#!/bin/bash
set -e
PROGNAME=`basename $0`

BUSERVER_HOSTNAME=macaroni
BUMASTER_HOSTNAME=fiori      #  should be a host with unfettered ssh access everywhere
#BUCLIENT_HOSTNAMES="lasagne $(rocon -m LinuxHosts and not SometimesDownHosts)"
BUCLIENT_HOSTNAMES="$(rocon -m LinuxHosts and not SometimesDownHosts and not torchio)"

main()
{
    local BUCLIENT_HOSTNAME

    #  Set defaults for stuff modifiable by command line options like '-v' or '--debug=xxx'
    VERBOSELEVEL=2

    #  Option processing
    while [ "X$1" != X ]; do
        case $1 in
            -v|--verbose)             VERBOSELEVEL=3 ;;
            -d)                       VERBOSELEVEL=$2; shift ;;
            --debug=*)                VERBOSELEVEL=${1#*=} ;;
            -h|--help)                usage 0 ;;
            #  Any other option is handled within each individual function
            *)                        break ;;
        esac
        shift
    done


    info "checking ssh access ..."
    [ $(uname -n) = $BUMASTER_HOSTNAME ] || { error "$(uname -n): backup master is $BUMASTER_HOSTNAME"; return 1; }
    HAD_AN_ERROR=false
    for HOST in $BUSERVER_HOSTNAME $BUCLIENT_HOSTNAMES; do
        SSH_OUTPUT="$(setsid ssh -n $HOST "echo OK" 2>&1 || true)"
        [ "X$SSH_OUTPUT" = XOK ] || { error "$HOST: no unprompted ssh access ($SSH_OUTPUT)"; HAD_AN_ERROR=true; }
    done
    ! $HAD_AN_ERROR || return 1

    #  If backup is within 15 minutes of the last one, then assume settings are the same, else ask.
    if [ -f  ~/.${PROGNAME}rc ] && [[ $(date +%s) < $(($(stat -c %Z ~/.${PROGNAME}rc) + 900)) ]]; then
        . ~/.${PROGNAME}rc
        BUSERVER_KDEV=$DFLT_BUSERVER_KDEV
        #  Touch the file so that next time we compare the time against *now*, not
        #  against the first time we asked.
        touch ~/.${PROGNAME}rc
    else
        echo -n "device on $BUSERVER_HOSTNAME [$DFLT_BUSERVER_KDEV]: "
        read BUSERVER_KDEV
        [ "X$BUSERVER_KDEV" != X ] || BUSERVER_KDEV=$DFLT_BUSERVER_KDEV
        echo "DFLT_BUSERVER_KDEV=$BUSERVER_KDEV" > ~/.${PROGNAME}rc
    fi
    BUSERVER_MNTPNT=/mnt
    BUCLIENT_MNTPNT=/mnt

    info "cleaning up previous incomplete backups ..."
    debug 10 "main: unmounting share on clients ..."
    for BUCLIENT_HOSTNAME in $BUCLIENT_HOSTNAMES; do
        debug 10 "main: unmounting share on $BUCLIENT_HOSTNAME ..."
        unshare $BUCLIENT_HOSTNAME || true
    done
    debug 10 "main: unmounting device on server ..."
    ssh $BUSERVER_HOSTNAME "umount $BUSERVER_MNTPNT" || true

    info "prologue ..."
    ssh $BUSERVER_HOSTNAME "mount $BUSERVER_KDEV $BUSERVER_MNTPNT"

    info "faking backing up all clients ..."
    FAILED=false
    for BUCLIENT_HOSTNAME in $BUCLIENT_HOSTNAMES; do
        share $BUCLIENT_HOSTNAME
        backup --fake $BUCLIENT_HOSTNAME || FAILED=true
        unshare $BUCLIENT_HOSTNAME
    done
    ! $FAILED || { error "at least one fake backup failed"; return 1; }

    #  This 'if true' is there to quicky disable the real backups when I'm testing
    if true; then
        info "really backing up all clients ..."
        for BUCLIENT_HOSTNAME in $BUCLIENT_HOSTNAMES; do
            share $BUCLIENT_HOSTNAME
            backup $BUCLIENT_HOSTNAME
            unshare $BUCLIENT_HOSTNAME
        done
    fi

    info "epilogue ..."
    ssh $BUSERVER_HOSTNAME "umount $BUSERVER_MNTPNT"
}

share()
{
    local BUCLIENT_HOSTNAME=$1

    info "backing up $BUCLIENT_HOSTNAME ..."

