#!/bin/bash
## Create by Stefan Sterz <hi@sterzy.com> in 2017

## General Settings
SOURCES=(/root /etc /home /boot)  # What folder should be saved?
TARGET="/home/sterzy/backup"      # Where should they be saved? (absolute path!)
EXCLUDEFROM=""                    # What files are supposed to be excluded?
MAILADRESS=""                     # To which email adress should the logs be sent?
LISTPACKAGES=""                   # Change to non empty string to save a list of 
                                  # installed packages!
LOG=$0.log                        # Log file name & location
RSYNCCONF=(--delete)              # Additional rsync flags  

## SSH Settings
TOSSH=""                          # What ssh server stores the backups?
FROMSSH=""                        # From what ssh server should the files be 
                                  # backuped?
                                  # For several reasons TOSSH and FROMSSH cannot
                                  # be used at the same time!
TOSSHUSER=""                      # The ssh user of the system on which the 
                                  # backup will be created
TOSSHPORT=22                      # The ssh port of the system on which the 
                                  # backup will be created
FROMSSHUSER=""                    # The ssh user of the system from which the 
                                  # files will be backed up
FROMSSHPORT=22                    # The ssh port of the system from which the 
                                  # files will be backed up
WEEKS=5                           # For how many weeks shall we save backups?

## Command variables, 
# These should be fine, but if something doesn't work these can be adjusted
MOUNT="/bin/mount"; FGREP="/bin/fgrep"; SSH="/usr/bin/ssh"; EXPR="/usr/bin/expr"
LN="/bin/ln"; ECHO="/bin/echo"; DATE="/bin/date"; MKDIR="/bin/mkdir"
DPKG="/usr/bin/dpkg"; AWK="/usr/bin/awk"; MAIL="/usr/bin/mail"
CUT="/usr/bin/cut"; TR="/usr/bin/tr"; RSYNC="/usr/bin/rsync"

## Helpers
LAST="last"; INC="--link-dest=$TARGET/$LAST"

# Format log information
function formatLog () 
{
  while IFS= read -r line; do
    printf "$($DATE):\t$line\n"
  done
}

# Backup function
# Creates a backup of the folders provides by $SOURCES in $TARGET in the sub 
# directory provided by the first parameter ($1)
function backup () 
{
  $ECHO "Creating backup in \"$TOSSH:$TARGET$1\"..." 2>&1 | formatLog >> $LOG

  if [ -n "$LISTPACKAGES" ] && [ -z "$FROMSSH" ]; then
    $ECHO "$DPKG --get-selections | $AWK '!/deinstall|purge|hold/'|$CUT -f1 | $TR 'n' ' '" 2>&1 | formatLog >> $LOG
    $DPKG --get-selections | $AWK '!/deinstall|purge|hold/'|$CUT -f1 |$TR '\n' ' ' >> $LOG 2>&1
  fi

  # Create folders that don't exist
  if [ -n "$S" ] && [ -n "$TOSSH" ] && [ -z "$FROMSSH" ]; then
    $ECHO "$S $TOSSH $MKDIR -p $TARGET$1" 2>&1 | formatLog >> $LOG  
    $S $TOSSH "$MKDIR -p \"$TARGET\"$1" 2>&1 | formatLog >> $LOG 2>&1
    if [ $? -ne 0 ]; then
      ERROR=1
    fi  
  elif ( [ -n "$S" ] && [ -n "$FROMSSH" ] && [ -z "$TOSSH" ] ) || ( [ -z "$S" ] );  then
    $ECHO "$MKDIR -p $TARGET$1" 2>&1 | formatLog >> $LOG
    $MKDIR -p "$TARGET"$1 2>&1 | formatLog >> $LOG 2>&1 
    if [ $? -ne 0 ]; then
      ERROR=1
    fi 
  fi

