#! /bin/bash
#
# Server to get and print files from remote queue.
#
# File:		printer_server
# Author:	Bob Walton <walton@deas.harvard.edu>
# Date:		Sun Sep  8 21:41:16 EDT 2019
#
# The authors have placed this program in the public
# domain; they make no warranty and accept no liability
# for this program.

case "$1" in
   "" | -* )
   	echo "
printer_server QUEUE-DIRECTORY

    Act as a server for printer_client: see that program
    for user documentation.

    This program is intended to be invoked from an
    .ssh/authorized_keys file line of the form:

        command=\"printer_server QUEUE-DIRECTORY\" ...

    The QUEUE-DIRECTORY name must be absolute.

    The QUEUE-DIRECTORY holds files to be printed.  When
    it is being written, such a file has the .out
    extension.  When it is ready for printing, the
    extension name is changed to .ps.  When it has been
    printed, the extension name is changed to .done.

    The printer_server reads commands from its standard
    input and executes them.  In these commands FILE
    refers to a file name that cannot contain a slash
    (/) or begin with a dot (.).  The commands are:

    get FILE
        Return the QUEUE-DIRECTORY/FILE file in the
	standard output.

    sum FILE
        Return the MD5 sum of QUEUE-DIRECTORY/FILE file
	in the standard output.

    done FILE
        Change the extension of QUEUE-DIRECTORY/FILE to
	.done.  The file must previously have had
	extension .ps or .done.

    ready FILE
        Ditto but change the extension to .ps instead
	of to .done.

    remove FILE
        Remove QUEUE-DIRECTORY/FILE.  File must have
	extension .out, .ps, or .done.

    listfiles
        List all the files in the QUEUE-DIRECTORY, one
	line per file name, in lexical order.

    listdir
        List QUEUE-DIRECTORY as per \`ls -ltr'.  Error
	messages are treated as standard output

    After producing any required output, each of these
    commands outputs a line containing just:

    	%%-HPCM_DONE-%%

    Any errors terminate the command and output:

        %%-HPCM_ERROR-%%
	error messages
	%%-HPCM_DONE-%%

    It is assumed %%-HPCM_XXX-%% lines never appear in
    a postscript file or as a file name.
"	| less -F -K
    	exit 1
	;;
esac

dir="$1"

WS='[\ 	]'
NWS='[^\ 	]'

while read -r
do
    case "$REPLY" in
    listfiles )
        out="`if cd $dir 2>&1; then ls -1; \
	                       else exit 1; fi`"
	if [ $? -ne 0 ]
	then
	    echo '%%-HPCM_ERROR-%%'
	fi
	if [[ "$out" =~ ^${WS}*$ ]]
	then
	    x=x # do nothing
	else
	    echo "$out"
	fi
	echo '%%-HPCM_DONE-%%'
	;;
    listdir )
        (cd $dir; ls -ltr 2>&1 )
	echo '%%-HPCM_DONE-%%'
	;;
    get* | sum* )
	[[ "$REPLY" =~ ^(get|sum) ]]
	op=${BASH_REMATCH[1]}
        if [[ "$REPLY" =~ \
	          ^${op}${WS}+(.*${NWS})${WS}*$ ]]
	then
	    file="${BASH_REMATCH[1]}"
	    if [[ "$file" =~ ^.*/.*$ ]]
	    then
		echo '%%-HPCM_ERROR-%%'
		echo "$file contains a slash (/)"
	    elif [[ "$file" =~ ^\. ]]
	    then
		echo '%%-HPCM_ERROR-%%'
		echo "$file begins with a dot (.)"
	    elif test -r "$dir/$file"
	    then
	        if [ $op = "get" ]
		then
		    cat "$dir/$file"
		else
		    [[ `md5sum "$dir/$file"` \
		       =~ ^([^\ \t]*)${WS} ]]
		    echo "${BASH_REMATCH[1]}"
		fi
	    else
		echo '%%-HPCM_ERROR-%%'
		echo Cannot read "$dir/$file"
	    fi
	else
	    echo '%%-HPCM_ERROR-%%'
	    echo Badly Formed Command: $REPLY
	fi
	echo '%%-HPCM_DONE-%%'
	;;
    done* | ready* | remove* )

	[[ "$REPLY" =~ ^(done|ready|remove) ]]
	op=${BASH_REMATCH[1]}
	if [ $op = "done" ]
	then
	    src=ps
	    des=done
	else
	    src=done
	    des=ps
	fi

        if [[ "$REPLY" =~ \
	          ^${op}${WS}+(.*${NWS})${WS}*$ ]]
	then
	    file="${BASH_REMATCH[1]}"
	    if [[ "$file" =~ ^.*/.*$ ]]
	    then
		echo '%%-HPCM_ERROR-%%'
		echo "$file contains a slash (/)"
	    elif [[ "$file" =~ ^\. ]]
	    then
		echo '%%-HPCM_ERROR-%%'
		echo "$file begins with a dot (.)"
	    elif [[ "$file" =~ ^(.*)(\.${NWS}*)$ ]]
	    then
		base="${BASH_REMATCH[1]}"
		ext="${BASH_REMATCH[2]}"
		case $op in
		remove)
		    if [[ "$ext" =~ (.out|.ps|.done) ]]
		    then
			rm -f "$dir/$file"
		    else
			echo '%%-HPCM_ERROR-%%'
			echo "extension of $file is" \
			     "not .out, .ps, or .done"
		    fi
		    ;;
		done | ready )
		    if [[ "$ext" =~ (.ps|.done) ]]
		    then
			if [ -e "$dir/${base}.$src" ]
			then
			    mv -f "$dir/${base}.$src" \
			       "$dir/${base}.$des" \
			       >& /dev/null
			elif [ ! -e \
			       "$dir/${base}.$des" ]
			then
			    echo '%%-HPCM_ERROR-%%'
			    echo "${base}.{ps,done}" \
			         does not exist
			fi
		    else
			echo '%%-HPCM_ERROR-%%'
			echo "extension of $file is" \
			     "not .ps or .done"
		    fi
		    ;;
		esac
	    else
		echo '%%-HPCM_ERROR-%%'
		echo "$file" does not have \
		     extension
	    fi
	else
	    echo '%%-HPCM_ERROR-%%'
	    echo Badly Formed Command: $REPLY
	fi
	echo '%%-HPCM_DONE-%%'
	;;
    * )
	echo '%%-HPCM_ERROR-%%'
	echo Cannot understand: $REPLY
	echo '%%-HPCM_DONE-%%'
	;;
    esac
done

exit 0