#!/usr/bin/env bash

# This is my Linux server configuration utility (sconfig.sh)
# Read more about it here: https://git.socialnerds.org/david/sconfig

# ***** CONFIG *****

# general information
NAME="sconfig"
TITLE="Server Configuration"
DESCRIPTION="The Linux server configuration utility"
VERSION="0.2"
AUTHOR="david@socialnerds.org"
WEBSITE="https://git.socialnerds.org/david/sconfig"
REPO="$WEBSITE.git"
LICENSE="https://git.socialnerds.org/david/sconfig/raw/branch/main/LICENSE"

# default settings
CONFIGFILE="/etc/sconfig/sconfig.conf"
DEBUG=0
LOGFILE=""
INTERACTIVE=2

declare -A CONFIG
CONFIG=([debug_enabled]=$DEBUG
        [logfile]="$LOGFILE"
        [btrfs_enabled]=
        [btrfs_subvols]="/"
        [btrfs_versions]=30
        [miab_enabled]=
        [miab_host]="box.example.com"
        [miab_user]="admin@example.com"
        [miab_password]="verysecret!=+%password"
        [healthchecks_enabled]=
        [healthchecks_baseurl]=""
        [healthchecks_id]="")

declare -A PACKAGES
PACKAGES=([ubuntu]="curl less vim"
          [arch]="curl less vim"
          [debian]="curl less vim")

# external library files and command prerequsites
#LIBRARIES=("library.sh" "ui.sh")
DEPENDENCIES=("sort" "stat" "date" "whoami" "id"
              "tput" "chmod" "chown" "dirname"
              "basename" "seq")

# ***** FUNCTION DEFINITIONS *****
# execute upon Ctrl-C detection
function bashtrap {
  if [ $INTERACTIVE -eq 1 ]; then
    header
    echo "Detected Ctrl-C"; echo "Dropping to shell"; sleep 1
    clear; exit 2
  else
    library_log warn "Ctrl-C detected, exiting"
    exit 2
  fi
}



# return 1/false if not executed as root
function amiroot {
  if [ "$(whoami)" != "root" ]; then
    return 1
  fi
}

# check if stdout is a TTY and return 1 if it is not
# for detecting if executed by cron (or user)
function amitty {
  if [ ! -t 1 ]; then
    return 1
  fi
}

# general text output method
# usage: output <loglevel> <message>
function library_log {
  if [ "$1" != "debug" -o $DEBUG -eq 1 ]; then
    echo "[$1] ${@:2}"
    if [ "$LOGFILE" -a -w "$LOGFILE" ]; then
      echo "[$(date +%Y%m%d%H%M%S)][$1] ${@:2}" >> "$LOGFILE"
    fi
  fi
}

# very simple configfile parser
# it fills a global variable with key=value pairs from a configfile
# usage: config_read <path/to/configfile>
function config_read {
  if [ "$1" -a -r "$1" ]; then
    local FILE="$1"
    while read -r LINE || [ -n "$LINE" ]; do
      local FILTER='^[0-9a-zA-Z]+[_-]?[0-9a-zA-Z]+=.*$'
      if [[ "$LINE" =~ $FILTER ]]; then
        CONFIG[${LINE%%=*}]=${LINE#*=}
      fi
    done < $FILE
  else
    return 1
  fi
}

# very simple configfile writer
# it (over)writes a configfile with key=value pairs from a global variable
# usage: config_write <path/to/configfile>
function config_write {
  if [ "$1" ]; then
    local FILE="$1"
    for KEY in ${!CONFIG[@]}; do
      echo "$KEY=${CONFIG[$KEY]}"
    done | sort > $FILE
  else
    return 1
  fi
}

# get the linux distribution id from /etc/os-release
# only systems with this file present are supported
function get_distro {
  local RELEASE_FILE="/etc/os-release"
  if [ -r $RELEASE_FILE ]; then
    while read -r LINE || [ -n "$LINE" ]; do
      local FILTER='^ID='
      if [[ "$LINE" =~ $FILTER ]]; then
        echo "${LINE#*=}"; break
      fi
    done < $RELEASE_FILE
  fi
}

function set_fs_permissions {
  #TODO: check if $1 is a valid mask
  #TODO: check if is ownership is wrong
  if [ $# -eq 2 ]; then
    if [ -f "$2" -o -d "$2" ]; then
      local PERM="$1"
      local FILE="$2"
      local STAT=$(stat -c "%a" "$FILE")
      if [ $PERM -ne $STAT ]; then
        library_log debug "Fixing wrong file permissions [$FILE: $STAT -> $PERM]"
        chown $USERID:$GROUPID "$FILE"
        chmod $PERM "$FILE"
      fi
    fi
  else
    return 1
  fi
}

# retrieve path to this script
#function get_scriptpath {
#  local DIRNAME="$(dirname $0)"
#  if [ -L $0 ]; then
#    local DIRLINK="$(dirname $(readlink $0))"
#    if [ $DIRLINK == "."  ]; then
#      local SCRIPTPATH="$DIRNAME"
#    else
#      local SCRIPTPATH="$DIRNAME/$DIRLINK"
#    fi
#  else
#    local SCRIPTPATH="$DIRNAME"
#  fi
#  if [[ $SCRIPTPATH =~ ^/.* ]]; then
#    echo "$SCRIPTPATH"
#  else
#    #TODO: redirect stdout and stderr for cd to /dev/null
#    cd $SCRIPTPATH; echo "$PWD"
#  fi
#}

