#!/usr/bin/env bash
# -*- coding: utf-8; mode: sh indent-tabs-mode: nil -*-
# SPDX-License-Identifier: AGPL-3.0-or-later
# shellcheck disable=SC2119,SC2001

# shellcheck source=utils/lib.sh
source "$(dirname "${BASH_SOURCE[0]}")/lib.sh"
source_dot_config

# ----------------------------------------------------------------------------
# config
# ----------------------------------------------------------------------------

FILTRON_URL_PATH="${FILTRON_URL_PATH:-$(echo "${PUBLIC_URL}" \
| sed -e 's,^.*://[^/]*\(/.*\),\1,g')}"
[[ "${FILTRON_URL_PATH}" == "${PUBLIC_URL}" ]] && FILTRON_URL_PATH=/

FILTRON_ETC="/etc/filtron"

FILTRON_RULES="$FILTRON_ETC/rules.json"

FILTRON_API="127.0.0.1:4005"
FILTRON_LISTEN="127.0.0.1:4004"
FILTRON_TARGET="127.0.0.1:8888"

SERVICE_NAME="filtron"
SERVICE_USER="${SERVICE_NAME}"
SERVICE_HOME="/home/${SERVICE_USER}"
SERVICE_SYSTEMD_UNIT="${SYSTEMD_UNITS}/${SERVICE_NAME}.service"

# shellcheck disable=SC2034
SERVICE_GROUP="${SERVICE_USER}"

GO_ENV="${SERVICE_HOME}/.go_env"
GO_PKG_URL="https://dl.google.com/go/go1.13.5.linux-amd64.tar.gz"
GO_TAR=$(basename "$GO_PKG_URL")

# Apache Settings

APACHE_FILTRON_SITE="searx.conf"

# shellcheck disable=SC2034
CONFIG_FILES=(
    "${FILTRON_RULES}"
    "${SERVICE_SYSTEMD_UNIT}"
)

# ----------------------------------------------------------------------------
usage() {
# ----------------------------------------------------------------------------

    # shellcheck disable=SC1117
    cat <<EOF

usage:

  $(basename "$0") shell
  $(basename "$0") install    [all|user]
  $(basename "$0") update     [filtron]
  $(basename "$0") remove     [all]
  $(basename "$0") activate   [service]
  $(basename "$0") deactivate [service]
  $(basename "$0") inspect    [service]
  $(basename "$0") option     [debug-on|debug-off]
  $(basename "$0") apache     [install|remove]


shell
  start interactive shell from user ${SERVICE_USER}
install / remove
  all:        complete setup of filtron service
  user:       add/remove service user '$SERVICE_USER' at $SERVICE_HOME
update filtron
  Update filtron installation of user ${SERVICE_USER}
activate service
  activate and start service daemon (systemd unit)
deactivate service
  stop and deactivate service daemon (systemd unit)
inspect service
  show service status and log
option
  set one of the available options
apache
  install: apache site with a reverse proxy (ProxyPass)
  remove:  apache site ${APACHE_FILTRON_SITE}

If needed change the environment variable PUBLIC_URL of your WEB service in the
${DOT_CONFIG#"$REPO_ROOT/"} file:

  PUBLIC_URL   : ${PUBLIC_URL}
  PUBLIC_HOST  : ${PUBLIC_HOST}

EOF
    [ ! -z ${1+x} ] &&  echo -e "$1"
}

main() {
    rst_title "$SERVICE_NAME" part

    required_commands \
        dpkg apt-get install git wget curl \
        || exit

    local _usage="ERROR: unknown or missing $1 command $2"

    case $1 in
        --source-only)  ;;
        -h|--help) usage; exit 0;;

        shell)
            sudo_or_exit
            interactive_shell
            ;;
        inspect)
            case $2 in
                service)
                    sudo_or_exit
                    inspect_service
                    ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        install)
            sudo_or_exit
            case $2 in
                all) install_all ;;
                user) assert_user ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        update)
            sudo_or_exit
            case $2 in
                filtron) update_filtron ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        remove)
            sudo_or_exit
            case $2 in
                all) remove_all;;
                user) remove_user ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        activate)
            sudo_or_exit
            case $2 in
                service)  activate_service ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        deactivate)
            sudo_or_exit
            case $2 in
                service)  deactivate_service ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        apache)
            sudo_or_exit
            case $2 in
                install) install_apache_site ;;
                remove) remove_apache_site ;;
                *) usage "$_usage"; exit 42;;
            esac ;;
        option)
            sudo_or_exit
            case $2 in
                debug-on)  echo; enable_debug ;;
                debug-off)  echo; disable_debug ;;
                *) usage "$_usage"; exit 42;;
            esac ;;

