#!/bin/ksh

######################################################################
# Program:	tls - time ls
# Purpose:	Looks on a backup server and lists versions of files
#		available.
# Arguments:	files to list
# Author:	Perette Barella
#---------------------------------------------------------------------






######################################################################
# Function:	usage
# Purpose:	Displays the usage of this command.
# Author:	Perette Barella
#---------------------------------------------------------------------
function usage
{
	print "Usage: $arg0"
	exit 1
}
##### End of function usage #####






######################################################################
# Function:	parse_arguments
# Purpose:	Parses the command line arguments
# Arguments:	The command line arguments.
# Returns:	Number of arguments parsed.
# Author:	Perette Barella
#---------------------------------------------------------------------
function parse_arguments
{
	typeset option
	INTERACTIVE=false
	while getopts 'i?' option
	do
		case "$option" in
			i)	INTERACTIVE=true ;;
			*)	usage ;;
		esac
	done
	typeset status=0
	return $((OPTIND - 1))
}
##### End of function parse_arguments #####




######################################################################
# Function:	get_file_path
# Purpose:	Returns the file path relative to current user's home.
# Arguments:	$1 - the file to find the path to
# Returns:	0.
# Author:	Perette Barella
#---------------------------------------------------------------------
function get_file_path
{
	typeset file="$1"
	typeset path=$(dirname "$file")
	typeset fulldir=$(cd "$path"; pwd)
	typeset filename=$(basename "$file")
	print -- "$fulldir/$filename" |
		sed -e "s&$HOME/&&"
	return 0
}
##### End of function get_file_path #####






######################################################################
# Function:	list_dates
# Purpose:	Gets available backup dates for a file.
#		When a file hasn't changed between two or more dates,
#		only the earliest date is listed.  If the file is changed
#		and subsequently reverts to an earlier version, the
#		reverting version is listed again.
# Arguments:	$1 - the file to get data for
# Returns:	List of dates and server data.
# Author:	Perette Barella
#---------------------------------------------------------------------
function list_dates
{
	typeset status=0 file="$1"
	typeset cksum1 cksum2 lastcksum1="x" lastcksum2="x"

	for server in pmb1566@barella.org perette@sue.dnsalias.net
	do
		print -n "$server: " 1>&2
		ssh -n "$server" "cksum Backups/$USER*/*/$file" |
			awk "{print \$1 \" \" \$2 \" $server \" \$3}"
	done | sort -k 4,1 | while read cksum1 cksum2 server filename
	do
		if [ "$cksum1" != "$lastcksum1" -o "$cksum2" != "$lastcksum2" ]
		then
			date=$(print -- "$filename" | cut -d/ -f3)
			print "$date $server"
			lastcksum1="$cksum1"
			lastcksum2="$cksum2"
		fi
	done
	return $status
}
##### End of function list_dates #####




######################################################################
# Function:	present_file_dates
# Purpose:	List the dates at which a file is available on the
#		backup server.
# Arguments:	$1 - the filename
#		$2 - the file containing backup availability data
# Returns:	
# Author:	Perette Barella
#---------------------------------------------------------------------
function present_file_dates
{
	typeset status=0 file="$1" datelist="$2"
	if [ -s "$datelist" ]
	then
		print "$file:"
		awk '{print $1}' < "$datelist" | sed 's/^/	/'
		if [ -e "$HOME/$file" ]
		then
			ls -l "$HOME/$file"
		else
			print "No local file."
		fi
	else
		print "$file: No archival files found."
		status=1
	fi
	return $status
}
##### End of function present_file_dates #####









######################################################################
# Function:	retrieve_file
# Purpose:	
# Arguments:	
# Returns:	
# Author:	Perette Barella
#---------------------------------------------------------------------
function retrieve_file
{
	typeset status=0 file="$1" datelist="$2" date="$3" dest="$4"
	typeset date server
	[ ${#date} -eq 10 ] && date="$date.0"
	grep "^$date " "$datelist" | read date server
	if [ "$date" = "" ]
	then
		print "$date: date not available."
		return 1
	fi
	print -n -- "$server: "
	scp -p "$server:Backups/$USER*/$date/$file" "$dest"
	return $?
}
##### End of function retrieve_file #####







