[Need comments, low importance] Improve error reporting

Cargo.toml

@@ -4,20 +4,30 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-ashpd = { version = "0.12", default-features = false, features = ["tokio"] }
-chrono = { version = "0.4.41", default-features = false, features = [
-    "alloc",
-    "clock",
+# App
+chrono = { version = "0.4", default-features = false, features = [
+  "alloc",
+  "clock",
 ] }
+clap = { version = "4.5", features = ["derive"] }
 dirs = "6"
-tokio = { version = "1.47.1", default-features = false, features = ["macros"] }
-clap = { version = "4.5.46", features = ["derive"] }
-zbus = { version = "5", default-features = false }
+tokio = { version = "1", default-features = false, features = ["macros"] }
+
+# Screenshots/D-Bus comm
+ashpd = { version = "0.12", default-features = false, features = [
+  "tokio",
+  "tracing",
+] }
+zbus = { version = "5", default-features = false, features = ["tokio"] }
+
+# Logging
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 
 # Internationalization
 i18n-embed = { version = "0.16", features = [
-    "fluent-system",
-    "desktop-requester",
+  "fluent-system",
+  "desktop-requester",
 ] }
 i18n-embed-fl = "0.10"
 rust-embed = "8.5"

i18n/en/cosmic_screenshot.ftl

@@ -1,4 +1,10 @@
 cosmic-screenshot = COSMIC Screenshot
 
 screenshot-saved-to-clipboard = Screenshot saved to clipboard
-screenshot-saved-to = Screenshot saved to:
+screenshot-saved-to = Screenshot saved to:
+
+screenshot-cancelled = Screenshot canceled
+screenshot-dbus-err = Error from D-Bus
+screenshot-failed = Screenshot failed
+screenshot-no-dir = Unable to write screenshot to directory: {$path}
+screenshot-not-allowed = Screenshot not allowed: {$msg}

src/error.rs

@@ -0,0 +1,126 @@
+use std::{
+    error::Error as StdError,
+    fmt::{self, Display},
+    io,
+    path::{Path, PathBuf},
+};
+
+use ashpd::{Error as AshpdError, PortalError, desktop::ResponseError};
+use zbus::Error as ZbusError;
+
+use crate::fl;
+
+/// Error type for requesting screenshots from the XDG portal.
+///
+/// The primary purpose of this type is to provide simple user facing messages.
+#[derive(Debug)]
+pub enum Error {
+    /// Screenshot errors from the portal or D-Bus
+    Ashpd(AshpdError),
+    /// Failure to post a notification
+    Notify(ZbusError),
+    /// Invalid directory path passed AND no Pictures XDG directory
+    MissingSaveDirectory(Option<PathBuf>),
+    /// Screenshot succeeded but cannot be saved
+    SaveScreenshot {
+        error: io::Error,
+        context: &'static str,
+    },
+}
+
+impl StdError for Error {}
+
+// Log facing display messages for programmers or debugging
+impl Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Ashpd(e) => e.fmt(f),
+            Self::Notify(e) => write!(f, "posting a notification: {e}"),
+            Self::MissingSaveDirectory(p) => {
+                let msg = p
+                    .as_deref()
+                    .map(|path| format!("opening `{}` or the Pictures directory", path.display()));
+
+                write!(
+                    f,
+                    "{}",
+                    msg.as_deref().unwrap_or("opening Pictures directory")
+                )
+            }
+            Self::SaveScreenshot { error, context } => write!(f, "{context}: {error}"),
+        }
+    }
+}
+
+impl Error {
+    /// Localized, condensed error message for end users
+    pub fn to_user_facing(&self) -> String {
+        match self {
+            // _ if self.unsupported() => fl!("screenshot-unsupported"),
+            _ if self.cancelled() => fl!("screenshot-cancelled"),
+            _ if self.zbus() => fl!("screenshot-dbus-err"),
+            Self::MissingSaveDirectory(p) => {
+                fl!(
+                    "screenshot-no-dir",
+                    path = p.as_deref().unwrap_or(Path::new("")).to_string_lossy()
+                )
+            }
+            Self::Ashpd(AshpdError::Portal(PortalError::NotAllowed(msg))) => {
+                fl!("screenshot-not-allowed", msg = msg)
+            }
+            // Self::SaveScreenshot { .. } => "Screenshot captured but couldn't be saved".into(),
+            _ => fl!("screenshot-failed"),
+        }
+    }
+
+    /// Screenshot request cancelled
+    pub fn cancelled(&self) -> bool {
+        let Self::Ashpd(e) = self else {
+            return false;
+        };
+
+        match e {
+            AshpdError::Response(e) => *e == ResponseError::Cancelled,
+            AshpdError::Portal(PortalError::Cancelled(_)) => true,
+            _ => false,
+        }
+    }
+
+    /// Portal does not support screenshots
+    pub fn unsupported(&self) -> bool {
+        if let Self::Ashpd(e) = self {
+            match e {
+                // Requires version `x` but interface only supports version `y`
+                AshpdError::RequiresVersion(_, _) => true,
+                // Unsupported screenshot method or interface for screenshots not found
+                AshpdError::Portal(PortalError::ZBus(e)) => {
+                    *e == ZbusError::Unsupported || *e == ZbusError::InterfaceNotFound
+                }
+                AshpdError::Zbus(e) => {
+                    *e == ZbusError::Unsupported || *e == ZbusError::InterfaceNotFound
+                }
+                _ => false,
+            }
+        } else {
+            false
+        }
+    }
+
+    /// D-Bus communication problem
+    ///
+    /// [zbus::Error] encapsulates many different problems, many of which are programmer errors
+    /// which shouldn't occur during normal operation.
+    pub fn zbus(&self) -> bool {
+        matches!(
+            self,
+            Self::Ashpd(AshpdError::Zbus(_))
+                | Self::Ashpd(AshpdError::Portal(PortalError::ZBus(_)))
+        )
+    }
+}
+
+impl From<AshpdError> for Error {
+    fn from(value: AshpdError) -> Self {
+        Self::Ashpd(value)
+    }
+}