vim.bo.commentstring = "// %s"

local insert_include_guards = function(bufnr)
  bufnr = bufnr or 0

  -- foo.h -> FOO_H_
  local guard = string.gsub(string.upper(vim.fn.expand("%:t")), "%.", "_") .. "_"

  vim.api.nvim_buf_set_lines(bufnr, 0, 0, true, {
    string.format("#ifndef %s", guard),
    string.format("#define %s", guard),
    "",
  })

  local last_lineno = vim.api.nvim_buf_line_count(bufnr)
  vim.api.nvim_buf_set_lines(bufnr, last_lineno, last_lineno, true, {
    "",
    string.format("#endif  // %s", guard),
  })
end

vim.keymap.set(
  "n",
  "<localleader>ig",
  insert_include_guards,
  { desc = "Add include guards", buffer = true, silent = true }
)