feat: add log-file option (#383)

src/logger.rs

@@ -1,8 +1,14 @@
+use anyhow::{Context, Result};
 use chrono::{Local, SecondsFormat};
-use log::{Level, Metadata, Record};
-use log::{LevelFilter, SetLoggerError};
+use log::{Level, LevelFilter, Metadata, Record};
+use std::fs::{File, OpenOptions};
+use std::io::Write;
+use std::path::PathBuf;
+use std::sync::Mutex;
 
-struct SimpleLogger;
+struct SimpleLogger {
+    file: Option<Mutex<File>>,
+}
 
 impl log::Log for SimpleLogger {
     fn enabled(&self, metadata: &Metadata) -> bool {
@@ -12,10 +18,20 @@ impl log::Log for SimpleLogger {
     fn log(&self, record: &Record) {
         if self.enabled(record.metadata()) {
             let timestamp = Local::now().to_rfc3339_opts(SecondsFormat::Secs, true);
-            if record.level() < Level::Info {
-                eprintln!("{} {} - {}", timestamp, record.level(), record.args());
-            } else {
-                println!("{} {} - {}", timestamp, record.level(), record.args());
+            let text = format!("{} {} - {}", timestamp, record.level(), record.args());
+            match &self.file {
+                Some(file) => {
+                    if let Ok(mut file) = file.lock() {
+                        let _ = writeln!(file, "{text}");
+                    }
+                }
+                None => {
+                    if record.level() < Level::Info {
+                        eprintln!("{text}");
+                    } else {
+                        println!("{text}");
+                    }
+                }
             }
         }
     }
@@ -23,8 +39,23 @@ impl log::Log for SimpleLogger {
     fn flush(&self) {}
 }
 
-static LOGGER: SimpleLogger = SimpleLogger;
-
-pub fn init() -> Result<(), SetLoggerError> {
-    log::set_logger(&LOGGER).map(|()| log::set_max_level(LevelFilter::Info))
+pub fn init(log_file: Option<PathBuf>) -> Result<()> {
+    let file = match log_file {
+        None => None,
+        Some(log_file) => {
+            let file = OpenOptions::new()
+                .create(true)
+                .append(true)
+                .open(&log_file)
+                .with_context(|| {
+                    format!("Failed to open the log file at '{}'", log_file.display())
+                })?;
+            Some(Mutex::new(file))
+        }
+    };
+    let logger = SimpleLogger { file };
+    log::set_boxed_logger(Box::new(logger))
+        .map(|_| log::set_max_level(LevelFilter::Info))
+        .with_context(|| "Failed to init logger")?;
+    Ok(())
 }