var stream_list = (function () {

var exports = {};

exports.update_count_in_dom = function (unread_count_elem, count) {
    var count_span = unread_count_elem.find('.count');
    var value_span = count_span.find('.value');

    if (count === 0) {
        count_span.hide();
        if (count_span.parent().hasClass("subscription_block")) {
            count_span.parent(".subscription_block").removeClass("stream-with-count");
        }
        value_span.text('');
        return;
    }

    count_span.show();

    if (count_span.parent().hasClass("subscription_block")) {
        count_span.parent(".subscription_block").addClass("stream-with-count");
    }
    value_span.text(count);
};


exports.stream_sidebar = (function () {
    var self = {};

    self.rows = new Dict(); // stream id -> row widget

    self.set_row = function (stream_id, widget) {
        self.rows.set(stream_id, widget);
    };

    self.get_row = function (stream_id) {
        return self.rows.get(stream_id);
    };

    self.has_row_for = function (stream_id) {
        return self.rows.has(stream_id);
    };

    self.remove_row = function (stream_id) {
        // This only removes the row from our data structure.
        // Our caller should use build_stream_list() to re-draw
        // the sidebar, so that we don't have to deal with edge
        // cases like removing the last pinned stream (and removing
        // the divider).

        self.rows.del(stream_id);
    };

    return self;
}());

function get_search_term() {
    var search_box = $(".stream-list-filter");
    var search_term = search_box.expectOne().val().trim();
    return search_term;
}

exports.remove_sidebar_row = function (stream_id) {
    exports.stream_sidebar.remove_row(stream_id);
    exports.build_stream_list();
};

exports.create_initial_sidebar_rows = function () {
    // This code is slightly opaque, but it ends up building
    // up list items and attaching them to the "sub" data
    // structures that are kept in stream_data.js.
    var subs = stream_data.subscribed_subs();

    _.each(subs, function (sub) {
        exports.create_sidebar_row(sub);
    });
};

exports.build_stream_list = function () {
    // This function assumes we have already created the individual
    // sidebar rows.  Our job here is to build the bigger widget,
    // which largely is a matter of arranging the individual rows in
    // the right order.
    var streams = stream_data.subscribed_streams();
    if (streams.length === 0) {
        return;
    }

    // The main logic to build the list is in stream_sort.js, and
    // we get three lists of streams (pinned/normal/dormant).
    var stream_groups = stream_sort.sort_groups(get_search_term());

    if (stream_groups.same_as_before) {
        return;
    }

    var parent = $('#stream_filters');
    var elems = [];

    function add_sidebar_li(stream) {
        var sub = stream_data.get_sub(stream);
        var sidebar_row = exports.stream_sidebar.get_row(sub.stream_id);
        sidebar_row.update_whether_active();
        elems.push(sidebar_row.get_li());
    }

    parent.empty();

    _.each(stream_groups.pinned_streams, add_sidebar_li);

    var any_pinned_streams = stream_groups.pinned_streams.length > 0;
    var any_normal_streams = stream_groups.normal_streams.length > 0;
    var any_dormant_streams = stream_groups.dormant_streams.length > 0;

    if (any_pinned_streams && (any_normal_streams || any_dormant_streams)) {
        elems.push('<hr class="stream-split">');
    }

    _.each(stream_groups.normal_streams, add_sidebar_li);

    if (any_dormant_streams && any_normal_streams) {
        elems.push('<hr class="stream-split">');
    }

    _.each(stream_groups.dormant_streams, add_sidebar_li);

    parent.append(elems);
};

exports.get_stream_li = function (stream_id) {
    var row = exports.stream_sidebar.get_row(stream_id);
    if (!row) {
        // Not all streams are in the sidebar, so we don't report
        // an error here, and it's up for the caller to error if
        // they expected otherwise.
        return;
    }

    var li = row.get_li();
    if (!li) {
        blueslip.error('Cannot find li for id ' + stream_id);
        return;
    }

    if (li.length > 1) {
        blueslip.error('stream_li has too many elements for ' + stream_id);
        return;
    }

    return li;
};

function zoom_in(options) {
    popovers.hide_all();
    topic_list.zoom_in();
    $("#streams_list").expectOne().removeClass("zoom-out").addClass("zoom-in");

