add tmux plugin: prefix_highlight

.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