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//! Utility things.

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

/// Helper `Result` type for easy access.
pub type Ev3Result<T> = Result<T, Ev3Error>;

/// Custom error type for internal errors.
#[derive(Debug)]
pub enum Ev3Error {
    /// Internal error with error `msg`.
    InternalError {
        /// Original error message.
        msg: String,
    },
    /// No matching device found.
    NotConnected {
        /// Corresponding device
        device: String,
        /// Device was expected to be on this port (None if no port was specified)
        port: Option<String>,
    },
    /// More than one matching device found.
    MultipleMatches {
        /// Corresponding device
        device: String,
        /// Devices of the requested type were found on this ports.
        ports: Vec<String>,
    },
}

impl fmt::Display for Ev3Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Ev3Error::InternalError { msg } => write!(f, "InternalError: {}!", msg),
            Ev3Error::NotConnected { device, port } => {
                write!(f, "'{}' not connected at port {:?}!", device, port)
            }
            Ev3Error::MultipleMatches { device, ports } => {
                write!(f, "Multiple '{}' connected at ports {:?}!", device, ports)
            }
        }
    }
}

impl Error for Ev3Error {}

impl From<std::io::Error> for Ev3Error {
    fn from(err: std::io::Error) -> Self {
        Ev3Error::InternalError {
            msg: format!("{}", err),
        }
    }
}

impl From<std::string::FromUtf8Error> for Ev3Error {
    fn from(err: std::string::FromUtf8Error) -> Self {
        Ev3Error::InternalError {
            msg: format!("{}", err),
        }
    }
}

impl From<std::num::ParseIntError> for Ev3Error {
    fn from(err: std::num::ParseIntError) -> Self {
        Ev3Error::InternalError {
            msg: format!("{}", err),
        }
    }
}

#[cfg(feature = "screen")]
impl From<framebuffer::FramebufferError> for Ev3Error {
    fn from(err: framebuffer::FramebufferError) -> Self {
        Ev3Error::InternalError {
            msg: format!("{:?}", err),
        }
    }
}

/// EV3 ports
pub trait Port {
    /// Returns the name of the port.
    fn address(&self) -> String;
}

/// Helper trait to convert an option to an error.
/// Polyfill for the `Try` trait until it is stable.
pub trait OrErr<T> {
    /// Consumes the `Option<T>` and returns an `Ev3Result<T>`.
    fn or_err(self) -> Ev3Result<T>;
}

impl<T> OrErr<T> for Option<T> {
    fn or_err(self) -> Ev3Result<T> {
        self.ok_or(Ev3Error::InternalError {
            msg: "Cannot unwrap option".to_owned(),
        })
    }
}