    // Hide stream list titles and pinned stream splitter
    $(".stream-filters-label").each(function () {
        $(this).hide();
    });
    $(".stream-split").each(function () {
        $(this).hide();
    });

    $("#stream_filters li.narrow-filter").each(function () {
        var elt = $(this);
        var stream_id = options.stream_id.toString();

        if (elt.attr('data-stream-id') === stream_id) {
            elt.show();
        } else {
            elt.hide();
        }
    });
}

function zoom_out(options) {
    popovers.hide_all();
    topic_list.zoom_out();

    if (options.stream_li) {
        exports.scroll_stream_into_view(options.stream_li);
    }
    exports.show_all_streams();
}

exports.show_all_streams = function () {
    // Show stream list titles and pinned stream splitter
    $(".stream-filters-label").each(function () {
        $(this).show();
    });
    $(".stream-split").each(function () {
        $(this).show();
    });

    $("#streams_list").expectOne().removeClass("zoom-in").addClass("zoom-out");
    $("#stream_filters li.narrow-filter").show();
};

exports.set_in_home_view = function (stream_id, in_home) {
    var li = exports.get_stream_li(stream_id);
    if (!li) {
        blueslip.error('passed in bad stream id ' + stream_id);
        return;
    }

    if (in_home) {
        li.removeClass("out_of_home_view");
    } else {
        li.addClass("out_of_home_view");
    }
};

function build_stream_sidebar_li(sub) {
    var name = sub.name;
    var args = {name: name,
                id: sub.stream_id,
                uri: narrow.by_stream_uri(name),
                not_in_home_view: (stream_data.in_home_view(sub.stream_id) === false),
                invite_only: sub.invite_only,
                color: stream_data.get_color(name),
                pin_to_top: sub.pin_to_top,
               };
    args.dark_background = stream_color.get_color_class(args.color);
    var list_item = $(templates.render('stream_sidebar_row', args));
    return list_item;
}

function build_stream_sidebar_row(sub) {
    var self = {};
    var list_item = build_stream_sidebar_li(sub);

    self.update_whether_active = function () {
        if (stream_data.is_active(sub)) {
            list_item.removeClass('inactive_stream');
        } else {
            list_item.addClass('inactive_stream');
        }
    };

    self.get_li = function () {
        return list_item;
    };

    self.remove = function () {
        list_item.remove();
    };


    self.update_unread_count = function () {
        var count = unread.num_unread_for_stream(sub.stream_id);
        exports.update_count_in_dom(list_item, count);
    };

    self.update_unread_count();

    exports.stream_sidebar.set_row(sub.stream_id, self);
}

exports.create_sidebar_row = function (sub) {
    if (exports.stream_sidebar.has_row_for(sub.stream_id)) {
        // already exists
        blueslip.warn('Dup try to build sidebar row for stream ' + sub.stream_id);
        return;
    }
    build_stream_sidebar_row(sub);
};

exports.redraw_stream_privacy = function (sub) {
    var li = exports.get_stream_li(sub.stream_id);
    if (!li) {
        // We don't want to raise error here, if we can't find stream in subscription
        // stream list. Cause we allow org admin to update stream privacy
        // even if they don't subscribe to public stream.
        return;
    }

    var div = li.find('.stream-privacy');
    var dark_background = stream_color.get_color_class(sub.color);

    var args = {
        invite_only: sub.invite_only,
        dark_background: dark_background,
    };

    var html = templates.render('stream_privacy', args);
    div.html(html);
};

function set_stream_unread_count(stream_id, count) {
    var unread_count_elem = exports.get_stream_li(stream_id);
    if (!unread_count_elem) {
        // This can happen for legitimate reasons, but we warn
        // just in case.
        blueslip.warn('stream id no longer in sidebar: ' + stream_id);
        return;
    }
    exports.update_count_in_dom(unread_count_elem, count);
}

exports.update_streams_sidebar = function () {
    exports.build_stream_list();

    // highlight new top stream
    $('#stream_filters li.highlighted_stream').removeClass('highlighted_stream');
    if (exports.searching()) {
        var all_streams = $('#stream_filters li.narrow-filter');
        exports.highlight_first(all_streams, 'highlighted_stream');
    }

    if (! narrow_state.active()) {
        return;
    }

    var filter = narrow_state.filter();

    exports.update_stream_sidebar_for_narrow(filter);
};

exports.update_dom_with_unread_counts = function (counts) {
    // counts.stream_count maps streams to counts
    counts.stream_count.each(function (count, stream_id) {
        set_stream_unread_count(stream_id, count);
    });

