#!/bin/bash
# Brett Kelly
CONF_DIR="/root/.cephfs/cephfssyncd.conf"
mkdir -p /var/lib/ceph/cephfssync/
source $CONF_DIR

## CHECKS
# check cluster membership & permission
# check cephfs is mounted.
# check recv'r connection
# check recv FS exists and is writable
# turn on snapshots

## FUNCTIONS
getrctime(){
    # getrctime <directory> <1||2>
    # Returns recursive ctime of <directory>
    local ctime=$(getfattr --absolute-names -n ceph.dir.rctime $1 --only-values | cut -d. -f$2)
    echo "$ctime"
}
getsubdirs(){
    # getsubdir <directory> 
    # Returns number of subdirs in <directory>
    local subdir=$(getfattr --absolute-names -n ceph.dir.subdir $1 --only-values)
    echo "$subdir"
}
getfiles(){
    # getfiles <directory> 
    # Return number of files in <directory>
    local files=$(getfattr --absolute-names -n ceph.dir.files $1 --only-values)
    echo "$files"
}
takesnap(){
    # takesnap <rctime>
    # Creates snapshot and appends timestamp to name, updates last_rctime to the moment after the snapshot
    # Returns snapshot directory to sync from
    local RCTIME_1=$1
    local SNAP_DIR="$SND_SYNC_DIR/.snap/$RCTIME_1"
    mkdir $SNAP_DIR 
    echo "$SNAP_DIR"
}
formattime(){
    # converts epoch time to human readable
    # for logging purposes only
    local EPOCH=$1
    local TIME=$(date -d @$EPOCH '+%Y-%m-%d %H:%M:%S')
    echo $TIME
}
log(){
    # log <message> <log_level>
    if [  "$2" -lt $(( LOG_LEVEL + 1 )) ];then
            echo $1
    fi
}
main(){
    local RCTIME_0=$1
    local DIR=$2
    for dir in $DIR/*;do
        if [ -d $dir ];then
            local RCTIME_1=$(getrctime $dir 1)
            log "parent:$(formattime $RCTIME_0) dir:$(formattime $RCTIME_1):$dir" 2 
            if [ "$RCTIME_1" -eq "$RCTIME_0" ];then
                log "CHANGE DETECTED IN $dir" 0
                if [ $(getfiles $dir) -gt 0 ];then 
                    cephfssync $dir $RECV_SYNC_HOST $RECV_SYNC_DIR sync $RCTIME_1 &
                fi
                main $RCTIME_0 $dir
            elif [ "$RCTIME_1" -lt "$RCTIME_0" ];then
                log "NO CHANGE DETECTED IN $dir OR BELOW" 1
            elif [ "$RCTIME_1" -gt "$RCTIME_0" ];then
                log "$dir WAS MODIFIED AFTER STARTING CHECK. WAIT FOR NEXT CYCLE" 0
                log "This really should not happen if syncing from a snapshot" 0
            fi
        fi
    done
}

# START HERE
log "started" 0
SYNC_FREQ=5
while sleep $SYNC_FREQ ; do
    SYNC_FREQ=$(cat $CONF_DIR | grep "SYNC_FREQ" | cut -d= -f2)
    log "watching : $SND_SYNC_DIR" 1
    if [ -e /var/lib/ceph/cephfssync/last_rctime ];then
        log "last_rctime exists, init RCTIME=last_rctime" 2
        RCTIME_0=$(cat /var/lib/ceph/cephfssync/last_rctime)
    else
        log "last_rctime does not exist, init RCTIME=0" 2
        RCTIME_0=0
    fi
    RCTIME_1=$(getrctime $SND_SYNC_DIR 1)
    log "rctime_0 : $RCTIME_0 " 2
    log "rctime_1 : $RCTIME_1 " 2
    
    if [ "$RCTIME_1" -gt "$RCTIME_0" ];then
        log "CHANGE DETECTED IN $SND_SYNC_DIR" 0
        SNAP_DIR=$(takesnap $RCTIME_1)
        RCTIME_SNAP=$(getrctime $SND_SYNC_DIR 1)
        echo "$RCTIME_SNAP" > /var/lib/ceph/cephfssync/last_rctime
        /usr/bin/cephfssync $SNAP_DIR $RECV_SYNC_HOST $RECV_SYNC_DIR init $RCTIME_1
        if [ $(getfiles $SND_SYNC_DIR) -gt 0 ];then
            /usr/bin/cephfssync $SNAP_DIR $RECV_SYNC_HOST $RECV_SYNC_DIR sync $RCTIME_1 &
        fi
        main $RCTIME_1 $SNAP_DIR
    fi
    syncwatcher $RCTIME_1 $SNAP_DIR &
    
    ## If changes were detected kick off (parallel)? rsync of that dir to the recv. 
    #  -- Complete. Single threaded rsync per subdir, but running multiple subdir sync at once.
    # If directory is already currently syncing dont start again
    # Dont start too many rsync tasks at once. Limit based on # CPU thread
    #     cpu_count=$(cat /proc/cpuinfo|grep processor | wc -l)
    #     let max_threads=cpu_count*30
    
done