#!/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