######################################################################
# Function:	perform_diff
# Purpose:	Compares a date and local or two dated versions of a file.
# Author:	Perette Barella
#---------------------------------------------------------------------
function perform_diff
{
	typeset status=0 file="$1" datelist="$2" date1="$3" date2="$4"
	typeset file1=/var/tmp/$arg0.diff.1.$$
	typeset file2=/var/tmp/$arg0.diff.2.$$
	if [ $# -lt 3 -o $# -gt 4 ]
	then
		print "Usage: diff <date> [date]"
		print "With one date, compares to local version."
		return 1
	fi
	if !  retrieve_file "$file" "$datelist" "$date1" "$file1"
	then
		status=1
	elif [ $# -eq 3 ]
	then
		cp "$HOME/$file" "$file2"
		status=$?
	else
		retrieve_file "$file" "$datelist" "$date2" "$file2"
		status=$?
	fi
	if [ $status -eq 0 ]
	then
		diff "$file1" "$file2"
		status=$?
		[ $status -eq 0 ] && echo "Files are the same."
	fi
	rm -f "$file1" "$file2"
	return $status
}
##### End of function perform_diff #####





######################################################################
# Function:	perform_vi
# Purpose:	Gets a file and edits it read-only.
# Author:	Perette Barella
#---------------------------------------------------------------------
function perform_vi
{
	typeset status=0 file="$1" datelist="$2" date="$3"
	typeset dest=/var/tmp/$arg0.vi.$$
	if [ $# -lt 3 -o $# -gt 3 ]
	then
		print "Usage: vi <date>"
		print "Views the specified version of the file (read-only)."
		return 1
	fi
	if ! retrieve_file "$file" "$datelist" "$date" "$dest"
	then
		status=1
	else
		${EDITOR:-view} "$dest"
	fi
	rm -f "$dest"
	return $status
}
##### End of function perform_vi #####



######################################################################
# Function:	perform_get
# Purpose:	Retrieves a dated file version to a local file.
# Author:	Perette Barella
#---------------------------------------------------------------------
function perform_get
{
	typeset file="$1" datelist="$2" date="$3" dest="$4"
	if [ $# -lt 3 -o $# -gt 4 ]
	then
		print "Usage: get <date> [local file]"
		print "Copy date to local file.  If local file is not specified, overwrites existing."
		return 1
	fi
	[ $# -eq 3 ] && dest="$HOME/$file"
	retrieve_file "$file" "$datelist" "$date" "$dest"
	return $?
}
##### End of function perform_get #####







######################################################################
# Function:	do_cli
# Purpose:	Implements a rudimentary command line for doing stuff
#		after seeing the available versions of a file.
# Author:	Perette Barella
#---------------------------------------------------------------------
function do_cli
{
	typeset status=0 file="$1" datelist="$2"
	typeset command="" options
	while [ "$command" != "quit" ]
	do
		print -n "tls $file> "
		read command options || command="quit"
		case "$command" in
			quit)	: ;;
			diff)	perform_diff "$file" "$datelist" $options ;;
			get)	perform_get "$file" "$datelist" $options ;;
			vi|view)
				perform_vi "$file" "$datelist" $options ;;
			ls)	present_file_dates "$file" "$datelist" ;;
			!)	if [ "$options" = "" ]
				then
					${SHELL:-/bin/sh}
				else
					${SHELL:-/bin/sh} -c "$options"
				fi ;;
			*)	print -- "$command: Unknown command." ;;
		esac
	done
	return $status
}
##### End of function do_cli #####









##### Start of main #####

arg0=$(basename $0)
dir0=$(dirname $0)
[ "$dir0" = "." ] && dir0="$(pwd)"
BASE=$(dirname $dir0)

parse_arguments "$@"
shift $?

if [ $# -eq 0 ]
then
	set -- *
fi

filelist="/var/tmp/$arg0.$$.tmp"

for file in "$@"
do
	fullfile=$(get_file_path "$file")
	list_dates "$fullfile" > "$filelist"
	present_file_dates "$fullfile" "$filelist"
	$INTERACTIVE && [ -s "$filelist" ] && do_cli "$fullfile" "$filelist"
	rm "$filelist"
done


##### End of main #####