#!/bin/sh

argv0="$0"

die() { printf "$*" >/dev/stderr && exit 1; }

# A lot of these break convention when recording errors because this tries to
# imitate other implementations.
[ -n "$1" ] || die "What manual page do you want?\nFor example, try 'man man'.\n"

[ -n "$LANG" ] || LANG="C"

[ -n "$MANPATH" ] || MANPATH="/usr/share/man"
[ -d "$MANPATH" ] || die "$0: \$MANPATH: $MANPATH: Does not exist\n"
[ -n "$MANSECTIONS" ] \
	&& default_mansections="$MANSECTIONS" \
	|| default_mansections="1nl830254967" 
[ -d "$MANPATH"/"$LANG" ] \
	&& MANDIR="$MANPATH/$LANG" \
	|| MANDIR="$MANPATH"

if [ -z "$PAGER" ]; then
	for prog in $(printf "
less
more
cat
dd
	"); do
		if which "$prog" >/dev/null 2>&1; then
			PAGER="$prog"
			break
		fi
	done
fi

man() {
	eq $# 2 || die "$argv0: man() called with $# arguments. Expected 2. This is a programmer error\n"
	MANSECTIONS="$1"
	NAME="$2"

	# the way manpages are laid out SUCKS
	# so, yeah, each man section is one character. which means it's totally
	# bueno to just iterate over the string like this. but $MANDIR/man1 can
	# have both man.1.gz AND man.1p.gz. ARGH!!!!
	for SECTION in $(printf "$MANSECTIONS" | sed 's/\(.\)/\1\n/g'); do
		PAGE="$(find "$MANDIR/man$SECTION" -type f 2>/dev/null | grep "\/$NAME\.\|\/$NAME$" | sed q)"
		[ -z "$PAGE" ] || break
	done

	! [ -n "$PAGE" ] \
		&& printf "No manual entry for $NAME\n" \
		&& return 1

	case "$(file -bir --no-buffer "$PAGE")" in
		("text/"*)
			COMMAND="cat" ;;
		("application/gzip"*)
			COMMAND="zcat" ;;
		(*)
			die "$argv0: $PAGE: Unknown file type.\n" ;;
	esac

	$COMMAND "$PAGE" | nroff -man | $PAGER
}

# this seems to be what the popular man does
# so like `man foo -k bar` will show the manpages for foo, -k, and bar
# expected behavior imo would be manpage for foo, then gist for bar
# but let's not break things
if streq "$1" "-k"; then # -k
	printf "Not yet implemented\n" && exit 1
else # not -k
	while gt $# 0; do
		if eq $(fdivide $# 2) 0 && gt 1 $# || ! stris int "$1"; then
			MANSECTIONS="$default_mansections"
			NAME="$1"
			SHIFTING=1
		elif gt 1 $(fdivide $# 2); then
			MANSECTIONS="$1"
			NAME="$2"
			SHIFTING=2
		else exit 0 # no more args
		fi
		man "$MANSECTIONS" "$NAME"
		shift $SHIFTING
	done
fi