#function main {
#  for MODULE in ${MODULES[@]}; do
#    library_log debug "Module found ($MODULE)"
#  done
#  library_log info "This is an informational message"; sleep 2
#}

# print the usage message
function usage {
  echo; echo "Usage: $(basename $0) <OPTIONS>"
  echo ""; echo "OPTIONS:"
  echo "  -h           Show help message"
  echo "  -i           Show script information (Version, etc.)"
  echo "  -c <file>    Use custom configuration file"
  echo "  -l <file>    Use custom log file"
  echo "  -n           Force non-interactive mode"
  echo "  -d|-v        Enable verbose output"; echo
}

# print general information
function info {
  echo; echo "$NAME - $DESCRIPTION"; echo
  echo "Version:     $VERSION"
  echo "Author:      $AUTHOR"
  echo "Website:     $WEBSITE"
  echo "License:     $LICENSE"; echo
}

#print header
header() {
  clear
  local cols=$(tput cols); local char="="
  if [ $cols -gt 59 ]; then
    local i=0; while [ $i != $((cols)) ]; do local chars="$chars$char"; i=$((i+1)); done
    echo $chars; echo "$TITLE"; echo -e "$chars\n"
  else
    echo "error: terminal not wide enough (it must be at least 60 characters wide)"; exit 1
  fi
}

#print content
content() {
  local lines=$(tput lines)
  if [ $lines -gt 14 ]; then
    for i in $(seq 1 $#); do
      echo "${!i}"
    done
    local l=5; while [ $l != $((lines-$#)) ]; do echo ""; l=$((l+1)); done
  else
    clear
    echo "error: terminal not high enough (it must be at least 15 lines high)"; exit 1
  fi
}

#get user input
prompt() {
  local input=""
  case $1 in
    password)
      read -s -p "Enter [sudo] password: " input; echo $input
      ;;
    string)
      read -p "Enter string: " input; echo $input
      ;;
    *)
      read -n 1 -p "Enter number to select an option: " input
      if [[ $input =~ ^[1-9]+$ ]]; then echo $input; fi
      ;;
  esac
}

# get sudo
#makemeasandwich()
#{
#  while true; do
#    if $(sudo -n true 2>/dev/null); then
#      return 0
#    else
#      header
#      content "With great power comes great responsibility!"
#      password=$(prompt password)
#      echo "$password" | sudo -S -v 2>/dev/null
#      if [ $? -ne 0 ]; then
#        header
#        echo "Wrong password. Try again."; sleep 1
#        continue
#      fi
#    fi
#  done
#}

# ask for confirmation
function areyousure {
  echo "i am sure"
}

# update package repositories and install required packages
function update_package_repos {
  case "$(get_distro)" in
    debian|ubuntu|raspbian)
      library_log info "Updating package repositories"
      apt-get update > /dev/null
      if [ $? -eq 0 ]; then
        library_log debug "Success!"
      else
        library_log error "An error occured while updating package repositories"
        exit 1
      fi
      ;;
    arch)
      library_log info "Updating package repositories"
      pacman -Sy > /dev/null
      if [ $? -eq 0 ]; then
        library_log debug "Success!"
      else
        library_log error "An error occured while updating package repositories"
        exit 1
      fi
      ;;
    *)
      library_log error "Could not determine your operating system"
      exit 1
      ;;
  esac
}

# ***** START *****
# bashtrap initialization
trap bashtrap INT

# require root
if ! amiroot; then
  library_log error "You need to run this script with elevated privileges"
  exit 1
fi

# checking for the availibility of ${DEPENDENCIES[@]}
#TODO: rename to PREREQISITES
MISSING_DEPENDENCIES=()
for DEPENDENCY in ${DEPENDENCIES[@]}; do
  if ! $(command -v $DEPENDENCY &> /dev/null); then
    MISSING_DEPENDENCIES+=("$DEPENDENCY")
  fi
done
if [ $MISSING_DEPENDENCIES ]; then
  library_log error "Dependencies not found [${MISSING_DEPENDENCIES[@]}]"
  exit 1
fi

# option handler
while getopts "c:l:ndvih" ARG; do
  case $ARG in
    c)
      CONFIGFILE="$OPTARG"
      library_log debug "Custom config file set by command line option [-$ARG $OPTARG]"
      ;;
    l)
      LOGFILE="$OPTARG"
      library_log debug "Custom log file set by command line option [-$ARG $OPTARG]"
      ;;
    n)
      INTERACTIVE=0
      library_log debug "Forcing non-interactive mode by command line option [-$ARG]"
      ;;
    d|v)
      if [ ! $DEBUG -eq 1 ]; then
        DEBUG=1
        library_log debug "Debug mode enabled by command line option [-$ARG]"
      fi
      ;;
    i)
      info; exit 0
      ;;
    h)
      usage; exit 0
      ;;
    *)
      usage; exit 1
      ;;
  esac
done

