#!/bin/sh
set -eu

CONFIG_DIR="${CONFIG_DIR:-/config}"
DOWNLOAD_DIR="${DOWNLOAD_DIR:-/downloads}"
DEFAULTS_DIR="${DEFAULTS_DIR:-/defaults}"
RUNTIME_DIR="${RUNTIME_DIR:-/run/aria2-rust-pro}"
BASE_CONFIG="${CONFIG_DIR}/aria2.conf"
SESSION_FILE="${CONFIG_DIR}/aria2.session"
RUNTIME_CONFIG="${RUNTIME_DIR}/aria2.generated.conf"
ARIA2_BIN="${ARIA2_BIN:-/usr/local/bin/aria2c}"
SCRIPT_DIR="${CONFIG_DIR}/script"
SCRIPT_CONFIG="${CONFIG_DIR}/script.conf"
TRACKER_SNAPSHOT="${DEFAULTS_DIR}/bt-tracker.txt"
explicit_aria2_command=0

if [ "$#" -gt 0 ]; then
    case "$1" in
        aria2c|aria2-rust-pro)
            explicit_aria2_command=1
            shift
            ;;
        -*)
            ;;
        *)
            exec "$@"
            ;;
    esac
fi

if [ "${explicit_aria2_command}" -eq 1 ] && [ "$#" -gt 0 ]; then
    case "$1" in
        --version|-v|--help|-h|--help=*)
            exec "${ARIA2_BIN}" "$@"
            ;;
    esac
fi

mkdir -p "${CONFIG_DIR}" "${DOWNLOAD_DIR}" "${RUNTIME_DIR}"

if [ ! -f "${BASE_CONFIG}" ]; then
    cp "${DEFAULTS_DIR}/aria2.conf" "${BASE_CONFIG}"
fi

if [ ! -f "${SESSION_FILE}" ]; then
    : > "${SESSION_FILE}"
fi

copy_default_if_missing() {
    src="$1"
    dest="$2"
    if [ ! -e "${dest}" ]; then
        cp "${src}" "${dest}"
    fi
}

copy_mode_script() {
    script_name="$1"
    mkdir -p "${SCRIPT_DIR}"
    copy_default_if_missing "${DEFAULTS_DIR}/script/${script_name}" "${SCRIPT_DIR}/${script_name}"
    chmod 755 "${SCRIPT_DIR}/${script_name}"
}

apply_bt_tracker_snapshot() {
    if [ ! -f "${TRACKER_SNAPSHOT}" ]; then
        return
    fi

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

    if [ -z "${bundled_trackers}" ]; then
        return
    fi

    if grep -Eq '^bt-tracker=.+$' "${RUNTIME_CONFIG}"; then
        return
    fi

    if grep -q '^bt-tracker=' "${RUNTIME_CONFIG}"; then
        tmp_file="$(mktemp)"
        awk -v value="bt-tracker=${bundled_trackers}" '
            BEGIN { replaced = 0 }
            /^bt-tracker=/ { print value; replaced = 1; next }
            { print }
            END { if (!replaced) print value }
        ' "${RUNTIME_CONFIG}" > "${tmp_file}"
        cat "${tmp_file}" > "${RUNTIME_CONFIG}"
        rm -f "${tmp_file}"
        return
    fi

    append_line "bt-tracker=${bundled_trackers}"
}

configure_special_mode() {
    mode="${SPECIAL_MODE:-}"
    case "${mode}" in
        "")
            return
            ;;
        move)
            copy_mode_script "move.sh"
            copy_default_if_missing "${DEFAULTS_DIR}/script.conf" "${SCRIPT_CONFIG}"
            append_line "on-download-complete=${SCRIPT_DIR}/move.sh"
            ;;
        rclone)
            copy_mode_script "upload.sh"
            copy_default_if_missing "${DEFAULTS_DIR}/script.conf" "${SCRIPT_CONFIG}"
            copy_default_if_missing "${DEFAULTS_DIR}/script/rclone.env" "${CONFIG_DIR}/rclone.env"
            if ! command -v rclone >/dev/null 2>&1; then
                printf 'warning: SPECIAL_MODE=rclone was requested but the rclone binary is not available\n' >&2
            fi
            append_line "on-download-complete=${SCRIPT_DIR}/upload.sh"
            ;;
        *)
            printf 'warning: unknown SPECIAL_MODE "%s"; expected empty, move, or rclone\n' "${mode}" >&2
            ;;
    esac
}

append_line() {
    printf '%s\n' "$1" >> "${RUNTIME_CONFIG}"
}

cp "${BASE_CONFIG}" "${RUNTIME_CONFIG}"
append_line ""
append_line "# Generated overrides"
append_line "dir=${DOWNLOAD_DIR}"
append_line "input-file=${SESSION_FILE}"
append_line "save-session=${SESSION_FILE}"
append_line "save-session-interval=60"
append_line "enable-rpc=true"
append_line "rpc-listen-port=${RPC_PORT:-6800}"
append_line "listen-port=${LISTEN_PORT:-6888}"
append_line "dht-listen-port=${LISTEN_PORT:-6888}"
if [ "${IPV6_MODE:-false}" = "true" ] || [ "${IPV6_MODE:-false}" = "TRUE" ] || [ "${IPV6_MODE:-false}" = "1" ]; then
    append_line "disable-ipv6=false"
else
    append_line "disable-ipv6=true"
fi

if [ -n "${DISK_CACHE:-}" ]; then
    append_line "disk-cache=${DISK_CACHE}"
fi

if [ -n "${RPC_SECRET:-}" ]; then
    append_line "rpc-secret=${RPC_SECRET}"
    append_line "rpc-listen-all=true"
else
    printf 'warning: RPC_SECRET is empty; RPC stays loopback-only unless the base config overrides it\n' >&2
fi

apply_bt_tracker_snapshot
configure_special_mode

if [ "${UPDATE_TRACKERS:-false}" = "true" ] || [ "${UPDATE_TRACKERS:-false}" = "TRUE" ] || [ "${UPDATE_TRACKERS:-false}" = "1" ]; then
    if ! "${DEFAULTS_DIR}/script/tracker.sh" "${RUNTIME_CONFIG}"; then
        printf 'warning: tracker update failed; continuing with bundled or existing tracker data\n' >&2
    fi
fi

if [ -n "${PUID:-}" ] && [ -n "${PGID:-}" ]; then
    chown -R "${PUID}:${PGID}" "${CONFIG_DIR}" "${DOWNLOAD_DIR}" "${RUNTIME_DIR}"
fi

umask "${UMASK_SET:-022}"

if [ -n "${PUID:-}" ] && [ -n "${PGID:-}" ]; then
    exec gosu "${PUID}:${PGID}" "${ARIA2_BIN}" --enable-rpc --conf-path="${RUNTIME_CONFIG}" "$@"
fi

exec "${ARIA2_BIN}" --enable-rpc --conf-path="${RUNTIME_CONFIG}" "$@"