#!/bin/sh -u
#
# =head1 NAME
#
# apphelper - a generic wrapper for email attachments or web browser file helpers, offering both save and view choices
#

: ${TMPDIR:=/tmp}
: ${PAGER:=less}
: ${SAVEDIR:=$HOME/dl}
: ${APPHELPER_REMAPFILE:=$HOME/rc/remap}
: ${APPHELPER_SAVEMAP:="remap \"\$APPHELPER_REMAPFILE\" | tr '[A-Z_]' '[a-z-]'"}
: ${APPHELPER_SAVEMODE:=auto}
: ${APPHELPER_SAVEPOST:=''}
: ${APPHELPER_IDSET:=$HOME/var/apphelper}
: ${APPHELPER_DOVIEW:=''}
: ${APPHELPER_EXTRACT_GLOBS:=''}
: ${APPHELPER_OPTS:=''}
: ${APPHELPER_PREOPTS:=''}
: ${APPHELPER_LASTVALUE:=savedir}

cmd=`basename "$0"`

doterm=
itype=
savedir=
doview=$APPHELPER_DOVIEW
savemode=$APPHELPER_SAVEMODE
extract=
extract_globs=$APPHELPER_EXTRACT_GLOBS
termname=
pager=$PAGER
savepost=$APPHELPER_SAVEPOST
trace=	##set-x
arg1opts=

# =head1 SYNOPSIS
#
# apphelper [{-t|+t|-T title}] file [{-n|-y}]] [-d savedir] [-i type] [-p pager] [arg1opts...] viewer [viewer-args...]
#
usage="Usage: $cmd [{-t|+t|-T title}] file [{-n|-y}] [-d savedir] [-i type] [-p pager] [arg1opts...] \\
		viewer [viewer-args...]
	-t		Run apphelper in a new terminal window.
	+t		Do not run apphelper in a new terminal window.
	-T title	Title for new terminal window. Implies -t.
			Default: $termname
	NB: -t or +t must preceed the file.
	The file may be \"-\" to read it from standard input.

	-b		File basename, offered for saving.
	-n		Don't run the viewer at all.
	-y		Run viewer immediately.
	-N		Don't offer to save the file.
	-Y		Save the file without asking questions.
	-A		Auto-notsave if file already present.
	-X		Extract archive and run apphelper for each entry.
	-x		trace execution of subcommands.
	-i type		Specify MIME type of file.
	-d savedir	Save directory (from \$SAVEDIR: $savedir).
	-p pager	Pager (default viewer, from \$PAGER: $pager).
	arg1opts	Options as for arg1(1cs). Default: none.
			If specified, the viewer is run via arg1."

unset tmpdir
trap 'rm -r "$tmpdir"' 0
tmpdir=`mkdirn "$TMPDIR/$cmd"` || exit 1
tmpfile=$tmpdir/$cmd$$

# =head1 DESCRIPTION
#
# Apphelper is a generic handler for a file.
# It was originally coded for use with netscape and mozilla
# which persist in directly opening files they have handlers for,
# offering no handy "save as?" accompaniment.
# This was particularly aggravating for PDF files,
# which I often want to keep around for later perusal.
#
# Apphelper offers to view the file with the named viewer
# and after viewing, to save the file in a location of your choice.
#
# =head2 Pre-File Options
#
# The following terminal related options must preceed the filename.
#
# =over 4
#
badopts=

# =item -t
#
# Open a fresh terminal window in which to run apphelper.
# Generally desirable when invoking inside a GUI web browser.
#
# =item +t
#
# Do not open a terminal window.
#
# =item -T I<title>
#
# Specify the title of the fresh terminal in which to run apphelper.
# Implies the B<-t> option.
#
set -x
set -- $APPHELPER_PREOPTS ${1+"$@"}
set +x
ttyopts=
doterm=; [ -t 0 -a -t 1 ] || doterm=1
while [ $# -gt 0 ]
do
  case $1 in
    -t)	doterm=1; ttyopts="$ttyopts $1" ;;
    -T)	termname=$2; shift; doterm=1 ;;
    +t)	doterm=; ttyopts="$ttyopts $1" ;;
    *)  break ;;
  esac
  shift
done

