use strict;
use warnings;

use Test::More;
use Data::Dumper;

BEGIN {
    use_ok('Bio::EnsEMBL::Utils::Iterator');
}

my ($it, $num, $i);

# check that a coderef works as an argument to the constructor

$it = Bio::EnsEMBL::Utils::Iterator->new(sub {return 3});

is($it->next, 3, "got expected value from iterator created from coderef");

# from now on we create an iterator from an arrayref because it's simpler

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

ok($it->has_next, 'iterator still has elements');

$i = 0;

while ($num = $it->next) {
    is($num, ++$i, "$num is next element");
}

is($i, 3, 'got right number of elements');

# test empty iterator

my $empty_it = Bio::EnsEMBL::Utils::Iterator->new;

ok((not $empty_it->has_next), 'empty iterator has no elements');

# test grepping and mapping

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3,4]);

my $even_it = $it->grep(sub {$_ % 2 == 0});

$i = 0;

while ($num = $even_it->next) {
    $i++;
    ok($num % 2 == 0, "$num is even");
}

is($i, 2, 'got right number of grepped elements back');

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

my $doubled_it = $it->map(sub {$_ * 2});

$i = 0;

while ($num = $doubled_it->next) {
    is($num, ++$i * 2, "$num = $i * 2");
}

is($i, 3, 'got right number of mapped elements back');

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

my $filtered_mapped_it = $it->map(sub {$_ * 3})->grep(sub {$_ % 2 == 0});

is($filtered_mapped_it->next, 6, "filtering and mapping together work");

ok(!$filtered_mapped_it->has_next, "only got one result from filtering and mapping");

# test combining iterators

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

$empty_it = Bio::EnsEMBL::Utils::Iterator->new;

my $it2 = Bio::EnsEMBL::Utils::Iterator->new([4,5,6]);

my $combined_it = $it->append($empty_it, $it2);

$i = 0;

while ($num = $combined_it->next) {
    $i++;
}

is($i, 6, 'got right number of elements from combined iterators');

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

my $el = $it->peek;

is($el, $it->next, 'peek did not remove element');

# test converting iterator to an arrayref

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3]);

is_deeply($it->to_arrayref, [1,2,3], 'to_arrayref returned expected array');

# test take and skip

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3,4])->take(2);

is_deeply($it->to_arrayref, [1,2], 'took correct elements');

$it = Bio::EnsEMBL::Utils::Iterator->new([1,2,3,4])->skip(2);

is_deeply($it->to_arrayref, [3,4], 'skipped expected elements');

# test reduce

$num = Bio::EnsEMBL::Utils::Iterator->new([1,2,3,4])->reduce(sub {$_[0] + $_[1]});

is($num, 10, "reduce calculated sum correctly");

# test reduce with initial accumulator value

$num = Bio::EnsEMBL::Utils::Iterator->new([1,2,3,4])->reduce(sub {$_[0] + $_[1]}, 10);

is($num, 20, "reduce with initial value calculated sum correctly");

done_testing;