#!/usr/bin/env bash
set -euo pipefail

# runit's run script for sww, run again whenever sww
# exits; the wait spaces out the restarts. SWW_COMMAND names the
# command to run: rproxy when it is unset or empty, or waf. With any
# other value the script starts nothing and stops with a message naming it.
# exec, so that the signal `sv stop` sends reaches sww itself.
main() {
    sleep 1
    local command="${SWW_COMMAND:-rproxy}"
    case "$command" in
        rproxy) ;;
        waf)
            give_state_dir_to_sww
            make_cache_dir_for_sww
            ;;
        *)
            printf 'SWW_COMMAND: "%s" is not rproxy or waf\n' \
                "$command" >&2
            exit 1
            ;;
    esac
    exec chpst -u sww:sww /usr/local/bin/sww "$command"
}

# give_state_dir_to_sww gives the state directory and every file in
# it to the sww user, so that a volume mounted there needs no change
# of owner; chown -R changes a symbolic link itself, never what it points
# to. When SWW_WAF_STATE_DIR, in either form, cannot be read or is not the
# absolute path of a directory, no owner is changed, and waf starts and
# stops with a message naming the setting. A change of owner that fails, as
# on a volume mounted read-only, does not end the script either: waf
# reports a directory it cannot write.
give_state_dir_to_sww() {
    local dir
    if dir="$(setting SWW_WAF_STATE_DIR /var/lib/sww)" &&
        [[ "$dir" == /* && -d "$dir" ]]; then
        chown -R sww:sww "$dir" || true
    fi
}

# make_cache_dir_for_sww makes the cache directory, SWW_WAF_CACHE_DIR in
# either form, and gives it and every file in it to the sww user, as
# give_state_dir_to_sww does the state directory. Unlike that one, it is
# made when it is missing, since the cache files need no volume. As there,
# a setting that cannot be read or is not an absolute path changes
# nothing, and a failure does not end the script.
make_cache_dir_for_sww() {
    local dir
    if dir="$(setting SWW_WAF_CACHE_DIR /var/cache/sww)" && [[ "$dir" == /* ]]; then
        { mkdir -p -- "$dir" && chown -R sww:sww "$dir"; } || true
    fi
}

# setting prints the setting named $1, $2 when it is unset, or what is in
# the file the setting $1_FILE names, less every newline at its end. It
# fails when both are set or the file cannot be read.
setting() {
    local name="$1" file_name="$1_FILE"
    if [[ ! -v "$file_name" ]]; then
        printf '%s\n' "${!name-$2}"
    elif [[ ! -v "$name" ]]; then
        cat -- "${!file_name}" 2>/dev/null
    else
        return 1
    fi
}

main "$@"