finished withdraw, create transiction

lib/rocketpay.ex

@@ -1,9 +1,11 @@
 defmodule Rocketpay do
   alias Rocketpay.Users.Create, as: UserCreate
 
-  alias Rocketpay.Accouns.Deposit
+  alias Rocketpay.Accounts.{Deposit, Withdraw}
 
   defdelegate create_user(params), to: UserCreate, as: :call
 
   defdelegate deposit(params), to: Deposit, as: :call
+  defdelegate withdraw(params), to: Withdraw, as: :call
+
 end

lib/rocketpay/account.ex

@@ -15,8 +15,8 @@ defmodule Rocketpay.Account do
     timestamps()
   end
 
-  def changeset(params) do
-    %__MODULE__{}
+  def changeset(struct \\ %__MODULE__{}, params) do
+    struct
       |> cast(params, @required_params)
       |> validate_required(@required_params)
       |> check_constraint(:balance, name: :balance_must_be_positive_or_zero)

lib/rocketpay/accounts/deposit.ex

@@ -1,45 +1,17 @@
 defmodule Rocketpay.Accounts.Deposit do
-  alias Ecto.Multi
+  alias Rocketpay.Accounts.Operation
+  alias Rocketpay.Repo
 
-  alias Rocketpay.{Account, Repo}
-
-  def call(%{"id" => id, "value" => value}) do
-    Multi.new()
-      |> Multi.run(:account, fn repo, _changes -> get_account(repo, id) end)
-      |> Multi.run(:update_balance, fn repo, %{account: account} ->
-        update_balance(repo, account, value)
-      end)
+  def call(params) do
+    params
+      |> Operation.call(:deposit)
+      |> run_transaction()
   end
 
-  defp get_account(repo, id) do
-    case repo.get(Account, id) do
-      nil -> {:error, "Account, not found!"}
-      account -> {:ok,  account}
+  defp run_transaction(multi) do
+    case Repo.transaction(multi) do
+      {:error, _opration, reason, _changes} -> {:error, reason}
+      {:ok, %{update_balance: account}} -> {:ok, account}
     end
   end
-
-  defp update_balance(repo, account, value) do
-    account
-      |> sum_values(value)
-      |> update_account(repo)
-  end
-
-  defp sum_values(%Account{balance: balance}, value) do
-    value
-      |>Decimal.cast()
-      |> handle_cast(balance)
-  end
-
-  defp handle_cast({:ok, value}, balance), do: Decimal.add(value, balance)
-  defp handle_cast(:error, _balanace), do: {:error, "Invalid deposit value!"}
-
-  defp update_account({:error, _reason} = error, _repo), do: error
-
-  defp update_account(value, repo) do
-    params = %{balance: value}
-
-    params
-      |> Account.changeset()
-      |>  repo.update()
-  end
 end

lib/rocketpay/accounts/operation.ex

@@ -0,0 +1,54 @@
+defmodule Rocketpay.Accounts.Operation do
+  alias Ecto.Multi
+
+  alias Rocketpay.{Account, Repo}
+
+  def call(%{"id" => id, "value" => value}, operation) do
+    operation_name = account_operation_name(operation)
+
+    Multi.new()
+      |> Multi.run(operation_name, fn repo, _changes -> get_account(repo, id) end)
+      |> Multi.run(:update_balance, fn repo, changes ->
+        account = Map.get(changes, operation_name)
+        update_balance(repo, account, value, operation)
+      end)
+  end
+
+  defp get_account(repo, id) do
+    case repo.get(Account, id) do
+      nil -> {:error, "Account not found!"}
+      account -> {:ok,  account}
+    end
+  end
+
+  defp update_balance(repo, account, value, operation) do
+    account
+      |> operation(value, operation)
+      |> update_account(repo, account)
+  end
+
+  defp operation(%Account{balance: balance}, value, operation) do
+    value
+      |>Decimal.cast()
+      |> handle_cast(balance, operation)
+  end
+
+  defp handle_cast({:ok, value}, balance, :deposit), do: Decimal.add(balance, value)
+  defp handle_cast({:ok, value}, balance, :withdraw), do: Decimal.sub(balance, value)
+  defp handle_cast(:error, _balanace, operation), do: {:error, "Invalid #{operation} value!"}
+
+  defp update_account({:error, _reason} = error, _repo, _account), do: error
+
+  defp update_account(value, repo, account) do
+    params = %{balance: value}
+
+    account
+      |> Account.changeset(params)
+      |>  repo.update()
+  end
+
+  defp account_operation_name(operation) do
+    "account_#{Atom.to_string(operation)}"
+      |> String.to_atom()
+  end
+end

