feat(backend): relay contact requests to SMTP server

backend/src/settings.rs

@@ -1,12 +1,41 @@
+//! Application configuration settings.
+//!
+//! This module provides configuration structures that can be loaded from:
+//! - YAML configuration files (base.yaml and environment-specific files)
+//! - Environment variables (prefixed with APP__)
+//!
+//! Settings include application details, email server configuration, and environment settings.
+
+/// Application configuration settings.
+///
+/// Loads configuration from YAML files and environment variables.
 #[derive(Debug, serde::Deserialize, Clone, Default)]
 pub struct Settings {
+    /// Application-specific settings (name, version, host, port, etc.)
     pub application: ApplicationSettings,
+    /// Debug mode flag
     pub debug: bool,
+    /// Email server configuration for contact form
     pub email: EmailSettings,
+    /// Frontend URL for CORS configuration
     pub frontend_url: String,
 }
 
 impl Settings {
+    /// Creates a new `Settings` instance by loading configuration from files and environment variables.
+    ///
+    /// # Errors
+    ///
+    /// Returns a `config::ConfigError` if:
+    /// - Configuration files cannot be read or parsed
+    /// - Required configuration values are missing
+    /// - Configuration values cannot be deserialized into the expected types
+    ///
+    /// # Panics
+    ///
+    /// Panics if:
+    /// - The current directory cannot be determined
+    /// - The `APP_ENVIRONMENT` variable contains an invalid value (not "dev", "development", "prod", or "production")
     pub fn new() -> Result<Self, config::ConfigError> {
         let base_path = std::env::current_dir().expect("Failed to determine the current directory");
         let settings_directory = base_path.join("settings");
@@ -31,20 +60,30 @@ impl Settings {
     }
 }
 
+/// Application-specific configuration settings.
 #[derive(Debug, serde::Deserialize, Clone, Default)]
 pub struct ApplicationSettings {
+    /// Application name
     pub name: String,
+    /// Application version
     pub version: String,
+    /// Port to bind to
     pub port: u16,
+    /// Host address to bind to
     pub host: String,
+    /// Base URL of the application
     pub base_url: String,
+    /// Protocol (http or https)
     pub protocol: String,
 }
 
+/// Application environment.
 #[derive(Debug, PartialEq, Eq, Default)]
 pub enum Environment {
+    /// Development environment
     #[default]
     Development,
+    /// Production environment
     Production,
 }
 
@@ -80,12 +119,116 @@ impl TryFrom<&str> for Environment {
     }
 }
 
+/// Email server configuration for the contact form.
 #[derive(Debug, serde::Deserialize, Clone, Default)]
 pub struct EmailSettings {
+    /// SMTP server hostname
     pub host: String,
+    /// SMTP server port
+    pub port: u16,
+    /// SMTP authentication username
     pub user: String,
-    pub password: String,
+    /// Email address to send from
     pub from: String,
+    /// SMTP authentication password
+    pub password: String,
+    /// Email address to send contact form submissions to
+    pub recipient: String,
+    /// STARTTLS configuration
+    pub starttls: Starttls,
+    /// Whether to use implicit TLS (SMTPS)
+    pub tls: bool,
+}
+
+/// STARTTLS configuration for SMTP connections.
+#[derive(Debug, PartialEq, Eq, Default, Clone)]
+pub enum Starttls {
+    /// Never use STARTTLS (unencrypted connection)
+    #[default]
+    Never,
+    /// Use STARTTLS if available (opportunistic encryption)
+    Opportunistic,
+    /// Always use STARTTLS (required encryption)
+    Always,
+}
+
+impl TryFrom<&str> for Starttls {
+    type Error = String;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value.to_lowercase().as_str() {
+            "off" | "no" | "never" => Ok(Self::Never),
+            "opportunistic" => Ok(Self::Opportunistic),
+            "yes" | "always" => Ok(Self::Always),
+            other => Err(format!(
+                "{other} is not a supported option. Use either `yes`, `no`, or `opportunistic`"
+            )),
+        }
+    }
+}
+
+impl TryFrom<String> for Starttls {
+    type Error = String;
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        value.as_str().try_into()
+    }
+}
+
+impl From<bool> for Starttls {
+    fn from(value: bool) -> Self {
+        if value { Self::Always } else { Self::Never }
+    }
+}
+
+impl std::fmt::Display for Starttls {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let self_str = match self {
+            Self::Never => "never",
+            Self::Opportunistic => "opportunistic",
+            Self::Always => "always",
+        };
+        write!(f, "{self_str}")
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for Starttls {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        struct StartlsVisitor;
+
+        impl serde::de::Visitor<'_> for StartlsVisitor {
+            type Value = Starttls;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a string or boolean representing STARTTLS setting (e.g., 'yes', 'no', 'opportunistic', true, false)")
+            }
+
+            fn visit_str<E>(self, value: &str) -> Result<Starttls, E>
+            where
+                E: serde::de::Error,
+            {
+                Starttls::try_from(value).map_err(E::custom)
+            }
+
+            fn visit_string<E>(self, value: String) -> Result<Starttls, E>
+            where
+                E: serde::de::Error,
+            {
+                Starttls::try_from(value.as_str()).map_err(E::custom)
+            }
+
+            fn visit_bool<E>(self, value: bool) -> Result<Starttls, E>
+            where
+                E: serde::de::Error,
+            {
+                Ok(Starttls::from(value))
+            }
+        }
+
+        deserializer.deserialize_any(StartlsVisitor)
+    }
 }
 
