set_global('pm_conversations', {
    recent: {},
});

zrequire('muting');
zrequire('unread');
zrequire('stream_data');
zrequire('stream_topic_history');
zrequire('stream_sort');
const tg = zrequire('topic_generator');

function is_even(i) { return i % 2 === 0; }
function is_odd(i) { return i % 2 === 1; }

run_test('basics', () => {
    let gen = tg.list_generator([10, 20, 30]);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    const gen1 = tg.list_generator([100, 200]);
    const gen2 = tg.list_generator([300, 400]);
    const outers = [gen1, gen2];
    gen = tg.chain(outers);
    assert.equal(gen.next(), 100);
    assert.equal(gen.next(), 200);
    assert.equal(gen.next(), 300);
    assert.equal(gen.next(), 400);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.wrap([5, 15, 25, 35], 25);
    assert.equal(gen.next(), 25);
    assert.equal(gen.next(), 35);
    assert.equal(gen.next(), 5);
    assert.equal(gen.next(), 15);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.wrap_exclude([5, 15, 25, 35], 25);
    assert.equal(gen.next(), 35);
    assert.equal(gen.next(), 5);
    assert.equal(gen.next(), 15);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.wrap([5, 15, 25, 35], undefined);
    assert.equal(gen.next(), 5);

    gen = tg.wrap_exclude([5, 15, 25, 35], undefined);
    assert.equal(gen.next(), 5);

    gen = tg.wrap([5, 15, 25, 35], 17);
    assert.equal(gen.next(), 5);

    gen = tg.wrap([], 42);
    assert.equal(gen.next(), undefined);

    let ints = tg.list_generator([1, 2, 3, 4, 5]);
    gen = tg.filter(ints, is_even);
    assert.equal(gen.next(), 2);
    assert.equal(gen.next(), 4);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    ints = tg.list_generator([]);
    gen = tg.filter(ints, is_even);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    ints = tg.list_generator([10, 20, 30]);

    function mult10(x) { return x * 10; }

    gen = tg.map(ints, mult10);
    assert.equal(gen.next(), 100);
    assert.equal(gen.next(), 200);
});

run_test('reverse', () => {
    let gen = tg.reverse_list_generator([10, 20, 30]);
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    // If second parameter is not in the list, we just traverse the list
    // in reverse.
    gen = tg.reverse_wrap_exclude([10, 20, 30]);
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.reverse_wrap_exclude([10, 20, 30], 'whatever');
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    // Witness the mostly typical cycling behavior.
    gen = tg.reverse_wrap_exclude([5, 10, 20, 30], 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), 5);
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.reverse_wrap_exclude([5, 10, 20, 30], 5);
    assert.equal(gen.next(), 30);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.reverse_wrap_exclude([5, 10, 20, 30], 30);
    assert.equal(gen.next(), 20);
    assert.equal(gen.next(), 10);
    assert.equal(gen.next(), 5);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    // Test small lists.
    gen = tg.reverse_wrap_exclude([], 5);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.reverse_wrap_exclude([5], 5);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    gen = tg.reverse_wrap_exclude([5], 10);
    assert.equal(gen.next(), 5);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);
});

run_test('fchain', () => {
    const mults = function (n) {
        let ret = 0;
        return {
            next: function () {
                ret += n;
                return ret <= 100 ? ret : undefined;
            },
        };
    };

    let ints = tg.list_generator([29, 43]);
    let gen = tg.fchain(ints, mults);
    assert.equal(gen.next(), 29);
    assert.equal(gen.next(), 58);
    assert.equal(gen.next(), 87);
    assert.equal(gen.next(), 43);
    assert.equal(gen.next(), 86);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    ints = tg.wrap([33, 34, 37], 37);
    ints = tg.filter(ints, is_odd);
    gen = tg.fchain(ints, mults);
    assert.equal(gen.next(), 37);
    assert.equal(gen.next(), 74);
    assert.equal(gen.next(), 33);
    assert.equal(gen.next(), 66);
    assert.equal(gen.next(), 99);
    assert.equal(gen.next(), undefined);
    assert.equal(gen.next(), undefined);

    const undef = function () {
        return;
    };

    blueslip.expect('error', 'Invalid generator returned.');
    ints = tg.list_generator([29, 43]);
    gen = tg.fchain(ints, undef);
    gen.next();
});

