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

#[derive(Debug)]
pub enum Errors {
    MissingBit,
    InvalidBit,
    MissingLength,
    InvalidLength,
    UnknownType,
    ConversionError{
        byte: u32,
        type_string: String,
    }
}

impl Errors {
    fn conversion(&self) -> &str {
        match self {
            Self::MissingBit => "Missing bit position.",
            Self::InvalidBit => "Invalid value for bit. Expecting u8 between 0 and 7.",
            Self::MissingLength => "Missing data length.",
            Self::InvalidLength => "Invalid value for data_length in DBItem. Expecting u32.",
            Self::UnknownType => "Unknown datatype",
            Self::ConversionError{byte: _, type_string: _} => "Cannot convert data into type.",
        }
    }
}

impl fmt::Display for Errors {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let err_msg = self.conversion();

        write!(f, "{}", err_msg)
    }
}

impl Error for Errors {
    fn description(&self) -> &str {
        self.conversion()
    }
}

pub fn serial_error(name: String, pos: u32) -> anyhow::Error {
    anyhow!(
        "Cannot convert Serial data for type '{}' at position {}.",
        name,
        pos
    )
}

pub fn s7_read_error(name: String, pos: u32) -> anyhow::Error {
    anyhow!("Cannot read Byte for type '{}' at position {}.", name, pos)
}