my-nvim-setup/lua/core/hooks.lua

local hooks, overrides, M = {}, {}, {};
local allowed_hooks = {
  "install_plugins",
  "setup_mappings",
  "ready",
}

local function has_value (tab, val)
  for _, value in ipairs(tab) do
    if value == val then
      return true
    end
  end

  return false
end

M.add = function(name, fn)
  if not(has_value(allowed_hooks, name)) then
    error("Custom lua uses unallowed hook " .. name)
  end
  if hooks[name] == nil then
    hooks[name] = {}
  end
  table.insert(hooks[name], fn);
end

M.run = function(name, args)
  if hooks[name] == nil then
    return;
  end

  for _, hook in pairs(hooks[name]) do
    hook(args)
  end
end

M.createOverrides = function(module)
  local O = {};

  O.get = function(name, default)
    local current = default;
    if overrides[module] and overrides[module][name] then
      if type(overrides[module][name]) == "function" then
         current = overrides[module][name]
      elseif type(overrides[module][name]) == "table" then
         for _, override in pairs(overrides[module][name]) do
           current = override(current)
         end
      end
    end
    return current;
  end

  return O;
end

M.override = function(module, name, overwrite)
  if overrides[module] == nil then
    overrides[module] = {};
  end
  if overrides[module][name] == nil then
    overrides[module][name] = {};
  end
  table.insert(overrides[module][name], overwrite)
end


return M;