#!/bin/bash

# Copyright (c) 2021 Cisco Systems and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# A simple script that installs stats_fs, a Fuse file system
# for the stats segment

set -eo pipefail

OPT_ARG=${1:-}

STATS_FS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"/
cd "${STATS_FS_DIR}"/../../
VPP_DIR=$(pwd)/
BUILD_ROOT=${VPP_DIR}build-root/
BINARY_DIR=${BUILD_ROOT}install-vpp-native/vpp/bin/
DEBUG_DIR=${BUILD_ROOT}install-vpp_debug-native/vpp/bin/
RUN_DIR=/run/vpp/

GOROOT=${GOROOT:-}
GOPATH=${GOPATH:-}

[ -z "${GOROOT}" ] && GOROOT="${HOME}/.go" && PATH=$GOROOT/bin:$PATH
[ -z "${GOPATH}" ] && GOPATH="${HOME}/go"  && PATH=$GOPATH/bin:$PATH

function install_tools() {
  echo "Installing downloading tools"
  apt-get update
  apt-get install git wget curl -y
}

# Install latest GO version
function install_go() {
  local TMP="/tmp"

  echo "Installing latest GO"
  if [[ -x "$(command -v go)" ]]; then
    local installed_ver installed_ver_fmt
    installed_ver=$(go version)
    installed_ver_fmt=${installed_ver#"go version go"}
    echo "Found installed version ${installed_ver_fmt}"
    return
  fi

  mkdir -p "${GOROOT}"
  mkdir -p "${GOPATH}/"{src,pkg,bin}

  wget "https://dl.google.com/go/$(curl https://golang.org/VERSION?m=text).linux-amd64.tar.gz" -O "${TMP}/go.tar.gz"
  tar -C "$GOROOT" --strip-components=1 -xzf "${TMP}/go.tar.gz"

  rm -f "${TMP}/go.tar.gz"

  # export path for current session to install vpp_stast_fs
  export GOROOT=${GOROOT}
  export PATH=$GOROOT/bin:$PATH
  export GOPATH=$GOPATH
  export PATH=$GOPATH/bin:$PATH

  echo "Installed $(go version)"
}

function install_fuse() {
  echo "Installing Fuse"
  apt-get update
  apt-get install fuse -y
}

function install_nohup() {
  echo "Installing nohup"
  apt-get update
  apt-get install nohup -y
}

function install_go_dep() {
  echo "Installing Go dependencies"
  if [[ ! -x "$(command -v go)" ]]; then
    echo "GO is not installed"
    exit 1
  fi

  if [ ! -e "go.mod" ]; then
    go mod init stats_fs
    # We require a specific govpp commit for compatibility
    go get git.fd.io/govpp.git@da95997338b77811bc2ea850db393c652b3bd18e
    go get git.fd.io/govpp.git/adapter/statsclient@da95997338b77811bc2ea850db393c652b3bd18e
    go get github.com/hanwen/go-fuse/v2
  fi
}

# Resolve stats_fs dependencies and builds the binary
function build_statfs() {
  echo "Installing statfs"
  go build
  if [ -d "${BINARY_DIR}" ]; then
    mv stats_fs "${BINARY_DIR}"/stats_fs
  elif [ -d "${DEBUG_DIR}" ]; then
    mv stats_fs "${DEBUG_DIR}"/stats_fs
  else
    echo "${BINARY_DIR} and ${DEBUG_DIR} directories does not exist, the binary is installed at ${STATS_FS_DIR}stats_fs instead"
  fi
}

function install_statfs() {
  if [[ ! -x "$(command -v go)" ]]; then
    install_tools
    install_go
  fi

  if [[ ! -x "$(command -v fusermount)" ]]; then
    install_fuse
  fi

  if [[ ! -x "$(command -v nohup)" ]]; then
    install_nohup
  fi

  if [ ! -d "${STATS_FS_DIR}" ]; then
    echo "${STATS_FS_DIR} directory does not exist"
    exit 1
  fi
  cd "${STATS_FS_DIR}"

  if [[ ! -x "$(command -v ${STATS_FS_DIR}stats_fs)" ]]; then
    install_go_dep
    build_statfs
  else
    echo "stats_fs already installed at path ${STATS_FS_DIR}stats_fs"
  fi
}

