defmodule PhoenixApiToolkit.TestHelpers do
  @moduledoc """
  Various helper functions for writing tests.
  """
  alias Plug.Conn
  require Logger

  @doc """
  Returns the jwks used to sign JWT's in tests by `gen_jwt/1`, as base64-encoded JSON.

  ## Examples

      # the keyset is returned as base64-encoded JSON string with a list of keys
      iex> test_jwks() |> Base.decode64!() |> Jason.decode!() |> List.first() |> Map.get("kid")
      "my_test_key"
  """
  @spec test_jwks :: binary
  def test_jwks() do
    """
    [
      {
        "kty": "RSA",
        "d": "PHxWm6NfF7KucMLkInmy07mPYOCAbd-Kv5Su25dGNYxm3iWqzByIl-CHk-rBdI5lOg7w3QQgXUynjjRSQPpUEx6Na6gokMOeWET-xXVx3MTlSItO_iEx0V_UpY6jrKAxM1Mp-IQOxzwyAAg2SxCgNdhinzpn8Fj-71ezrAfDUfPOWq0hVzvTwcG_mJdbuYbVYh19EXRv3kY-FKssJS8OqoZwSKF6xcmTND8kixXaFZ86fjI9xuh1Nuk-fU7kdO4LHCnAHsi0Vpaou0AfSXHjsM1A31_K79aeV6fP40hzDgLpmHLhN4CywqpI0v4A-8wXlp1474B0Ut8P_QfwWfudoQ",
        "e": "AQAB",
        "use": "sig",
        "kid": "my_test_key",
        "alg": "RS256",
        "n": "oIU4cfgBMV-HSXshwcyocv0pINmgYjDfvaYQpsGkw0o3xv1ttMDS27f31fpQCvIIu7fBWDfzqG9DBzQTVilqIvZVbAD_W0IJGcD7jreqhTI_MC3bQWIePAn5BwK9ONE23V6Q5jK556tsIpBjOGna2fi6Qr__x5236kH7lMNsBqxTK3kNRkrLlKUwni419Jpgh9A5Gl3pfSKjvtEDA3FLaWzUHzuoizUr9VnKwxpe4rKx0boQgxsCteBp1-sOLegRSeYvzK9x3p9XEUxEdUlQw_SiPUKC5XlMfbIWcTrSCR9SztTqa6I6COu3ohdwryna2oPcm2sS4M_T9jfzzb8Nkw"
      }
    ]
    """
    |> Base.encode64()
  end

  @doc """
  Returns the secret used to sign request body's with HMACs by `put_hmac/3`.
  """
  @spec test_hmac_secret :: binary
  def test_hmac_secret(), do: "supersecretkey"

  defp default_jwk() do
    test_jwks()
    |> Base.decode64!()
    |> Jason.decode!()
    |> List.first()
  end

  @doc """
  Returns the default JWT payload generated by `gen_jwt/1`. The "exp" claim is set to
  NOW + 5 minutes.

  ## Examples

      iex> default_payload() |> Map.drop([:exp])
      %{
        iss: "https://some_oauth2_provider/my_account_id",
        scope: "admin",
        username: "integration-test-user",
        aud: "my resource server"
      }
  """
  @spec default_payload :: %{
          exp: integer,
          iss: binary,
          scope: binary,
          username: binary,
          aud: binary
        }
  def default_payload() do
    %{
      iss: "https://some_oauth2_provider/my_account_id",
      exp: (DateTime.utc_now() |> DateTime.to_unix(:second)) + 300,
      scope: "admin",
      username: "integration-test-user",
      aud: "my resource server"
    }
  end

  defp default_jws(), do: %{"alg" => default_jwk()["alg"], "kid" => default_jwk()["kid"]}

  @typedoc "Options for use by `gen_jwt/1`"
  @type gen_jwt_opts :: [
          jwk: map(),
          payload: map(),
          jws: map()
        ]

  @doc """
  Generate a JSON Web Token for testing purposes.
  It is possible to override parts of the signing key, payload and signature to test with different
  scopes, expiration times, issuers, key ID's etc, override the entire signing key, payload or signature.
  The defaults generate a valid JWT, so overrides are not necessary unless you wish to test the JWT verification
  itself. For use with endpoints secured with `PhoenixApiToolkit.Security.Oauth2Plug`.

