?client_prefix, $prefix ,$fallback}#[default]"
+    tmux set-option -gq "$status" "${status_value/$place_holder/$highlight_on_prefix}"
+}
+
+main() {
+    local -r \
+        prefix=$(tmux_option prefix) \
+        fg_color=$(tmux_option "$fg_color_config" "$default_fg") \
+        bg_color=$(tmux_option "$bg_color_config" "$default_bg") \
+        show_copy_mode=$(tmux_option "$show_copy_config" "off") \
+        copy_attr=$(tmux_option "$copy_attr_config" "$default_copy_attr")
+
+    local -r short_prefix=$(
+        echo "$prefix" | tr "[:lower:]" "[:upper:]" | sed 's/C-/\^/'
+    )
+
+    local -r \
+        prefix_highlight="#[fg=$fg_color,bg=$bg_color]" \
+        copy_highlight="${copy_attr:+#[default,$copy_attr]}"
+
+    highlight "status-right" "$short_prefix" "$prefix_highlight" "$show_copy_mode" "$copy_highlight"
+    highlight "status-left" "$short_prefix" "$prefix_highlight" "$show_copy_mode" "$copy_highlight"
+}
+
+main