run_test('streams', () => {
    function assert_next_stream(curr_stream, expected) {
        const actual = tg.get_next_stream(curr_stream);
        assert.equal(actual, expected);
    }

    global.stream_sort.get_streams = function () {
        return ['announce', 'muted', 'devel', 'test here'];
    };

    assert_next_stream(undefined, 'announce');
    assert_next_stream('NOT THERE', 'announce');

    assert_next_stream('announce', 'muted');
    assert_next_stream('test here', 'announce');

    function assert_prev_stream(curr_stream, expected) {
        const actual = tg.get_prev_stream(curr_stream);
        assert.equal(actual, expected);
    }

    assert_prev_stream(undefined, 'test here');
    assert_prev_stream('test here', 'devel');
    assert_prev_stream('announce', 'test here');

});

run_test('topics', () => {
    const streams = [1, 2, 3, 4];
    const topics = new Map([
        [1, ['read', 'read', '1a', '1b', 'read', '1c']],
        [2, []],
        [3, ['3a', 'read', 'read', '3b', 'read']],
        [4, ['4a']],
    ]);

    function has_unread_messages(stream, topic) {
        return topic !== 'read';
    }

    function get_topics(stream) {
        return topics.get(stream);
    }

    function next_topic(curr_stream, curr_topic) {
        return tg.next_topic(
            streams,
            get_topics,
            has_unread_messages,
            curr_stream,
            curr_topic);
    }

    assert.deepEqual(next_topic(1, '1a'),
                     {stream: 1, topic: '1b'});
    assert.deepEqual(next_topic(1, undefined),
                     {stream: 1, topic: '1a'});
    assert.deepEqual(next_topic(2, 'bogus'),
                     {stream: 3, topic: '3a'});
    assert.deepEqual(next_topic(3, '3b'),
                     {stream: 3, topic: '3a'});
    assert.deepEqual(next_topic(4, '4a'),
                     {stream: 1, topic: '1a'});
    assert.deepEqual(next_topic(undefined, undefined),
                     {stream: 1, topic: '1a'});

    // Now test the deeper function that is wired up to
    // real functions stream_data/stream_sort/unread.

    global.stream_sort.get_streams = function () {
        return ['announce', 'muted', 'devel', 'test here'];
    };

    const muted_stream_id = 400;
    const devel_stream_id = 401;

    const stream_id_dct = {
        muted: muted_stream_id,
        devel: devel_stream_id,
    };

    stream_topic_history.get_recent_topic_names = function (stream_id) {
        switch (stream_id) {
        case muted_stream_id:
            return ['ms-topic1', 'ms-topic2'];
        case devel_stream_id:
            return ['muted', 'python'];
        }

        return [];
    };

    global.stream_data.get_stream_id = function (stream_name) {
        return stream_id_dct[stream_name];
    };

    global.stream_data.is_stream_muted_by_name = function (stream_name) {
        return stream_name === 'muted';
    };

    global.unread.topic_has_any_unread = function (stream_id) {
        return [devel_stream_id, muted_stream_id].includes(stream_id);
    };

    global.muting.is_topic_muted = function (stream_name, topic) {
        return topic === 'muted';
    };

    let next_item = tg.get_next_topic('announce', 'whatever');
    assert.deepEqual(next_item, {
        stream: 'devel',
        topic: 'python',
    });

    next_item = tg.get_next_topic('muted', undefined);
    assert.deepEqual(next_item, {
        stream: 'muted',
        topic: 'ms-topic1',
    });
});

run_test('get_next_unread_pm_string', () => {
    pm_conversations.recent.get_strings = function () {
        return ['1', 'read', '2,3', '4', 'unk'];
    };

    unread.num_unread_for_person = function (user_ids_string) {
        if (user_ids_string === 'unk') {
            return;
        }

        if (user_ids_string === 'read') {
            return 0;
        }

        return 5; // random non-zero value
    };

    assert.equal(tg.get_next_unread_pm_string(), '1');
    assert.equal(tg.get_next_unread_pm_string('4'), '1');
    assert.equal(tg.get_next_unread_pm_string('unk'), '1');
    assert.equal(tg.get_next_unread_pm_string('4'), '1');
    assert.equal(tg.get_next_unread_pm_string('1'), '2,3');
    assert.equal(tg.get_next_unread_pm_string('read'), '2,3');
    assert.equal(tg.get_next_unread_pm_string('2,3'), '4');
});