#!/usr/bin/env bash

set -eEuo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly SCRIPT_DIR
readonly PASSWD_FILE="/etc/mosquitto/passwd"
readonly BROKER_SERVICE_NAME="mosquitto.service"
readonly HUB_STATUS_SERVICE_NAME="fapg-daq-hub-status.service"
readonly HUB_STATUS_SERVICE_FILE="/etc/systemd/system/${HUB_STATUS_SERVICE_NAME}"
readonly REPO_DIR="/opt/fapg/fapg-daq"
readonly HUB_STATUS_BIN="${REPO_DIR}/roles/daq-hub/bin/fapg-daq-hub-status"
readonly ENV_DIR="/etc/fapg-daq"
readonly HUB_STATUS_ENV_FILE="${ENV_DIR}/hub-status.env"
readonly RUN_USER="fapg-daq"
readonly RUN_GROUP="fapg-daq"
readonly MQTT_HOST="127.0.0.1"
readonly MQTT_PORT="1883"
readonly MQTT_USERNAME="fapg_hub"
readonly HUB_STATUS_INTERVAL="5"
HUB_MQTT_PASSWORD=""

function die() {
    echo "ERROR: $*" >&2
    exit 1
}

function require_root() {
    if [[ "${EUID}" -ne 0 ]]; then
        die "run as root, e.g. sudo $0"
    fi
}

function passwd_has_user() {
    local user="$1"

    [[ -f "${PASSWD_FILE}" ]] || return 1
    grep -qE "^${user}:" "${PASSWD_FILE}"
}

function ensure_mosquitto_password() {
    local user="$1"

    if passwd_has_user "${user}"; then
        echo "Mosquitto password for ${user} already exists; leaving it unchanged."
        return
    fi

    echo "Enter password for ${user}"
    if [[ -f "${PASSWD_FILE}" ]]; then
        mosquitto_passwd "${PASSWD_FILE}" "${user}"
    else
        mosquitto_passwd -c "${PASSWD_FILE}" "${user}"
    fi
}

function read_hub_mqtt_password() {
    if [[ -n "${HUB_MQTT_PASSWORD:-}" ]]; then
        return
    fi

    read -rsp "MQTT password for user '${MQTT_USERNAME}': " HUB_MQTT_PASSWORD
    echo

    [[ -n "${HUB_MQTT_PASSWORD:-}" ]] || die "MQTT password is required."
}

function ensure_hub_mosquitto_password() {
    if passwd_has_user "${MQTT_USERNAME}"; then
        echo "Mosquitto password for ${MQTT_USERNAME} already exists; leaving it unchanged."
        return
    fi

    read_hub_mqtt_password

    if [[ -f "${PASSWD_FILE}" ]]; then
        mosquitto_passwd -b "${PASSWD_FILE}" "${MQTT_USERNAME}" "${HUB_MQTT_PASSWORD}"
    else
        mosquitto_passwd -b -c "${PASSWD_FILE}" "${MQTT_USERNAME}" "${HUB_MQTT_PASSWORD}"
    fi
}

function install_os_dependencies() {
    apt update && apt install -y \
        perl \
        mosquitto \
        mosquitto-clients \
        libnet-mqtt-simple-perl
}

function create_runtime_user() {
    if ! getent group "${RUN_GROUP}" > /dev/null; then
        addgroup --system "${RUN_GROUP}"
    fi

    if ! id "${RUN_USER}" > /dev/null 2>&1; then
        adduser \
            --system \
            --ingroup "${RUN_GROUP}" \
            --home /var/lib/fapg-daq \
            --no-create-home \
            --disabled-login \
            "${RUN_USER}"
    fi
}

function check_repo_layout() {
    [[ -d "${REPO_DIR}" ]] || die "Repo not found at ${REPO_DIR}."
    [[ -x "${HUB_STATUS_BIN}" ]] || die "${HUB_STATUS_BIN} does not exist or is not executable."
}

function write_hub_status_env_file() {
    mkdir -p "${ENV_DIR}"

    if [[ -f "${HUB_STATUS_ENV_FILE}" ]]; then
        echo "${HUB_STATUS_ENV_FILE} already exists; leaving it unchanged."
        chown root:"${RUN_GROUP}" "${HUB_STATUS_ENV_FILE}"
        chmod 0640 "${HUB_STATUS_ENV_FILE}"
        return
    fi

    read_hub_mqtt_password

    cat > "${HUB_STATUS_ENV_FILE}" <<EOF
MQTT_SIMPLE_ALLOW_INSECURE_LOGIN=1

MQTT_HOST=${MQTT_HOST}
MQTT_PORT=${MQTT_PORT}
MQTT_USERNAME=${MQTT_USERNAME}
MQTT_PASSWORD=${HUB_MQTT_PASSWORD}

HUB_STATUS_INTERVAL=${HUB_STATUS_INTERVAL}
EOF

    chown root:"${RUN_GROUP}" "${HUB_STATUS_ENV_FILE}"
    chmod 0640 "${HUB_STATUS_ENV_FILE}"
}

function install_systemd_services() {
    install -d -m 0755 -o root -g root /etc/systemd/system

    install -m 0644 -o root -g root \
        "${SCRIPT_DIR}/etc/systemd/system/fapg-daq-hub-status.service" \
        "${HUB_STATUS_SERVICE_FILE}"
}

require_root
install_os_dependencies
create_runtime_user
check_repo_layout

# Install files

install -d -m 0755 -o root -g root /etc/mosquitto/conf.d

install -m 0640 -o mosquitto -g mosquitto \
	"${SCRIPT_DIR}/etc/mosquitto/acl" \
	/etc/mosquitto/acl

install -m 0644 -o root -g root \
	"${SCRIPT_DIR}/etc/mosquitto/conf.d/fapg-home.conf" \
	/etc/mosquitto/conf.d/fapg-home.conf

# Password management

ensure_mosquitto_password fapg_zero
ensure_hub_mosquitto_password
ensure_mosquitto_password fapg_vps

chown mosquitto:mosquitto "${PASSWD_FILE}"
chmod 0640 "${PASSWD_FILE}"

# System service activation

write_hub_status_env_file
install_systemd_services

systemctl daemon-reload
systemctl enable "${BROKER_SERVICE_NAME}" "${HUB_STATUS_SERVICE_NAME}"
systemctl restart "${BROKER_SERVICE_NAME}"
systemctl restart "${HUB_STATUS_SERVICE_NAME}"

systemctl --no-pager --full status "${BROKER_SERVICE_NAME}"
systemctl --no-pager --full status "${HUB_STATUS_SERVICE_NAME}"