#!/bin/bash

# Copyright (C) 2013-2018 Ole Tange and Free Software Foundation, Inc.
#
# 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 3 of the License, or
# (at your option) any later version.
#
# This script downloads the latest version of GNU Parallel, checks
# the signature and installs it.
#
# It first tries to install it globally.
# If that fails, it does a personal installation.
# If that fails, it copies to $HOME/bin
#
# You can download and run the script directly by:
#   (lynx -source pi.dk/3 || wget -O - pi.dk/3 || curl pi.dk/3/ || fetch -o - http://pi.dk/3) | bash

run() {
    # tail on openindiana must be /usr/xpg4/bin/tail
    TAIL=$(echo | tail -n 1 2>/dev/null && echo tail ||
		      (echo | /usr/xpg4/bin/tail -n 1 && echo /usr/xpg4/bin/tail))
    # grep on openindiana must be /usr/xpg4/bin/grep
    GREP=$(echo | grep -vE . 2>/dev/null && echo grep ||
		      (echo | /usr/xpg4/bin/grep -vE . && echo /usr/xpg4/bin/grep))
    # FreeBSD prefers 'fetch', MacOS prefers 'curl', Linux prefers 'wget'
    GET=$(
	(lynx -source /dev/null && echo lynx -source) ||
	    (fetch -o /dev/null file:///bin/sh && echo fetch -o -) ||
	    (curl -h >/dev/null && echo curl -L) ||
	    (wget -h >/dev/null && echo wget -qO -) ||
	    echo 'No lynx, wget, curl, fetch: Please inform parallel@gnu.org what you use for downloading URLs' >&2
       )
    if test "$GET" = ""; then
	exit 1
    fi

    if ! perl -e 1; then
	echo No perl installed. GNU Parallel depends on perl. Install perl and retry.
	exit 1
    fi

    LANG=C
    LATEST=$($GET http://ftpmirror.gnu.org/parallel |
		    perl -ne '/.*(parallel-\d{8})/ and print $1."\n"' |
		    sort | $TAIL -n1)
    if test \! -e $LATEST.tar.bz2; then
	# Source tar does not exist
	rm -f $LATEST.tar.bz2 $LATEST.tar.bz2.sig
	$GET http://ftpmirror.gnu.org/parallel/$LATEST.tar.bz2 > $LATEST.tar.bz2
	$GET http://ftpmirror.gnu.org/parallel/$LATEST.tar.bz2.sig > $LATEST.tar.bz2.sig
    fi

    fetch_keys() {
	if gpg -h 2>/dev/null >/dev/null ; then
	    # GnuPG installed
	    # Setup .gnupg/gpg.conf if not already done
	    echo | gpg 2>/dev/null >/dev/null
	    keyserver1=keys.gnupg.net
	    keyserver2=pool.sks-keyservers.net
	    if gpg --keyserver $keyserver1 --recv-key 0xFFFFFFF1 ||
		    gpg --keyserver $keyserver2 --recv-key 0xFFFFFFF1 ; then
		if gpg --keyserver $keyserver1 --recv-key 0x88888888 ||
			gpg --keyserver $keyserver2 --recv-key 0x88888888; then
		    # OK
		    return 0
		else
		    echo
		    echo "Cannot fetch keyID 0x88888888, so the signature cannot be checked."
		    return 1
		fi
	    else
		echo
		echo "Cannot fetch keyID 0xFFFFFFF1, so the signature cannot be checked."
		return 1
	    fi
	else
	    # GnuPG not installed
	    echo
	    echo "GnuPG (gpg) is not installed so the signature cannot be checked."
	    return 1
	fi
    }


    # Check signature - in case ftpmirror.gnu.org is compromised
    if fetch_keys; then
	if gpg --with-fingerprint $LATEST.tar.bz2.sig 2>&1 |
	       $GREP -E '^Primary key fingerprint: BE9C B493 81DE 3166 A3BC  66C1 2C62 29E2 FFFF FFF1|^Primary key fingerprint: CDA0 1A42 08C4 F745 0610  7E7B D1AB 4516 8888 8888' ; then
	    # Source code signed by Ole Tange <ole@tange.dk>
	    # KeyID FFFFFFF1/88888888
	    true
	else
	    # GnuPG signature failed
	    echo
	    echo "The signature on $LATEST.tar.bz2 is wrong. This may indicate that a criminal has changed the code."
	    echo "THIS IS BAD AND THE CODE WILL NOT BE INSTALLED."
	    echo
	    echo "See http://git.savannah.gnu.org/cgit/parallel.git/tree/README for other installation methods."
	    exit 1
	fi
    else
	# GnuPG not installed or public keys not downloaded
	echo "This means that if the code has been changed by criminals, you will not discover that!"
	echo
	echo "Continue anyway? (y/n)"
	read YN </dev/tty
	if test "$YN" = "n"; then
  	    # Stop
  	    exit 2
	else
  	    # Continue
  	    true
	fi
    fi

    bzip2 -dc $LATEST.tar.bz2 | tar xf -
    cd $LATEST || exit 2
    if ./configure && make && make install; then
	echo
	echo GNU $LATEST installed globally
    else
	if ./configure --prefix=$HOME && make && make install; then
	    echo
	    echo GNU $LATEST installed in $HOME/bin
	else
	    mkdir -p $HOME/bin/;
	    chmod 755 src/*;
	    cp src/parallel src/env_parallel* src/sem src/sql src/niceload src/parcat $HOME/bin;
	    echo
	    echo GNU $LATEST copied to $HOME/bin
	fi

	# Is $HOME/bin already in $PATH?
	if echo $PATH | grep $HOME/bin >/dev/null; then
	    # $HOME/bin is already in $PATH
	    true
	else
	    # Add $HOME/bin to $PATH for both bash and csh
	    echo 'PATH=$PATH:$HOME/bin' >> $HOME/.bashrc
	    echo 'setenv PATH ${PATH}:${HOME}/bin' >> $HOME/.cshrc
	fi

	# Is $HOME/share/man already in $MANPATH?
	if echo $MANPATH | grep $HOME/share/man >/dev/null; then
	    # $HOME/share/man is already in $MANPATH
	    true
	else
	    # Add $HOME/share/man to $MANPATH for both bash and csh
	    echo 'MANPATH=$MANPATH:$HOME/share/man' >> $HOME/.bashrc
	    echo 'setenv MANPATH ${MANPATH}:${HOME}/share/man' >> $HOME/.cshrc
	fi
    fi
}

# Make sure the whole script is downloaded before starting
run