chore: separate backend from frontend

src/startup.rs

@@ -0,0 +1,228 @@
+//! Application startup and server configuration.
+//!
+//! This module handles:
+//! - Building the application with routes and middleware
+//! - Setting up the OpenAPI service and Swagger UI
+//! - Configuring CORS
+//! - Starting the HTTP server
+
+use poem::middleware::{AddDataEndpoint, Cors, CorsEndpoint};
+use poem::{EndpointExt, Route};
+use poem_openapi::OpenApiService;
+
+use crate::{
+    middleware::rate_limit::{RateLimit, RateLimitConfig},
+    route::Api,
+    settings::Settings,
+};
+
+use crate::middleware::rate_limit::RateLimitEndpoint;
+
+type Server = poem::Server<poem::listener::TcpListener<String>, std::convert::Infallible>;
+/// The configured application with rate limiting, CORS, and settings data.
+pub type App = AddDataEndpoint<CorsEndpoint<RateLimitEndpoint<Route>>, Settings>;
+
+/// Application builder that holds the server configuration before running.
+pub struct Application {
+    server: Server,
+    app: poem::Route,
+    host: String,
+    port: u16,
+    settings: Settings,
+}
+
+/// A fully configured application ready to run.
+pub struct RunnableApplication {
+    server: Server,
+    app: App,
+}
+
+impl RunnableApplication {
+    /// Runs the application server.
+    ///
+    /// # Errors
+    ///
+    /// Returns a `std::io::Error` if the server fails to start or encounters
+    /// an I/O error during runtime (e.g., port already in use, network issues).
+    pub async fn run(self) -> Result<(), std::io::Error> {
+        self.server.run(self.app).await
+    }
+}
+
+impl From<RunnableApplication> for App {
+    fn from(value: RunnableApplication) -> Self {
+        value.app
+    }
+}
+
+impl From<Application> for RunnableApplication {
+    fn from(value: Application) -> Self {
+        // Configure rate limiting based on settings
+        let rate_limit_config = if value.settings.rate_limit.enabled {
+            tracing::event!(
+                target: "backend::startup",
+                tracing::Level::INFO,
+                burst_size = value.settings.rate_limit.burst_size,
+                per_seconds = value.settings.rate_limit.per_seconds,
+                "Rate limiting enabled"
+            );
+            RateLimitConfig::new(
+                value.settings.rate_limit.burst_size,
+                value.settings.rate_limit.per_seconds,
+            )
+        } else {
+            tracing::event!(
+                target: "backend::startup",
+                tracing::Level::INFO,
+                "Rate limiting disabled (using very high limits)"
+            );
+            // Use very high limits to effectively disable rate limiting
+            RateLimitConfig::new(u32::MAX, 1)
+        };
+
+        let app = value
+            .app
+            .with(RateLimit::new(&rate_limit_config))
+            .with(Cors::new())
+            .data(value.settings);
+
+        let server = value.server;
+        Self { server, app }
+    }
+}
+
+impl Application {
+    fn setup_app(settings: &Settings) -> poem::Route {
+        let api_service = OpenApiService::new(
+            Api::from(settings).apis(),
+            settings.application.clone().name,
+            settings.application.clone().version,
+        )
+        .url_prefix("/api");
+        let ui = api_service.swagger_ui();
+        poem::Route::new()
+            .nest("/api", api_service.clone())
+            .nest("/specs", api_service.spec_endpoint_yaml())
+            .nest("/", ui)
+    }
+
+    fn setup_server(
+        settings: &Settings,
+        tcp_listener: Option<poem::listener::TcpListener<String>>,
+    ) -> Server {
+        let tcp_listener = tcp_listener.unwrap_or_else(|| {
+            let address = format!(
+                "{}:{}",
+                settings.application.host, settings.application.port
+            );
+            poem::listener::TcpListener::bind(address)
+        });
+        poem::Server::new(tcp_listener)
+    }
+
+    /// Builds a new application with the given settings and optional TCP listener.
+    ///
+    /// If no listener is provided, one will be created based on the settings.
+    #[must_use]
+    pub fn build(
+        settings: Settings,
+        tcp_listener: Option<poem::listener::TcpListener<String>>,
+    ) -> Self {
+        let port = settings.application.port;
+        let host = settings.application.clone().host;
+        let app = Self::setup_app(&settings);
+        let server = Self::setup_server(&settings, tcp_listener);
+        Self {
+            server,
+            app,
+            host,
+            port,
+            settings,
+        }
+    }
+
+    /// Converts the application into a runnable application.
+    #[must_use]
+    pub fn make_app(self) -> RunnableApplication {
+        self.into()
+    }
+
+    /// Returns the host address the application is configured to bind to.
+    #[must_use]
+    pub fn host(&self) -> String {
+        self.host.clone()
+    }
+
+    /// Returns the port the application is configured to bind to.
+    #[must_use]
+    pub const fn port(&self) -> u16 {
+        self.port
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn create_test_settings() -> Settings {
+        Settings {
+            application: crate::settings::ApplicationSettings {
+                name: "test-app".to_string(),
+                version: "1.0.0".to_string(),
+                port: 8080,
+                host: "127.0.0.1".to_string(),
+                base_url: "http://localhost:8080".to_string(),
+                protocol: "http".to_string(),
+            },
+            debug: false,
+            email: crate::settings::EmailSettings::default(),
+            frontend_url: "http://localhost:3000".to_string(),
+            rate_limit: crate::settings::RateLimitSettings {
+                enabled: false,
+                burst_size: 100,
+                per_seconds: 60,
+            },
+        }
+    }
+
+    #[test]
+    fn application_build_and_host() {
+        let settings = create_test_settings();
+        let app = Application::build(settings.clone(), None);
+        assert_eq!(app.host(), settings.application.host);
+    }
+
+    #[test]
+    fn application_build_and_port() {
+        let settings = create_test_settings();
+        let app = Application::build(settings, None);
+        assert_eq!(app.port(), 8080);
+    }
+
+    #[test]
+    fn application_host_returns_correct_value() {
+        let settings = create_test_settings();
+        let app = Application::build(settings, None);
+        assert_eq!(app.host(), "127.0.0.1");
+    }
+
+    #[test]
+    fn application_port_returns_correct_value() {
+        let settings = create_test_settings();
+        let app = Application::build(settings, None);
+        assert_eq!(app.port(), 8080);
+    }
+
+    #[test]
+    fn application_with_custom_listener() {
+        let settings = create_test_settings();
+        let tcp_listener =
+            std::net::TcpListener::bind("127.0.0.1:0").expect("Failed to bind random port");
+        let port = tcp_listener.local_addr().unwrap().port();
+        let listener = poem::listener::TcpListener::bind(format!("127.0.0.1:{port}"));
+
+        let app = Application::build(settings, Some(listener));
+        assert_eq!(app.host(), "127.0.0.1");
+        assert_eq!(app.port(), 8080);
+    }
+}