#!/bin/sh

################################################################################
#
# groffdown - (legacy shellscript version)
#
# Usage: groffdown [--debug] [-o PREFIX] FILE
#
################################################################################

set -eu
umask 0022
export LC_ALL=C

# usage [CODE]
# CODE: default to 1. Error code.
usage(){
    set -- "${1:-1}"

    _redirect=2
    case "$1" in 0) _redirect=1; esac

    printf '%s\n' "Usage: ${0##*/} [--debug] [-o PREFIX] FILE" 1>&$_redirect
    exit $1
}

# error_exit MSG
error_exit(){
    printf '%s\n' "${0##*/}: $1" 1>&2
    exit 1
}

# == Flags and global arguments ==
DEBUG=
OUTPUT_FILE=

# == Parse argument ==
case $# in 0) usage 1; esac

while :; do
    case $# in 0) break; esac

    case $1 in -|[!-]*)        break; esac
    case $1 in --)      shift; break; esac

    case $1 in --help|--usage|'-?')
	 usage 0
    esac

    case $1 in --d|--de|--deb|--debu|--debug)
	DEBUG=1
	shift
	continue
    esac

    case $1 in -o)
	 OUTPUT_FILE="$2"
	 shift 2
	 continue
    esac

    case $1 in -?*)
	 error_exit "$1: Unknown option"
    esac
done

case $# in 0) usage 1; esac

# == Variables ==
file="$OUTPUT_FILE"; : ${file:="$( readlink -f "$1" )"}
dir=$(dirname "$file")
base="${file%.*}"

# == Readable regular file? ==
if test -f "$1" && test -r "$1"; then
    : # NOP
else
    error_exit "${1##*/}: Not a readable regular file"
fi

# == Hyphened file to be real argument ==
case "$1" in -*) set -- "./$1";; esac

# == Main section ==

# -- Translate markdown to groff ms. --

cat "$1" |
#
# Yaml-specifics.
awk '
BEGIN {
    is_in_yaml = 0;
}

# -- Beginning of yaml. --
NR == 1 && /^-+$/ {
    is_in_yaml = 1;
    next;
}

# -- End of yaml. --
is_in_yaml && /^-+$/ {
    is_in_yaml = 0;
    # YYY(Tpaefawzen): Seems like line for end of yaml should be preserved?
}

is_in_yaml {
    # -- Yaml metadata. --
    sub("title: *", ".TL\n");
    sub("author: *", ".AU\n");
    sub("date: *", ".ND\n");
    sub("institution: *", ".AI\n");
}

1' |
#
# Others are context-free.
sed '
    # -- LaTeX-style abstract. --
    s/\\begin{abstract}/\.AB/
    s/\\end{abstract}/\.AE/

    # -- Sections. --
    s/^\#####.\(.*\)/\.NH 5\n\1\n\.PP/g
    s/^\####.\(.*\)/\.NH 4\n\1\n\.PP/g
    s/^\###.\(.*\)/\.NH 3\n\1\n\.PP/g
    s/^\##.\(.*\)/\.NH 2\n\1\n\.PP/g
    s/^\#.\(.*\)/\.NH 1\n\1\n\.PP/g

    # -- Bold and italic. --
    s/\*\*\*\(.*\)\*\*\*$/\n\.BI\ \"\1\"\ /g
    s/\*\*\*\(.*\)\*\*\*\(.\)$/\n\.BI\ \"\1\"\ \"\2\"/g
    s/\*\*\*\(.*\)\*\*\*\(.\)/\n\.BI\ \"\1\"\ \"\2\"\n/g

    # -- Bold. --
    s/\*\*\(.*\)\*\*$/\n\.B\ \"\1\"\ /g
    s/\*\*\(.*\)\*\*\(.\)$/\n\.B\ \"\1\"\ \"\2\"/g
    s/\*\*\(.*\)\*\*\(.\)/\n\.B\ \"\1\"\ \"\2\"\n/g

    # -- Italic. --
    s/\*\(.*\)\*$/\n\.I\ \"\1\"\ /g
    s/\*\(.*\)\*\(.\)$/\n\.I\ \"\1\"\ \"\2\"/g
    s/\*\(.*\)\*\(.\)/\n\.I\ \"\1\"\ \"\2\"\n/g

    # -- Inline code. --
    s/`\(.*\)`$/\n\.CW\ \"\1\"\ /g
    s/`\(.*\)`\(.\)$/\n\.CW\ \"\1\"\ \"\2\"/g
    s/`\(.*\)`\(.\)/\n\.CW\ \"\1\"\ \"\2\"\n/g

    # -- List items. --
    s/^\ ...............-\ /.IP\ \\(bu\ 10\n/g
    s/^\ ...........-\ /.IP\ \\(bu\ 8\n/g
    s/^\ .......-\ /.IP\ \\(bu\ 6\n/g
    s/^\ ...-\ /.IP\ \\(bu\ 4\n/g
    s/^-\ /.IP\ \\(bu\ 2\n/g
    s/^\ .*-\ /.IP\ \\(bu\ 12\n/g

    # -- Begin a new paragraph. --
    s/^$/.PP/g
' |
#
# Parsing for ms things ends.
cat > "$base.ms.tmp"

tmpfname="$base.ms.tmp"

# To PDF when required.
case "$DEBUG" in "")
    if cat "$base.ms.tmp" | groff -ms -Tpdf > "$base.pdf.tmp"; then
	rm "$base.ms.tmp"
    else
	error_exit "could not convert to PDF with groff (code: $?)"
    fi

    tmpfname="$base.pdf.tmp"
    ;;
esac

mv "$tmpfname" "${tmpfname%.tmp}"

# == Finally ==
exit $?

# vim: set shiftwidth=4 softtabstop=4: