#!/bin/bash

#
# synchole.sh
# Pi-Hole syncronizer
#

#  ****  configuration  ****

MASTER="10.1.3.2" #IP or hostname of the MASTER server
DEBUG=1 #enable verbose output (1=on, 0=off)
BACKUP_VERSIONS=10 #how many backups should be kept
BACKUP_PATH="/etc/pihole/synchole-backups" #path to backups
DOWNLOAD_PATH="/tmp/synchole-downloads" #path to list downloads

LISTS="whitelist.txt blacklist.txt regex.list" #pihole files to sync
LISTS_PATH="/etc/pihole" #pihole files path

NAME="synchole"
VERSION="0.1"
AUTHOR="david@socialnerds.org"
LICENSE="GPLv3"
DEPENDENCIES="wget"


#  ****  functions  ****

## check for elevated privileges
amiroot() {
  if [ $(whoami) != "root" ]; then
    return 1
  fi
}

## check if pi-hole is installed
amipihole() {
  if [ ! $(which /usr/local/bin/pihole) ]; then
    return 1
  fi
}

## output handling
log() {

  if [ -t 1 ]; then
    CRON=0
  else
    CRON=1
  fi

  case $1 in
    "error")
      level="\033[31m✗\033[0m"
      ;;
    "warn")
      level="\033[33m!\033[0m"
      ;;
    "debug")
      if [ $DEBUG -eq 1 ] && [ $CRON -eq 0 ]; then
	      level="\033[2md\033[0m"
      else
	      return 0
      fi
      ;;
    "success")
      if [ $CRON -eq 0 ]; then
        level="\033[32m✓\033[0m"
      else
        return 0
      fi
      ;;
    "info")
      if [ $CRON -eq 0 ]; then
        level="i"
      else
        return 0
      fi
      ;;
    *)
      level="\033[31mLoglevel unknown. Programming error? ($1)\033[0m"
      ;;
  esac

  sleep 0.5; echo -e "[$NAME]-[$level] ${@:2}"
}

## backup single list file to $BACKUP_PATH
backup_list() {
  if [ -z $1 ]; then
    return 1
  else
    for VERSION in $(eval echo {$BACKUP_VERSIONS..1}); do
      if [ -w $BACKUP_PATH/$1.$VERSION ]; then
      	if [ $VERSION -eq $BACKUP_VERSIONS ]; then
      	  rm $BACKUP_PATH/$1.$VERSION
      	else
      	  mv $BACKUP_PATH/$1.$VERSION $BACKUP_PATH/$1.$(($VERSION+1))
      	fi
      fi
    done
    if [ -w $BACKUP_PATH/$1 ]; then
      cp $BACKUP_PATH/$1 $BACKUP_PATH/$1.1
    fi
    if [ -r $LISTS_PATH/$1 ]; then
      cp $LISTS_PATH/$1 $BACKUP_PATH/$1
      if [ $? -ne 0 ]; then
        return 1
      fi
    fi
  fi
}

## create path/to/folder if it does not exist
create_path() {
  if [ -z $1 ]; then
    return 1
  else
    if [ ! -d $1 ]; then
      mkdir -p $1
      if [ $? -ne 0 ]; then
        return 1
      fi
    fi
  fi
}

## update pi-hole lists (run updateGravity)
update_gravity() {
  /usr/local/bin/pihole -g > /dev/null
  if [ $? -ne 0 ]; then
    return 1
  fi
}

## install new list
install_list() {
  if [ -z $1 ]; then
    return 1
  else
    cp $DOWNLOAD_PATH/$1 $LISTS_PATH/$1
    if [ $? -ne 0 ]; then
      return 1
    fi
  fi
}

## download remote file
download_list() {
  if [ -z $1 ]; then
    return 1
  else
    wget http://$MASTER/synchole/$1 -q -O $DOWNLOAD_PATH/$1
    if [ $? -ne 0 ]; then
      return 1
    fi
  fi
}

#  ****  start of script  ****

log debug "Starting synchole"

## preflight checks
log debug "Running preflight checks"


if ! amiroot; then
  log error "You must be root"
  exit 1
fi

if ! amipihole; then
  log error "I am no pihole"
  exit 1
fi

for DEPENDENCY in $DEPENDENCIES; do
  if [ ! $(which $DEPENDENCY) ]; then
    log error "$DEPENDENCY is not installed"
    exit 1
  fi
done

log success "Preflight checks passed successfully"

## generate $BACKUP_PATH and $DOWNLOAD_PATH if not available
if ! create_path $DOWNLOAD_PATH; then
  log error "Something went wrong while creating $DOWNLOAD_PATH"
  exit 1
fi

if ! create_path $BACKUP_PATH; then
  log error "Something went wrong while creating $BACKUP_PATH"
  exit 1
fi

## download remote files from MASTER and backup local lists
CHANGES=0
for LIST in $LISTS; do
  log debug "Downloading $LIST from $MASTER"
  if ! download_list $LIST; then
    log error "Something went wrong while downloading $LIST"
    exit 1
  else
    log success "Successfully downloaded $LIST"
  fi

  #TODO: don't install new list if to many changes or
  #      somehow verify if new file is an actual list
  #      maybe check if wget actually downloaded a file or were we redirected
  diff $DOWNLOAD_PATH/$LIST $LISTS_PATH/$LIST
  if [ $? -ne 0 ]; then
    log debug "Backing up $LIST"
    if [ -r $LISTS_PATH/$LIST ]; then
      if ! backup_list $LIST; then
        log error "Something went wrong while backing up $LIST"
        exit 1
      else
        log debug "Successfully backed up $LIST"
      fi
    else
      log debug "$LIST not found, skipping"
    fi

    log debug "Installing $LIST."
    if ! install_list $LIST; then
      log error "Something went wrong while installing $LIST"
      exit 1
    else
      log success "Successfully installed new $LIST"
      CHANGES=1
    fi
  else
    log debug "No changes in $LIST"
  fi
done

## run updateGravity
if [ $CHANGES -eq 1 ]; then
  log debug "Updating gravity"
  if ! update_gravity; then
    log error "Something went wrong while updating gravity"
    exit 1
  else
    log success "Gravity has been successfully updated"
  fi
else
  log debug "No files have been changed, skipping gravity update"
fi

#TODO: sync hosts and restartdns on changes

exit 0

#  ****  end of script  ****