use std::{error::Error, fmt};

#[derive(Debug)]
enum ErrorType {
    TableAddFieldDuplicate(String),
}

impl fmt::Display for ErrorType {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ErrorType::TableAddFieldDuplicate(data) => write!(f, "field '{}' already exists", data),
        }
    }
}

#[derive(Debug)]
struct MTTError {
    err: ErrorType,
}

impl MTTError {
    fn new(err: ErrorType) -> Self {
        Self { 
            err: err,
        }
    }
}

impl Error for MTTError {}

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

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

    #[test]
    fn get_error() {
        let err = MTTError::new(ErrorType::TableAddFieldDuplicate("tester".to_string()));
        assert_eq!(err.to_string(), "field 'tester' already exists");
        assert!(err.source().is_none());
        let err = MTTError::new(ErrorType::TableAddFieldDuplicate("other".to_string()));
        assert_eq!(err.to_string(), "field 'other' already exists");
        assert!(err.source().is_none());
    }
}