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use crate::raw::{ExtensibleData, ExtensibleDataFixed};

use super::{preview_u16_from_buf, validate_length, DynamicSizeError, FixedSizeError, Parse, ParseExtend};

extern crate alloc;
use alloc::vec;

impl Parse for ExtensibleDataFixed {
    type Error = FixedSizeError;

    fn from_buf<T: bytes::Buf>(buf: &mut T) -> Result<Self, Self::Error>
    where
        Self: Sized,
    {
        let remaining = buf.remaining();
        validate_length(remaining, Self::SIZE_IN_BYTES, FixedSizeError::UnsufficientExactBytes)?;
        Ok(Self {
            header_id: buf.get_u16_le(),
            data_size: buf.get_u16_le(),
        })
    }

    fn to_buf<T: bytes::BufMut>(&self, buf: &mut T) -> Result<(), Self::Error> {
        let remaining = buf.remaining_mut();
        validate_length(remaining, Self::SIZE_IN_BYTES, FixedSizeError::UnsufficientExactBytes)?;
        buf.put_u16_le(self.header_id);
        buf.put_u16_le(self.data_size);
        Ok(())
    }
}

impl ParseExtend for ExtensibleData {
    type Error = DynamicSizeError;
    type Fixed = ExtensibleDataFixed;

    fn from_buf_fixed<T: bytes::Buf>(buf: &mut T, fixed: Self::Fixed) -> Result<Self, (Self::Error, Self::Fixed)>
    where
        Self: Sized,
    {
        let total = fixed.data_size as usize;
        if let Err(e) = validate_length(buf.remaining(), total, DynamicSizeError::UnsufficientExactBytes) {
            return Err((e, fixed));
        };

        let mut data = vec![0; fixed.data_size as usize];
        buf.copy_to_slice(&mut data);

        Ok(Self { fixed, data })
    }
}

impl Parse for ExtensibleData {
    type Error = DynamicSizeError;

    fn from_buf<T: bytes::Buf>(buf: &mut T) -> Result<Self, Self::Error>
    where
        Self: Sized,
    {
        let remaining = buf.remaining();
        const SIZE: usize = ExtensibleDataFixed::SIZE_IN_BYTES;
        validate_length(remaining, SIZE, DynamicSizeError::UnsufficientAtLeastBytes)?;
        let chunk = buf.chunk();
        let data_length: u16 = preview_u16_from_buf(chunk, SIZE - 2).ok_or(DynamicSizeError::NotContiguous)?;
        let total = SIZE + data_length as usize;
        validate_length(remaining, total, DynamicSizeError::UnsufficientExactBytes)?;

        let fixed = ExtensibleDataFixed::from_buf(buf)?;
        Self::from_buf_fixed(buf, fixed).map_err(|e| e.0)
    }

    fn to_buf<T: bytes::BufMut>(&self, buf: &mut T) -> Result<(), Self::Error> {
        let remaining = buf.remaining_mut();
        let total = ExtensibleDataFixed::SIZE_IN_BYTES + self.data.len();
        validate_length(remaining, total, FixedSizeError::UnsufficientExactBytes)?;
        self.fixed.to_buf(buf)?;
        buf.put_slice(&self.data);
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::{super::*, *};

    #[test]
    fn cycle_local_file_header() {
        let data = vec![48, 49, 32];
        let lf = ExtensibleData {
            fixed: ExtensibleDataFixed {
                header_id: 0x0001,
                data_size: data.len() as u16,
            },
            data:  data.clone(),
        };
        let mut buf = vec![];
        lf.to_buf(&mut buf).unwrap();
        assert_eq!(buf.len(), ExtensibleDataFixed::SIZE_IN_BYTES + data.len());
        let mut readbuf = buf.as_slice();
        let lf2 = ExtensibleData::from_buf(&mut readbuf).unwrap();
        assert_eq!(lf, lf2);
        assert_eq!(lf2.data, data);
    }
}