  ## Examples

      # by default, a valid JWT is generated using defaults for jwk, payload and jws
      # the header, payload and signature can be inspected using JOSE.JWS.peek* functions
      iex> jwt = gen_jwt()
      iex> jwt |> JOSE.JWS.peek_protected() |> Jason.decode!()
      %{"alg" => "RS256", "kid" => "my_test_key", "typ" => "JWT"}
      iex> expected_pl = default_payload() |> Map.drop([:exp]) |> to_string_map()
      iex> expected_pl == jwt |> JOSE.JWS.peek_payload() |> Jason.decode!() |> Map.drop(["exp"])
      true

      # the jwk, payload and jws can be overriden for testing purposes
      iex> gen_jwt(payload: %{}) |> JOSE.JWS.peek_payload() |> Jason.decode!()
      %{}

      # this is most useful when combined with gen_jwk/gen_payload/gen_jws functions
      # to override parts of the jwk/payload/jws
      iex> gen_jwt(jws: gen_jws(%{"kid" => "other key"})) |> JOSE.JWS.peek_protected() |> Jason.decode!()
      %{"alg" => "RS256", "kid" => "other key", "typ" => "JWT"}
      iex> gen_jwt(payload: gen_payload(%{exp: 12345})) |> JOSE.JWS.peek_payload() |> Jason.decode!() |> Map.get("exp")
      12345
  """
  @spec gen_jwt(gen_jwt_opts) :: binary
  def gen_jwt(overrides \\ []) do
    overrides =
      overrides
      |> Keyword.put_new_lazy(:jwk, &gen_jwk/0)
      |> Keyword.put_new_lazy(:payload, &gen_payload/0)
      |> Keyword.put_new_lazy(:jws, &gen_jws/0)

    JOSE.JWT.sign(overrides[:jwk], overrides[:jws], overrides[:payload])
    |> JOSE.JWS.compact()
    |> elem(1)
  end

  @doc """
  Generate a JSON Web Key for testing purposes. See `gen_jwt/1` for details.
  """
  @spec gen_jwk(map) :: map
  def gen_jwk(overrides \\ %{}) do
    Map.merge(default_jwk(), overrides)
  end

  @doc """
  Generate a JSON Web Token payload for testing purposes. See `gen_jwt/1` for details.
  """
  @spec gen_payload(map) :: map
  def gen_payload(overrides \\ %{}) do
    Map.merge(default_payload(), overrides)
  end

  @doc """
  Generate a JSON Web Signature for testing purposes. See `gen_jwt/1` for details.
  """
  @spec gen_jws(map) :: map
  def gen_jws(overrides \\ %{}) do
    Map.merge(default_jws(), overrides)
  end

  @doc """
  Adds a HMAC-SHA256 signature to the connection's `authorization` header for the request body.
  Use `create_hmac_plug_body/4` to generate a valid body. For use with endpoints secured
  with `PhoenixApiToolkit.Security.HmacPlug`.

  It is possible to override the HMAC secret. The default generates a valid signature, so
  overrides are not necessary unless you wish to test the HMAC verification itself.

  ## Examples

      use Plug.Test

      iex> body = %{greeting: "world"} |> Jason.encode!()
      iex> conn = conn(:post, "/hello", body)
      iex> put_hmac(conn, body) |> get_req_header("authorization")
      ["oseq9TrQc/cyOBU7ujrkKM07tFewcVoaLRK0MgslSos="]
  """
  @spec put_hmac(Conn.t(), binary, binary) :: Conn.t()
  def put_hmac(conn, body, secret \\ test_hmac_secret()) do
    conn
    |> Conn.put_req_header(
      "authorization",
      :crypto.hmac(:sha256, secret, body) |> Base.encode64()
    )
  end

  @doc """
  Generate a request body for an endpoint secured with `PhoenixApiToolkit.Security.HmacPlug`.
  Use `put_hmac/3` to generate a valid signature.

  It is possible to override the timestamp set in the request body. The default generates a valid
  request body, so overrides are not necessary unless you wish to test the HMAC verification itself.

