Use error variants instead of static strings

data/src/config.rs

@@ -159,6 +159,9 @@ impl Config {
         }
 
         let path = Self::path();
+        if !path.try_exists()? {
+            return Err(Error::ConfigMissing { has_yaml_config: has_yaml_config()? });
+        }
         let content = fs::read_to_string(path)
             .await
             .map_err(|e| Error::LoadConfigFile(e.to_string()))?;
@@ -294,8 +297,8 @@ pub fn random_nickname_with_seed<R: Rng>(rng: &mut R) -> String {
 }
 
 /// Has YAML configuration file.
-pub fn has_yaml_config() -> bool {
-    config_dir().join("config.yaml").exists()
+fn has_yaml_config() -> Result<bool, Error> {
+    Ok(config_dir().join("config.yaml").try_exists()?)
 }
 
 fn default_tooltip() -> bool {
@@ -318,16 +321,14 @@ pub enum Error {
     StringUtf8Error(#[from] string::FromUtf8Error),
     #[error(transparent)]
     LoadSounds(#[from] audio::LoadError),
-}
-
-impl Error {
-    pub fn is_expected_on_first_load(&self) -> bool {
-        match self {
-            // If a user doesn't have a config when we start up, then we end up with a read error
-            Error::LoadConfigFile(_) => true,
-            _ => false,
-        }
-    }
+    #[error("Only one of password, password_file and password_command can be set.")]
+    DuplicatePassword(),
+    #[error("Only one of nick_password, nick_password_file and nick_password_command can be set.")]
+    DuplicateNickPassword(),
+    #[error("Exactly one of sasl.plain.password, sasl.plain.password_file or sasl.plain.password_command must be set.")]
+    DuplicateSaslPassword(),
+    #[error("Config does not exist")]
+    ConfigMissing { has_yaml_config: bool },
 }
 
 impl From<std::io::Error> for Error {

data/src/server.rs

@@ -12,9 +12,6 @@ use crate::config::server::Sasl;
 use crate::config::Error;
 
 pub type Handle = Sender<proto::Message>;
-const DUP_PASS_MSG: &str = "Only one of password, password_file and password_command can be set.";
-const DUP_NICK_PASS_MSG: &str = "Only one of nick_password, nick_password_file and nick_password_command can be set.";
-const DUP_SASL_PASS_MSG: &str = "Exactly one of sasl.plain.password, sasl.plain.password_file or sasl.plain.password_command must be set.";
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct Server(String);
@@ -103,27 +100,27 @@ impl Map {
         for (_, config) in self.0.iter_mut() {
             if let Some(pass_file) = &config.password_file {
                 if config.password.is_some() || config.password_command.is_some() {
-                    return Err(Error::Parse(DUP_PASS_MSG.to_string()));
+                    return Err(Error::DuplicatePassword());
                 }
                 let pass = fs::read_to_string(pass_file).await?;
                 config.password = Some(pass);
             }
             if let Some(pass_command) = &config.password_command {
                 if config.password.is_some() {
-                    return Err(Error::Parse(DUP_PASS_MSG.to_string()));
+                    return Err(Error::DuplicatePassword());
                 }
                 config.password = Some(read_from_command(pass_command).await?);
             }
             if let Some(nick_pass_file) = &config.nick_password_file {
                 if config.nick_password.is_some() || config.nick_password_command.is_some() {
-                    return Err(Error::Parse(DUP_NICK_PASS_MSG.to_string()));
+                    return Err(Error::DuplicateNickPassword());
                 }
                 let nick_pass = fs::read_to_string(nick_pass_file).await?;
                 config.nick_password = Some(nick_pass);
             }
             if let Some(nick_pass_command) = &config.nick_password_command {
                 if config.password.is_some() {
-                    return Err(Error::Parse(DUP_NICK_PASS_MSG.to_string()));
+                    return Err(Error::DuplicateNickPassword());
                 }
                 config.password = Some(read_from_command(nick_pass_command).await?);
             }
@@ -154,7 +151,7 @@ impl Map {
                         *password = Some(pass);
                     }
                     Sasl::Plain { .. } => {
-                        return Err(Error::Parse(DUP_SASL_PASS_MSG.to_string()));
+                        return Err(Error::DuplicateSaslPassword());
                     }
                     Sasl::External { .. } => {
                         // no passwords to read

src/main.rs

@@ -151,30 +151,28 @@ impl Halloy {
                     command.map(Message::Dashboard),
                 )
             }
-            Err(error) => {
-                if config::has_yaml_config() {
-                    // If we have a YAML file, but end up in this arm
-                    // it means the user tried to load Halloy with a YAML configuration, but it expected TOML.
-                    (
-                        Screen::Migration(screen::Migration::new()),
-                        Config::default(),
-                        Task::none(),
-                    )
-                } else if error.is_expected_on_first_load() {
-                    // Show regular welcome screen for new users.
-                    (
-                        Screen::Welcome(screen::Welcome::new()),
-                        Config::default(),
-                        Task::none(),
-                    )
-                } else {
-                    (
-                        Screen::Help(screen::Help::new(error)),
-                        Config::default(),
-                        Task::none(),
-                    )
-                }
-            },
+            // If we have a YAML file, but end up in this arm
+            // it means the user tried to load Halloy with a YAML configuration, but it expected TOML.
+            Err(config::Error::ConfigMissing {
+                has_yaml_config: true,
+            }) => (
+                Screen::Migration(screen::Migration::new()),
+                Config::default(),
+                Task::none(),
+            ),
+            // Show regular welcome screen for new users.
+            Err(config::Error::ConfigMissing {
+                has_yaml_config: false,
+            }) => (
+                Screen::Welcome(screen::Welcome::new()),
+                Config::default(),
+                Task::none(),
+            ),
+            Err(error) => (
+                Screen::Help(screen::Help::new(error)),
+                Config::default(),
+                Task::none(),
+            ),
         };
 
         (