#!/bin/sh

set -eu

# Permission bits of a file, or 600 if they cannot be read. GNU stat spells this
# `-c %a` while BSD/macOS spells it `-f %Lp`, and each mis-parses the other's
# form -- GNU treats `-f` as --file-system and prints a block of filesystem info
# before failing -- so try one at a time and only accept an octal answer.
file_mode() {
    _m=$(stat -c '%a' "$1" 2>/dev/null) || _m=''
    case "$_m" in
        [0-7][0-7][0-7] | [0-7][0-7][0-7][0-7]) printf '%s\n' "$_m"; return 0 ;;
    esac
    _m=$(stat -f '%Lp' "$1" 2>/dev/null) || _m=''
    case "$_m" in
        [0-7][0-7][0-7] | [0-7][0-7][0-7][0-7]) printf '%s\n' "$_m"; return 0 ;;
    esac
    printf '600\n'
}

config_dir=${1:-"$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"}

for appearance in dark light no-preference; do
    config_file="$config_dir/$appearance-theme.auto.conf"
    [ -f "$config_file" ] || continue

    if awk '
        $1 == "macos_titlebar_color" {
            count++
            if ($2 == "background") correct++
        }
        END { exit !(count == 1 && correct == 1) }
    ' "$config_file"; then
        continue
    fi

    tmp=$(mktemp "$config_file.tmp.XXXXXX")
    trap 'rm -f "$tmp"' EXIT HUP INT TERM
    awk '$1 != "macos_titlebar_color"' "$config_file" > "$tmp"
    printf '\nmacos_titlebar_color background\n' >> "$tmp"
    chmod "$(file_mode "$config_file")" "$tmp"
    mv -f "$tmp" "$config_file"
    trap - EXIT HUP INT TERM
done