# loading config values (from $CONFIGFILE)
if ! config_read "$CONFIGFILE"; then
  library_log warning "Could not read config file, skipping [$CONFIGFILE]"
fi

# setting runtime variables
USERID=$(id -u)
GROUPID=$(id -g)
DISTRO=$(get_distro)
#SCRIPTPATH="$(get_scriptpath)"
#MODULES=($(ls $SCRIPTPATH/modules/*.sh))
if [ ! $DEBUG -eq 1 ]; then
  DEBUG=${CONFIG[debug_enabled]}
fi
if [ -z $LOGFILE ]; then
  LOGFILE=${CONFIG[logfile]}
fi
if [ ! $INTERACTIVE -eq 0 ]; then
  if amitty; then
    INTERACTIVE=1
  fi
fi

# create logfile if missing
if [ "$LOGFILE" -a ! -w "$LOGFILE" ]; then
  if [ ! -d $(dirname "$LOGFILE") ]; then
    mkdir -p $(dirname "$LOGFILE")
  fi
  touch "$LOGFILE"
fi

# create configfile if missing
if [ ! -w $CONFIGFILE ]; then
  if [ ! -d $(dirname $CONFIGFILE) ]; then
    mkdir -p $(dirname $CONFIGFILE)
  fi
  # write config values (to $CONFIGFILE)
  library_log info "Creating new config file [$CONFIGFILE]"
  if ! config_write "$CONFIGFILE"; then
    library_log warning "Could not write to config file [$CONFIGFILE]"
  fi
fi

# change file permissions if wrong
#TODO: check return code
set_fs_permissions 600 "$CONFIGFILE"
set_fs_permissions 644 "$LOGFILE"

# loading libraries
#for LIBRARY in ${LIBRARIES[@]}; do
#  if [ -r $SCRIPTPATH/$LIBRARY ]; then
#    source $SCRIPTPATH/$LIBRARY
#    if [ $DEBUG -eq 1 ]; then
#      echo "[debug] Library loaded [$LIBRARY]"
#    fi
#  else
#    echo "[error] Library not found [$LIBRARY]"
#    exit 1
#  fi
#done

# log start of main script
library_log debug "*****  START  *****"

if [ $INTERACTIVE -eq 1 ]; then
  # run text ui
  while true; do
    # Main menu
    header
    content "1) System status" \
            "2) Configuration" \
            "3) Maintenance" \
            "" \
            "4) Reboot" \
            "5) Shutdown" \
            "6) Exit to shell"
    case $(prompt) in
      1)
        header
        echo "Not yet implemented"; sleep 1
        ;;
      2)
        while true; do
          # Configuration submenu
          header
          content "1) Users" \
                  "2) Install admin utilities" \
                  "" \
                  "*) Return to main menu"
          case $(prompt) in
            1)
              header
              echo "Not yet implemented"; sleep 1
              ;;
            2)
              header
              echo "Not yet implemented"; sleep 1
              ;;
            *)
              break
              ;;
          esac
        done
        ;;
      3)
        while true; do
          # Maintenance submenu
          header
          content "1) System updates" \
                  "2) Backup" \
                  "3) Update this script" \
                  "" \
                  "*) Return to main menu"
          case $(prompt) in
            1)
              #update system packages
              makemeasandwich
              if [ $? -eq 0 ]; then
                clear; header; sudo apt update && sudo apt dist-upgrade -y && sudo apt autoremove -y && sudo apt autoclean -y
                clear; header; echo "System is up-to-date"; sleep 1
              fi
              ;;
            2)
              header
              echo "Not yet implemented"; sleep 1
              ;;
            3)
              # Update this script submenu
              header
              #TODO: check for new version
              if false; then #this should run the check
                content "A new version of sconfig is available." \
                        "Do you want to update?" \
                        "" \
                        "1) Yes" \
                        "2) No"
                if [ $(prompt) -eq 1 ]; then
                    #run self update
                    header
                    echo "Update not yet implemented"; sleep 1
                fi
              else
                header
                echo "You are already up-to-date."; sleep 1
              fi
              ;;
            *)
              break
              ;;
          esac
        done
        ;;
      4)
        # Reboot submenu
        header
        content "1) Yes, i really want to reboot." \
                "*) Get me out of here!"
        case $(prompt) in
          1)
            #reboot server
            header
            echo "Rebooting server"; sleep 1
            shutdown -r now
            ;;
          *)
            continue
            ;;
        esac
        ;;
      5)
        # Shutdown submenu
        header
        content "1) Yes, i really want to shutdown." \
                "*) Get me out of here!"
        case $(prompt) in
          1)
            #shutdown server
            header
            echo "Shutting down server"; sleep 1
            shutdown -h now
            ;;
          *)
            continue
            ;;
        esac
        ;;
      6)
        header
        echo "Dropping to shell"; sleep 1
        clear; break
        ;;
    esac
  done
else
  # run scheduled tasks
  library_log info "Running scheduled tasks"
  update_package_repos
fi

# ***** END *****
library_log debug "*****  END  *****"
exit 0