Major Subsystem Rewrite (Reconciler Mk5) (#217)

server/src/snapshot_middleware/error.rs

@@ -0,0 +1,99 @@
+use std::{
+    fmt,
+    error::Error,
+    path::PathBuf,
+};
+
+use crate::{
+    snapshot::InstanceSnapshot,
+};
+
+pub type SnapshotResult<'a> = Result<Option<InstanceSnapshot<'a>>, SnapshotError>;
+
+#[derive(Debug)]
+pub struct SnapshotError {
+    detail: SnapshotErrorDetail,
+    path: Option<PathBuf>,
+}
+
+impl SnapshotError {
+    pub fn new(detail: SnapshotErrorDetail, path: Option<impl Into<PathBuf>>) -> Self {
+        SnapshotError {
+            detail,
+            path: path.map(Into::into),
+        }
+    }
+
+    pub(crate) fn file_did_not_exist(path: impl Into<PathBuf>) -> SnapshotError {
+        SnapshotError {
+            detail: SnapshotErrorDetail::FileDidNotExist,
+            path: Some(path.into()),
+        }
+    }
+
+    pub(crate) fn file_name_bad_unicode(path: impl Into<PathBuf>) -> SnapshotError {
+        SnapshotError {
+            detail: SnapshotErrorDetail::FileNameBadUnicode,
+            path: Some(path.into()),
+        }
+    }
+
+    pub(crate) fn file_contents_bad_unicode(
+        inner: std::str::Utf8Error,
+        path: impl Into<PathBuf>,
+    ) -> SnapshotError {
+        SnapshotError {
+            detail: SnapshotErrorDetail::FileContentsBadUnicode {
+                inner,
+            },
+            path: Some(path.into()),
+        }
+    }
+}
+
+impl Error for SnapshotError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        self.detail.source()
+    }
+}
+
+impl fmt::Display for SnapshotError {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match &self.path {
+            Some(path) => write!(formatter, "{} in path {}", self.detail, path.display()),
+            None => write!(formatter, "{}", self.detail),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum SnapshotErrorDetail {
+    FileDidNotExist,
+    FileNameBadUnicode,
+    FileContentsBadUnicode {
+        inner: std::str::Utf8Error,
+    },
+}
+
+impl SnapshotErrorDetail {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        use self::SnapshotErrorDetail::*;
+
+        match self {
+            FileContentsBadUnicode { inner } => Some(inner),
+            _ => None
+        }
+    }
+}
+
+impl fmt::Display for SnapshotErrorDetail {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        use self::SnapshotErrorDetail::*;
+
+        match self {
+            FileDidNotExist => write!(formatter, "file did not exist"),
+            FileNameBadUnicode => write!(formatter, "file name had malformed Unicode"),
+            FileContentsBadUnicode { inner } => write!(formatter, "file had malformed unicode: {}", inner),
+        }
+    }
+}