chore: add a panic hook to catch panic msg (#793)

src-tauri/src/main.rs

@@ -1,5 +1,104 @@
 // Prevents additional console window on Windows in release, DO NOT REMOVE!!
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
+
+use std::fs::OpenOptions;
+use std::io::Write;
+use std::path::PathBuf;
+
+/// Helper function to return the log directory.
+///
+/// This should return the same value as `tauri_app_handle.path().app_log_dir().unwrap()`.
+fn app_log_dir() -> PathBuf {
+    // This function `app_log_dir()` is for the panic hook, which should be set
+    // before Tauri performs any initialization. At that point, we do not have
+    // access to the identifier provided by Tauri, so we need to define our own
+    // one here.
+    //
+    // NOTE: If you update identifier in the following files, update this one
+    // as well!
+    //
+    // src-tauri/tauri.linux.conf.json
+    // src-tauri/Entitlements.plist
+    // src-tauri/tauri.conf.json
+    // src-tauri/Info.plist
+    const IDENTIFIER: &str = "rs.coco.app";
+
+    #[cfg(target_os = "macos")]
+    let path = dirs::home_dir()
+        .expect("cannot find the home directory, Coco should never run in such a environment")
+        .join("Library/Logs")
+        .join(IDENTIFIER);
+
+    #[cfg(not(target_os = "macos"))]
+    let path = dirs::data_local_dir()
+        .expect("app local dir is None, we should not encounter this")
+        .join(IDENTIFIER)
+        .join("logs");
+
+    path
+}
+
+/// Set up panic hook to log panic information to a file
+fn setup_panic_hook() {
+    std::panic::set_hook(Box::new(|panic_info| {
+        let timestamp = chrono::Local::now();
+        let datetime_str = timestamp.format("%Y-%m-%d %H:%M:%S%.3f").to_string();
+
+        let log_dir = app_log_dir();
+
+        // Ensure the log directory exists
+        if let Err(e) = std::fs::create_dir_all(&log_dir) {
+            eprintln!("Panic hook error: failed to create log directory: {}", e);
+            return;
+        }
+
+        let panic_file = log_dir.join(format!("{}.panic", datetime_str));
+
+        // Prepare panic information
+        let panic_message = if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
+            s.to_string()
+        } else if let Some(s) = panic_info.payload().downcast_ref::<String>() {
+            s.clone()
+        } else {
+            "Unknown panic message".to_string()
+        };
+
+        let location = if let Some(location) = panic_info.location() {
+            format!(
+                "{}:{}:{}",
+                location.file(),
+                location.line(),
+                location.column()
+            )
+        } else {
+            "Unknown location".to_string()
+        };
+
+        let panic_log = format!(
+            "[{}] PANIC: {} at {}\n",
+            datetime_str, panic_message, location
+        );
+
+        // Write to panic file
+        match OpenOptions::new()
+            .create(true)
+            .append(true)
+            .open(&panic_file)
+        {
+            Ok(mut file) => {
+                if let Err(e) = writeln!(file, "{}", panic_log) {
+                    eprintln!("Panic hook error: Failed to write panic to file: {}", e);
+                }
+            }
+            Err(e) => {
+                eprintln!("Panic hook error: Failed to open panic log file: {}", e);
+            }
+        }
+    }));
+}
+
 fn main() {
+    // Panic hook should be the first thing to do, everything could panic!
+    setup_panic_hook();
     coco_lib::run();
 }