Merge pull request #13 from PagoPlus/feat/display-decimal-amount

fermuch · web-flow · commit d1d1bfab30c3 · 2025-02-27T16:08:04.000-03:00
[FEAT] Displays decimal amount
diff --git a/README.md b/README.md
@@ -152,8 +152,9 @@ Where result will be something like this:
 ```elixir
 iex> %{
 ...>   postings: [
-  ...>           %Numscriptex.Posting{
+...>           %Numscriptex.Posting{
 ...>             amount: 100,
+...>             decimal_amount: 1.0,
 ...>             asset: "USD/2",
 ...>             destination: "bar",
 ...>             source: "foo"
@@ -164,19 +165,25 @@ iex> %{
 ...>             account: "foo",
 ...>             asset: "EUR/2",
 ...>             final_balance: 300,
-...>             initial_balance: 300
+...>             initial_balance: 300,
+...>             decimal_final_balance: 3.0,
+...>             decimal_initial_balance: 3.0,
 ...>           },
 ...>           %Numscriptex.Balance{
 ...>             account: "foo",
 ...>             asset: "USD/2",
 ...>             final_balance: 400,
-...>             initial_balance: 500
+...>             initial_balance: 500,
+...>             decimal_final_balance: 4.0,
+...>             decimal_initial_balance: 5.0,
 ...>           },
 ...>           %Numscriptex.Balance{
 ...>             account: "bar",
 ...>             asset: "USD/2",
 ...>             final_balance: 100,
-...>             initial_balance: 0
+...>             initial_balance: 0,
+...>             decimal_final_balance: 1.0,
+...>             decimal_initial_balance: 0.0,
 ...>           }
 ...>         ],
 ...>   accountMeta: %{}
diff --git a/lib/numscriptex/balance.ex b/lib/numscriptex/balance.ex
@@ -5,26 +5,34 @@ defmodule Numscriptex.Balance do
   can see the results of all transactions.
   """
 
+  alias Numscriptex.Utilities
+
   @derive JSON.Encoder
   defstruct account: nil,
             asset: nil,
             final_balance: nil,
-            initial_balance: nil
+            decimal_final_balance: nil,
+            initial_balance: nil,
+            decimal_initial_balance: nil
 
   @typedoc """
   Type that represents `Numscriptex.Balance` struct.
 
   ## Fields
   * `:account` the account name
   * `:asset` the asset were the transaction was made
-  * `:final_balance` balance after the transactions
-  * `:initial_balance` balance before the transactions
+  * `:final_balance` balance after the transactions (integer)
+  * `:decimal_final_balance` balance after the transactions, but as float
+  * `:initial_balance` balance before the transactions (integer)
+  * `:decimal_initial_balance` balance after the transactions, but as float
   """
   @type t() :: %__MODULE__{
           account: bitstring(),
           asset: bitstring(),
-          final_balance: non_neg_integer(),
-          initial_balance: non_neg_integer()
+          final_balance: integer(),
+          decimal_final_balance: float(),
+          initial_balance: integer(),
+          decimal_initial_balance: float()
         }
 
   @doc """
@@ -57,19 +65,25 @@ defmodule Numscriptex.Balance do
       account: "foo",
       asset: "EUR/2",
       final_balance: 300,
-      initial_balance: 300
+      decimal_final_balance: 3.0,
+      initial_balance: 300,
+      decimal_initial_balance: 3.0
     },
     %Numscriptex.Balance{
       account: "foo",
       asset: "USD/2",
       final_balance: 400,
-      initial_balance: 500
+      decimal_final_balance: 4.0,
+      initial_balance: 500,
+      decimal_initial_balance: 5.0
     },
     %Numscriptex.Balance{
       account: "bar",
       asset: "USD/2",
       final_balance: 100,
-      initial_balance: 0
+      decimal_final_balance: 1.0,
+      initial_balance: 0,
+      decimal_initial_balance: 0.0
     }
   ]
   ```
@@ -82,9 +96,8 @@ defmodule Numscriptex.Balance do
     |> handle_initial_balance(account_assets)
     |> handle_final_balance(postings)
     |> maybe_drop_balance()
-    |> then(fn balances ->
-      Enum.map(balances, &struct(__MODULE__, &1))
-    end)
+    |> put_decimal_values()
+    |> Enum.map(&struct(__MODULE__, &1))
   end
 
