#!/bin/bash
# Copyright 2021 Luca Paris
#This file is part of masync.

#masync is free software: you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation, either version 3 of the License, or
#(at your option) any later version.

#masync is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.

#You should have received a copy of the GNU General Public License
#along with masync.  If not, see <http://www.gnu.org/licenses/>.

## REQUIREMENT
# apt-get install inotify-tools
# @1   hash to retrieve sync
# @2   local path to sync
# @3   remote path to sync
#echo "$1, $2, $3"
source ~/bin/.synccmd.sh
source ~/bin/.colordef.sh
TMPQUEUEFILE=~/.syncdir_$1.queue
TMPQUEUEDELETES=~/.syncdir_$1.deletes

LOCALPATH_HASH=$1
LOCALPATH=$2
REMOTEPATH=$3

REMOTEHOST=$(echo "$REMOTEPATH" | cut -d : -f 1 | cut -d @ -f 2)
REMOTERELATIVEPATH=$(echo "$REMOTEPATH" | cut -d : -f 2)

#acquire lock_deletes file descritptor
exec {lock_deletes}>>${TMPQUEUEDELETES}
#acquire lock queue file descriptor
exec {lock_queue}>>${TMPQUEUEFILE}

min() {
  if [ $1 -gt $2 ]; then 
    echo $2
  else 
    echo $1
  fi
}

synccycle() {
  lastsynctime="$(date -u +%s.%N)"
  ### initial max waiting time for pull (seconds) used as unit
  ### first pulliteration zero cause immediate pulling from remote
  pulllimitunit=60
  pulliteration=0
  maxpulliteration=5
  let "maxpulllimit = $pulllimitunit * $pulliteration"
  ### max waiting time for pull (seconds) 10 min
  thresholdpulllimit=600
  while :
  do
    if [ -f "$TMPQUEUEFILE" ] || [ -f "$TMPQUEUEDELETES" ]; then 
      ### DELETES WHILE LOOP
      if [ -f "$TMPQUEUEDELETES" ]; then 
        ndeletes=$(wc -l < ${TMPQUEUEDELETES})
        while [ $ndeletes -gt 0 ]; do
          echo "Remote files to delete: ${GREEN}$(head -n $ndeletes ${TMPQUEUEDELETES} | tr '\n', ' ')${ENDCOLOR}"
          ssh $REMOTEHOST "rm -rf $(head -n $ndeletes ${TMPQUEUEDELETES} | tr '\n', ' ')"
          # remove the first ndeletes lines
          flock $lock_deletes
          tmpfile=$(mktemp)
          tail -n +$(expr ${ndeletes} + 1) < ${TMPQUEUEDELETES} > ${tmpfile}
          cat ${tmpfile} > ${TMPQUEUEDELETES}
          rm -f ${tmpfile}
          flock -u $lock_deletes
          ndeletes=$(wc -l < ${TMPQUEUEDELETES})
          echo "ndeletes: $ndeletes"
        done
      fi

      ### PUSH WHILE LOOP
      if [ -f "$TMPQUEUEFILE" ]; then 
        nqueue=$(wc -l < ${TMPQUEUEFILE})
        while [ $nqueue -gt 0 ]; do
          echo "${TMPQUEUEFILE} not empty consume ${nqueue} updates in queue"
          sync $LOCALPATH_HASH $LOCALPATH $REMOTEPATH 
          # remove the first nqueue lines from queue
          flock $lock_queue
          tmpfile=$(mktemp)
          tail -n +$(expr ${nqueue} + 1) < ${TMPQUEUEFILE} > ${tmpfile}
          cat ${tmpfile} > ${TMPQUEUEFILE}
          rm -f ${tmpfile}
          flock -u $lock_queue
          #lastsynctime="$(date -u +%s.%N)"
          nqueue=$(wc -l < ${TMPQUEUEFILE})
        done
      fi
    fi
    now="$(date -u +%s.%N)"
    elapsed="$(bc <<<"$now-$lastsynctime")"
    ## if elapsed is greater than maxpulllimit sync from remote with delete option
    if [ 1 -eq $(echo "$elapsed>$maxpulllimit" | bc) ]; then
      echo "Maxpulllimit: $maxpulllimit reached: sync from remote with --delete option"
      sync $LOCALPATH_HASH $REMOTEPATH $LOCALPATH '--delete' 
      lastsynctime="$(date -u +%s.%N)"
      ## increment the pull iteration or reset it
      if [ ${pulliteration} -eq  ${maxpulliteration} ]; then
        pulliteration=0
      else
        let pulliteration++
      fi
      let "limit = $pulliteration * $pulliteration * $pulllimitunit"
      maxpulllimit=$(min $limit $thresholdpulllimit)
    fi
    sleep 10
  done
}

synccycle &

# exclude swp,swpx and 4913 files created by vim
inotifywait -m -r -e create -e close_write -e move -e delete --exclude "\.swp|\.swx|4913|.txt~" $LOCALPATH | while read dir action file; do
    if [ $action = 'DELETE' ] || [ $action = 'DELETE,ISDIR' ]  || [ $action = 'MOVED_FROM' ] || [ $action = 'MOVED_FROM,ISDIR' ]; then
      echo "Enqueue delete: $dir$file"
      flock $lock_deletes
      echo $dir$file | sed -e "s~$LOCALPATH~$REMOTERELATIVEPATH~g" | tee -a ${TMPQUEUEDELETES}
      flock -u $lock_deletes
    else
      flock $lock_queue
      echo "Add notify to queue: file '$file' in directory '$dir' for '$action'" | tee -a ${TMPQUEUEFILE}
      flock -u $lock_queue
    fi
  done