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//! Error handling.
use std::char::ParseCharError;
use std::fmt;
use std::process::exit;

/// Trait that adds the `or_exit_with`  method to a struct. To be used to create a way to retrieve a
/// value, or exit with a specified error code.
pub trait WithOrExit<T> {
    fn or_exit_with(self, exit_code: i32) -> T;
}

impl<T, E: fmt::Debug> WithOrExit<T> for Result<T, E> {
    /// Unwraps the value from a Result, or terminates the process with the specified exit code.
    fn or_exit_with(self, exit_code: i32) -> T {
        match self {
            Ok(v) => v,
            Err(e) => {
                eprintln!("{:?}", e);
                exit(exit_code);
            }
        }
    }
}

impl<T> WithOrExit<T> for Option<T> {
    fn or_exit_with(self, exit_code: i32) -> T {
        match self {
            Some(v) => v,
            None => {
                eprintln!("Empty option");
                exit(exit_code);
            }
        }
    }
}

/// Generic parsing error.
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct ParseError(pub String);

impl ParseError {
    /// Produces a `ParseError` from a `&str`.
    #[deprecated(since = "0.6.1", note = "Please use the parse_error! macro instead.")]
    pub fn of(s: &str) -> ParseError {
        ParseError(s.to_string())
    }
}

impl fmt::Display for ParseError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl From<std::io::Error> for ParseError {
    fn from(err: std::io::Error) -> Self {
        ParseError(format!("{:?}", err))
    }
}

impl From<std::num::ParseIntError> for ParseError {
    fn from(err: std::num::ParseIntError) -> Self {
        ParseError(format!("{:?}", err))
    }
}

impl From<std::char::ParseCharError> for ParseError {
    fn from(err: ParseCharError) -> Self {
        ParseError(format!("{:?}", err))
    }
}

// TODO:
// impl From<std::option::NoneError> for ParseError {
//     fn from(err: std::option::NoneError) -> Self {
//         ParseError(format!("{:?}", err))
//     }
// }

/// Macro to produce a ParseError, with optional interpolation (using format!).
#[macro_export]
macro_rules! parse_error {
    ($err:expr) => {{
        $crate::error::ParseError($err.to_string())
    }};
    ($err:expr, $($args:tt)*) => {{
        $crate::error::ParseError(format!($err, $($args)*))
    }};
}

/// Macro to produce a ParseError wrapped in an Err, with optional interpolation (using format!).
#[macro_export]
macro_rules! err_parse_error {
    ($err:expr) => {{
        Err($crate::parse_error!($err))
    }};
    ($err:expr, $($args:tt)*) => {{
        Err($crate::parse_error!($err, $($args)*))
    }};
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_macro_parse_error_simple() {
        let err = parse_error!["This is a simple error."];
        assert_eq!(err, ParseError("This is a simple error.".to_string()));
    }

    #[test]
    fn test_macro_parse_error_with_formatting() {
        let err = parse_error!["This is an error with {}.", "formatting"];
        assert_eq!(
            err,
            ParseError("This is an error with formatting.".to_string())
        );
    }

    #[test]
    fn test_macro_err_parse_error_simple() {
        let err: Result<(), ParseError> = err_parse_error!["This is a simple error."];
        assert_eq!(err, Err(ParseError("This is a simple error.".to_string())));
    }

    #[test]
    fn test_macro_err_parse_error_with_formatting() {
        let err: Result<(), ParseError> =
            err_parse_error!["This is an error with {}.", "formatting"];

        assert_eq!(
            err,
            Err(ParseError("This is an error with formatting.".to_string()))
        );
    }
}