#!/bin/bash
# shellcheck disable=SC2250
#
# pdfman - View UNIX manual pages as Portable Document Format (PDF) files
# Copyright (c)2010,2013,2016,2019,2023 Barton IT-Consulting, Alexander Barton
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.
# See the GNU General Public License for more details.
#

CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/pdfman"

while [[ $# -gt 0 ]]; do
	case "$1" in
		"-v")
			# Enable verbose mode.
			VERBOSE="-p"
			;;
		"-T")
			# Force using man(1)!
			shift
			man "$@"
			exit $?
			;;
		"--help")
			echo "Usage: pdfman [-v] [-T] [<section>] <topic> ..." >&2
			echo "       pdfman <man(1) options> <arguments> ..." >&2
			echo "       pdfman {--help|--version>}" >&2
			echo >&2
			man --help
			exit 2
			;;
		"--version")
			echo "pdfman, version 1" >&2
			man --version
			exit 2
			;;
		-*)
			# Unknown options passed; use man(1).
			man "$@"
			exit $?
			;;
		*)
			break
	esac
	shift
done

run_ps2pdf() {
	# Ghostscript ps2pdf(1)
	ps2pdf - "$1"
}

run_pstopdf() {
	# Apple pstopdf(1)
	pstopdf -i -o "$1" >/dev/null
}

# Manual page name(s) given?
if [[ -z "$1" ]]; then
	# Give man's wtf error ("help message"):
	man
	exit $?
fi

# Make sure there is a terminal available ...
if [[ ! -t 1 ]]; then
	man "$@"
	exit $?
fi

# Detect "opener" to use ...
if command -v xdg-open >/dev/null; then
	open_command=xdg-open
elif command -v open >/dev/null; then
	open_command=open
else
	man "$@"
	exit $?
fi

# Detect PS-to-PDF converter to use ...
if command -v ps2pdf >/dev/null; then
	ps_to_pdf_function=run_ps2pdf
elif command -v pstopdf >/dev/null; then
	ps_to_pdf_function=run_pstopdf
else
	man "$@"
	exit $?
fi

[[ -n "$VERBOSE" ]] && echo "Using ${ps_to_pdf_function#*_}(1) and ${open_command}(1) ..."

# Try to move old cache directory ...
if [[ -d "$HOME/.pdfman" && ! -d "$CACHE" ]]; then
	echo "Moving cache folder to new location ..."
	mv -v "$HOME/.pdfman" "$CACHE" || exit 1
fi

# Make sure that cache directory exists and is writable
mkdir -p "$CACHE"
[[ -w "$CACHE" ]] || CACHE="/tmp"

# Handle arguments, manual page name(s) ...
# shellcheck disable=SC2312
man -w "$@" | while read -r MANFILE; do
	MANPAGE=$(basename "$MANFILE" | sed -e 's/\.gz$//g')
	NAME=${MANPAGE%.*}
	SECTION=${MANPAGE##*.}
	PDF=$CACHE/$SECTION/$NAME.$SECTION.pdf
	[[ -n "$VERBOSE" ]] && echo "Manual page \"$NAME($SECTION)\":"

	# Check if cached PDF is available and still up to date:
	if [[ -e "$PDF" && "$PDF" -ot "$MANFILE" ]]; then
		[[ -n "$VERBOSE" ]] && echo "Deleting outdated cached PDF file ..."
		rm "$PDF"
	fi

	# if there's no cached PDF file, create one!
	if [[ ! -r "$PDF" ]]; then
		mkdir -p "$CACHE/$SECTION"
		[[ -n "$VERBOSE" ]] && echo "Converting \"$MANFILE\" to \"$PDF\" ..."
		if ! man -t "$MANFILE" | $ps_to_pdf_function "$PDF"; then
			echo "Failed to convert manual page to PDF!" >&2
			exit 1
		fi
	else
		[[ -n "$VERBOSE" ]] && echo "Using cached PDF file ..."
	fi

	[[ -n "$VERBOSE" ]] && echo "Opening \"$PDF\" ..."
	$open_command "$PDF"
done