#!/bin/bash
#
if [ -z "$RECALL_HIST" ]
then
  export RECALL_HIST="`history 1 | awk '{ print $1 }'`"
  if [ -z "$RECALL_HIST" ]
  then
    if [ -s "$HISTFILE" -a -r "$HISTFILE" ]
    then
	export RECALL_HIST=$[`wc -l < $HISTFILE` - 2]
      else
	export RECALL_HIST=1
      fi
  fi
fi
export RECALL_INTERVAL=${RECALL_INTERVAL:-30}
export RECALL_DUMP=${RECALL_DUMP:-~/.TR/dump}
export RECALL_TTY="`tty | sed 's;/dev/;;'`"
#
# Alarm generator.
function recall_alrm ()
{
    #
    # Directories sometimes disappear, so post
    # the pending ALRM from / using a subshell.
    ( cd /
      echo "kill -ALRM $$ 2>/dev/null # $RECALL_TTY" | \
      at now + $[$RECALL_INTERVAL+($RANDOM/8192)]minutes ) 2>/dev/null
}
#
# State dumper.
function recall_dump ()
{
  #
  # Restart for next time.
  if [ "$RECALL_EXIT" != yes ]
  then
    recall_alrm
  else
    echo recall_dump: final.
  fi
  #
  # We only dump if there's been activity.
  newhist="`history 1 | awk '{ print $1 }'`"
  if [ $newhist -ne $RECALL_HIST ]
  then
    #
    # The dir may not be ready yet.
    thishost="`echo $HOSTNAME | sed -e 's/\..*$//'`"
    workdir="$RECALL_DUMP"/"$thishost"/"$RECALL_TTY"
    if [ ! -d "$workdir" ]
    then
      mkdir -p "$workdir"
      chmod 700 "$RECALL_DUMP"
    fi
    timestamp="`date '+%Y~%m~%d-%H:%M:%S'`"
    #
    # Bury this background invocation THREE shells deep (triple paren)
    # to avoid the job being seen as a product of the topmost shell:
    # Note placement of backgroundifying `&'.
    ( ( (   echo --pid=$$
	    echo --tty="$RECALL_TTY"
	    geometry="`stty -a < /dev/$RECALL_TTY | grep columns | sed -e 's/^.*rows \([0-9]*\); columns \([0-9]*\).*$/\2x\1/'`"
	    echo -geometry "$geometry"
	    echo -e '\n--dirstack-begin'
	    builtin dirs -l
	    echo -e '--dirstack-end\n\n--history-begin'
	    history $[$newhist-$RECALL_HIST]
	    echo -e '--history-end\n\n--environment-begin'
	    RECALL_TIMESTAMP="$timestamp" printenv | sort
	    echo -e '--environment-end'
	    if [ "$RECALL_DIRLIST" ]
	    then
		echo -e '\n--changes-begin'
		( find . `echo "$RECALL_DIRLIST" | tr : ' '` -xdev \
		    -maxdepth 2 -mtime -1 -type f -print |
		    xargs ls -ld ) 2>/dev/null
		echo -e '--changes-end'
	    fi
	) < /dev/null > "$workdir"/"$timestamp"
	case "$RECALL_MAIL" in
	    1 | [Yy] | yes | YES | on | ON)
		mail -s "Total Recall: $timestamp $HOSTNAME $RECALL_TTY" "$USER" < "$workdir"/"$timestamp"
		rm -f "$workdir"/"$timestamp"
		;;
	    *)
		;; # nothing more to do.
	esac ) & )
    export RECALL_HIST="$newhist"
  fi
}
#
# We will pick up on this with alarm signals and on exit.
trap "RECALL_EXIT=yes recall_dump" EXIT
trap "recall_dump" ALRM
#
# And we'll start the process now.
recall_alrm