#!/usr/bin/perl

use strict;
use warnings;
use IO::Prompter;
use File::Which qw( which );

# Configurable variables
my $lang = 'en-CA';
my $install = "$ENV{HOME}/.local/bin";
my $working = "/tmp/firefox.new";

# Download link as provided by https://www.mozilla.org/$lang/firefox/developer/
my $url = 'https://download.mozilla.org/?product=firefox-devedition-latest-ssl'
        . '&os=linux64&lang='.$lang;

# Ensure that we can unzip
unless (which("bunzip2")) {
        die "Requires bunzip2. Try:\n"
                . "sudo apt install zutils or your distro's equivalent\n";
}

# Only understood argument is to not bother verifying the package
my ($download_key, $verify) = (0,1);
if (defined $ARGV[0]) {
        if ($ARGV[0] eq '--no-verify') {
                $verify = 0;
        } else {
                die "Didn't understand argument $ARGV[0]\n";
        }
}

# If verification is to be done, make sure we have the key
unless ($verify) {
        print "Checking for Mozilla GPG key in keyring...\n";
        system("gpg --list-keys release\@mozillla.com 2>&1 > /dev/null");
        if ($?) {
                my $YN = prompt (-in => *STDIN, "You don't currently have "
                        . "Mozilla's GPG key in your keyring.\n"
                        . "Would you like to install it? If not, installation "
                        . "will not be verified. [y/N]: ",
                        -single
                );
                if ($YN eq 'y' || $YN eq 'Y') {
                        $download_key = 1;
                } else {
                        $verify = 0;
                }
        }
}

# If a previous download still exists remove it
if ( -e $working ) {
        system("rm -rf $working");
        if ($?) {
                die "Working directory "
                        . $working
                        . "already exists and failed to remove: $!\n";
        }
}

# Get version currently installed
my $current = `$install/firefox/firefox-bin --version`;
$current =~ s/.*\s([^\s])/$1/;
chomp $current;

use WWW::Mechanize;
my $mech = WWW::Mechanize->new();

# $url is actually going to redirect to the proper current dowload so just get
# the redirect.
my $head = $mech->head($url);

my ($location, $version);
# This redirect will have the version id, so we can use that to determine if a
# new version actually exists
if ($head->{'_msg'}) {
        $version = $location = $head->{'_previous'}->{'_headers'}->{'location'};
        $version =~ s/^.*\-([^\-]*)\.tar\.bz2$/$1/;
        if ($version eq $current) {
                die "Current ($current) is the same as New ($version)\n";
        }
} else {
        print "unable to find new download\n";
}

mkdir($working) || die "Couldn't make $working: $!\n";

# Download package
print "Fetching package $location...\n";
$mech->get($location);
$mech->save_content( $working."/firefox-".$version.".tar.bz2",
        binmode => ':raw',
        decoded_by_headers => 1
);

# If verification is required, get signature as well
if ($verify) {
        $location .= '.asc';
        print "Fetching GPG signature $location...\n";
        $mech->get($location);
        $mech->save_content( $working."/firefox-".$version.".tar.bz2.asc",
                binmode => ':raw',
                decoded_by_headers => 1
        );
}

# If key still needs to be fetched, get it
if ($download_key) {
        $location =~ s/linux-x86_64.*$/KEY/;
        print "Fetching GPG key $location...\n";
        $mech->get($location);
        $mech->save_content( $working."/mozilla.pgp",
                binmode => ':raw',
                decoded_by_headers => 1
        );
        # And install it
        print "Installing Mozilla GPG key in keyring...\n";
        system("gpg --import $working/mozilla.pgp 2>&1 > /dev/null");
        if ($?) {
                die "Warning: failed to import key. Cannot verify integrity.\n"
                        . "Downloaded to "
                        . $working
                        . ". You can check and install it to "
                        . $install
                        . "manually: "
                        . $!
                        . "\n";
        }
        unlink("$working/mozilla.pgp");
}

# Verify the package
if ($verify) {
        print "Verifying download with Mozilla GPG key...\n";
        system("gpg --verify $working/firefox-$version.tar.bz2.asc");
        if ($?) {
                die "Warning: failed to verify download. Signing failed.\n"
                        . "Downloaded to "
                        . $working
                        . ". You can check and install it to "
                        . $install
                        . " manually: "
                        . $!
                        . "\n";
        }
}

# Uncompress
print "Uncompressing download with bunzip2...\n";
system("bunzip2 $working/firefox-$version.tar.bz2");
if ($?) {
        die "Failed to uncompress: $!\n";
}

# Extract
print "Extracting from TAR archive...\n";
system("tar -xf $working/firefox-$version.tar -C $working");
if ($?) {
        die "Failed to extract: $!\n";
}

# Bin the old backup
if (-e "$install/.firefox.old") {
        print "Removing previous backup folder...\n";
        system("rm -rf $install/.firefox.old");
        if ($?) {
                die "Failed to remove: $!\n";
        }
}

# Move current to old
print "Backing up currently installed version ("
        . $current
        . ") to "
        . $install
        . "/.firefox.old...\n";
system("mv $install/firefox $install/.firefox.old");
if ($?) {
        die "Failed to move: $!\n";
}

# Move new to current
print "Moving new version to $install for final installation...\n";
system("mv $working/firefox $install/");
if ($?) {
        die "Failed to move: $!\n";
}

# Hurray!
print "Installation of version "
        . $version
        . " complete. You should restart firefox whenever it is convenient.\n";
exit();