// We don't need an andSelf() here because we already know
// that our next element is *not* a message_row, so this
// isn't going to end up empty unless we're at the bottom or top.
exports.next_visible = function (message_row) {
    if (message_row === undefined || message_row.length === 0) {
        return $();
    }
    const row = message_row.next('.selectable_row');
    if (row.length !== 0) {
        return row;
    }
    const recipient_row = exports.get_message_recipient_row(message_row);
    const next_recipient_rows = $(recipient_row).nextAll('.recipient_row');
    if (next_recipient_rows.length === 0) {
        return $();
    }
    return $('.selectable_row', next_recipient_rows[0]).first();
};

exports.prev_visible = function (message_row) {
    if (message_row === undefined || message_row.length === 0) {
        return $();
    }
    const row = message_row.prev('.selectable_row');
    if (row.length !== 0) {
        return row;
    }
    const recipient_row = exports.get_message_recipient_row(message_row);
    const prev_recipient_rows = $(recipient_row).prevAll('.recipient_row');
    if (prev_recipient_rows.length === 0) {
        return $();
    }
    return $('.selectable_row', prev_recipient_rows[0]).last();
};

exports.first_visible = function () {
    return $('.focused_table .selectable_row').first();
};

exports.last_visible = function () {
    return $('.focused_table .selectable_row').last();
};

exports.id = function (message_row) {
    /*
        For blueslip errors, don't return early, since
        we may have some code now that actually relies
        on the NaN behavior here.  We can try to clean
        that up in the future, but we mainly just want
        more data now.
    */
    if (message_row.length !== 1) {
        blueslip.error("Caller should pass in a single row.");
    }

    const zid = message_row.attr('zid');

    if (zid === undefined) {
        blueslip.error("Calling code passed rows.id a row with no zid attr.");
    }

    return parseFloat(zid);
};

const valid_table_names = {
    zhome: true,
    zfilt: true,
};

exports.get_table = function (table_name) {
    if (!valid_table_names.hasOwnProperty(table_name)) {
        return $();
    }

    return $('#' + table_name);
};

exports.get_message_id = function (elem) {
    // Gets the message_id for elem, where elem is a DOM
    // element inside a message.  This is typically used
    // in click handlers for things like the reaction button.
    const row = $(elem).closest(".message_row");
    const message_id = exports.id(row);
    return message_id;
};

exports.get_closest_group = function (element) {
    // This gets the closest message row to an element, whether it's
    // a recipient bar or message.  With our current markup,
    // this is the most reliable way to do it.
    return $(element).closest("div.recipient_row");
};

exports.first_message_in_group = function (message_group) {
    return $('div.message_row', message_group).first();
};

exports.get_message_recipient_row = function (message_row) {
    return $(message_row).parent('.recipient_row').expectOne();
};

exports.get_message_recipient_header = function (message_row) {
    return $(message_row).parent('.recipient_row').find('.message_header').expectOne();
};

exports.recipient_from_group = function (message_group) {
    return message_store.get(exports.id($(message_group).children('.message_row').first().expectOne()));
};

exports.id_for_recipient_row = function (recipient_row) {
    // A recipient row can be either a normal recipient row, or
    // the FRB, which is a fake recipient row. If it's a FRB, it has
    // a 'zid' property that stores the message id it is directly over
    const msg_row = exports.first_message_in_group(recipient_row);
    if (msg_row.length === 0) {
        // If we're narrowing from the FRB, take the msg id
        // directly from it
        return exports.id(recipient_row);
    }
    return exports.id(msg_row);
};

window.rows = exports;