        *) usage "ERROR: unknown or missing command $1"; exit 42;;
    esac
}

install_all() {
    rst_title "Install $SERVICE_NAME (service)"
    assert_user
    wait_key
    install_go
    wait_key
    install_filtron
    wait_key
    install_service
    wait_key
    echo
    if ! service_is_available "http://${FILTRON_LISTEN}" ; then
        err_msg "Filtron does not listening on: http://${FILTRON_LISTEN}"
    fi
    if apache_is_installed; then
        info_msg "Apache is installed on this host."
        if ask_yn "Do you want to install a reverse proxy (ProxyPass)" Yn; then
            install_apache_site
        fi
    fi
    if ask_yn "Do you want to inspect the installation?" Yn; then
        inspect_service
    fi

}

remove_all() {
    rst_title "De-Install $SERVICE_NAME (service)"

    rst_para "\
It goes without saying that this script can only be used to remove
installations that were installed with this script."

    remove_service
    wait_key
    remove_user
    rm -r "$FILTRON_ETC" 2>&1 | prefix_stdout
    if service_is_available "${PUBLIC_URL}"; then
        MSG="** Don't forget to remove your public site! (${PUBLIC_URL}) **" wait_key 10
    fi
}

install_service() {
    rst_title "Install System-D Unit ${SERVICE_NAME}.service" section
    echo
    install_template "${SERVICE_SYSTEMD_UNIT}" root root 644
    wait_key
    activate_service
}

remove_service() {
    if ! ask_yn "Do you really want to deinstall $SERVICE_NAME?"; then
        return
    fi
    deactivate_service
    rm "${SERVICE_SYSTEMD_UNIT}"  2>&1 | prefix_stdout
}

activate_service() {
    rst_title "Activate $SERVICE_NAME (service)" section
    echo
    tee_stderr <<EOF | bash 2>&1
systemctl enable $SERVICE_NAME.service
systemctl restart $SERVICE_NAME.service
EOF
    tee_stderr <<EOF | bash 2>&1
systemctl status --no-pager $SERVICE_NAME.service
EOF
}

deactivate_service() {
    rst_title "De-Activate $SERVICE_NAME (service)" section
    echo
    tee_stderr <<EOF | bash 2>&1 | prefix_stdout
systemctl stop $SERVICE_NAME.service
systemctl disable $SERVICE_NAME.service
EOF
}

user_is_available() {
    sudo -i -u "$SERVICE_USER" echo \$HOME &>/dev/null
}

assert_user() {
    rst_title "user $SERVICE_USER" section
    echo
    tee_stderr 1 <<EOF | bash | prefix_stdout
sudo -H adduser --shell /bin/bash --system --home $SERVICE_HOME \
    --disabled-password --group --gecos 'Filtron' $SERVICE_USER
sudo -H usermod -a -G shadow $SERVICE_USER
groups $SERVICE_USER
EOF
    SERVICE_HOME="$(sudo -i -u "$SERVICE_USER" echo \$HOME)"
    export SERVICE_HOME
    echo "export SERVICE_HOME=$SERVICE_HOME"

    cat > "$GO_ENV" <<EOF
export GOPATH=\$HOME/go-apps
export PATH=\$PATH:\$HOME/local/go/bin:\$GOPATH/bin
EOF
    echo "Environment $GO_ENV has been setup."

    tee_stderr <<EOF | sudo -i -u $SERVICE_USER
grep -qFs -- 'source $GO_ENV' ~/.profile || echo 'source $GO_ENV' >> ~/.profile
EOF
}

remove_user() {
    rst_title "Drop $SERVICE_USER HOME" section
    if ask_yn "Do you really want to drop $SERVICE_USER home folder?"; then
        userdel -r -f "$SERVICE_USER" 2>&1 | prefix_stdout
    else
        rst_para "Leave HOME folder $(du -sh "$SERVICE_HOME") unchanged."
    fi
}

interactive_shell(){
    echo "// exit with ${_BCyan}CTRL-D${_creset}"
    sudo -H -u ${SERVICE_USER} -i
}

_service_prefix="  |$SERVICE_USER| "

go_is_available() {
    sudo -i -u "$SERVICE_USER" which go &>/dev/null
}

install_go() {
    rst_title "Install Go in user's HOME" section

    rst_para "download and install go binary .."
    cache_download "${GO_PKG_URL}" "${GO_TAR}"

    tee_stderr 0.1 <<EOF | sudo -i -u "$SERVICE_USER" | prefix_stdout "$_service_prefix"
echo \$PATH
echo \$GOPATH
mkdir -p \$HOME/local
rm -rf \$HOME/local/go
tar -C \$HOME/local -xzf ${CACHE}/${GO_TAR}
EOF
    sudo -i -u "$SERVICE_USER" <<EOF | prefix_stdout
! which go >/dev/null &&  echo "ERROR - Go Installation not found in PATH!?!"
which go >/dev/null &&  go version && echo "congratulations -- Go installation OK :)"
EOF
}

filtron_is_installed() {
    [[ -f $SERVICE_HOME/go-apps/bin/filtron ]]
}

install_filtron() {
    rst_title "Install filtron in user's ~/go-apps" section
    echo
    tee_stderr <<EOF | sudo -i -u "$SERVICE_USER" 2>&1 | prefix_stdout "$_service_prefix"
go get -v -u github.com/asciimoo/filtron
EOF
    install_template --no-eval "$FILTRON_RULES" root root 644
}

update_filtron() {
    rst_title "Update filtron" section
    echo
    tee_stderr <<EOF | sudo -i -u "$SERVICE_USER" 2>&1 | prefix_stdout "$_service_prefix"
go get -v -u github.com/asciimoo/filtron
EOF
}

inspect_service() {

    rst_title "service status & log"

    cat <<EOF

sourced ${DOT_CONFIG#"$REPO_ROOT/"} :