   defp build_balances(account_assets, postings) do
@@ -100,8 +113,10 @@ defmodule Numscriptex.Balance do
         %{
           account: account,
           asset: asset,
+          final_balance: 0,
+          decimal_final_balance: 0,
           initial_balance: 0,
-          final_balance: 0
+          decimal_initial_balance: 0
         }
       end)
     end)
@@ -113,14 +128,18 @@ defmodule Numscriptex.Balance do
         %{
           account: posting["source"],
           asset: posting["asset"],
+          final_balance: 0,
+          decimal_final_balance: 0,
           initial_balance: 0,
-          final_balance: 0
+          decimal_initial_balance: 0
         },
         %{
           account: posting["destination"],
           asset: posting["asset"],
+          final_balance: 0,
+          decimal_final_balance: 0,
           initial_balance: 0,
-          final_balance: 0
+          decimal_initial_balance: 0
         }
       ]
     end)
@@ -177,4 +196,19 @@ defmodule Numscriptex.Balance do
       balance.initial_balance == 0 and balance.final_balance == 0
     end)
   end
+
+  defp put_decimal_values(balances) do
+    Enum.map(balances, fn
+      %{initial_balance: initial_balance, final_balance: final_balance} = balance ->
+        decimal_places = Utilities.decimal_places_from_asset(balance.asset)
+        decimal_initial_balance = Utilities.integer_to_decimal(initial_balance, decimal_places)
+        decimal_final_balance = Utilities.integer_to_decimal(final_balance, decimal_places)
+
+        %{
+          balance
+          | decimal_initial_balance: decimal_initial_balance,
+            decimal_final_balance: decimal_final_balance
+        }
+    end)
+  end
 end
diff --git a/lib/numscriptex/posting.ex b/lib/numscriptex/posting.ex
@@ -3,8 +3,11 @@ defmodule Numscriptex.Posting do
   `Numscriptex.Postings` represents a financial transaction made with [Numscript](https://docs.formance.com/numscript/)
   """
 
+  alias Numscriptex.Utilities
+
   @derive JSON.Encoder
   defstruct amount: nil,
+            decimal_amount: nil,
             asset: nil,
             destination: nil,
             source: nil
@@ -17,21 +20,37 @@ defmodule Numscriptex.Posting do
   * `:asset` the asset were the transaction was made
   * `:destination` account whose the money will go to
   * `:amount` amount of money transferred (integer)
+  * `:decimal_amount` amount of money transferred, but as float
   """
   @type t() :: %__MODULE__{
           amount: pos_integer(),
+          decimal_amount: float(),
           asset: bitstring(),
           destination: bitstring(),
           source: bitstring()
         }
 
-  @spec from_list(map()) :: list(__MODULE__.t())
+  @spec from_list(list(map())) :: list(__MODULE__.t())
   def from_list(postings) do
     Enum.map(postings, &from_map/1)
   end
 
-  @spec from_list(map()) :: __MODULE__.t()
-  def from_map(map) do
-    struct(%__MODULE__{}, map)
+  @spec from_map(map()) :: __MODULE__.t()
+  def from_map(posting) do
+    put_decimal_amount(posting)
+  end
+
+  defp put_decimal_amount(posting) when not is_struct(posting) do
+    posting
+    |> Map.put(:decimal_amount, 0)
+    |> then(fn elem -> struct(%__MODULE__{}, elem) end)
+    |> put_decimal_amount()
+  end
+
+  defp put_decimal_amount(posting) do
+    decimal_places = Utilities.decimal_places_from_asset(posting.asset)
+    decimal_amount = Utilities.integer_to_decimal(posting.amount, decimal_places)
+
+    %{posting | decimal_amount: decimal_amount}
   end
 end
diff --git a/lib/numscriptex/utilities.ex b/lib/numscriptex/utilities.ex
@@ -43,4 +43,64 @@ defmodule Numscriptex.Utilities do
 
