#!/bin/bash
#
#*****************************************************************************
# syncit - synchronize files                                                 *
#*****************************************************************************
# Author:  Christian Habermann                                               *
#          christian (at) habermann-net (point) de                           *
#                                                                            *
# Version: 1.0.0                                                             *
#                                                                            *
# Date:    27. Jan. 2004                                                     *
#                                                                            *
# Copyright 2003 Christian Habermann, distributed under the terms of GPL     *
#                                                                            *
# History: - V0.1.0, 20. Nov. 2003                                           *
#            initial version                                                 *
#                                                                            *
#          - V1.0.0, 27. Jan. 2004                                           *
#            first release                                                   *
#            - documentation improved                                        *
#            - added ASK_BEFORE_STARTING_SCRIPT                              *
#              ask before starting to synchronize                            *
#            - added ASK_BEFORE_SYNCHRONIZING                                *
#              ask for each file separately whether it should be             *
#              synchronized or not                                           *
#                                                                            *
#                                                                            *
#*****************************************************************************
# Description:                                                               *
#   This script can be used to keep shared files on Windows and Linux        *
#   systems up to date.                                                      *
#                                                                            *
#   Typical use case:                                                        *
#     PC at home (e.g. Linux)                                                *
#     PC at work (e.g. Windows, with cygwin to run this script)              *
#     Data files are carried via USB-memory stick between work and home.     *
#                                                                            *
#     When leaving PC1 to use PC2, start this script on PC1 in order to      *
#     update files on transport device (e.g. USB-memory stick). At PC2 start *
#     this script in order to update files on PC2. And vice versa.           *
#                                                                            *
#   Date/time of last modification of files on FAT filesystem has a          *
#   resolution of 2 seconds. Seconds can have values of 0, 2, 4, ... 58.     *
#   Linux filesystems have a resolution of 1 second for date/time of last    *
#   modification.                                                            *
#   In order to decide whether files on FAT and Linux-filesystems are        *
#   equally old, it is necessary to reduce date/time resolution to 2         *
#   seconds for Linux filesystems too.                                       *
#   This means files with e.g. 34 and 35 seconds are treated as equally old. *
#                                                                            *
#                                                                            *
#   See below "USER SETTINGS" for how to select files which should be        *
#   synchronized on different systems.                                       *
#                                                                            *
#                                                                            *
#*****************************************************************************


#*****************************************************************************
#***************************** USER SETTINGS *********************************
#*****************************************************************************

         #***                                                      ***
         #*** USER: Adapt the following settings to you own needs. ***
         #***                                                      ***

TRANSDEV_LIN="/mnt/penhdd/"      # path to transportable device for linux
TRANSDEV_WIN="e:/"               # and windows

MAX_NUM_OF_FILES=20          # max. number of files that can be specified to
                             # be synchronized

#*** specify a file ***
# For each file, four variables must be specified:
#   NAME_x:       a short text describing type of file
#                 Hint: if you want a well formated output, give all NAME_x
#                       the same length (use spaces if necessary)
#   FILE_LIN_x:   file on Linux system
#   FILE_WIN_x:   file on Windows system
#   FILE_TRANS_x: file on transport system
#
#   x is a unique number in the range of 1 ... MAX_NUM_OF_FILES


# EXAMPLE: keep Opera bookmarks and vim-config-files up to date
#NAME_1="Opera Bookmarks"
#FILE_LIN_1="$HOME/.opera/opera6.adr"
#FILE_WIN_1="c:/programme/Opera7/operadef6.adr"
#FILE_TRANS_1="opera/opera6.adr"
#
#NAME_2="Vim .vimrc     "
#FILE_LIN_2="$HOME/.vimrc"
#FILE_WIN_2="c:/_vimrc"
#FILE_TRANS_2="vim/_vimrc"
#
#NAME_3="Vim .gvimrc    "
#FILE_LIN_3="$HOME/.gvimrc"
#FILE_WIN_3="c:/_gvimrc"
#FILE_TRANS_3="vim/_gvimrc"



# set this to 0 if you don't want to be asked to start synchronizing
ASK_BEFORE_STARTING_SCRIPT=1

# set this to 0 if you don't want to be asked for each file separately whether you
# really want to synchronize it or not
# ATTENTION: IF THIS IS 0 NEWER FILES ARE COPIED OVER OLDER ONES WITHOUT WARNING.
ASK_BEFORE_SYNCHRONIZING=1



# IMPORTANT: set this to 1, else syncit will deny to start.
# This is done to ensure that user has configured this script.
USER_SETTINGS_DONE=0


                         #*** end of user's section ***


#*****************************************************************************
#******************************* CONSTANTS ***********************************
#*****************************************************************************

                            ### make some initialisations
VERSION="1.0.0"                    # used to print version number
SCRIPTNAME="syncit"                # name of file
PROGNAME="SyncIt"                  # name of this tool

SYS_LINUX=0
SYS_WINDOWS=1



#*****************************************************************************
#******************************* FUNCTIONS ***********************************
#*****************************************************************************