  PUBLIC_URL          : ${PUBLIC_URL}
  PUBLIC_HOST         : ${PUBLIC_HOST}
  FILTRON_URL_PATH    : ${FILTRON_URL_PATH}
  FILTRON_API         : ${FILTRON_API}
  FILTRON_LISTEN      : ${FILTRON_LISTEN}
  FILTRON_TARGET      : ${FILTRON_TARGET}

EOF

    apache_is_installed && info_msg "Apache is installed."

    if user_is_available; then
        info_msg "service account $SERVICE_USER available."
    else
        err_msg "service account $SERVICE_USER not available!"
    fi
    if go_is_available; then
        info_msg "~$SERVICE_USER: go is installed"
    else
        err_msg "~$SERVICE_USER: go is not installed"
    fi
    if filtron_is_installed; then
        info_msg "~$SERVICE_USER: filtron app is installed"
    else
        err_msg "~$SERVICE_USER: filtron app is not installed!"
    fi

    if ! service_is_available "http://${FILTRON_API}"; then
        err_msg "API not available at: http://${FILTRON_API}"
    fi

    if ! service_is_available "http://${FILTRON_LISTEN}" ; then
        err_msg "Filtron does not listening on: http://${FILTRON_LISTEN}"
    fi

    if ! service_is_available ""http://${FILTRON_TARGET}"" ; then
        info_msg "Filtron's target is available at: http://${FILTRON_TARGET}"
    fi

    if ! service_is_available "${PUBLIC_URL}"; then
        err_msg "Public service at ${PUBLIC_URL} is not available!"
    fi

    local _debug_on
    if ask_yn "Enable filtron debug mode?"; then
        enable_debug
        _debug_on=1
    fi

    echo
    systemctl --no-pager -l status filtron.service
    echo
    # shellcheck disable=SC2059
    printf "// use ${_BCyan}CTRL-C${_creset} to stop monitoring the log"
    read -r -s -n1 -t 2
    echo
    while true;  do
        trap break 2
        journalctl -f -u filtron
    done

    if [[ $_debug_on == 1 ]]; then
        disable_debug
    fi
    return 0
}


enable_debug() {
    info_msg "try to enable debug mode ..."
    python <<EOF
import sys, json

debug = {
    u'name': u'debug request'
    , u'filters': []
    , u'interval': 0
    , u'limit': 0
    , u'actions': [{u'name': u'log'}]
}

with open('$FILTRON_RULES') as rules:
    j = json.load(rules)

pos = None
for i in range(len(j)):
    if j[i].get('name') == 'debug request':
        pos = i
        break
if pos is not None:
    j[pos] = debug
else:
    j.append(debug)
with open('$FILTRON_RULES', 'w') as rules:
    json.dump(j, rules, indent=2, sort_keys=True)

EOF
    systemctl restart "${SERVICE_NAME}.service"
}

disable_debug() {
    info_msg "try to disable debug mode ..."
    python <<EOF
import sys, json
with open('$FILTRON_RULES') as rules:
    j = json.load(rules)

pos = None
for i in range(len(j)):
    if j[i].get('name') == 'debug request':
        pos = i
        break
if pos is not None:
    del j[pos]
    with open('$FILTRON_RULES', 'w') as rules:
         json.dump(j, rules, indent=2, sort_keys=True)
EOF
    systemctl restart "${SERVICE_NAME}.service"
}

install_apache_site() {

    rst_title "Install Apache site $APACHE_FILTRON_SITE"

    rst_para "\
This installs a reverse proxy (ProxyPass) into apache site (${APACHE_FILTRON_SITE})"

    ! apache_is_installed && err_msg "Apache is not installed."

    if ! ask_yn "Do you really want to continue?"; then
        return
    fi

    a2enmod headers
    a2enmod proxy
    a2enmod proxy_http

    echo
    apache_install_site --variant=filtron "${APACHE_FILTRON_SITE}"

    info_msg "testing public url .."
    if ! service_is_available "${PUBLIC_URL}"; then
        err_msg "Public service at ${PUBLIC_URL} is not available!"
    fi
}

remove_apache_site() {

    rst_title "Remove Apache site $APACHE_FILTRON_SITE"

    rst_para "\
This removes apache site ${APACHE_FILTRON_SITE}."

    ! apache_is_installed && err_msg "Apache is not installed."

    if ! ask_yn "Do you really want to continue?"; then
        return
    fi

    apache_remove_site "$APACHE_FILTRON_SITE"
}

# ----------------------------------------------------------------------------
main "$@"
# ----------------------------------------------------------------------------