1 files changed, 72 insertions, 0 deletions
diff --git a/apps/cassiopeia/src/error.rs b/apps/cassiopeia/src/error.rs
new file mode 100644
index 000000000000..31f5414c4f86
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+++ b/apps/cassiopeia/src/error.rs
@@ -0,0 +1,72 @@
+//! A set of error types for cassiopeia
+
+use std::error::Error;
+use std::fmt::{self, Display, Formatter};
+
+/// User errors that can occur when using cassiopeia
+///
+/// None of these errors are the fault of the program, but rather
+/// fault of the user for giving invalid commands.  They must never
+/// make the program crash, but instead need to print human friendly
+/// error messages.
+#[derive(Debug)]
+pub enum UserError {
+    /// Trying to start a session when one exists
+    ActiveSessionExists,
+    /// Trying to stop a session when none exists
+    NoActiveSession,
+    /// Trying to create a second invoice on the same day
+    SameDayInvoice,
+    /// No work was done since the last invoice
+    NoWorkInvoice,
+}
+
+impl Display for UserError {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "You're doing it wrong!")
+    }
+}
+
+impl Error for UserError {}
+
+pub type UserResult<T> = Result<T, UserError>;
+
+/// Errors that occur when parsing a file
+///
+/// These errors can pre-maturely terminate the run of the program,
+/// but must print a detailed error about what is wrong.  Also,
+/// because they are technically a superset of
+/// [`UserError`](self::UserError), one of the variants is an embedded
+/// user error.
+#[derive(Debug)]
+pub enum ParseError {
+    /// An embedded user error
+    ///
+    /// This error means that the structure of the parsed file is
+    /// wrong, with an invalid sequence of events expressed
+    User(UserError),
+    /// An invalid keyword was found
+    BadKeyword { line: usize, tokn: String },
+    /// A bad timestamp was found
+    BadTimestamp { line: usize, tokn: String },
+    /// A bad date was found
+    BadDate { line: usize, tokn: String },
+    /// An unknown parse error occured
+    Unknown,
+}
+
+impl Display for ParseError {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "The parsed file was bad :(")
+    }
+}
+
+impl Error for ParseError {}
+
+pub type ParseResult<T> = Result<T, ParseError>;
+
+impl From<UserError> for ParseError {
+    fn from(user: UserError) -> Self {
+        ParseError::User(user)
+    }
+}