    // counts.topic_count maps streams to hashes of topics to counts
    counts.topic_count.each(function (subject_hash, stream_id) {
        subject_hash.each(function (count, subject) {
            topic_list.set_count(stream_id, subject, count);
        });
    });
};

exports.rename_stream = function (sub) {
    // The sub object is expected to already have the updated name
    build_stream_sidebar_row(sub);
    exports.update_streams_sidebar(); // big hammer
};

exports.refresh_pinned_or_unpinned_stream = function (sub) {
    // Pinned/unpinned streams require re-ordering.
    // We use kind of brute force now, which is probably fine.
    build_stream_sidebar_row(sub);
    exports.update_streams_sidebar();

    // Only scroll pinned topics into view.  If we're unpinning
    // a topic, we may be literally trying to get it out of
    // our sight.
    if (sub.pin_to_top) {
        var stream_li = exports.get_stream_li(sub.stream_id);
        if (!stream_li) {
            blueslip.error('passed in bad stream id ' + sub.stream_id);
            return;
        }
        exports.scroll_stream_into_view(stream_li);
    }
};

function clear_topics() {
    topic_list.close();
    exports.show_all_streams();
}

exports.get_sidebar_stream_topic_info  = function (filter) {
    var result = {
        stream_id: undefined,
        topic_selected: false,
    };

    var op_stream = filter.operands('stream');
    if (op_stream.length === 0) {
        return result;
    }

    var stream_name = op_stream[0];
    var stream_id = stream_data.get_stream_id(stream_name);

    if (!stream_id) {
        return result;
    }

    if (!stream_data.id_is_subscribed(stream_id)) {
        return result;
    }

    result.stream_id = stream_id;

    var op_subject = filter.operands('topic');
    result.topic_selected = (op_subject.length === 1);

    return result;
};

function deselect_stream_items() {
    $("ul#stream_filters li").removeClass('active-filter active-sub-filter');
}

exports.update_stream_sidebar_for_narrow = function (filter) {
    var info = exports.get_sidebar_stream_topic_info(filter);

    deselect_stream_items();

    var stream_id = info.stream_id;

    if (!stream_id) {
        clear_topics();
        return;
    }

    var stream_li = exports.get_stream_li(stream_id);

    if (!stream_li) {
        // It should be the case then when we have a subscribed
        // stream, there will always be a stream list item
        // corresponding to that stream in our sidebar.  We have
        // evidence that this assumption breaks down for some users,
        // but we are not clear why it happens.
        blueslip.error('No stream_li for subscribed stream ' + stream_id);
        clear_topics();
        return;
    }

    if (!info.topic_selected) {
        stream_li.addClass('active-filter');
    }

    if (stream_id !== topic_list.active_stream_id()) {
        clear_topics();
    }

    topic_list.rebuild(stream_li, stream_id);

    return stream_li;
};

exports.handle_narrow_activated = function (filter) {
    var stream_li = exports.update_stream_sidebar_for_narrow(filter);
    if (stream_li) {
        exports.scroll_stream_into_view(stream_li);
    }
    // Update scrollbar size.
    ui.update_scrollbar($("#stream-filters-container"));
};

exports.handle_narrow_deactivated = function () {
    deselect_stream_items();
    clear_topics();
};

function focus_stream_filter(e) {
    if ($('#stream_filters li.narrow-filter.highlighted_stream').length === 0) {
        // Highlight
        var all_streams = $('#stream_filters li.narrow-filter');
        exports.highlight_first(all_streams, 'highlighted_stream');
    }
    e.stopPropagation();
}

function focusout_stream_filter() {
    // Undo highlighting
    $('#stream_filters li.narrow-filter.highlighted_stream').removeClass('highlighted_stream');
}

function keydown_enter_key() {
    // Is there at least one stream?
    if ($('#stream_filters li.narrow-filter').length > 0) {
        var selected_stream_id = $('#stream_filters li.narrow-filter.highlighted_stream')
                                    .expectOne().data('stream-id');

        var top_stream = stream_data.get_sub_by_id(selected_stream_id);