  ## Examples

      iex> create_hmac_plug_body("/hello", "GET", %{hello: "world"}, 12345) |> Jason.decode!()
      %{
        "contents" => %{"hello" => "world"},
        "method" => "GET",
        "path" => "/hello",
        "timestamp" => 12345
      }
  """
  @spec create_hmac_plug_body(binary, binary, any, integer) :: binary
  def create_hmac_plug_body(
        path,
        method,
        contents \\ %{},
        timestamp \\ DateTime.utc_now() |> DateTime.to_unix(:second)
      ) do
    %{
      path: path,
      method: method,
      timestamp: timestamp,
      contents: contents
    }
    |> Jason.encode!()
  end

  @doc """
  Put a raw request body in `conn.assigns.raw_body` for testing purposes.

  ## Examples

      use Plug.Test

      iex> body = %{hello: "world"}
      iex> raw_body = body |> Jason.encode!()
      iex> conn = conn(:post, "/") |> put_raw_body(raw_body)
      iex> conn.adapter |> elem(1) |> Map.get(:req_body) |> Jason.decode!()
      %{"hello" => "world"}
  """
  @spec put_raw_body(Conn.t(), binary) :: Conn.t()
  def put_raw_body(%{adapter: {adapter, state}} = conn, raw_body) do
    conn |> Map.put(:adapter, {adapter, Map.put(state, :req_body, raw_body)})
  end

  @doc """
  Add JWT to the conn. By default a token that is valid in testing is added,
  generated by `gen_jwt/1`.

  ## Examples

      use Plug.Test

      iex> conn(:get, "/") |> put_jwt("my_jwt") |> get_req_header("authorization")
      ["Bearer: my_jwt"]
  """
  @spec put_jwt(Conn.t(), binary()) :: Conn.t()
  def put_jwt(conn, jwt \\ gen_jwt()),
    do: conn |> Conn.put_req_header("authorization", "Bearer: #{jwt}")

  @doc """
  Remove volatile fields from maps in the data.
  Volatile fields like "id" mess up test comparisons.
  Recursively cleans maps and lists.

  ## Examples

      iex> my_data = [
      ...>   %{
      ...>     "updated_at" => 12345
      ...>   },
      ...>   %{
      ...>     "some_thing" => [
      ...>       %{
      ...>         "id" => 1
      ...>       },
      ...>       12345
      ...>     ]
      ...>   }
      ...> ]
      iex> clean_volatile_fields(my_data)
      [%{}, %{"some_thing" => [%{}, 12345]}]
  """
  @spec clean_volatile_fields(any) :: any
  def clean_volatile_fields(data) when is_map(data) do
    data
    |> Map.drop(["id", "inserted_at", "updated_at"])
    |> Stream.map(fn {k, v} -> {k, clean_volatile_fields(v)} end)
    |> Enum.into(%{})
  end

  def clean_volatile_fields(data) when is_list(data),
    do: data |> Enum.map(&clean_volatile_fields/1)

  def clean_volatile_fields(data), do: data

  @doc """
  Put a whole map (or keyword list) of query params on a `%Conn{}`.

  ## Examples

      use Plug.Test

      iex> conn(:get, "/") |> put_query_params(user: "Peter") |> Map.get(:query_params)
      %{user: "Peter"}
  """
  @spec put_query_params(Conn.t(), map | keyword) :: Conn.t()
  def put_query_params(conn, params), do: conn |> Map.put(:query_params, params |> Map.new())

  @doc """
  Put request header "content-type: application/json" on the conn.

  ## Examples

      use Plug.Test

      iex> conn(:post, "/") |> application_json() |> get_req_header("content-type")
      ["application/json"]
  """
  @spec application_json(Conn.t()) :: Conn.t()
  def application_json(conn),
    do: conn |> Conn.put_req_header("content-type", "application/json")

  @doc """
  Converts a map with atom or mixed keys to a map with only string keys.

  ## Examples

      iex> %{:first_name => "Peter", "last_name" => "Pan"} |> to_string_map()
      %{"first_name" => "Peter", "last_name" => "Pan"}
  """
  @spec to_string_map(map) :: map
  def to_string_map(map), do: map |> Jason.encode!() |> Jason.decode!()
end