#! /bin/bash

# DESCRIPTION:
#   Building Python from sources.
#
# DEPENDENCIES:
#
# PARAMETERS:
#   1: "qn" - execution without pauses
#   2: version of Python. Defaults to 3.9.5
#   3: path to log
#
# FUNCTIONS:
#

#######################################
# Print message and add to log.
# Globals:
#   logs
# Arguments:
#   1: message to print and logging
#######################################
addtologs() {
  echo "$(date +'%Y.%m.%d-%H:%M:%S') $1" | tee -a "${logs}"
}

#######################################
# Waiting for press [ENTER].
# Globals:
#   None
# Arguments:
#   None
#######################################
execpause() {
  read -r -p "Press [ENTER] to continue... "
}

#######################################
# Exit procedure.
# Globals:
#   show
# Arguments:
#   None
#######################################
execquite() {
  addtologs "execution time is $(($(date +%s)-time)) seconds, exit"
  if [ "${show}" != "qn" ]; then
  execpause
  fi
  exit
}

#######################################
# Error exit procedure with Telegram notification.
# Globals:
#   telegramapiurl
#   telegramchatid
# Arguments:
#   1: message to print and logging
#######################################
execerror() {
  addtologs "error: $1"
  execquite
}

#######################################
# Checking user rights.
# Globals:
#   None
# Arguments:
#   None
# return:
#   0 - if privileged rights, 1 - if not privileged rights
#######################################
checkroot() {
  if [ "${EUID}" -ne 0 ]; then
    return 1 # false
  else
    return 0 # true
  fi
}

#######################################
# Installing required packages.
# Globals:
#   None
# Arguments:
#   None
#######################################
installutils(){
  if grep '^NAME=' /etc/os-release | grep -q 'Debian' || \
     grep '^NAME=' /etc/os-release | grep -q 'Ubuntu'; then
    apt-get update
    apt-get install -y \
      wget \
      tar \
      build-essential \
      tk-dev \
      libncurses5-dev \
      libncursesw5-dev \
      libreadline6-dev \
      libdb5.3-dev \
      libgdbm-dev \
      libsqlite3-dev \
      libssl-dev \
      libbz2-dev \
      libexpat1-dev \
      liblzma-dev \
      zlib1g-dev \
      libffi-dev
  fi
  if grep '^NAME=' /etc/os-release | grep -q 'CentOS'; then
    yum install -y \
      wget \
      tar \
      gcc \
      openssl-devel \
      bzip2-devel \
      libffi-devel \
      zlib-devel \
      xz-devel
  fi
}

#######################################
# Downloading and unpacking sources.
# Globals:
#   None
# Arguments:
#   1: version of Python
#######################################
# shellcheck disable=SC2317
downloadcode(){
  subvers=$1
  version=$(echo "${subvers}" | cut -d. -f1,2)
  wget "https://www.python.org/ftp/python/${subvers}/Python-${subvers}.tgz"
  tar zxf "Python-${subvers}.tgz"
}

#######################################
# Downloading and unpacking sources.
# Globals:
#   version
# Arguments:
#   None
#######################################
bulidingcode(){
  cd "Python-${subvers}" || execerror "cd"
  ./configure --enable-optimizations --prefix=/usr/local/opt/python-"${version}"
  make
}

#######################################
# Installing and cleaning after.
# Globals:
#   subvers
# Arguments:
#   None
#######################################
installclean(){
  make altinstall
  cd ..
  rm -r "Python-${subvers}"*
  if grep '^NAME=' /etc/os-release | grep -q 'Debian' || \
     grep '^NAME=' /etc/os-release | grep -q 'Ubuntu'; then
     apt-get autoremove -y
  fi
  if grep '^NAME=' /etc/os-release | grep -q 'CentOS'; then
    yum autoremove -y
  fi
}

#
# VARIABLES:
#

show=$1
vers=$2
logs=$3
time=$(date +%s)
cd "$(dirname "$(realpath "$0")")" || cd "${HOME}" || execerror "cd"
if [ -z "${logs}" ]; then
  logs=/dev/null
elif [ ! -e "${logs}" ]; then
  touch "${logs}"
fi
if [ -z "${vers}" ]; then
  vers=3.9.5
fi

#
# MAIN:
#

if checkroot; then
  addtologs "Installing dependencies..."
  if installutils >> "${logs}" 2>&1; then
    addtologs "Downolading sources..."
    if downloadcode "${vers}" >> "${logs}" 2>&1; then
      addtologs "Making package..."
      if bulidingcode >> "${logs}" 2>&1; then
        addtologs "Installing package and cleaning..."
        if installclean >> "${logs}" 2>&1; then
          addtologs "Installed $(/usr/local/opt/python-"${version}"/bin/python"${version}" -V)"
          execquite
        else
          execerror "Installing package and cleaning..."
        fi
      else
        execerror "Making package..."
      fi
    else
      execerror "Downolading sources..."
    fi
  else
    execerror "Installing dependencies..."
  fi
else
  execerror "Restart this as root!"
fi