utils.lua

local api = vim.api

local function nvim_loaded_buffers()
    local result = {}
    local buffers = api.nvim_list_bufs()
    for _, buf in ipairs(buffers) do
        if api.nvim_buf_is_loaded(buf) then
            table.insert(result, buf)
        end
    end
    return result
end

-- Kill the target buffer (or the current one if 0/nil)
function buf_kill(target_buf, should_force)
    if not should_force and vim.bo.modified then
        return api.nvim_err_writeln('Buffer is modified. Force required.')
    end
    local command = 'bd'
    if should_force then command = command .. '!' end
    if target_buf == 0 or target_buf == nil then
        target_buf = api.nvim_get_current_buf()
    end
    local buffers = nvim_loaded_buffers()
    if #buffers == 1 then
        api.nvim_command(command)
        return
    end
    api.nvim_command("BufferLineCycleNext")
    api.nvim_command(table.concat({ command, target_buf }, ' '))
end