Set default values for API base url and home

lib/hunter.ex

@@ -631,7 +631,7 @@ defmodule Hunter do
     * `base_url` - API base url, default: `https://mastodon.social`
 
   """
-  defdelegate log_in(app, username, password, base_url \\ "https://mastodon.social"), to: Hunter.Client
+  defdelegate log_in(app, username, password, base_url \\ nil), to: Hunter.Client
 
   @doc """
   Returns Hunter version

lib/hunter/application.ex

@@ -56,7 +56,7 @@ defmodule Hunter.Application do
   @spec create_app(String.t, String.t, [String.t], String.t, Keyword.t) :: Hunter.Application.t | no_return
   def create_app(name, redirect_uri \\ "urn:ietf:wg:oauth:2.0:oob", scopes \\ ["read"], website \\ nil, options \\ []) do
     save? = Keyword.get(options, :save?, false)
-    base_url = Keyword.get(options, :api_base_url, "https://mastodon.social")
+    base_url = Keyword.get(options, :api_base_url, Hunter.Config.api_base_url())
 
     app = @hunter_api.create_app(name, redirect_uri, scopes, website, base_url)
 
@@ -75,14 +75,14 @@ defmodule Hunter.Application do
   """
   @spec load_credentials(String.t) :: Hunter.Application.t
   def load_credentials(name) do
-    "~/.hunter/apps/#{name}.json"
-    |> Path.expand()
+    Hunter.Config.home()
+    |> Path.join("apps/#{name}.json")
     |> File.read!()
     |> Poison.decode!(as: %Hunter.Application{})
   end
 
   defp save_credentials(name, app) do
-    home = Path.expand("~/.hunter/apps")
+    home = Path.join(Hunter.Config.home(), "apps")
 
     unless File.exists?(home), do: File.mkdir_p!(home)
 

lib/hunter/client.ex

@@ -47,7 +47,7 @@ defmodule Hunter.Client do
 
   """
   @spec log_in(Hunter.Application.t, String.t, String.t, String.t) :: Hunter.Client.t
-  def log_in(app, username, password, base_url \\ "https://mastodon.social") do
-    @hunter_api.log_in(app, username, password, base_url)
+  def log_in(app, username, password, base_url \\ nil) do
+    @hunter_api.log_in(app, username, password, base_url || Hunter.Config.api_base_url())
   end
 end

lib/hunter/config.ex

@@ -2,8 +2,17 @@ defmodule Hunter.Config do
   @moduledoc false
 
   @hunter_api Application.get_env(:hunter, :hunter_api, Hunter.Api.HTTPClient)
+  @api_base_url "https://mastodon.social"
 
   def hunter_api() do
    @hunter_api
   end
+
+  def api_base_url() do
+    @api_base_url
+  end
+
+  def home() do
+    Path.expand(System.get_env("HUNTER_HOME") || "~/.hunter")
+  end
 end