# =back
#
# =head2 File Designation
#
# After the terminal related pre-file options
# comes the file designation.
# Usually this will be a filename,
# however the following notations are also supported:
#
# =over 4
#
if [ $# = 0 ]
then
  echo "$cmd: missing file" >&2
  badopts=1
else
  file=$1; shift
  case "$file" in
    # =item B<->
    #
    # Read data from stdin.
    # This will be placed in a temporary file.
    #
    -)
      if cat >"$tmpfile"
      then
	  tmpfile=`fixexts -i "$itype" "$tmpfile"` || exit 1
	  file=$tmpfile
      else
	  echo "$cmd: can't cat stdin to $tmpfile, aborting" >&2
	  badopts=1
      fi
      ;;
    # =item I<URL>
    #
    # Names commencing with B<http://> or B<ftp://>
    # are taken to be URLs and fetched.
    #
    http://* | ftp://*)
      exec $trace withurl -0 "$file" "$0" "$@"
      ;;
    *)
      # handed real filename
      if [ ! -s "$file" ]
      then
	echo "$cmd: bad file?" >&2
	ls -ld "$file" >&2
	badopts=1
      else
	if [ $doterm ]
	then
	  tmpfile=$tmpdir/`basename "$file"`
	  if cp "$file" "$tmpfile"
	  then  tmpfile=`fixexts -i "$itype" "$tmpfile"` || exit 1
		file=$tmpfile
	  else  echo "$cmd: can't cp $file to $tmpfile, aborting" >&2
		badopts=1
	  fi
	fi
      fi
      ;;
  esac
  #
  # =back
  #

  # fork off a terminal if need be
  if [ $doterm ]
  then
      [ -n "$DISPLAY" ] || { echo "$cmd: can't make new terminal: no \$DISPLAY!" >&2
			     exit 1
			   }
      ( [ -n "$termname" ] || termname="$cmd - $file"
	exec $trace term -n "$termname" +a -e "$0" +t "$file" ${1+"$@"}
      )
      rm -f "$tmpfile"
      exit 0
  fi

  [ -t 0 ] || exec </dev/tty;	[ -t 0 ] || exit 1
  [ -t 1 ] || exec >/dev/tty;	[ -t 1 ] || exit 1

  # =head2 Post-File Options
  #
  # =over 4
  #
  set -- $APPHELPER_OPTS ${1+"$@"}
  apphopts=
  while [ $# -gt 0 ]
  do
      apphopt=$1
      apphopt2=
      case $1 in
	  # =item B<-d> I<directory>
	  #
	  # Specify a default directory in which to save files.
	  # Lacking this, use the value of the envvar B<$SAVEDIR>
	  # or B<$HOME/dl> if that is not set.
	  #
	  -d)	apphopt2=$2 savedir=$2; shift ;;
	  # =item B<-n>
	  #
	  # No: do not run the viewer program.
	  # The default is to ask first.
	  #
	  -n)	doview=0 ;;
	  # =item B<-y>
	  #
	  # Yes: always run the viewer program.
	  # The default is to ask first.
	  #
	  -y)	doview=1 ;;
	  # =item B<-N>
	  #
	  # No: do not offer to save the file.
	  # The default is to ask.
	  #
	  -N)	savemode=no ;;
	  # =item B<-Y>
	  #
	  # Yes: save the file without asking.
	  # The default is to ask.
	  #
	  -Y)	savemode=yes ;;
	  # =item B<-a>
	  #
	  # Ask: ask to save the file even if the file's already there.
	  #
	  -a)	savemode=ask ;;
	  # =item B<-A>
	  #
	  # Auto: don't ask to save the file if the file's already there.
	  # The default is to auto.
	  #
	  -A)	savemode=auto ;;
	  # =item B<-X>
	  #
	  # Extract the file (if we know how)
	  # with the x(1) command
	  # and run apphelper on each component.
	  #
	  -X)	extract=1 apphopt= ;;
	  # =item B<-x>
	  #
	  # Trace execution of subcommands.
	  #
	  -x)	trace=set-x ;;
	  # =item B<-i> I<type>
	  #
	  # Specify the MIME I<type>.
	  # Otherwise the type will be guessed from the file content.
	  #
	  -i)	itype=$2; shift ;;
	  # =item I<arg1-option>
	  #
	  # Supply an argument for I<arg1>, one of
	  # B<-discard>, B<-end>, B<->I<n>.
	  # If specified,
	  # the view will be invoked via I<arg1>.
	  # See arg1(1cs) for semantics.
	  # This permits mailcap entries like this:
	  #
	  #   image/jpeg; ah %s -end xv; gui
	  #
	  # which will correctly invoke I<xv> with the possibly modified filename I<ah> may use.
	  #
	  -stdin|-end|-[0-9]*)
		arg1opts="$arg1opts $1"
		;;
	  --)	shift; break ;;
	  -?*)	echo "$cmd: unrecognised option: $1" >&2; badopts=1 ;;
	  *)	break ;;
      esac
      shift
      apphopts="$apphopts $apphopt $apphopt2"
  done
fi

