#[derive(Debug, PartialEq, Clone, Eq)]
pub struct TicketDescription(String);

#[derive(Debug, thiserror::Error)]
pub enum TicketDescriptionError {
    #[error("The description cannot be empty")]
    Empty,
    #[error("The description cannot be longer than 500 characters")]
    TooLong,
}

impl TryFrom<String> for TicketDescription {
    type Error = TicketDescriptionError;

    fn try_from(value: String) -> Result<Self, Self::Error> {
        validate(&value)?;
        Ok(Self(value))
    }
}

impl TryFrom<&str> for TicketDescription {
    type Error = TicketDescriptionError;

    fn try_from(value: &str) -> Result<Self, Self::Error> {
        validate(value)?;
        Ok(Self(value.to_string()))
    }
}

fn validate(description: &str) -> Result<(), TicketDescriptionError> {
    if description.is_empty() {
        Err(TicketDescriptionError::Empty)
    } else if description.len() > 500 {
        Err(TicketDescriptionError::TooLong)
    } else {
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use common::{overly_long_description, valid_description};
    use std::convert::TryFrom;

    #[test]
    fn test_try_from_string() {
        let input = valid_description();
        let description = TicketDescription::try_from(input.clone()).unwrap();
        assert_eq!(description.0, input);
    }

    #[test]
    fn test_try_from_empty_string() {
        let err = TicketDescription::try_from("".to_string()).unwrap_err();
        assert_eq!(err.to_string(), "The description cannot be empty");
    }

    #[test]
    fn test_try_from_long_string() {
        let err = TicketDescription::try_from(overly_long_description()).unwrap_err();
        assert_eq!(
            err.to_string(),
            "The description cannot be longer than 500 characters"
        );
    }

    #[test]
    fn test_try_from_str() {
        let description = TicketDescription::try_from("A description").unwrap();
        assert_eq!(description.0, "A description");
    }
}