/* eslint indent: "off" */

var buddy_list = (function () {
    var self = {};

    self.container_sel = '#user_presences';
    self.item_sel = 'li.user_sidebar_entry';

    self.items_to_html = function (opts) {
        var user_info = opts.items;
        var html = templates.render('user_presence_rows', {users: user_info});
        return html;
    };

    self.item_to_html = function (opts) {
        var html = templates.render('user_presence_row', opts.item);
        return html;
    };

    self.find_li = function (opts) {
        var user_id = opts.key;
        var sel = self.item_sel + "[data-user-id='" + user_id + "']";
        return self.container.find(sel);
    };

    self.get_key_from_li = function (opts) {
        var user_id = opts.li.expectOne().attr('data-user-id');
        return user_id;
    };

    self.get_data_from_keys = function (opts) {
        var keys = opts.keys;
        var data = buddy_data.get_items_for_users(keys);
        return data;
    };

    self.compare_function = buddy_data.compare_function;

    // Try to keep code below this line generic, so that we can
    // extract a widget.

    self.keys = [];

    self.populate = function (opts) {
        // We rely on our caller to give us items
        // in already-sorted order.
        self.keys = _.map(opts.keys, function (k) {
            return k.toString();
        });

        var items = self.get_data_from_keys({
            keys: self.keys,
        });
        var html = self.items_to_html({items: items});
        self.container = $(self.container_sel);
        self.container.html(html);
    };

    self.get_items = function () {
        var obj = self.container.find(self.item_sel);
        return obj.map(function (i, elem) {
            return $(elem);
        });
    };

    self.first_key = function () {
        return self.keys[0];
    };

    self.prev_key = function (key) {
        var i = self.keys.indexOf(key.toString());

        if (i <= 0) {
            return;
        }

        return self.keys[i - 1];
    };

    self.next_key = function (key) {
        var i = self.keys.indexOf(key.toString());

        if (i < 0) {
            return;
        }

        return self.keys[i + 1];
    };

    self.maybe_remove_key = function (opts) {
        var pos = self.keys.indexOf(opts.key);

        if (pos < 0) {
            return;
        }

        self.keys.splice(pos, 1);

        var li = self.find_li({key: opts.key});
        li.remove();
    };

    self.find_position = function (opts) {
        var key = opts.key;
        var i;

        for (i = 0; i < self.keys.length; i += 1) {
            var list_key = self.keys[i];

            if (self.compare_function(key, list_key) < 0) {
                return i;
            }
        }

        return self.keys.length;
    };

    self.insert_new_html = function (opts) {
        var other_key = opts.other_key;
        var html = opts.html;

        if (other_key === undefined) {
            self.container.append(html);
            return;
        }

        var li = self.find_li({key: other_key});
        li.before(html);
    };

    self.insert_or_move = function (opts) {
        var key = opts.key.toString();
        var item = opts.item;

        self.maybe_remove_key({key: key});

        var pos = self.find_position({
            key: key,
        });

        // Order is important here--get the other_key
        // before mutating our list.  An undefined value
        // corresponds to appending.
        var other_key = self.keys[pos];

        self.keys.splice(pos, 0, key);

        var html = self.item_to_html({item: item});
        self.insert_new_html({
            html: html,
            other_key: other_key,
        });
    };

    // This is a bit of a hack to make sure we at least have
    // an empty list to start, before we get the initial payload.
    self.container = $(self.container_sel);

    return self;
}());

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

window.buddy_list = buddy_list;