show alert dialog on error

v2/src/config.rs

@@ -286,7 +286,7 @@ impl UserConfig {
                 match fs::read(&path) {
                     Ok(bytes) =>
                         return serde_yaml::from_slice(&bytes)
-                            .with_context(|| format!("Could not parse config file as YAML: {:?}. To reset config file, try --generate-config-file", path)),
+                            .with_context(|| format!("Could not parse a configuration file at {:?}. To reset config file, try --generate-config-file", path)),
                     Err(err) => {
                         log::debug!("Could not read config file from {:?}: {}", path, err);
                     }

v2/src/dialog.rs

@@ -1,23 +1,32 @@
 use crate::config::FileExtensions;
-use rfd::FileDialog;
+use rfd::{FileDialog, MessageDialog, MessageLevel};
 use std::path::{Path, PathBuf};
 
 pub trait Dialog: Default {
-    fn pick_file(&mut self, dir: &Path, extensions: &FileExtensions) -> Option<PathBuf>;
-    fn pick_dir(&mut self, dir: &Path) -> Option<PathBuf>;
+    fn pick_file(&self, dir: &Path, extensions: &FileExtensions) -> Option<PathBuf>;
+    fn pick_dir(&self, dir: &Path) -> Option<PathBuf>;
+    fn alert(&self, title: impl Into<String>, message: impl Into<String>);
 }
 
 #[derive(Default)]
 pub struct SystemDialog;
 
 impl Dialog for SystemDialog {
-    fn pick_file(&mut self, dir: &Path, extensions: &FileExtensions) -> Option<PathBuf> {
+    fn pick_file(&self, dir: &Path, extensions: &FileExtensions) -> Option<PathBuf> {
         // `FileDialog::add_filter` requires `&[&str]` but we have `Vec<String>` in config
         let extensions: Vec<&str> = extensions.as_slice().iter().map(String::as_str).collect();
         FileDialog::new().add_filter("Markdown", &extensions).set_directory(dir).pick_file()
     }
 
-    fn pick_dir(&mut self, dir: &Path) -> Option<PathBuf> {
+    fn pick_dir(&self, dir: &Path) -> Option<PathBuf> {
         FileDialog::new().set_directory(dir).pick_folder()
     }
+
+    fn alert(&self, title: impl Into<String>, message: impl Into<String>) {
+        MessageDialog::new()
+            .set_level(MessageLevel::Error)
+            .set_title(title.into())
+            .set_description(message.into())
+            .show();
+    }
 }

v2/src/renderer.rs

@@ -210,4 +210,5 @@ pub trait EventHandler {
     fn handle_user_event(&mut self, event: UserEvent) -> Result<RenderingFlow>;
     fn handle_menu_event(&mut self, item: MenuItem) -> Result<RenderingFlow>;
     fn handle_exit(&self) -> Result<()>;
+    fn handle_error(&self, err: Error) -> RenderingFlow;
 }

v2/src/shiba.rs

@@ -8,8 +8,9 @@ use crate::renderer::{
     RenderingFlow, UserEvent,
 };
 use crate::watcher::{PathFilter, Watcher};
-use anyhow::{Context as _, Result};
+use anyhow::{Context as _, Error, Result};
 use std::collections::VecDeque;
+use std::fmt::Write as _;
 use std::fs;
 use std::mem;
 use std::path::{Path, PathBuf, MAIN_SEPARATOR};
@@ -188,6 +189,17 @@ impl PreviewContent {
     }
 }
 
+fn alert_error<D: Dialog>(dialog: &D, error: &Error) {
+    let mut errs = error.chain();
+    let title = format!("Error: {}", errs.next().unwrap());
+    let mut message = title.clone();
+    for err in errs {
+        write!(message, "\n  Caused by: {}", err).unwrap();
+    }
+    log::error!("{}", message);
+    dialog.alert(title, message);
+}
+
 pub struct Shiba<R: Rendering, O, W, D> {
     renderer: R::Renderer,
     opener: O,
@@ -210,8 +222,13 @@ where
     where
         Self: 'static,
     {
-        let mut rendering = R::new()?;
-        let dog = Self::new(options, &mut rendering)?;
+        fn on_err<D: Dialog>(err: Error) -> Error {
+            let err = err.context("Could not launch application");
+            alert_error(&D::default(), &err);
+            err
+        }
+        let mut rendering = R::new().map_err(on_err::<D>)?;
+        let dog = Self::new(options, &mut rendering).map_err(on_err::<D>)?;
         rendering.start(dog)
     }
 
@@ -506,4 +523,9 @@ where
         data_dir.save_recent_files(self.history.iter(), self.config.max_recent_files())?;
         Ok(())
     }
+
+    fn handle_error(&self, err: Error) -> RenderingFlow {
+        alert_error(&self.dialog, &err);
+        RenderingFlow::Continue
+    }
 }

v2/src/wry/event_loop.rs

@@ -2,7 +2,7 @@ use crate::config::Config;
 use crate::renderer::{EventHandler, Rendering, RenderingFlow, UserEvent, UserEventSender};
 use crate::wry::menu::{Menu, MenuEvents};
 use crate::wry::webview::{EventLoop, WebViewRenderer};
-use anyhow::{Error, Result};
+use anyhow::Result;
 use wry::application::event::{Event, StartCause, WindowEvent};
 use wry::application::event_loop::{ControlFlow, EventLoopBuilder, EventLoopProxy};
 
@@ -73,12 +73,6 @@ impl Rendering for Wry {
         H: EventHandler + 'static,
     {
         self.event_loop.run(move |event, _, control| {
-            fn log_causes(err: Error) {
-                for err in err.chain() {
-                    log::error!("  Caused by: {}", err);
-                }
-            }
-
             let flow = match event {
                 Event::NewEvents(StartCause::Init) => {
                     log::debug!("Application has started");
@@ -89,9 +83,7 @@ impl Rendering for Wry {
                     RenderingFlow::Exit
                 }
                 Event::UserEvent(event) => handler.handle_user_event(event).unwrap_or_else(|err| {
-                    log::error!("Could not handle user event");
-                    log_causes(err);
-                    RenderingFlow::Continue
+                    handler.handle_error(err.context("Could not handle user event"))
                 }),
                 _ => self
                     .menu_events
@@ -101,9 +93,7 @@ impl Rendering for Wry {
                         None => Ok(RenderingFlow::Continue),
                     })
                     .unwrap_or_else(|err| {
-                        log::error!("Could not handle menu event");
-                        log_causes(err);
-                        RenderingFlow::Continue
+                        handler.handle_error(err.context("Could not handle menu event"))
                     }),
             };
 
@@ -112,8 +102,7 @@ impl Rendering for Wry {
                 RenderingFlow::Exit => match handler.handle_exit() {
                     Ok(()) => ControlFlow::Exit,
                     Err(err) => {
-                        log::error!("Could not handle application exit correctly");
-                        log_causes(err);
+                        handler.handle_error(err.context("Could not handle application exit"));
                         ControlFlow::ExitWithCode(1)
                     }
                 },