#!/bin/sh

set -eu

# Settings the generated theme files must carry whatever theme was saved into
# them. kitty applies <appearance>-theme.auto.conf after -- and with priority
# over -- kitty.conf, so a theme naming one of these wins and there is nowhere
# else left to say otherwise:
#
#   macos_titlebar_color background   titlebar follows the theme's background
#   tab_bar_background none           tab bar uses the terminal background,
#                                     kitty's default and what kitty.conf asks
#                                     for; Catppuccin Latte and others pin a
#                                     contrasting grey, which leaves the tab
#                                     bar a visibly different colour from the
#                                     window it sits above
#
# The canonical copies in ./theme-modes stay exactly as the themes kitten wrote
# them; only these generated files are normalised.

# 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'
}

# The theme with those settings stripped and re-appended in a fixed form.
# Trailing blank lines go too, so running this over its own output reproduces it
# byte for byte and repeated repairs cannot make the file grow.
normalised() {
    awk '
        $1 == "macos_titlebar_color" || $1 == "tab_bar_background" { next }
        { line[++n] = $0 }
        END {
            while (n > 0 && line[n] ~ /^[ \t]*$/) n--
            for (i = 1; i <= n; i++) print line[i]
        }
    ' "$1"
    printf '\nmacos_titlebar_color background\ntab_bar_background none\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

    tmp=$(mktemp "$config_file.tmp.XXXXXX")
    trap 'rm -f "$tmp"' EXIT HUP INT TERM

    normalised "$config_file" > "$tmp"
    if cmp -s "$tmp" "$config_file"; then
        rm -f "$tmp"
    else
        chmod "$(file_mode "$config_file")" "$tmp"
        mv -f "$tmp" "$config_file"
    fi

    trap - EXIT HUP INT TERM
done