// MIT License
//
// Copyright (c) 2023 Robin Doer
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

#[cfg(test)]
mod tests;

use thiserror::Error;

/// Error type for the [`TakeBytes`] trait.
#[derive(Debug, Error, PartialEq)]
pub enum TakeBytesError {
    /// Failed to read the requested number of bytes. No more bytes are
    /// available for reading.
    #[error("no more bytes are available for reading")]
    Eof,
}

/// Trait that describes a reader of binary data.
///
/// The [`Reader`](crate::Reader) utility accepts all types that implements
/// this trait.
pub trait TakeBytes {
    /// Reads some bytes from the source and puts them into the given buffer
    /// `buf`.
    ///
    /// # Errors
    ///
    /// If not enough data are available to fill `buf` the implementator should
    /// return a [`TakeBytesError::Eof`] error.
    fn take_bytes(&mut self, buf: &mut [u8]) -> Result<(), TakeBytesError>;
}

/// `TakeBytes` is implemented for `&[u8]` by taking the first part of the
/// slice.
///
/// Note that taking bytes updates the slice to point to the yet unread part.
/// The slice will be empty when EOF is reached.
impl TakeBytes for &[u8] {
    fn take_bytes(&mut self, buf: &mut [u8]) -> Result<(), TakeBytesError> {
        if buf.len() <= self.len() {
            let (a, b) = self.split_at(buf.len());

            *self = b;
            buf.copy_from_slice(a);

            Ok(())
        } else {
            Err(TakeBytesError::Eof)
        }
    }
}