# =back
#

# default to "v" for the command
[ $# = 0 ] && set v '%s'

[ $badopts ] && { echo "$usage" >&2; exit 2; }

if [ $extract ]
then
  mtype=`file2mime "$file"` || mtype=
  [ "$mtype" = application/octet-stream ] && mtype=
  [ -n "$mtype" ] || mtype=`ext2mime "$file"`
  if [ -n "$mtype" ] \
  && action=`mailcap -s "$file" "$mtype" unpack !gui`
  then
      case "$file" in
	  /*) absfile=$file ;;
	  *)  absfile=`pwd`/$file ;;
      esac
      xdir=`mkdirn "$TMPDIR/$cmd$$.x"` || exit 1
      (
	cd "$xdir" || exit 1
	$trace x "$absfile"
	set --
	sep=
	# ugly workaround for weird bash glob/quoting bug:-(
	if [ -n "$extract_globs" ]
	then
	  for glob in $extract_globs
	  do
	    set -- ${1+"$@"} $sep -name "$glob"
	    sep=-o
	  done
	else
	  set -- ${1+"$@"} -name '*'
	fi
	$trace find . -type f -size +0 \( "$@" \) -exec $trace ifnewfile -v -discard {} "$0" +t {} $apphopts -A ';'
      )
      rm -rf "$xdir"
      exit
  fi
fi

file2=`fixexts -i "$itype" "$file"` && file=$file2

fbase=`basename "$file"`
case "$fbase" in
    =\?*\?Q\?*\?= )
	# deuglify the font spec
	fdir=`dirname "$file"`
	nfbase=`unfontise "$fbase"`
	nfile=$fdir/$nfbase
	ln "$file" "$nfile" || exit 1
	fbase=$nfbase
	file=$nfile
	;;
esac
export file fbase

file "$file" | noesc; echo

# =head1 OPERATION
#
# =head2 Viewing The File
#
# Apphelper first asks whether to view the file,
# offering the supplied view command in [square brackets]
# as the default.
# Pressing return or entering "B<y>" or "B<yes>' accepts this default and runs the viewer.
# Entering "B<n>" or "B<no>" skips running the viewer.
# Other answers are taken to be the name (and optional arguments) of a viewing program.
#
# If the viewer has a nonzero exit code (failure)
# then this is reported and the user is prompted for an alternative viewing program.
# Pressing return or entering "B<n>" or "B<no>" skips the second attempt.
# Other answers are taken to be the name (and optional arguments) of a viewing program.
#

if [ -z "$doview" ]
then
    necho "View [$*]? "
    read viewit || exit 0
    case "$viewit" in
	''|y|yes)	doview=1 ;;
	n|no)		doview=0 ;;
	*)		set -- $viewit "$file"
			doview=1 ;;
    esac
fi

if [ "$doview" = 1 ]
then
    # transmute %s into the (possibly renamed by fixexts or remap) file and run viewer
    (
      echo "$0: view args=[$*]" >&2
      first=1
      for arg
      do
	[ $first ] && { set --; first=; }
	if [ "x$arg" = 'x%s' ]
	then  set -- ${1+"$@"} "$file"
	else  set -- ${1+"$@"} "$arg"
	fi
      done
      [ -n "$trace" ] && set -- $trace ${1+"$@"}
      [ -n "$arg1opts" ] && set -- arg1 $arg1opts -- "$file" ${1+"$@"}
      set -x
      exec "$@"
    ) \
    || { echo "failed: $* $file"
	 viewit=`readline 'View with? '` || exit 0
	 case "$viewit" in
	    ''|n|no)	;;
	    *)		$viewit "$file" ;;
	 esac
       }
fi