 #[cfg(test)]
@@ -106,18 +249,42 @@ mod tests {
 
     #[test]
     fn environment_from_str_development() {
-        assert_eq!(Environment::try_from("development").unwrap(), Environment::Development);
-        assert_eq!(Environment::try_from("dev").unwrap(), Environment::Development);
-        assert_eq!(Environment::try_from("Development").unwrap(), Environment::Development);
-        assert_eq!(Environment::try_from("DEV").unwrap(), Environment::Development);
+        assert_eq!(
+            Environment::try_from("development").unwrap(),
+            Environment::Development
+        );
+        assert_eq!(
+            Environment::try_from("dev").unwrap(),
+            Environment::Development
+        );
+        assert_eq!(
+            Environment::try_from("Development").unwrap(),
+            Environment::Development
+        );
+        assert_eq!(
+            Environment::try_from("DEV").unwrap(),
+            Environment::Development
+        );
     }
 
     #[test]
     fn environment_from_str_production() {
-        assert_eq!(Environment::try_from("production").unwrap(), Environment::Production);
-        assert_eq!(Environment::try_from("prod").unwrap(), Environment::Production);
-        assert_eq!(Environment::try_from("Production").unwrap(), Environment::Production);
-        assert_eq!(Environment::try_from("PROD").unwrap(), Environment::Production);
+        assert_eq!(
+            Environment::try_from("production").unwrap(),
+            Environment::Production
+        );
+        assert_eq!(
+            Environment::try_from("prod").unwrap(),
+            Environment::Production
+        );
+        assert_eq!(
+            Environment::try_from("Production").unwrap(),
+            Environment::Production
+        );
+        assert_eq!(
+            Environment::try_from("PROD").unwrap(),
+            Environment::Production
+        );
     }
 
     #[test]
@@ -154,4 +321,61 @@ mod tests {
         let env = Environment::default();
         assert_eq!(env, Environment::Development);
     }
+
+    #[test]
+    fn startls_deserialize_from_string_never() {
+        let json = r#""never""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Never);
+
+        let json = r#""no""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Never);
+
+        let json = r#""off""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Never);
+    }
+
+    #[test]
+    fn startls_deserialize_from_string_always() {
+        let json = r#""always""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Always);
+
+        let json = r#""yes""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Always);
+    }
+
+    #[test]
+    fn startls_deserialize_from_string_opportunistic() {
+        let json = r#""opportunistic""#;
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Opportunistic);
+    }
+
+    #[test]
+    fn startls_deserialize_from_bool() {
+        let json = "true";
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Always);
+
+        let json = "false";
+        let result: Starttls = serde_json::from_str(json).unwrap();
+        assert_eq!(result, Starttls::Never);
+    }
+
+    #[test]
+    fn startls_deserialize_from_string_invalid() {
+        let json = r#""invalid""#;
+        let result: Result<Starttls, _> = serde_json::from_str(json);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn startls_default_is_never() {
+        let startls = Starttls::default();
+        assert_eq!(startls, Starttls::Never);
+    }
 }