refactor: split logger into focused modules

src/logger/sink.rs

@@ -0,0 +1,60 @@
+use crate::logger::{LogLevel, Record};
+
+/// Destination for log records.
+///
+/// Implement this trait to forward logs into a serial console, buffer, test
+/// collector, or host integration.
+pub trait Logger: Sync {
+    /// Receives a single log record.
+    fn log(&self, record: &Record<'_>);
+}
+
+/// Small filter-only logger for integrations that want a concrete type early.
+///
+/// This logger intentionally performs no output. It only exposes the same
+/// filtering decision a real sink would make, which is useful while wiring up a
+/// platform-specific backend later.
+pub struct CompatibilityLogger {
+    min_level: LogLevel,
+}
+
+impl CompatibilityLogger {
+    /// Creates a logger that accepts `min_level` and anything more severe.
+    #[must_use]
+    pub const fn new(min_level: LogLevel) -> Self {
+        Self { min_level }
+    }
+
+    /// Returns whether a record at `level` would be accepted.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use unshell::logger::{CompatibilityLogger, LogLevel};
+    ///
+    /// let logger = CompatibilityLogger::new(LogLevel::Warn);
+    ///
+    /// assert!(!logger.accepts(LogLevel::Info));
+    /// assert!(logger.accepts(LogLevel::Error));
+    /// ```
+    #[must_use]
+    pub fn accepts(&self, level: LogLevel) -> bool {
+        level >= self.min_level
+    }
+}
+
+impl Logger for CompatibilityLogger {
+    fn log(&self, record: &Record<'_>) {
+        if !self.accepts(record.level) {
+            return;
+        }
+
+        let _ = record;
+    }
+}
+
+pub(crate) struct NullLogger;
+
+impl Logger for NullLogger {
+    fn log(&self, _record: &Record<'_>) {}
+}