package inc::Installer::TargetHandler;
use strict;
use base qw(
    inc::Installer 
    inc::Installer::Logger 
    inc::Installer::OptionsProviderI 
    inc::Installer::EnvObservableI
);
use ExtUtils::Installed;
{
    my $SINGLETON;
    sub new {
        my $class = shift;
        if ( $SINGLETON ) {
            my %targets = @_;
            $SINGLETON->{$_} = $targets{$_} for ( keys %targets );
        }
        else {
            my %targets = @_;
            bless \%targets, $class;
            $SINGLETON = \%targets;
        }
        return $SINGLETON;
    }
}
sub AddTarget {
    my ( $self, $target, $metadata ) = @_;
    $self->debug("Adding target '$target'");
    if ( defined $metadata and UNIVERSAL::isa( $metadata, 'HASH' ) ) {
        $self->{$target} = $metadata;
    }
    else {
        $self->{$target} = {
            'enable' => 1,
            'prereq' => [],
        };
    }
    return $self;
}
{
    my $mod_checker;
    sub Check {
        $mod_checker = ExtUtils::Installed->new if not $mod_checker;
        my ( $self, $key ) = @_;
        undef($@);
        no warnings 'redefine';
        $key .= ' ()' if $key =~ qr/Scalar::Util/;
        eval { $mod_checker->validate( $key ) };
        my $MISSING = $@;
        undef($@);
        my $file = $key;
        $file =~ s/::/\//g;
        $file .= '.pm';
        delete $INC{$file} if exists $INC{$file};
        return $MISSING ? [ 0, 1 ] : [ 'ok', 1 ];
    }
}
sub Keys {
    my $self = shift;
    my @keys;
    for my $target ( $self->GetTargets ) {
        next if not $self->{$target}->{'enable'};
        push @keys, map { $_->StandardName } @{ $self->{$target}->{'prereq'} };
    }
    return @keys;
}
sub RemoveTarget {
    my ( $self, $target ) = @_;
    $self->debug("Removing target '$target'");   
    delete $self->{$target}; 
    return $self;
}
sub EnableTarget {
    my ( $self, $target ) = @_;
    $self->debug("Enabling target '$target'");
    $self->fatal("Target '$target' does not exist!") if not exists $self->{$target};
    if ( UNIVERSAL::isa( $self->{$target}, 'HASH' ) ) {
        $self->{$target}->{'enable'} = 1;
    }
    else {
        $self->{$target} = {
            'enable' => 1,   
            'prereq' => [], 
        };
    }
    return $self;
}
sub DisableTarget {
    my ( $self, $target ) = @_;
    $self->debug("Disabling target '$target'");
    $self->fatal("Target '$target' does not exist!") if not exists $self->{$target};
    if ( UNIVERSAL::isa( $self->{$target}, 'HASH' ) ) {
        $self->{$target}->{'enable'} = 0;
    }
    else {        
        $self->{$target} = {
            'enable' => 0,
            'prereq' => [],
        };
    }
    return $self;
}
sub GetTargets {
    my $self = shift;
    $self->debug("Getting targets");    
    return keys %$self;
}
sub GetPrereqsForTarget {
    my ( $self, $target ) = @_;
    $self->debug("Getting prerequisites for target '$target'");
    return @{ $self->{$target}->{'prereq'} };
}
sub Options { 
    my $self = shift;
    my %options;
    for my $target ( sort { $a cmp $b } keys %$self ) {
        $options{"disable-$target"}  = sub { $self->DisableTarget( $target ) };
        $options{"enable-$target"}   = sub { $self->EnableTarget(  $target ) };
    }
    return %options;
}
sub OptionsHelp {
    my $self = shift;
    my $help = "  Targets:\n";
    $help .= sprintf("    --[disable|enable]-$_\n      Current setting: %s\n\n", $self->{$_}->{'enable'} ? 'enabled' : 'disabled' ) for ( sort { $a cmp $b } keys %$self );
    return $help;
}
sub GetEUMMArgs {
    my $self = shift;
    my %args;
    for my $target ( keys %$self ) {
        next if not $self->{$target}->{'enable'};
        for my $prereq ( @{ $self->{$target}->{'prereq'} } ) {
            $args{ $prereq->StandardName } = 0;
        }
    }
    #return 'PREREQ_PM' => \%args;
    return 'PREREQ_PM' => {};
}
1;