rugyoga

  @spec delta_simple(path(), term(), term()) :: [delta()]
  defp delta_simple(_path, a, b) when a == b, do: []

  defp delta_simple(path, a, b) do
    cond do
      empty?(a) -> [{path, {:add, b}}]
      empty?(b) -> [{path, {:delete, a}}]
      true -> [{path, {:update, a, b}}]
    end
  end

rugyoga

  @empty [false, "", nil, [], 0, 0.0]

  @spec empty?(any()) :: boolean()
  def empty?(value) when value in @empty, do: true
  def empty?(value) when is_list(value), do: Enum.all?(value, &empty?/1)
  def empty?(value) when is_tuple(value), do: value |> Tuple.to_list() |> empty?()
  def empty?(value) when is_struct(value), do: value |> Map.from_struct() |> empty?()
  def empty?(value) when is_map(value), do: value |> Map.values() |> empty?()
  def empty?(_), do: false

rugyoga

  @key :__audit_trail__
  @enabled? Application.compile_env(:audit, :enabled?, false)

  @type file_t :: binary()
  @type line_t :: non_neg_integer()
  @type trail_t :: {struct(), file_t(), line_t()}
  @type change_t :: {struct(), trail_t()}

rugyoga

@spec audit_fun(struct(), Macro.Env.t()) :: struct()
def audit_fun(r, e) do
  r |> struct([{@key, payload(r, e)}])
end

@spec payload(struct(), Macro.Env) :: trail_t()
def payload(r, e), do: {r, e.file, e.line}

rugyoga

defmacro audit(record) do
  quote generated: true do
    unquote(__MODULE__).audit_fun(unquote(record), __ENV__)
  end
end

rugyoga

  @spec changelist(term) :: [change_t()]
  defp changelist(r = %_{__audit_trail__: audit_trail}) do
    if audit_trail, do: [{r, audit_trail} | changelist(record(audit_trail))], else: []
  end

  defp changelist(_), do: []

rugyoga

def to_string(r) do
  r
  |> changelist()
  |> Enum.map_join("\n=====\n", &stringify_change/1)
end
  
@spec changelist(term) :: [change_t()]
defp changelist(r = %_{__audit_trail__: audit_trail}) do
  if audit_trail, do: [{r, audit_trail} | changelist(record(audit_trail))], else: []
end

rugyoga

defmodule Audit.FileCache do
  @moduledoc """
  Simple File cache Agent
  """
  use Agent

  def start_link(_args) do
    Agent.start_link(fn -> %{} end, name: __MODULE__)
  end

rugyoga

defmodule Audit.Github do
  @moduledoc """
  Helper functions for generating Github URLs from filename and line number
  """

  @type line_number_t :: binary | non_neg_integer()
  @type filename_t :: binary()
  @type git_t :: binary() | nil

  @spec git([binary()]) :: git_t()

rugyoga

iex> nil |> Tree.add(2) |> Tree.add(1) |> Tree.add(3) |> Audit.to_string() |> IO.puts
github url: https://github.com/rugyoga/tree_ex/tree/main/lib/tree.ex#L15
local path: lib/tree.ex:15
code: item > i -> %Tree{audit(tree) | right: add(r, item)}
diff: [{[:right], {:add, %Tree{item: 3, left: nil, right: nil}}}]
=====
github url: https://github.com/rugyoga/tree_ex/tree/main/lib/tree.ex#L14
local path: lib/tree.ex:14
code: item < i -> %Tree{audit(tree) | left: add(l, item)}
diff: [{[:left], {:add, %Tree{item: 1, left: nil, right: nil}}}]