  # Backup files
  for SOURCE in "${SOURCES[@]}" 
    do
      if [ -n "$S" ] && [ -n "$TOSSH" ] && [ -z "$FROMSSH" ]; then 
        $ECHO "$RSYNC -e \"$S\" -avR \"$SOURCE\" ${RSYNCCONF[@]} \"$TOSSH:$TARGET$1\" $INC --exclude-from=\"$EXCLUDEFROM\"" 2>&1 | formatLog >> $LOG
        $RSYNC -e "$S" -avR "$SOURCE" "${RSYNCCONF[@]}" "$TOSSH:\"$TARGET\"$1" $INC --exclude-from="$EXCLUDEFROM" 2>&1 | formatLog >> $LOG 2>&1 
        if [ $? -ne 0 ]; then
          ERROR=1
        fi
      elif [ -n "$S" ] && [ -z "$TOSSH" ] && [ -n "$FROMSSH" ]; then
        $ECHO "$RSYNC -e \"$S\" -avR \"$FROMSSH:$SOURCE\" ${RSYNCCONF[@]} $TARGET$1 $INC --exclude-from=\"$EXCLUDEFROM\"" 2>&1 | formatLog >> $LOG 
        $RSYNC -e "$S" -avR "$FROMSSH:\"$SOURCE\"" "${RSYNCCONF[@]}" "$TARGET"$1 $INC --exclude-from="$EXCLUDEFROM" 2>&1 | formatLog >> $LOG 2>&1 
        if [ $? -ne 0 ]; then
          ERROR=1
        fi
      elif [-z "$S"] && [ -z "$TOSSH" ] && [ -z "$FROMSSh" ]; then
        $ECHO "$RSYNC -avR \"$SOURCE\" ${RSYNCCONF[@]} $TARGET$1 $INC --exclude-from=\"$EXCLUDEFROM\"" 2>&1 | formatLog >> $LOG 
        $RSYNC -avR "$SOURCE" "${RSYNCCONF[@]}" "$TARGET"$1 $INC --exclude-from="$EXCLUDEFROM" 2>&1 | formatLog >> $LOG 2>&1 
        if [ $? -ne 0 ]; then
          ERROR=1
        fi
      fi
  done 

  # Create a link to the latest backup
  if [ -n "$S" ] && [ -n "$TOSSH" ] && [ -z "$FROMSSH" ]; then
    $ECHO "$S $TOSSH $LN -nsf $TARGET$1 $TARGET$LAST" 2>&1 | formatLog >> $LOG  
    $S $TOSSH "$LN -nsf \"$TARGET\"$1 \"$TARGET\"$LAST" 2>&1 | formatLog >> $LOG 2>&1
    if [ $? -ne 0 ]; then
      ERROR=1
    fi  
  elif ( [ -n "$S" ] && [ -n "$FROMSSH" ] && [ -z "$TOSSH" ] ) || ( [ -z "$S" ] );  then
    $ECHO "$LN -nsf $TARGET$1 $TARGET$LAST" 2>&1 | formatLog >> $LOG
    $LN -nsf "$TARGET"$1 "$TARGET"$LAST  2>&1 | formatLog >> $LOG 2>&1 
    if [ $? -ne 0 ]; then
      ERROR=1
    fi 
  fi

  $ECHO "Done creating backup in \"$TOSSH:$TARGET$1\"" 2>&1 | formatLog >> $LOG
}

# Clear log
$ECHO -n "" > $LOG

# Make sure the provided path is absolute
if [ "${TARGET:${#TARGET}-1:1}" != "/" ]; then
  TARGET=$TARGET/
fi

# Handle SSH info
if [ -n "$TOSSH" ] && [ -z "$FROMSSH" ]; then 
  S="$SSH -p $TOSSHPORT -l $TOSSHUSER"
elif [ -z "$TOSSH" ] && [ -n "$FROMSSH" ]; then
  S="$SSH -p $FROMSSHPORT -l $FROMSSHUSER"
elif [ -n "$TOSSH" ] && [ -n "$FROMSSH" ]; then
  ERROR=1
  $ECHO "Plese don't provide to and from ssh information!" 2>&1 | formatLog >> $LOG
  $ECHO "No backup performed!" 2>&1 | formatLog >> $LOG
  exit 1
fi

# Get date etc.
WEEKDAY=$($DATE +"%u")                # %a = weekday as number
DAY=$($DATE +"%d")                    # %d = day in month as number
MONTH=$($DATE +%m)                    # %m = month as number
HOUR=$($DATE +"%H")                   # %H = hour as number
WEEK=$($EXPR $($DATE +"%W") % $WEEKS) # %W = week as number, used to save backups for the past $WEEKS weeks

# Create a backup every first day in a month
if [[ $DAY = 01 ]]; then
  backup "monthly/$MONTH-$($DATE +"%B")"
fi

# Create a special backup approx every week
if [[ $WEEKDAY = 7 ]]; then
  backup "weekly/$WEEK"
fi

# Create daily backups
backup "daily/$WEEKDAY-$($DATE +"%A")/$HOUR"

# Send email if an adress was provided
if [ -n "$MAILADRESS" ]; then  
  if [ $ERROR ]; then
    $MAIL -s "[Backup] error occured during backup - $LOG" $MAILADRESS < $LOG
  else
    $MAIL -s "[Backup] backup created successfully - $LOG" $MAILADRESS < $LOG
  fi
fi