   defp keys_to_atom({key, value}),
     do: {String.to_existing_atom(key), value}
+
+  @doc """
+  Converts an integer value to float
+
+  ```elixir
+  iex> Utilities.integer_to_decimal(1000, 2)
+  10.0
+
+  iex> Utilities.integer_to_decimal(1000, 3)
+  1.0
+
+  iex> Utilities.integer_to_decimal(1000, 4)
+  0.1
+
+  iex> Utilities.integer_to_decimal(1000, 5)
+  0.01
+  ```
+  """
+  @spec integer_to_decimal(pos_integer(), pos_integer() | nil) :: float()
+  def integer_to_decimal(amount, decimal_places \\ 2)
+
+  def integer_to_decimal(amount, nil), do: integer_to_decimal(amount)
+
+  def integer_to_decimal(amount, decimal_places) do
+    divisor =
+      10
+      |> Integer.pow(decimal_places)
+      |> trunc()
+
+    amount / divisor
+  end
+
+  @doc """
+  Gets the decimal places from an asset if has any (e.g. decimal places for "USD/2" would be 2).
+  You can choose a default value (the second argument), but if you don't choose any the default will be 2.
+
+  ```elixir
+  iex> Utilities.decimal_places_from_asset("USD/2")
+  2
+
+  iex> Utilities.decimal_places_from_asset("USD/4")
+  4
+
+  iex> Utilities.decimal_places_from_asset("USD")
+  2
+
+  iex> Utilities.decimal_places_from_asset("USD", 3)
+  3
+  ```
+  """
+  @spec decimal_places_from_asset(bitstring(), pos_integer()) :: pos_integer()
+  def decimal_places_from_asset(asset, default \\ 2) do
+    if String.length(asset) >= 5 do
+      asset
+      |> String.last()
+      |> String.to_integer()
+    else
+      default
+    end
+  end
 end
diff --git a/test/numscriptex/balance_test.exs b/test/numscriptex/balance_test.exs
@@ -38,19 +38,25 @@ defmodule Numscriptex.BalanceTest do
           account: "bar",
           asset: "USD/2",
           final_balance: 50,
-          initial_balance: 0
+          decimal_final_balance: 0.5,
+          initial_balance: 0,
+          decimal_initial_balance: 0.0
         },
         %Numscriptex.Balance{
           account: "baz",
           asset: "USD/2",
           final_balance: 49,
-          initial_balance: 0
+          decimal_final_balance: 0.49,
+          initial_balance: 0,
+          decimal_initial_balance: 0.0
         },
         %Numscriptex.Balance{
           account: "foo",
           asset: "USD/2",
           final_balance: 1,
-          initial_balance: 100
+          initial_balance: 100,
+          decimal_final_balance: 0.01,
+          decimal_initial_balance: 1.0
         }
       ]
 
diff --git a/test/numscriptex/posting_tests.exs b/test/numscriptex/posting_tests.exs
@@ -6,7 +6,7 @@ defmodule Numscriptex.PostingTest do
   doctest Numscriptex.Posting
 
   describe "from_map/1" do
-    setup_all do
+    setup do
       postings = [
         %{
           amount: 100,
@@ -18,7 +18,7 @@ defmodule Numscriptex.PostingTest do
           amount: 100,
           asset: "USD/2",
           destination: "baz",
-          source: "foo"
+          source: "bar"
         }
       ]
 
@@ -31,12 +31,14 @@ defmodule Numscriptex.PostingTest do
       assert postings == [
                %Numscriptex.Posting{
                  amount: 100,
+                 decimal_amount: 1.0,
                  asset: "USD/2",
                  destination: "bar",
                  source: "foo"
                },
                %Numscriptex.Posting{
                  amount: 100,
+                 decimal_amount: 1.0,
                  asset: "USD/2",
                  destination: "baz",
                  source: "bar"
@@ -49,6 +51,7 @@ defmodule Numscriptex.PostingTest do
 
       assert posting == %Numscriptex.Posting{
                amount: 100,
+               decimal_amount: 1.0,
                asset: "USD/2",
                destination: "bar",
                source: "foo"
diff --git a/test/numscriptex_test.exs b/test/numscriptex_test.exs