# Starts the statfs binary
function start_statfs() {
  EXE_DIR=$STATS_FS_DIR
  if [ -d "${BINARY_DIR}" ]; then
    EXE_DIR=$BINARY_DIR
  elif [ -d "${DEBUG_DIR}" ]; then
    EXE_DIR=$DEBUG_DIR
  fi

  if [[ $(pidof "${EXE_DIR}"stats_fs) ]]; then
    echo "The service stats_fs has already been launched"
    exit 1
  fi

  mountpoint="${RUN_DIR}stats_fs_dir"

  if [[ -x "$(command -v ${EXE_DIR}stats_fs)" ]] ; then
    if [ ! -d "$mountpoint" ] ; then
      mkdir "$mountpoint"
    fi
    nohup "${EXE_DIR}"stats_fs $mountpoint 0<&- &>/dev/null &
    return
  fi

  echo "stats_fs is not installed, use 'make stats-fs-install' first"
  exit 1
}

function stop_statfs() {
  EXE_DIR=$STATS_FS_DIR
  if [ -d "${BINARY_DIR}" ]; then
    EXE_DIR=$BINARY_DIR
  elif [ -d "${DEBUG_DIR}" ]; then
    EXE_DIR=$DEBUG_DIR
  fi
  if [[ ! $(pidof "${EXE_DIR}"stats_fs) ]]; then
    echo "The service stats_fs is not running"
    exit 1
  fi

  PID=$(pidof "${EXE_DIR}"stats_fs)
  kill "$PID"
  if [[ $(pidof "${EXE_DIR}"stats_fs) ]]; then
    echo "Check your syslog file (default is /var/log/syslog)."
    echo "It may be that the file system is busy."
    exit 1
  fi

  if [ -d "${RUN_DIR}stats_fs_dir" ] ; then
    rm -df "${RUN_DIR}stats_fs_dir"
  fi
}

function force_unmount() {
  if (( $(mount | grep "${RUN_DIR}stats_fs_dir" | wc -l) == 1 )) ; then
    fusermount -uz "${RUN_DIR}stats_fs_dir"
  else
    echo "The default directory ${RUN_DIR}stats_fs_dir is not mounted."
  fi

  if [ -d "${RUN_DIR}stats_fs_dir" ] ; then
    rm -df "${RUN_DIR}stats_fs_dir"
  fi
}

# Remove stats_fs Go module
function cleanup() {
  echo "Cleaning up stats_fs"
  if [ ! -d "${STATS_FS_DIR}" ]; then
    echo "${STATS_FS_DIR} directory does not exist"
    exit 1
  fi

  cd "${STATS_FS_DIR}"

  if [ -e "stats_fs" ]; then
    rm -f stats_fs
  fi

  if [ -d "${BINARY_DIR}" ]; then
    if [ -e "${BINARY_DIR}stats_fs" ]; then
      rm -f ${BINARY_DIR}stats_fs
    fi
  elif [ -d "${DEBUG_DIR}" ]; then
    if [ -e "${DEBUG_DIR}stats_fs" ]; then
      rm -f ${DEBUG_DIR}stats_fs
    fi
  fi

  if [ -d "${RUN_DIR}stats_fs_dir" ] ; then
    rm -df "${RUN_DIR}stats_fs_dir"
  fi
}

# Show available commands
function help() {
  cat <<__EOF__
  Stats-fs installer

  install        - Installs requirements (Go, GoVPP, GoFUSE) and builds stats_fs
  start          - Launches the stats_fs binary and creates a mountpoint
  clean          - Removes stats_fs binary
  stop           - Stops the executable, unmounts the file system
                   and removes the mountpoint directory
  force-unmount  - Forces the unmount of the filesystem even if it is busy

__EOF__
}

# Resolve chosen option and call appropriate functions
function resolve_option() {
  local option=$1
  case ${option} in
  "start")
    start_statfs
    ;;
  "install")
    install_statfs
    ;;
  "clean")
    cleanup
    ;;
  "unmount")
    force_unmount
    ;;
  "stop")
    stop_statfs
    ;;
  "help")
    help
    ;;
  *) echo invalid option ;;
  esac
}

if [[ -n ${OPT_ARG} ]]; then
  resolve_option "${OPT_ARG}"
else
  PS3="--> "
  options=("install" "cleanup" "help" "start" "unmount")
  select option in "${options[@]}"; do
    resolve_option "${option}"
    break
  done
fi