-- keymap function which simplifies mapping keys
M.map = function(mode, keys, cmd, opt, bufnr)
  local options = { noremap = true, silent = true }
  if opt then
    options = vim.tbl_extend("force", options, opt)
  end

  -- all valid modes allowed for mappings
  -- :h map-modes
  local valid_modes = {
    [""] = true,
    ["n"] = true,
    ["v"] = true,
    ["s"] = true,
    ["x"] = true,
    ["o"] = true,
    ["!"] = true,
    ["i"] = true,
    ["l"] = true,
    ["c"] = true,
    ["t"] = true,
  }

  -- helper function for M.map
  -- can be given multiple modes and keys
  -- if given a buffer number will set the key specific to that buffer
  local function map_wrapper(mode, lhs, rhs, options, bufnr)
    if type(lhs) == "table" then
      for _, key in ipairs(lhs) do
        map_wrapper(mode, key, rhs, options, bufnr)
      end
    else
      if type(mode) == "table" then
        for _, m in ipairs(mode) do
          map_wrapper(m, lhs, rhs, options, bufnr)
        end
      else
        if valid_modes[mode] and lhs and rhs then
          if bufnr then
            vim.api.nvim_buf_set_keymap(bufnr, mode, lhs, rhs, options)
          else
            vim.api.nvim_set_keymap(mode, lhs, rhs, options)
          end
        else
          mode, lhs, rhs = mode or "", lhs or "", rhs or ""
          print("Cannot set mapping [ mode = '" .. mode .. "' | key = '" .. lhs .. "' | cmd = '" .. rhs .. "' ]")
        end
      end
    end
  end
  map_wrapper(mode, keys, cmd, options, bufnr)
end