1 files changed, 63 insertions, 0 deletions
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..e592e50
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,63 @@
+use std::{
+	env,
+	ffi::OsString,
+	fmt::{self, Display, Formatter},
+	io,
+	path::PathBuf,
+};
+
+pub enum Error {
+	BadArgs(Option<lexopt::Error>),
+	BadDecoding(String),
+	BadLengths,
+	DuplicateInput(PathBuf),
+	DuplicateOutput(PathBuf),
+	IO(io::Error),
+	Nop,
+	SpawnFailed(OsString, io::Error),
+}
+
+impl Display for Error {
+	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+		let p = env::args().next().unwrap();
+		match self {
+			Self::BadArgs(o) => {
+				if let Some(v) = o {
+					writeln!(f, "{p}: {v}")?;
+				}
+				writeln!(f, "Usage: {p} [-0eiv] command [argument ...]")
+			}
+			Self::BadDecoding(s) => writeln!(f, "{p}: Decoding the file “{s}” failed!"),
+			Self::BadLengths => writeln!(f, "{p}: Files have been added or removed during editing"),
+			Self::DuplicateInput(s) => writeln!(
+				f,
+				"{p}: Input file “{}” specified more than once",
+				s.to_string_lossy()
+			),
+			Self::DuplicateOutput(s) => writeln!(
+				f,
+				"{p}: Output file “{}” specified more than once",
+				s.to_string_lossy()
+			),
+			Self::IO(e) => writeln!(f, "{p}: {e}"),
+			Self::Nop => Ok(()),
+			Self::SpawnFailed(ed, e) => writeln!(
+				f,
+				"{p}: Failed to spawn utility “{}”: {e}",
+				ed.to_string_lossy()
+			),
+		}
+	}
+}
+
+impl From<io::Error> for Error {
+	fn from(e: io::Error) -> Self {
+		Self::IO(e)
+	}
+}
+
+impl From<lexopt::Error> for Error {
+	fn from(e: lexopt::Error) -> Self {
+		Self::BadArgs(Some(e))
+	}
+}