#!/bin/sh
set -eu

aria2_conf="${1:-/config/aria2.conf}"
tracker_url="${CUSTOM_TRACKER_URL:-https://trackerslist.com/all_aria2.txt}"
tmp_file="$(mktemp)"

cleanup() {
    rm -f "${tmp_file}" "${tmp_file}.conf"
}
trap cleanup EXIT

echo "[INFO] Updating BT trackers from ${tracker_url}"

if ! curl -fsSL --connect-timeout 10 --max-time 20 "${tracker_url}" -o "${tmp_file}"; then
    echo "[WARN] Failed to download tracker list from ${tracker_url}" >&2
    exit 1
fi

trackers="$(
    sed 's/\r$//' "${tmp_file}" |
        awk 'NF {print}' |
        paste -sd, -
)"

if [ -z "${trackers}" ]; then
    echo "[WARN] Tracker list is empty" >&2
    exit 1
fi

if grep -q '^bt-tracker=' "${aria2_conf}"; then
    awk -v value="bt-tracker=${trackers}" '
        BEGIN { replaced = 0 }
        /^bt-tracker=/ { print value; replaced = 1; next }
        { print }
        END { if (!replaced) print value }
    ' "${aria2_conf}" > "${tmp_file}.conf"
else
    cp "${aria2_conf}" "${tmp_file}.conf"
    printf '\nbt-tracker=%s\n' "${trackers}" >> "${tmp_file}.conf"
fi

cat "${tmp_file}.conf" > "${aria2_conf}"
echo "[INFO] Tracker file updated."