#!/bin/sh
# converts markdown to latex, then uses latex to make a PDF

pathfind () { # portable which(1), code taken from Debian Developer's Reference
    OLDIFS="$IFS"
    IFS=:
    for _p in $PATH; do
        if [ -x "$_p/$*" ]; then
            IFS="$OLDIFS"
            return 0
        fi
    done
    IFS="$OLDIFS"
    return 1
}

for p in pandoc pdflatex; do
    pathfind $p || {
        echo >&2 "You need '$p' to use this program!"
        exit 1
    }
done

ALL="$*"
ARGS=${ALL%% -- *} # only the part before ' -- ' delimiters is relevant
set -- $ARGS

REST=${ALL#$ARGS}; REST=${REST#--}
PANDOC_OPTS=${REST:-$PANDOC_OPTS}

outfile=
for option; do
    if [ -n "$prev" ]; then
        eval "$prev=\$option"
        prev=
        shift
        continue
    fi
    optarg=$(expr "x$option" : 'x[^=]*=\(.*\)')
    case $option in
    -h | --h | --help )
        help=1
        shift ;;
    -o | --o | --output )
        prev=outfile
        shift ;;
    -o=* | --o=* | --output=* )
        outfile=$optarg
        shift ;;
    -* ) echo >&2 "$0: unknown option: $option; aborting"
        exit 1 ;;
    * ) break ;;
    esac
done

[ -z "$help" ] || {
    echo >&2 "Usage: $0 [-o|--output output-file] [input-file]"
    exit 0
}

infile=$1
shift

if [ -n "$@" ]; then
    echo >&2 "Warning: extra arguments '$@' will be ignored!"
fi

if [ -z "$outfile" ]; then
    if [ -n "$infile" ]; then
        outfile=${infile%.*}.pdf
    else
        outfile='stdin.pdf' # input is STDIN, since no argument given
    fi
fi

BASE=${outfile##*/}
BASE=${BASE%.*}

set -e

TEMP=${TMPDIR-/tmp}/markdown2pdf.$$
trap "status=$?; rm -rf $TEMP; exit $status" 0 INT
mkdir -p $TEMP

iconv -t utf-8 $infile | \
pandoc $PANDOC_OPTS -w latex -s | \
iconv -f utf-8 > $TEMP/$BASE.tex && (
    cd $TEMP
    if ! pdflatex -interaction=batchmode $BASE.tex >/dev/null 2>&1; then
        echo >&2 "LaTeX errors:"
        sed -ne '/^!/,/^ *$/p' $BASE.log >&2
        exit 1
    fi
) || exit $?

is_target_exists=
if [ -f $outfile ]; then
    is_target_exists=1
    mv -f $outfile $outfile~
fi

mv -f $TEMP/$BASE.pdf $outfile

printf "Created $outfile" >&2
[ -z "$is_target_exists" ] || {
    printf " (previous file has been backed up as '$outfile~')" >&2
}
echo >&2 .