add application logging

add configuration of logging which save logs into dedicated files and
outputs logs into console (stderr) #NEU-9

Cargo.toml

@@ -80,6 +80,8 @@ strum = "0.26.3"
 human-panic = "2.0.2"
 crossbeam = { version = "0.8.4", features = ["crossbeam-channel"] }
 uuid = { version = "1.12.1", features = ["v4"] }
+etcetera = "0.8.0"
+tracing-appender = "0.2.3"
 
 [features]
 default = ["tui"]

docs/logging.md

@@ -0,0 +1,74 @@
+# Logging Configuration
+
+Neuronek implements a comprehensive logging system that provides both file-based and console-based logging capabilities. The logging system is designed to be XDG-compliant and supports multiple output layers with different configurations.
+
+## Log File Location
+
+Log files are stored following the XDG Base Directory Specification:
+
+- **Development/Debug Mode**: Logs are stored in the system's temporary directory as `neuronek.sqlite`
+- **Production Mode**: Logs are stored in the XDG cache directory: `~/.cache/neuronek/logs/debug.log` (Linux) or equivalent on other platforms
+
+## Logging Layers
+
+The logging system implements two main layers:
+
+### 1. File Appender
+
+The file appender writes detailed logs to a file with the following characteristics:
+
+- Includes file names and line numbers for precise error tracking
+- Records thread IDs for concurrent operation debugging
+- Maintains detailed context for debugging purposes
+- Stores logs in the XDG-compliant directory structure
+
+### 2. Console Appender
+
+The console appender provides a streamlined output to stderr:
+
+- Simplified output without file names or line numbers
+- No thread IDs to keep the output clean
+- ANSI color support for better readability
+- Focused on user-relevant information
+- Writes to stderr for clean JSON output compatibility
+
+## Log Levels
+
+The logging system supports multiple log levels through the `tracing` crate:
+
+- ERROR: For critical issues that prevent normal operation
+- WARN: For important issues that don't stop execution
+- INFO: For general information about program operation
+- DEBUG: For detailed information useful during development
+- TRACE: For very detailed debugging information
+
+By default, the logging level is set to INFO, but this can be adjusted through environment variables.
+
+## Configuration
+
+The logging system integrates with Neuronek's configuration system and respects the following settings:
+
+- Log file location is determined by the application mode (debug/release)
+- Environment variables can control the logging level
+- XDG base directories are used for log file storage
+
+## Usage Example
+
+```rust
+// Log messages at different levels
+error!("Critical error occurred");
+warn!("Warning: operation may be slow");
+info!("Operation completed successfully");
+debug!("Detailed debug information");
+trace!("Very detailed trace information");
+```
+
+## Implementation Details
+
+The logging system is implemented using the following crates:
+
+- `tracing`: Core logging functionality
+- `tracing-subscriber`: Logging subscriber implementation
+- `etcetera`: XDG base directory handling
+
+The setup is handled in `src/core/logging.rs` and integrates with the application's configuration system in `src/core/config.rs`.

src/core/logging.rs

@@ -1,13 +1,43 @@
-// TODO: Implement logging
-pub fn setup_logger()
-{
-    // let log_file_path = std::env::current_dir().unwrap().join("debug.log");
-    // let _ = std::fs::remove_file(&log_file_path);
-    //
-    // use tracing_subscriber::fmt;
-    // use tracing_subscriber::prelude::*;
-    //
-    // let file_layer = fmt::layer().with_writer(std::fs::File::create(log_file_path).unwrap());
-    //
-    // tracing_subscriber::registry().with(file_layer).init();
+use etcetera::base_strategy::{BaseStrategy, Xdg};
+use std::fs::create_dir_all;
+use tracing_subscriber::{fmt, prelude::*, EnvFilter};
+use tracing_appender::rolling::{RollingFileAppender, Rotation};
+use tracing_appender::non_blocking::WorkerGuard;
+
+pub fn setup_logger() -> Result<WorkerGuard, Box<dyn std::error::Error>> {
+    // Get XDG data directory
+    let xdg = Xdg::new()?.cache_dir().join("neuronek").join("logs");
+    create_dir_all(&xdg)?;
+
+    let file_appender = RollingFileAppender::new(
+        Rotation::DAILY,
+        &xdg,
+        "neuronek"
+    );
+
+    let (non_blocking_appender, guard) = tracing_appender::non_blocking(file_appender);
+
+    let file_layer = fmt::layer()
+        .with_file(true)
+        .with_line_number(true)
+        .with_thread_ids(true)
+        .with_target(false)
+        .with_writer(non_blocking_appender);
+
+    let console_layer = fmt::layer()
+        .with_target(false)
+        .with_thread_ids(false)
+        .with_file(false)
+        .with_line_number(false)
+        .with_ansi(true)
+        .with_writer(std::io::stderr);
+
+    tracing_subscriber::registry()
+        .with(EnvFilter::from_default_env()
+            .add_directive(tracing::Level::INFO.into()))
+        .with(file_layer)
+        .with(console_layer)
+        .init();
+
+    Ok(guard)
 }