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// dl_api
//
// Copyright (c) 2018 Jeron A. Lau
// Copyright (c) 2017 Szymon Wieloch
// Distributed under the MIT LICENSE (See accompanying file LICENSE.txt)

use std::error::Error as ErrorTrait;
use std::fmt::{Display, Formatter, Result as FmtResult};
use std::convert::From;
use std::ffi::NulError;
use std::io::Error as IoError;

/// Error type for this library.
#[derive(Debug)]
pub enum Error {
	///Provided string could not be coverted into `std::ffi::CString` because it contained null
	/// character.
	NullCharacter(NulError),
	///The library could not be opened.
	OpeningLibraryError(IoError),
	///The symbol could not be obtained.
	SymbolGettingError(IoError),
	///Value of the symbol was null.
	NullSymbol,
}

impl ErrorTrait for Error {
	fn description(&self) -> &str {
		match self {
			&Error::NullCharacter(_) => "String had a null character",
			&Error::OpeningLibraryError(_) => "Could not open library",
			&Error::SymbolGettingError(_) => "Could not obtain symbol from the library",
			&Error::NullSymbol => "The symbol is NULL",
		}
	}

	fn cause(&self) -> Option<&ErrorTrait> {
		match self {
			&Error::NullCharacter(ref val) => Some(val),
			&Error::OpeningLibraryError(_) | &Error::SymbolGettingError(_) | &Error::NullSymbol => {
				None
			}
		}
	}
}

impl Display for Error {
	fn fmt(&self, f: &mut Formatter) -> FmtResult {
		f.write_str(self.description())?;
		match self {
			&Error::OpeningLibraryError(ref msg) => {
				f.write_str(": ")?;
				msg.fmt(f)
			}
			&Error::SymbolGettingError(ref msg) => {
				f.write_str(": ")?;
				msg.fmt(f)
			}
			&Error::NullSymbol | &Error::NullCharacter(_) => Ok(()),
		}
	}
}

impl From<Error> for String {
	fn from(error: Error) -> Self {
		format!("{}", error)
	}
}

impl From<NulError> for Error {
	fn from(val: NulError) -> Error {
		Error::NullCharacter(val)
	}
}