Add a simple index page that explains the usage

Cargo.toml

@@ -13,6 +13,7 @@ chrono = { version = "0.4.19", features = ["serde"] }
 color-eyre = "0.6.1"
 reqwest = { version = "0.11.10", features = ["json"] }
 rocket = { version = "0.5.0-rc.2", features = ["json"] }
+rocket_dyn_templates = { version = "0.1.0-rc.2", features = ["tera"] }
 rss = "2.0.1"
 tempfile = "3"
 tokio = { version = "1.6.1", features = ["process"] }

src/lib.rs

@@ -15,6 +15,7 @@ use rocket::http::uri::Absolute;
 use rocket::response::Redirect;
 use rocket::serde::{Deserialize, Serialize};
 use rocket::{get, routes, uri, Build, Responder, Rocket, State};
+use rocket_dyn_templates::{context, Template};
 use rss::extension::itunes::{
     ITunesCategoryBuilder, ITunesChannelExtensionBuilder, ITunesItemExtensionBuilder,
 };
@@ -158,9 +159,16 @@ async fn feed(backend: &str, username: &str, config: &State<Config>) -> Option<R
     Some(feed)
 }
 
+/// Returns a simple index page that explains the usage.
+#[get("/")]
+pub(crate) async fn index(config: &State<Config>) -> Template {
+    Template::render("index", context! { url: &config.url })
+}
+
 /// Sets up Rocket.
 pub fn setup() -> Rocket<Build> {
     rocket::build()
-        .mount("/", routes![download, feed])
+        .mount("/", routes![download, feed, index])
         .attach(AdHoc::config::<Config>())
+        .attach(Template::fairing())
 }

templates/index.html.tera

@@ -0,0 +1,19 @@
+<h1>Welcome to Podbringer</h1>
+<p>
+  Podbringer currently has no front-end or web interface yet that can help you
+  use it. Until then, you just have to enter the right service-specific RSS feed
+  URL in your favorite podcast client to start using it.
+</p>
+<p>
+  Given the Mixcloud URL <https://www.mixcloud.com/myfavouriteband/>, the URL you
+  need to use for Podbringer is comprised of the following parts:
+
+  <pre>
+    https://my.domain.tld/podbringer/feed/mixcloud/myfavouriteband
+    |------------------------------|     |-------||--------------|
+     The Podbringer location URL          Service  User @ service
+  </pre>
+</p>
+<p>
+  The Podbringer location URL of this instance is: {{ url }}
+</p>