# =head2 Saving The File
#
# After the view phase
# apphelper offers to save the file
# with the default pathname in [square brackets].
# Pressing return or entering "B<n>" or "B<no>" skips the save.
# Entering "B<y>" or B"<yes>" saves the file under the supplied filename.
# Entering a string commencing with a bang (`!')
# performs a shell escape, running the tail of the string in the user's shell.
# Occurences of bangs in the command are replaced by the last command
# run from this instance of apphelper.
# Occurences of percents (`%') in the command are replaced by the filename.
#
# Other answers are taken to be a different filename under which to save the file.
#
# If the file is to be saved
# then the save filename is examined.
# If it starts with a tilde ("~")
# then the leading B<~> or B<~>I<username> is replaced with the approriate
# home directory path.
# Relative pathnames are taken to be relative to the default save directory.
#
# If there is a percent ("%") present
# then the rightmost precent is replaced with the basename of the attachment name.
# This is useful for repairing truncated filenames on attachments.
#
# If the filename points at a directory
# then the file is saved inside that directory
# with the basename of the attachment name.
#
# If the filename ends in a dash ("-")
# then the basename of the attachment name is appended.
# This is useful for attaching a prefix to some poorly chosen
# generic attachment name (like "10.pdf").
#
# If after all this the target filename already exists
# then the two files are compared.
# If they are the same
# then no action is taken.
# If they differ
# the then new file is copied onto the existing with via cp(1)
# with the B<-i> option,
# leaving it up to cp(1) to ask questions.
#

# offer remapped name if inferrable
remaptmp=$TMPDIR/$cmd-remap$$
if printf "%s\n" "$fbase" | eval "$APPHELPER_SAVEMAP" >"$remaptmp"
then
  exec 3<&0 0<"$remaptmp"
  if read -r oldname \
  && read -r newname \
  && [ -n "$newname" ] \
  && [ "x$oldname" != "x$newname" ]
  then
    case "$newname" in
      */*)
	savedir=`expr "x$newname" : 'x\(.*\)/.*'`
	newname=`expr "x$newname" : 'x.*/\(.*\)'`
	case "$savedir" in /*) ;; *) savedir=$SAVEDIR/$savedir ;; esac
	[ -n "$newname" ] && fbase=$newname
	;;
      ?*)
	fbase=$newname
	;;
    esac
  fi
  exec 0<&3 3<&-
fi
rm -f "$remaptmp"

# see if we've saved this before
if oldsave=`fileloc "$file"` \
&& cmp -s "$file" "$oldsave"
then
  savedir=`dirname "$oldsave"` || exit 1
  fbase=`basename "$oldsave"` || exit 1
fi

# no guesses? offer last save directory
if [ -z "$savedir" ]
then
    savedir=`lastvalue "$APPHELPER_LASTVALUE" 2>/dev/null`
    : ${savedir:=$SAVEDIR}
fi

