feat: Middleware.PathParams: add OpenAPI params

lib/tesla/middleware/path_params.ex

@@ -1,12 +1,33 @@
 defmodule Tesla.Middleware.PathParams do
   @moduledoc """
-  Use templated URLs with separate params.
+  Use templated URLs with provided parameters in either Phoenix style (`:id`)
+  or OpenAPI style (`{id}`).
 
-  Useful when logging or reporting metric per URL.
+  Useful when logging or reporting metrics per URL.
+
+  ## Parameter Values
+
+  Parameter values may be `t:struct/0` or must implement the `Enumerable`
+  protocol and produce `{key, value}` tuples when enumerated.
+
+  ## Parameter Name Restrictions
+
+  Phoenix style parameters may contain letters, numbers, or underscores,
+  matching this regular expression:
+
+    :[a-zA-Z][_a-zA-Z0-9]*\b
+
+  OpenAPI style parameters may contain letters, numbers, underscores, or
+  hyphens (`-`), matching this regular expression:
+
+    \{[a-zA-Z][-_a-zA-Z0-9]*\}
+
+  In either case, parameters that begin with underscores (`_`), hyphens (`-`),
+  or numbers (`0-9`) are ignored and left as-is.
 
   ## Examples
 
-  ```
+  ```elixir
   defmodule MyClient do
     use Tesla
 
@@ -16,27 +37,49 @@ defmodule Tesla.Middleware.PathParams do
 
     def user(id) do
       params = [id: id]
-      get("/users/:id", opts: [path_params: params])
+      get("/users/{id}", opts: [path_params: params])
+    end
+
+    def posts(id, post_id) do
+      params = [id: id, post_id: post_id]
+      get("/users/:id/posts/:post_id", opts: [path_params: params])
     end
   end
   ```
   """
 
   @behaviour Tesla.Middleware
 
-  @rx ~r/:([a-zA-Z]{1}[\w_]*)/
-
   @impl Tesla.Middleware
   def call(env, next, _) do
     url = build_url(env.url, env.opts[:path_params])
     Tesla.run(%{env | url: url}, next)
   end
 
+  @rx ~r/:([a-zA-Z][a-zA-Z0-9_]*)|[{]([a-zA-Z][-a-zA-Z0-9_]*)[}]/
+
   defp build_url(url, nil), do: url
 
-  defp build_url(url, params) do
-    Regex.replace(@rx, url, fn match, key ->
-      to_string(params[String.to_existing_atom(key)] || match)
+  defp build_url(url, params) when is_struct(params), do: build_url(url, Map.from_struct(params))
+
+  defp build_url(url, params) when is_map(params) or is_list(params) do
+    safe_params = Map.new(params, fn {name, value} -> {to_string(name), value} end)
+
+    Regex.replace(@rx, url, fn
+      # OpenAPI matches
+      match, "", name -> replace_param(safe_params, name, match)
+      # Phoenix matches
+      match, name, _ -> replace_param(safe_params, name, match)
     end)
   end
+
+  defp build_url(url, _params), do: url
+
+  defp replace_param(params, name, match) do
+    case Map.fetch(params, name) do
+      {:ok, nil} -> match
+      :error -> match
+      {:ok, value} -> URI.encode_www_form(to_string(value))
+    end
+  end
 end