#!/bin/sh
# Copyright (C) 2021  C. McEnroe <june@causal.agency>
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

set -eu

die() {
	echo "$@" >&2
	exit 1
}

system=${1:-}
[ -n "${system}" ] || die 'What system do you want?'
shift

export MANPATH="%%EXMANDIR%%/${system}"
[ -d "${MANPATH}" ] || die "No manuals for ${system}"

export MANSECT
for sect in "${MANPATH}"/man*/; do
	sect=${sect%/}
	sect=${sect##*/man}
	MANSECT="${MANSECT:-}${MANSECT:+:}${sect}"
done

# macOS man(1) refuses to search in directories such as "man3p", so do it
# manually here unless there are other flags passed.
hack() {
	case "${1:-}" in
		(-*) exec man "$@";;
		([0-9]*) MANSECT=$1; shift;;
	esac
	[ $# -gt 0 ] || die 'What manual page do you want?'
	for page in "$@"; do
		found=0
		IFS=:
		for sect in $MANSECT; do
			path="${MANPATH}/man${sect}/${page}"
			for ext in ".${sect}" ".${sect}.gz"; do
				[ -f "${path}${ext}" ] || continue
				man "${path}${ext}"
				found=1
				break
			done
			[ $found -eq 0 ] || break
		done
		[ $found -ne 0 ] || die "No manual entry for ${page}"
	done
}

if [ "$(uname)" = 'Darwin' ]; then
	hack "$@"
else
	exec man "$@"
fi