//! Reader-based compression/decompression streams

use std::io::prelude::*;
use std::io::{self, BufReader};

use bufread;
use Compression;

/// A compression stream which wraps an uncompressed stream of data. Compressed
/// data will be read from the stream.
pub struct BzEncoder<R: Read> {
    inner: bufread::BzEncoder<BufReader<R>>,
}

/// A decompression stream which wraps a compressed stream of data. Decompressed
/// data will be read from the stream.
pub struct BzDecoder<R: Read> {
    inner: bufread::BzDecoder<BufReader<R>>,
}

impl<R: Read> BzEncoder<R> {
    /// Create a new compression stream which will compress at the given level
    /// to read compress output to the give output stream.
    pub fn new(r: R, level: Compression) -> BzEncoder<R> {
        BzEncoder {
            inner: bufread::BzEncoder::new(BufReader::new(r), level),
        }
    }

    /// Acquires a reference to the underlying stream
    pub fn get_ref(&self) -> &R {
        self.inner.get_ref().get_ref()
    }

    /// Acquires a mutable reference to the underlying stream
    ///
    /// Note that mutation of the stream may result in surprising results if
    /// this encoder is continued to be used.
    pub fn get_mut(&mut self) -> &mut R {
        self.inner.get_mut().get_mut()
    }

    /// Unwrap the underlying writer, finishing the compression stream.
    pub fn into_inner(self) -> R {
        self.inner.into_inner().into_inner()
    }

    /// Returns the number of bytes produced by the compressor
    /// (e.g. the number of bytes read from this stream)
    ///
    /// Note that, due to buffering, this only bears any relation to
    /// total_in() when the compressor chooses to flush its data
    /// (unfortunately, this won't happen this won't happen in general
    /// at the end of the stream, because the compressor doesn't know
    /// if there's more data to come).  At that point,
    /// `total_out() / total_in()` would be the compression ratio.
    pub fn total_out(&self) -> u64 {
        self.inner.total_out()
    }

    /// Returns the number of bytes consumed by the compressor
    /// (e.g. the number of bytes read from the underlying stream)
    pub fn total_in(&self) -> u64 {
        self.inner.total_in()
    }
}

impl<R: Read> Read for BzEncoder<R> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.inner.read(buf)
    }
}

impl<R: Read> BzDecoder<R> {
    /// Create a new decompression stream, which will read compressed
    /// data from the given input stream and decompress it.
    pub fn new(r: R) -> BzDecoder<R> {
        BzDecoder {
            inner: bufread::BzDecoder::new(BufReader::new(r)),
        }
    }

    /// Acquires a reference to the underlying stream
    pub fn get_ref(&self) -> &R {
        self.inner.get_ref().get_ref()
    }

    /// Acquires a mutable reference to the underlying stream
    ///
    /// Note that mutation of the stream may result in surprising results if
    /// this encoder is continued to be used.
    pub fn get_mut(&mut self) -> &mut R {
        self.inner.get_mut().get_mut()
    }

    /// Unwrap the underlying writer, finishing the compression stream.
    pub fn into_inner(self) -> R {
        self.inner.into_inner().into_inner()
    }

    /// Returns the number of bytes produced by the decompressor
    /// (e.g. the number of bytes read from this stream)
    ///
    /// Note that, due to buffering, this only bears any relation to
    /// total_in() when the decompressor reaches a sync point
    /// (e.g. where the original compressed stream was flushed).
    /// At that point, `total_in() / total_out()` is the compression ratio.
    pub fn total_out(&self) -> u64 {
        self.inner.total_out()
    }

    /// Returns the number of bytes consumed by the decompressor
    /// (e.g. the number of bytes read from the underlying stream)
    pub fn total_in(&self) -> u64 {
        self.inner.total_in()
    }
}

impl<R: Read> Read for BzDecoder<R> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.inner.read(buf)
    }
}

#[cfg(test)]
mod tests {
    use std::io::prelude::*;
    use read::{BzEncoder, BzDecoder};
    use Compression;
    use rand::{thread_rng, Rng};

    #[test]
    fn smoke() {
        let m: &[u8] = &[1, 2, 3, 4, 5, 6, 7, 8];
        let mut c = BzEncoder::new(m, Compression::Default);
        let mut data = vec![];
        c.read_to_end(&mut data).unwrap();
        let mut d = BzDecoder::new(&data[..]);
        let mut data2 = Vec::new();
        d.read_to_end(&mut data2).unwrap();
        assert_eq!(data2, m);
    }

    #[test]
    fn smoke2() {
        let m: &[u8] = &[1, 2, 3, 4, 5, 6, 7, 8];
        let c = BzEncoder::new(m, Compression::Default);
        let mut d = BzDecoder::new(c);
        let mut data = vec![];
        d.read_to_end(&mut data).unwrap();
        assert_eq!(data, [1, 2, 3, 4, 5, 6, 7, 8]);
    }

    #[test]
    fn smoke3() {
        let m = vec![3u8; 128 * 1024 + 1];
        let c = BzEncoder::new(&m[..], Compression::Default);
        let mut d = BzDecoder::new(c);
        let mut data = vec![];
        d.read_to_end(&mut data).unwrap();
        assert!(data == &m[..]);
    }

    #[test]
    fn self_terminating() {
        let m = vec![3u8; 128 * 1024 + 1];
        let mut c = BzEncoder::new(&m[..], Compression::Default);

        let mut result = Vec::new();
        c.read_to_end(&mut result).unwrap();

        let v = thread_rng().gen_iter::<u8>().take(1024).collect::<Vec<_>>();
        for _ in 0..200 {
            result.extend(v.iter().map(|x| *x));
        }

        let mut d = BzDecoder::new(&result[..]);
        let mut data = Vec::with_capacity(m.len());
        unsafe { data.set_len(m.len()); }
        assert!(d.read(&mut data).unwrap() == m.len());
        assert!(data == &m[..]);
    }

    #[test]
    fn zero_length_read_at_eof() {
        let m = Vec::new();
        let mut c = BzEncoder::new(&m[..], Compression::Default);

        let mut result = Vec::new();
        c.read_to_end(&mut result).unwrap();

        let mut d = BzDecoder::new(&result[..]);
        let mut data = Vec::new();
        assert!(d.read(&mut data).unwrap() == 0);
    }

    #[test]
    fn zero_length_read_with_data() {
        let m = vec![3u8; 128 * 1024 + 1];
        let mut c = BzEncoder::new(&m[..], Compression::Default);

        let mut result = Vec::new();
        c.read_to_end(&mut result).unwrap();

        let mut d = BzDecoder::new(&result[..]);
        let mut data = Vec::new();
        assert!(d.read(&mut data).unwrap() == 0);
    }
}