package App::Rakubrew::Update;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT = qw();
use strict;
use warnings;
use 5.010;
use HTTP::Tinyish;
use JSON;
use FindBin qw( $RealBin $RealScript );
use File::Copy;
use File::Spec::Functions qw( catfile catdir );
use Fcntl;
use if scalar ($^O =~ /win32/i), 'Win32';
use if scalar ($^O =~ /win32/i), 'Win32::Process';
use if scalar ($^O =~ /win32/i), 'Win32::ShellQuote';
use App::Rakubrew;
use App::Rakubrew::Variables;
use App::Rakubrew::Config;
my $release_index_url   = 'https://rakubrew.org/releases';
my $download_url_prefix = 'https://rakubrew.org';
my %dl_urls = (
    fatpack => "$download_url_prefix/perl/rakubrew",
    win     => "$download_url_prefix/win/rakubrew.exe",
    macos   => "$download_url_prefix/macos/rakubrew",
);
sub update {
    my $quiet = shift;
    # For par packaged executables the following returns the path and name of
    # the par packaged file.
    my $current_rakubrew_file = catfile($RealBin, $RealScript);
    # check whether this is a CPAN installation. Abort if yes.
    if ($distro_format eq 'cpan') {
        say STDERR 'Rakubrew was installed via CPAN, use your CPAN client to update.';
        exit 1;
    }
    my $ht = HTTP::Tinyish->new();
        my $release_index = _download_release_index($ht);
    # check version
    if ($App::Rakubrew::VERSION >= $release_index->{latest}) {
        say 'Rakubrew is up-to-date!';
        exit 0;
    }
    # Display changes
    if (!$quiet) {
        say "Changes\n";
        say "=======\n";
        for my $change (@{$release_index->{releases}}) {
            next if $change->{version} <= $App::Rakubrew::VERSION;
            say $change->{version} . ':';
            say "    $_" for split(/^/, $change->{changes});
            say '';
        }
        print 'Shall we do the update? [y|N] ';
        my $reply = <STDIN>;
        chomp $reply;
        exit 0 if $reply ne 'y';
        say '';
    }
    mkdir catdir($prefix, 'update') unless (-d catdir($prefix, 'update'));
    my $update_file = catfile($prefix, 'update', $RealScript);
    # delete RAKUBREW_HOME/update/rakubrew
    unlink $update_file;
    # download latest to RAKUBREW_HOME/update/rakubrew
    my $res = $ht->get($dl_urls{$distro_format});
    unless ($res->{success}) {
        say STDERR "Couldn\'t download update. Error: $res->{status} $res->{reason}";
        exit 1;
    }
    my $fh;
    if (!sysopen($fh, $update_file, O_WRONLY|O_CREAT|O_EXCL, 0777)) {
        say STDERR "Couldn't write update file to $update_file. Aborting update.";
        exit 1;
    }
    binmode $fh;
    print $fh $res->{content};
    close $fh;
    if ($^O =~ /win32/i) {
        # Windows has no real exec(). In addition all the standard perl
        # utilities to start processes automatically make the started process
        # inherit all handles of the parent. This has the effect that it's
        # impossible in the child to delete the parents executable file even
        # when the parent has already exited. So we use the lower level
        # Win32::Process::Create with the 4th argument (inheritHandles) set to 0
        # to get rid of the handles preventing the deletion of the parent
        # executable.
        say 'You will now see a command prompt, even though the update process is still running.';
        say 'This is caused by a quirk in Windows\' process handling.';
        say 'Just wait a few seconds until an "Update successful!" message shows up';
        my $ProcessObj;
        if (!Win32::Process::Create(
            $ProcessObj,
            $update_file,
            Win32::ShellQuote::quote_native(
                $update_file,
                'internal_update',
                $App::Rakubrew::VERSION,
                $current_rakubrew_file),
            0,
            Win32::Process::NORMAL_PRIORITY_CLASS(),
            "."
        )) {
            say STDERR 'Failed to call the downloaded rakubrew executable! Aborting update.';
            exit 1;
        };
        exit 0;
    }
    else {
        { exec($update_file, 'internal_update', $App::Rakubrew::VERSION, $current_rakubrew_file) };
        say STDERR 'Failed to call the downloaded rakubrew executable! Aborting update.';
        exit 1;
    }
}
sub internal_update {
    my ($old_version, $old_rakubrew_file) = @_;
    my $current_script = catfile($RealBin, $RealScript);
    my $update_file = catfile($prefix, 'update', $RealScript);
    if ($update_file ne $current_script) {
        say STDERR "'internal_update' was called on a rakubrew ($current_script) that's not $update_file. That's probably wrong and dangerous. Aborting update.";
        exit 1;
    }
    # custom update procedures
    #if ($old_version < 2) {
    #    Do update stuff for version 2.
    #}
    # copy RAKUBREW_HOME/update/rakubrew to 'path/to/rakubrew'
    unlink $old_rakubrew_file or die "Failed to unlink old file: $old_rakubrew_file. Error: $!";
    my $fh;
    if (!sysopen($fh, $old_rakubrew_file, O_WRONLY|O_CREAT|O_EXCL, 0777)) {
        say STDERR "Couldn't copy update file to $old_rakubrew_file. Rakubrew is broken now. Try manually copying '$update_file' to '$old_rakubrew_file' to get it fixed again.";
        exit 1;
    }
    binmode $fh;
    if (!copy($update_file, $fh)) {
        close $fh;
        unlink $old_rakubrew_file;
        say STDERR "Couldn't copy update file to $old_rakubrew_file. Rakubrew is broken now. Try manually copying '$update_file' to '$old_rakubrew_file' to get it fixed again.";
        exit 1;
    }
    close $fh;
    unlink $update_file;
    say 'Update successful!';
}
sub _download_release_index {
    my $ht = shift;
    my $res = $ht->get($release_index_url);
    unless ($res->{success}) {
        say STDERR "Couldn\'t fetch release index at $release_index_url. Error: $res->{status} $res->{reason}";
;
        exit 1;
    }
    return decode_json($res->{content});
}