#*****************************************************************************
# input: $1: $name   name of what is to be synchronized (e.g. bookmarks,...) *
#        $2: $file1  file on system                                          *
#        $3: $file2  file on transport device                                *
#*****************************************************************************
#  Copy newer file over older file.                                          *
#  If neither $file1 nor $file2 does exist, don't copy, just print message.  *
#  If just one file exists, copy this to none-existing path/file.            *
#                                                                            *
#  Date/time is in seconds since 1970-1-1 00:00:00                           *
#  To be compatible to vfat-filesystems, granularity of date/time is reduced *
#  to 2 seconds (date/time can be ..., 1202, 1204, 1206, ... seconds)        *
#  Files with a real date/time of e.g. 1202 and 1203 are considered as files *
#  which have the same date/time.                                            *
#                                                                            *
#*****************************************************************************
SYI_Synchronize ()
{
  local name=$1
  local file1=$2
  local file2=$3


  echo -n "synchronize $name: "


  #*** get date/time of file in seconds since 1970-1-1 00:00:00
  #*** if file does not exist, date = -1
     # get date/time of file 1 with granularity of 2 seconds
  if [ -e "$file1" ]; then
    dateF1=$(date -r "$file1" +%s)

    dateF1=$(($dateF1 - $dateF1 % 2))
  else
    dateF1=-1
  fi


     # get date/time of file 2 with granularity of 2 seconds
  if [ -e "$file2" ]; then
    dateF2=$(date -r "$file2" +%s)
    
    dateF2=$(($dateF2 - $dateF2 % 2))
  else
    dateF2=-1
  fi


     # if none of the files exist, return
  if [ $dateF1 -eq -1 ] && [ $dateF2 -eq -1 ]; then
    echo "no file found"
    return 1
  fi



  #*** at least one of the files exists, copy newest over oldest
  #*** if enabled ask before copying
  #*** if files have identical date/time, do nothing
  if [ $dateF1 -gt $dateF2 ]; then
    echo -n "system --> device "

    awnser="y"

    # ask before copying?
    if [ $ASK_BEFORE_SYNCHRONIZING -ne 0 ]; then
      echo -n "[y, n]?"
      
      read -s -n 1 awnser
    fi
    
    if [ "$awnser" == "y" ]; then
      cp -a "$file1" "$file2"

      echo "... ok"
    else
      echo "... skipped"
    fi

  else

    if [ $dateF1 -lt $dateF2 ]; then
      echo -n "system <-- device "
      
      awnser="y"

      # ask before copying?
      if [ $ASK_BEFORE_SYNCHRONIZING -ne 0 ]; then
        echo -n "[y, n]?"
        
        read -s -n 1 awnser
      fi

      if [ "$awnser" == "y" ]; then
        cp -a "$file2" "$file1"

        echo "... ok"
      else
        echo "... skipped"
      fi
      
    else   # file 1 and 2 equally old => do nothing
      echo "... up to date"
    fi

  fi

}



#*****************************************************************************
# input:  none                                                               *
# output: SYS_LINUX:   linux                                                 *
#         SYS_WINDOWS: windows                                               *
#*****************************************************************************
# Returns on which system (linux or windows) this script is running.         *
# If c: exists, windows is assumed, else linux.                              *
#                                                                            *
#*****************************************************************************
SYI_WhichSystem()
{
  if [ -d "C:/" ]; then
    return $SYS_WINDOWS
  else
    return $SYS_LINUX
  fi
}



#*****************************************************************************
#***************************** START OF MAIN *********************************
#*****************************************************************************

#*** startup text
echo "$PROGNAME V$VERSION "


# exit if user has not done settings
if [ $USER_SETTINGS_DONE -eq 0 ] ; then
  echo "ERROR: It seems that $PROGNAME is not configured. Please adapt this"
  echo "       script to your own needs. See header of script for further"
  echo "       information."
  exit 1
fi



# ask user to start synchronizing files
if [ $ASK_BEFORE_STARTING_SCRIPT -ne 0  ]; then
  echo "Do you want to start synchronizing files?"
  
  if [ $ASK_BEFORE_SYNCHRONIZING -eq 0 ]; then
    echo "WARNING: older files are overwritten with newer ones without warning!"
  fi

  echo ""
  echo "press any key to start or ctrl-c to cancel"

  read -s -n 1
fi



#*** get system we are running on (linux or windows?)
SYI_WhichSystem
system=$?

if [ $system -eq $SYS_LINUX ]; then
  echo "running under Linux"
  mount "$TRANSDEV_LIN"
else
  echo "running under Windows"
fi



# main loop: synchronize files
for i in $(seq $MAX_NUM_OF_FILES); do
#for ((i=1; i <= 10; i++)); do
   
  # concatenate string and loop-counter to variable
  # principle:  NAME_${i}       expands to string NAME_1
  #             \$\{NAME_${i}\} builds string ${NAME_1}
  #             finally eval expands this string again 
  eval name=\$\{NAME_${i}\}
  eval file_trans=\$\{FILE_TRANS_${i}\} 
  eval file_lin=\$\{FILE_LIN_${i}\} 
  eval file_win=\$\{FILE_WIN_${i}\} 

  # if NAMExx is not empty synchronize this file
  if [ -n "$name" ]; then
      
    # synchronize file
    if [ $system -eq "$SYS_LINUX" ]; then    # Linux?
      SYI_Synchronize "$name" "$file_lin" "$TRANSDEV_LIN$file_trans"
    else                                     # Windows
      SYI_Synchronize "$name" "$file_win" "$TRANSDEV_WIN$file_trans"
    fi
    
  fi
  
done



#*** clean up
if [ $system -eq $SYS_LINUX ]; then
  sleep 2                # device needs time to get ready for umount 
  umount $TRANSDEV_LIN
fi


# that's it - bye bye
exit 0

# EOF