        if (overlays.is_active()) {
            ui_util.change_tab_to('#home');
        }
        exports.clear_and_hide_search();
        narrow.by('stream', top_stream.name,
                  {select_first_unread: true, trigger: 'sidebar enter key'});
    }
}

function keydown_stream_filter(e) {
    exports.keydown_filter(e, '#stream_filters li.narrow-filter',
     $('#stream-filters-container'), 'highlighted_stream', keydown_enter_key);
}

function actually_update_streams_for_search() {
    exports.update_streams_sidebar();
    resize.resize_page_components();
}

var update_streams_for_search = _.throttle(actually_update_streams_for_search, 50);

exports.initialize = function () {
    // TODO, Eventually topic_list won't be a big singleton,
    // and we can create more component-based click handlers for
    // each stream.
    topic_list.set_click_handlers({
        zoom_in: zoom_in,
        zoom_out: zoom_out,
    });

    $(document).on('subscription_add_done.zulip', function (event) {
        exports.create_sidebar_row(event.sub);
        exports.build_stream_list();
    });

    $(document).on('subscription_remove_done.zulip', function (event) {
        exports.remove_sidebar_row(event.sub.stream_id);
    });


    $('#stream_filters').on('click', 'li .subscription_block', function (e) {
        if (e.metaKey || e.ctrlKey) {
            return;
        }
        if (overlays.is_active()) {
            ui_util.change_tab_to('#home');
        }
        var stream_id = $(e.target).parents('li').attr('data-stream-id');
        var sub = stream_data.get_sub_by_id(stream_id);
        popovers.hide_all();
        narrow.by('stream', sub.name, {select_first_unread: true, trigger: 'sidebar'});

        exports.clear_and_hide_search();

        e.preventDefault();
        e.stopPropagation();
    });

    $(".stream-list-filter").expectOne()
        .on('click', focus_stream_filter)
        .on('focusout', focusout_stream_filter)
        .on('input', update_streams_for_search)
        .on('keydown', keydown_stream_filter);
    $('#clear_search_stream_button').on('click', exports.clear_search);

    $("#streams_header").expectOne().click(function (e) {
        exports.toggle_filter_displayed(e);
    });
};

exports.searching = function () {
    return $('.stream-list-filter').expectOne().is(':focus');
};

exports.escape_search = function () {
    var filter = $('.stream-list-filter').expectOne();
    if (filter.val() === '') {
        exports.clear_and_hide_search();
        return;
    }
    filter.val('');
    update_streams_for_search();
};

exports.clear_search = function () {
    var filter = $('.stream-list-filter').expectOne();
    if (filter.val() === '') {
        exports.clear_and_hide_search();
        return;
    }
    filter.val('');
    filter.blur();
    update_streams_for_search();
};

exports.initiate_search = function () {
    var filter = $('.stream-list-filter').expectOne();
    filter.parent().removeClass('notdisplayed');
    if (!$(".app-main .column-left").hasClass("expanded")) {
        popovers.hide_all();
        stream_popover.show_streamlist_sidebar();
    }
    filter.focus();

    // Highlight first result
    var all_streams = $('#stream_filters li.narrow-filter');
    exports.highlight_first(all_streams, 'highlighted_stream');
};

exports.clear_and_hide_search = function () {
    var filter = $('.stream-list-filter');
    if (filter.val() !== '') {
        filter.val('');
        update_streams_for_search();
    }
    filter.blur();
    filter.parent().addClass('notdisplayed');
};

function next_sibing_in_dir(elm, dir_up) {
    if (dir_up) {
        return elm.prev();
    }
    return elm.next();
}

function keydown_arrow_key(dir_up, all_streams_selector,
                           scroll_container, highlighting_class) {
    // Are there streams to cyle through?
    if ($(all_streams_selector).length > 0) {
        var current_sel = $(all_streams_selector + '.' + highlighting_class).expectOne();
        var next_sibling = next_sibing_in_dir(current_sel, dir_up);

        if (highlighting_class === 'highlighted_stream'
            && next_sibling.is('hr.stream-split')) {
            // Only for the left sidebar
            // Skip separator
            next_sibling = next_sibing_in_dir(next_sibling, dir_up);
        }

        if (!next_sibling.is('li.narrow-filter')) {
            // At the every bottom or top
            var all_streams = $(all_streams_selector);
            if (dir_up) {
                // top -> start at the bottom
                next_sibling = all_streams.last();
            } else {
                // bottom -> start at the top
                next_sibling = all_streams.first();
            }
        }

