Steven Leighton's engineering exercise

elixir/lib/homework/companies.ex

@@ -0,0 +1,121 @@
+defmodule Homework.Companies do
+  @moduledoc """
+  The Companies context.
+  """
+
+  import Ecto.Query, warn: false
+  alias Homework.Repo
+
+  alias Homework.Companies.Company
+
+  @doc """
+  Returns the list of companies.
+
+  ## Examples
+
+      iex> list_companies([])
+      [%Company{}, ...]
+
+  """
+  def list_companies(_args) do
+    Repo.all(Company)
+  end
+
+  @doc """
+  Gets a single company.
+
+  Raises `Ecto.NoResultsError` if the Company does not exist.
+
+  ## Examples
+
+      iex> get_company!(123)
+      %User{}
+
+      iex> get_company!(456)
+      ** (Ecto.NoResultsError)
+
+  """
+  def get_company!(id), do: Repo.get!(Company, id)
+
+  @doc """
+  Fuzzy search for companies by name.
+
+  ## Examples
+
+      iex> find_companies("some company")
+      [%Company{}, ...]
+
+  """
+  def find_companies(name) do
+    query =
+      from c in Company,
+           where: like(c.name, ^("%#{name}%")),
+           select: c
+    Repo.all(query)
+  end
+
+  @doc """
+  Creates a company.
+
+  ## Examples
+
+      iex> create_company(%{field: value})
+      {:ok, %Company{}}
+
+      iex> create_company(%{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def create_company(attrs \\ %{}) do
+    %Company{}
+    |> Company.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Updates a company.
+
+  ## Examples
+
+      iex> update_company(company, %{field: new_value})
+      {:ok, %Company{}}
+
+      iex> update_company(company, %{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def update_company(%Company{} = company, attrs) do
+    company
+    |> Company.changeset(attrs)
+    |> Repo.update()
+  end
+
+  @doc """
+  Deletes a company.
+
+  ## Examples
+
+      iex> delete_company(company)
+      {:ok, %Company{}}
+
+      iex> delete_company(company)
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def delete_company(%Company{} = company) do
+    Repo.delete(company)
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking company changes.
+
+  ## Examples
+
+      iex> change_company(company)
+      %Ecto.Changeset{data: %Company{}}
+
+  """
+  def change_company(%Company{} = company, attrs \\ %{}) do
+    Company.changeset(company, attrs)
+  end
+end

elixir/lib/homework/companies/company.ex

@@ -0,0 +1,20 @@
+defmodule Homework.Companies.Company do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  schema "companies" do
+    field(:name, :string)
+    field(:credit_line, :integer)
+    field(:available_credit, :integer)
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(company, attrs) do
+    company
+    |> cast(attrs, [:name, :credit_line, :available_credit])
+    |> validate_required([:name, :credit_line, :available_credit])
+  end
+end

elixir/lib/homework/merchants.ex

@@ -37,6 +37,23 @@ defmodule Homework.Merchants do
   """
   def get_merchant!(id), do: Repo.get!(Merchant, id)
 
+  @doc """
+  Fuzzy search for merchants by name.
+
+  ## Examples
+
+      iex> find_merchants("some name")
+      [%Merchant{}, ...]
+
+  """
+  def find_merchants(name) do
+    query =
+      from m in Merchant,
+           where: like(m.name, ^("%#{name}%")),
+           select: m
+    Repo.all(query)
+  end
+
   @doc """
   Creates a merchant.
 

elixir/lib/homework/transactions.ex

@@ -7,6 +7,8 @@ defmodule Homework.Transactions do
   alias Homework.Repo
 
   alias Homework.Transactions.Transaction
+  alias Homework.Users.User
+  alias Homework.Companies.Company
 
   @doc """
   Returns the list of transactions.
@@ -38,7 +40,25 @@ defmodule Homework.Transactions do
   def get_transaction!(id), do: Repo.get!(Transaction, id)
 
   @doc """
-  Creates a transaction.
+  Finds all transactions with an amount within a given range.
+
+  ## Examples
+
+      iex> find_transactions(123, 456)
+      [%Transaction{}, ...]
+
+  """
+  def find_transactions(min, max) do
+    query =
+      from t in Transaction,
+           where: t.amount >= ^min and t.amount <= ^max,
+           select: t
+    Repo.all(query)
+  end
+
+  @doc """
+  Creates a transaction. Also updates the available credit for the
+  company associated with the transaction.
 
   ## Examples
 
@@ -49,7 +69,16 @@ defmodule Homework.Transactions do
       {:error, %Ecto.Changeset{}}
 