lib/rocketpay/accounts/transaction.ex

@@ -0,0 +1,26 @@
+defmodule Rocketpay.Accounts.Transaction do
+  alias Ecto.Multi
+  alias Rocketpay.Repo
+  alias Rocketpay.Accounts.Operation
+
+  def call(%{"from" => from_id, "to" => to_id, "value" => value}) do
+    withdraw_params = build_params(from_id, value)
+    deposit_params = build_params(to_id, value)
+
+    Multi.new()
+      |> Multi.merge(fn _changes -> Operation.call(withdraw_params, :withdraw) end)
+      |> Multi.merge(fn _changes -> Operation.call(deposit_params, :deposit) end)
+      |> run_transaction()
+  end
+
+  defp build_params(id, value), do: %{"id" => id, "value" => value}
+
+  defp run_transaction(multi) do
+    case Repo.transaction(multi) do
+      {:error, _opration, reason, _changes} ->
+        {:error, reason}
+      {:ok, %{deposit: to_account, withdraw: from_account}} ->
+        {:ok, %{to_account: to_account, from_account: from_account}}
+    end
+  end
+end

lib/rocketpay/accounts/withdraw.ex

@@ -0,0 +1,17 @@
+defmodule Rocketpay.Accounts.Withdraw do
+  alias Rocketpay.Accounts.Operation
+  alias Rocketpay.Repo
+
+  def call(params) do
+    params
+      |> Operation.call(:withdraw)
+      |> run_transaction()
+  end
+
+  defp run_transaction(multi) do
+    case Repo.transaction(multi) do
+      {:error, _opration, reason, _changes} -> {:error, reason}
+      {:ok, %{update_balance: account}} -> {:ok, account}
+    end
+  end
+end

lib/rocketpay_web/controllers/accounts_controller.ex

@@ -14,6 +14,10 @@ defmodule RocketpayWeb.AccountsController do
   end
 
   def withdraw(conn, params) do
-
+    with {:ok, %Account{} = account} <- Rocketpay.withdraw(params) do
+      conn
+      |> put_status(:ok)
+      |> render("update.json", account: account)
+    end
   end
 end

lib/rocketpay_web/views/accounts_view.ex

@@ -0,0 +1,18 @@
+defmodule RocketpayWeb.AccountsView do
+  alias Rocketpay.Account
+
+  def render("update.json", %{
+        account: %Account{
+          id: account_id,
+          balance: balance
+        }
+      }) do
+    %{
+      message: "Ballance changed successfully",
+      account: %{
+        id: account_id,
+        balance: balance
+      }
+    }
+  end
+end

lib/rocketpay_web/views/error_view.ex

@@ -20,6 +20,10 @@ defmodule RocketpayWeb.ErrorView do
     %{message: translate_errors(changeset)}
   end
 
+  def render("400.json", %{result: message}) do
+    %{message: message}
+  end
+
   defp translate_errors(changeset) do
     traverse_errors(changeset, fn {msg, opts} ->
       Enum.reduce(opts, msg, fn {key, value}, acc ->

mix.exs

@@ -44,7 +44,8 @@ defmodule Rocketpay.MixProject do
       {:jason, "~> 1.0"},
       {:plug_cowboy, "~> 2.0"},
       {:credo, "~> 1.5", only: [:dev, :test], runtime: false},
-      {:bcrypt_elixir, "~> 2.0"}
+      {:bcrypt_elixir, "~> 2.0"},
+      {:decimal, "~> 2.0"}
     ]
   end