Deepcopy environment

--- Deep copy function, we need to make a bit custom so we can handle loops.
---@param t table The table to deep copy.
---@param lookup table? Initializes the lookup table to something else.
---@return table clone The clone of the table.
---@return table lookup The lookup table built from deep copying the environment.
local function deep_copy(t, lookup)
  lookup = lookup or {}

  -- If the value we are copying is not a table, we can just return it.
  if type(t) ~= "table" then
    return t, lookup
  end

  -- If we have already copied this table, we can just return the copy we have
  -- already made.
  if lookup[t] then
    return lookup[t], lookup
  end

  -- Create a new table to copy into.
  local copy = {}

  -- Add the copy to the lookup table so we can handle loops.
  lookup[t] = copy

  -- Copy the table.
  for k, v in pairs(t) do
    copy[deep_copy(k, lookup)] = deep_copy(v, lookup)
  end

  return copy, lookup
end

--- Copy the environment
---@param env table The environment to copy.
---@param g table The global environment to copy.
---@return table clone_env The clone of the environment.
---@return table clone_g The clone of the global environment, probably not needed as it will be the clone_env._G, but it's here for consistency.
local function deepcopy_environment(env, g)
  -- We need to copy the environment and the global environment separately.
  -- We keep the lookup table between clones so we can handle loops.
  local clone_env, lookup = deep_copy(env)
  local clone_g = deep_copy(g, lookup)

  return setmetatable(clone_env, {__index = clone_g}), clone_g
end

local cloned_env = deepcopy_environment(_ENV, _G)