   """
-  def create_transaction(attrs \\ %{}) do
+  def create_transaction(%{amount: amount, credit: credit, user_id: user_id} = attrs \\ %{}) do
+    change_amount = (if credit, do: 1, else: -1) * amount
+
+    query =
+      from c in Company,
+        join: u in User,
+        on: c.id == u.company_id,
+        where: u.id == ^user_id
+    Repo.update_all(query, inc: [available_credit: change_amount])
+
     %Transaction{}
     |> Transaction.changeset(attrs)
     |> Repo.insert()

elixir/lib/homework/transactions/transaction.ex

@@ -20,7 +20,7 @@ defmodule Homework.Transactions.Transaction do
   @doc false
   def changeset(transaction, attrs) do
     transaction
-    |> cast(attrs, [:user_id, :amount, :debit, :description, :merchant_id])
-    |> validate_required([:user_id, :amount, :debit, :description, :merchant_id])
+    |> cast(attrs, [:user_id, :amount, :credit, :debit, :description, :merchant_id])
+    |> validate_required([:user_id, :amount, :credit, :debit, :description, :merchant_id])
   end
 end

elixir/lib/homework/users.ex

@@ -37,6 +37,27 @@ defmodule Homework.Users do
   """
   def get_user!(id), do: Repo.get!(User, id)
 
+  @doc """
+  Fuzzy search for users by first and last name.
+
+  ## Examples
+
+      iex> find_users("Joe", "S")
+      [%User{}, ...]
+
+      iex> find_users("", "Smith")
+      [%User{}, ...]
+
+  """
+  def find_users(first, last) do
+    query =
+      from u in User,
+           where: like(u.first_name, ^("%#{first}%"))
+           and like(u.last_name, ^("%#{last}%")),
+           select: u
+    Repo.all(query)
+  end
+
   @doc """
   Creates a user.
 

elixir/lib/homework/users/user.ex

@@ -1,20 +1,23 @@
 defmodule Homework.Users.User do
   use Ecto.Schema
   import Ecto.Changeset
+  alias Homework.Companies.Company
 
   @primary_key {:id, :binary_id, autogenerate: true}
   schema "users" do
     field(:dob, :string)
     field(:first_name, :string)
     field(:last_name, :string)
 
+    belongs_to(:company, Company, type: :binary_id, foreign_key: :company_id)
+
     timestamps()
   end
 
   @doc false
   def changeset(user, attrs) do
     user
-    |> cast(attrs, [:first_name, :last_name, :dob])
-    |> validate_required([:first_name, :last_name, :dob])
+    |> cast(attrs, [:first_name, :last_name, :dob, :company_id])
+    |> validate_required([:first_name, :last_name, :dob, :company_id])
   end
 end

elixir/lib/homework_web/resolvers/companies_resolver.ex

@@ -0,0 +1,61 @@
+defmodule HomeworkWeb.Resolvers.CompaniesResolver do
+  alias Homework.Companies
+
+  @doc """
+  Get a list of companies
+  """
+  def companies(_root, args, _info) do
+    {:ok, Companies.list_companies(args)}
+  end
+
+  @doc """
+  Find companies by name
+  """
+  def find_companies(_root, %{name: name}, _info) do
+    {:ok, Companies.find_companies(name)}
+  end
+
+  @doc """
+  Create a new company
+  """
+  def create_company(_root, %{credit_line: credit_line} = args, _info) do
+    new_args = Map.put(args, :available_credit, credit_line)
+    case Companies.create_company(new_args) do
+      {:ok, company} ->
+        {:ok, company}
+
+      error ->
+        {:error, "could not create company: #{inspect(error)}"}
+    end
+  end
+
+  @doc """
+  Updates a company for an id with args specified.
+  """
+  def update_company(_root, %{id: id} = args, _info) do
+    company = Companies.get_company!(id)
+
+    case Companies.update_company(company, args) do
+      {:ok, company} ->
+        {:ok, company}
+
+      error ->
+        {:error, "could not update company: #{inspect(error)}"}
+    end
+  end
+
+  @doc """
+  Deletes a company for an id
+  """
+  def delete_company(_root, %{id: id}, _info) do
+    company = Companies.get_company!(id)
+
+    case Companies.delete_company(company) do
+      {:ok, company} ->
+        {:ok, company}
+
+      error ->
+        {:error, "could not update company: #{inspect(error)}"}
+    end
+  end
+end

elixir/lib/homework_web/resolvers/merchants_resolver.ex

@@ -8,6 +8,13 @@ defmodule HomeworkWeb.Resolvers.MerchantsResolver do
     {:ok, Merchants.list_merchants(args)}
   end
 
+  @doc """
+  Find merchants by name
+  """
+  def find_merchants(_root, %{name: name}, _info) do
+    {:ok, Merchants.find_merchants(name)}
+  end
+
   @doc """
   Create a new merchant
   """

elixir/lib/homework_web/resolvers/transactions_resolver.ex

@@ -24,6 +24,13 @@ defmodule HomeworkWeb.Resolvers.TransactionsResolver do
     {:ok, Merchants.get_merchant!(merchant_id)}
   end
 
+  @doc """
+  Find transactions by amount
+  """
+  def find_transactions(_root, %{min: min, max: max}, _info) do
+    {:ok, Transactions.find_transactions(min, max)}
+  end
+
   @doc """
   Create a new transaction
   """

elixir/lib/homework_web/resolvers/users_resolver.ex

@@ -8,6 +8,13 @@ defmodule HomeworkWeb.Resolvers.UsersResolver do
     {:ok, Users.list_users(args)}
   end
 
+  @doc """
+  Find users by first and last name
+  """
+  def find_users(_root, %{first_name: first, last_name: last}, _info) do
+    {:ok, Users.find_users(first, last)}
+  end
+
   @doc """
   Creates a user
   """