    #  Mount USB disk and share it.
    ssh $BUSERVER_HOSTNAME "[ $BUCLIENT_HOSTNAME = $BUSERVER_HOSTNAME ] || exportfs -v -o rw,no_root_squash,sync $BUCLIENT_HOSTNAME:$BUSERVER_MNTPNT > /dev/null"
 
    #  Mount share 
    ssh $BUCLIENT_HOSTNAME "[ $BUCLIENT_HOSTNAME = $BUSERVER_HOSTNAME ] || mount $BUSERVER_HOSTNAME:$BUSERVER_MNTPNT $BUCLIENT_MNTPNT"
}

backup()
{
    local BUCLIENT_HOSTNAME FAKE_FLAG

    FAKE_FLAG=false
    while [ "X$1" != X ]; do
        case $1 in
            --fake) FAKE_FLAG=true ;;
            --)     shift; break ;;
            -*)     internal "backup: $1: unknown option" ;;
            *)      break ;;
        esac
        shift
    done

    [ $# = 1 ] || internal "backup: $#: invalid argument count" 
    BUCLIENT_HOSTNAME=$1

    #  Do backup (recording time it took)
    if ! $FAKE_FLAG; then
        BACKUP_CMDLINE="ssh $BUCLIENT_HOSTNAME \"~/bin/usbbu2 -f ~/etc/usbbu2.conf $BUCLIENT_MNTPNT\""
        debug 10 "backup: BACKUP_CMDLINE=[$BACKUP_CMDLINE]"
        TIME_BEFORE=`date +%s`
        eval "$BACKUP_CMDLINE" || warning "usbbu2 failed"
        TIME_AFTER=`date +%s`
        TIME_DIFF=`echo "scale=2; $TIME_AFTER-$TIME_BEFORE" | bc -q`
        FORMATTED_DIFF=`printf "%02d:%02d:%02d\n" $(($TIME_DIFF / 3600)) $(($TIME_DIFF / 60 % 60)) $(($TIME_DIFF % 60))`
        echo "||[\"$BUCLIENT_HOSTNAME\"]||`date +%d/%m/%Y`||$FORMATTED_DIFF||"
    else
        BACKUP_CMDLINE="ssh $BUCLIENT_HOSTNAME \"~/bin/usbbu2 --fake -f ~/etc/usbbu2.conf $BUCLIENT_MNTPNT\""
        debug 10 "backup: BACKUP_CMDLINE=[$BACKUP_CMDLINE]"
        eval "$BACKUP_CMDLINE" || { error "usbbu2 failed"; return 1; }
    fi
}

unshare()
{
    local BUCLIENT_HOSTNAME=$1

    #  Unmount share
    ssh $BUCLIENT_HOSTNAME "[ $BUCLIENT_HOSTNAME = $BUSERVER_HOSTNAME ] || umount $BUCLIENT_MNTPNT"
 
    #  Unshare USB disk and unmount it.
    ssh $BUSERVER_HOSTNAME "[ $BUCLIENT_HOSTNAME = $BUSERVER_HOSTNAME ] || exportfs -uv $BUCLIENT_HOSTNAME:$BUSERVER_MNTPNT > /dev/null"
}

#  Messaging functions
debug()    { [ $VERBOSELEVEL -lt $1 ] || echo "$PROGNAME: DEBUG[$1]: $2"      >&2;         }
info()     { [ $VERBOSELEVEL -lt 3  ] || echo "$PROGNAME: INFO: $1"           >&2;         }
warning()  { [ $VERBOSELEVEL -lt 2  ] || echo "$PROGNAME: WARNING: $1"        >&2;         }
error()    { [ $VERBOSELEVEL -lt 1  ] || echo "$PROGNAME: ERROR: $1"          >&2;         }
internal() {                             echo "$PROGNAME: INTERNAL ERROR: $1" >&2; exit 2; }

main "$@"