        // Classes must be explicitly named
        if (highlighting_class === 'highlighted_stream') {
            current_sel.removeClass('highlighted_stream');
            next_sibling.addClass('highlighted_stream');
        } else if (highlighting_class === 'highlighted_user') {
            current_sel.removeClass('highlighted_user');
            next_sibling.addClass('highlighted_user');
        }

        exports.scroll_element_into_container(next_sibling, scroll_container);
    }
}

exports.keydown_filter = function (e, all_streams_selector, scroll_container,
                                   highlighting_class, enter_press_function) {
    // Function for left and right sidebar
    // Could be placed somewhere else but ui.js is already very full

    // Catch <enter> and <up-arrow>, <down-arrow> key presses
    var handled = false;

    switch (e.keyCode) {
        case 13: {
            // Enter key was pressed
            enter_press_function();
            handled = true;
            break;
        }
        case 38: {
            // Up-arrow key was pressed
            keydown_arrow_key(true, all_streams_selector,
                              scroll_container, highlighting_class);
            handled = true;
            break;
        }
        case 40: {
            // Down-arrow key was pressed
            keydown_arrow_key(false, all_streams_selector,
                              scroll_container, highlighting_class);
            handled = true;
            break;
        }
    }

    if (handled) {
        // Since we already handled the key event above, suppress the browser handling it.
        // We don't want the cursor to move when <arrow-up/down> is pressed.
        // In the <enter> case:
        // Prevent a newline from being entered into the soon-to-be-opened composebox
        e.preventDefault();
        e.stopPropagation();
    }
};

exports.highlight_first = function (all_streams, highlighting_class) {
    if (all_streams.length > 0) {
        // Classes must be explicitly named
        if (highlighting_class === 'highlighted_stream') {
            all_streams.first().addClass('highlighted_stream');
        } else if (highlighting_class === 'highlighted_user') {
            all_streams.first().addClass('highlighted_user');
        }
    }
};

exports.toggle_filter_displayed = function (e) {
    if (e.target.id === 'streams_inline_cog') {
        return;
    }
    if ($('#stream-filters-container .input-append.notdisplayed').length === 0) {
        exports.clear_and_hide_search();
    } else {
        exports.initiate_search();
    }
    e.preventDefault();
};

exports.scroll_stream_into_view = function (stream_li) {
    var container = $('#stream-filters-container');

    if (stream_li.length !== 1) {
        blueslip.error('Invalid stream_li was passed in');
        return;
    }

    exports.scroll_element_into_container(stream_li, container);
};

exports.scroll_delta = function (opts) {
    var elem_top = opts.elem_top;
    var container_height = opts.container_height;
    var elem_bottom = opts.elem_bottom;

    var delta = 0;

    if (elem_top < 0) {
        delta = Math.max(
            elem_top,
            elem_bottom - container_height
        );
        delta = Math.min(0, delta);
    } else {
        if (elem_bottom > container_height) {
            delta = Math.min(
                elem_top,
                elem_bottom - container_height
            );
            delta = Math.max(0, delta);
        }
    }

    return delta;
};

exports.scroll_element_into_container = function (elem, container) {
    // This is a generic function to make elem visible in
    // container by scrolling container appropriately.  We may want to
    // eventually move this into another module, but I couldn't find
    // an ideal landing space for this.  I considered a few modules, but
    // some are already kind of bloated (ui.js), some may be deprecated
    // (scroll_bar.js), and some just aren't exact fits (resize.js).
    //
    // This does the minimum amount of scrolling that is needed to make
    // the element visible.  It doesn't try to center the element, so
    // this will be non-intrusive to users when they already have
    // the element visible.

    var elem_top = elem.position().top;
    var elem_bottom = elem_top + elem.height();

    var opts = {
        elem_top: elem_top,
        elem_bottom: elem_bottom,
        container_height: container.height(),
    };

    var delta = exports.scroll_delta(opts);

    if (delta === 0) {
        return;
    }

    container.scrollTop(container.scrollTop() + delta);
};

return exports;
}());
if (typeof module !== 'undefined') {
    module.exports = stream_list;
}