#!/bin/rc
if(! test -e /n/dump/1991)
	9fs dump
fn nummon{
	switch($1){
	case Jan
		echo 01
	case Feb
		echo 02
	case Mar
		echo 03
	case Apr
		echo 04
	case May
		echo 05
	case Jun
		echo 06
	case Jul
		echo 07
	case Aug
		echo 08
	case Sep
		echo 09
	case Oct
		echo 10
	case Nov
		echo 11
	case Dec
		echo 12
	}
}

fn usage {
	echo 'usage: yesterday [-c] [-[[[yy]yy]mm]dd] file ...' >[1=2]
	exit 'usage'
}

year=`{date|sed 's/.* //'}
copy=no
switch($1){
case -c
	copy=yes
	shift
}
switch($1){
case -??
	mon=`{nummon `{date|sed 's/^....(...).*/\1/'}}
	last=/n/dump/$year/$mon ^`{echo $1|sed 's/^-//'}
	shift
case -????
	last=/n/dump/$year/ ^ `{echo $1|sed 's/^-//'}
	shift
case -??????
	last=/n/dump/ ^ `{echo $year|sed 's/..$//'} ^ `{echo $1|sed 's/^-(..)/\1\//'}
	shift
case -????????
	last=/n/dump/ ^ `{echo $1|sed 's/^-(....)/\1\//'}
	shift
case -*
	usage
case *
	last=`{ls -lt /n/dump/$year|sed 1q|sed 's/.* //'}
}
switch($1){
case -c
	copy=yes
	shift
}

if(~ $#* 0)
	usage

if(! test -e $last){
	echo 'yesterday:' \
		`{echo $last|sed 's/.n.dump.(....).(..)(..)/\1 \2 \3/'} \
		'is not a backup day'
	exit 'bad date'
}

dir=`{pwd}
if(! ~ $status ''){
	echo 'yesterday: can''t find directory'
	exit 'pwd failed'
}

for(i){
	switch($i){
	case /*
		if(~ $copy yes){
			echo cp $last^$i .
			cp $last^$i .
		}
		if not
			echo $last^$i
	case *
		if(~ $copy yes){
			echo cp $last^$dir/$i $i
			cp $last^$dir/$i $i
		}
		if not
			echo $last^$dir/$i
	}
}
exit ''