if [ "x$savemode" = xauto ]
then
  trysave=$savedir/$fbase
  if [ -s "$trysave" ] && cmp -s "$file" "$trysave"
  then  echo "This file already saved:"
	ls -ld "$trysave"
	savemode=no
  else  savemode=ask
  fi
fi
case "$savemode" in
    yes)	saveas=$savedir/$fbase ;;
    no)		saveas= ;;
    *)
		repeat=1
		lastshcmd=
		while [ $repeat ]
		do
		  repeat=
		  trysave=$savedir/$fbase
		  if [ -s "$trysave" ]
		  then
		      if cmp -s "$file" "$trysave"
		      then  echo "Exists, same data."
		      else  echo "Different data."
			    # pick a similar name
			    case "$fbase" in
			      *.*)	fext=`expr "x$fbase" : 'x.*\.\(.*\)'`
					fpre=`basename "$fbase" ".$fext"`
					;;
			      *)	fpre=$fbase
					if ftype=`file2mime "$file"`
					then  fext=`mimeext "$ftype"` || fext=dat
					else  fext=dat
					fi
					;;
			    esac
			    n=2
			    while trysave2=$savedir/$fpre$n.$fext
				  [ -s "$trysave2" ]
			    do  n=`expr $n + 1`
			    done
			    trysave=$trysave2
		      fi
		  fi
		  prompt="Save [$trysave]? "
		  saveas=`readline -d "$savedir" "$prompt"` || exit 0
		  case "$saveas" in
		    \!*)	repeat=1
				shcmd=`expr "x$saveas" : 'x! *\(.*\)'`
				case "$file" in
				  /*)	absfile=$file ;;
				  *)	absfile=`pwd`/$file ;;
				esac
				( [ -d "$savedir/." ] && cd "$savedir"
				  case "$shcmd" in
				    '')	${SHELL:-sh} ;;
				    *[%!]*)
					qfile=`shqstr "$absfile"`
					shcmd=`echo "$shcmd" | sed "s!$lastshcmdg"`
					lastshcmd=$shcmd
					shcmd=`echo "$shcmd" | sed "s%$qfileg"`
					"${SHELL:-sh}" -xc "$shcmd"
					;;
				    *)	"${SHELL:-sh}" -xc "$shcmd"
					;;

				  esac
				)
				;;
		    ''|n|no)	saveas= ;;
		    y|yes)	saveas=$trysave ;;
		    [/~]*)	;;
		    *)		saveas=$savedir/$saveas ;;
		  esac
		done
		;;
esac
[ -n "$saveas" ] || exit 0

case "$saveas" in
    \~*)	saveas=`untilde "$saveas"` ;;
esac

# %foo -> filefoo
case "$saveas" in
    *%*)	pre=`expr "x$saveas" : 'x\(.*\)%.*'`
		post=`expr "x$saveas" : 'x.*%\(.*\)'`
		saveas=$pre$fbase$post
		;;
esac

# dir -> dir/file
# foo- -> foo-file
case $saveas in
    */|*-)	saveas=$saveas$fbase ;;
    */. | */..)	saveas=$saveas/$fbase ;;
esac

case `basename "$saveas"` in
    *.*)	;;
    */$fbase)	;;
    *)		saveas=$saveas/$fbase ;;
esac

[ -d "$saveas/." ] && saveas=$saveas/$fbase

parent=`dirname "$saveas"`
[ -d "$parent/." ] \
|| if ask "mkdir $parent"
then  $trace mkdir -p "$parent" || exit 1
else  exit 0
fi

# stash savedir
( cd "$parent" || exit 1
  pwd | lastvalue "$APPHELPER_LASTVALUE" -
)

xit=1

if { [ -f "$saveas" -a -s "$saveas" ] && cmp -s "$file" "$saveas"; } \
|| $trace cp -i "$file" "$saveas"
then
  xit=0
  $trace fileloc -a "$saveas" || xit=1
  if [ -n "$savepost" ]
  then
    if qsaveas=`shqstr "$saveas"`
    then
      $trace sh -c "$savepost $qsaveas" || xit=1
    else
      xit=1
    fi
  fi
fi

exit $xit

# =head1 EXAMPLE
#
# My B<.mailcap> file contains this line for JPEG files:
#
#	image/jpeg; apphelper %s -y xv
#
# which causes mutt(1),
# on pressing enter on a JPEG attachment,
# to hand JPEG files to apphelper
# which runs xv(1) immediately
# and then offers a save option.
#
# This mailcap line:
#
#	application/pdf;apphelper %s -y xpdf
#
# causes mozilla to run xpdf(1) to view PDF files
# and then to offer a save option.
#
# =head1 AUTHOR
#
# Cameron Simpson E<lt>cs@zip.com.auE<gt> 18jun1998
#