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{{>licenseInfo}}
defmodule {{moduleName}}.Connection do
  @moduledoc """
  Handle Tesla connections for {{moduleName}}.

  Additional middleware can be set in the compile-time or runtime configuration:

      config :tesla, {{moduleName}}.Connection,
        base_url: "{{{basePath}}}",
        adapter: Tesla.Adapter.Hackney

  The default base URL can also be set as:

      config {{#atom}}{{#underscored}}{{packageName}}{{/underscored}}{{/atom}},
        :base_url, "{{{basePath}}}"
  """

  @default_base_url Application.compile_env(
                      {{#atom}}{{#underscored}}{{packageName}}{{/underscored}}{{/atom}},
                      :base_url,
                      "{{{basePath}}}"
                    )

  {{#hasOAuthMethods}}
  {{#oauthMethods}}
  @default_scopes [
    {{#scopes}}
    {{#description}}# {{.}}{{/description}}
    "{{scope}}"{{^-last}},{{/-last}}
    {{/scopes}}
  ]
  {{/oauthMethods}}

  @typedoc """
  An arity-1 function or module/function tuple specification which, given
  a list of scopes, obtains an OAuth2 token.
  """
  @type token_fetcher :: (scopes :: list(String.t()) -> String.t()) | {module(), atom()}
  {{/hasOAuthMethods}}

  @typedoc """
  The list of options that can be passed to new/1.

  - `base_url`: Overrides the base URL on a per-client basis.
  - `user_agent`: Overrides the User-Agent header.
  {{#hasOAuthMethods}}
  - `token`: An OAuth2 token or a token fetcher function.
  - `token_scopes`: A list of OAuth2 scope strings for use with a token
    fetcher function.
  {{/hasOAuthMethods}}
  {{#hasHttpBasicMethods}}
  - `username`: A username for basic authentication.
  - `password`: A password for basic authentication.
  {{/hasHttpBasicMethods}}
  {{#hasHttpBearerMethods}}
  - `bearer_token`: A bearer token for bearer authentication.
  {{/hasHttpBearerMethods}}
  """
  @type options :: [
          {:base_url, String.t()},
          {:user_agent, String.t()},
  {{#hasOAuthMethods}}
          {:token, String.t() | token_fetcher},
          {:token_scopes, list(String.t())},
  {{/hasOAuthMethods}}
  {{#hasHttpBasicMethods}}
          {:username, String.t() | nil},
          {:password, String.t() | nil},
  {{/hasHttpBasicMethods}}
  {{#hasHttpBearerMethods}}
          {:bearer_token, String.t() | nil},
  {{/hasHttpBearerMethods}}
        ]

  @doc "Forward requests to Tesla."
  @spec request(Tesla.Client.t(), [Tesla.option()]) :: Tesla.Env.result()
  defdelegate request(client, options), to: Tesla

  @doc """
  Configure a {{moduleName}} client.

  ### Parameters

  - `options`: an optional keyword list of {{moduleName}}.Connection.options.

  ### Returns

  Tesla.Env.client
  """
  @spec new(options) :: Tesla.Env.client()
  def new(options \\ []) do
    options
    |> middleware()
    |> Tesla.client(adapter())
  end

  @doc """
  Returns fully configured middleware for passing to Tesla.client/2.
  """
  @spec middleware(options) :: [Tesla.Client.middleware()]
  def middleware(options \\ []) do
    base_url =
      Keyword.get(
        options,
        :base_url,
        Application.get_env({{#atom}}{{#underscored}}{{packageName}}{{/underscored}}{{/atom}}, :base_url, @default_base_url)
      )

    tesla_options = Application.get_env(:tesla, __MODULE__, [])
    middleware = Keyword.get(tesla_options, :middleware, [])
    json_engine = Keyword.get(tesla_options, :json, JSON)

    user_agent =
      Keyword.get(
        options,
        :user_agent,
        Keyword.get(
          tesla_options,
          :user_agent,
          "openapi-generator - {{moduleName}} {{packageVersion}} - elixir"
        )
      )

    {{#hasHttpBasicMethods}}
    username = Keyword.get(options, :username)
    password = Keyword.get(options, :password)
    middleware =
      if username || password do
        [{Tesla.Middleware.BasicAuth, %{username: username, password: password}} | middleware]
      else
        middleware
      end
    {{/hasHttpBasicMethods}}

    {{#hasHttpBearerMethods}}
    bearer_token = Keyword.get(options, :bearer_token)
    middleware = [{Tesla.Middleware.BearerAuth, token: bearer_token} | middleware]
    {{/hasHttpBearerMethods}}

    {{#hasOAuthMethods}}
    middleware =
      if token = Keyword.get(options, :token) do
        scopes = Keyword.get(options, :token_scopes, @default_scopes)
        [authorization(token, scopes) | middleware]
      else
        middleware
      end
    {{/hasOAuthMethods}}

    [
      {Tesla.Middleware.BaseUrl, base_url},
      {Tesla.Middleware.Headers, [{"user-agent", user_agent}]},
      {Tesla.Middleware.EncodeJson, engine: json_engine}
      | middleware
    ]
  end

  {{#hasOAuthMethods}}
  @doc """
  Returns an authentication middleware tuple for a Tesla client that sets
  the `authorization` header to the value of the provided bearer token. If
  the token is provided as a function of arity one, it will be called with
  a list of requested scopes that will obtain an OAuth2 token.

  ### Parameters

  - `token`: a String or a function of arity one. This value, or the result
    of the function call, will be set as a bearer token in the
    `authorization` header.

  - `scopes`: an optional list of scopes for use with the token fetcher
    function. Ignored when `token` is provided as a String. Defaults to
    `#{inspect(@default_scopes)}`.

  ### Returns

  `{Tesla.Middleware.Headers, [{"authorization", TOKEN}]}`
  """
  @spec authorization(String.t() | token_fetcher, list(String.t())) ::
          Tesla.Client.middleware()
  def authorization(token, scopes \\ @default_scopes)

  def authorization(token, _scopes) when is_binary(token) do
    {Tesla.Middleware.Headers, [{"authorization", token}]}
  end

  def authorization({module, function}, scopes) when is_atom(module) and is_atom(function) do
    apply(module, function, [scopes])
  end

  def authorization(token_fetcher, scopes) when is_function(token_fetcher, 1) do
    authorization(token_fetcher.(scopes))
  end
  {{/hasOAuthMethods}}

  @doc """
  Returns the default adapter for this API.
  """
  def adapter do
    :tesla
    |> Application.get_env(__MODULE__, [])
    |> Keyword.get(:adapter, nil)
  end
end