extern crate ogg_sys;
extern crate vorbis_sys;
extern crate vorbisfile_sys;
extern crate vorbis_encoder;
extern crate libc;
extern crate rand;

use std::io::{self, Read, Seek};

/// Allows you to decode a sound file stream into packets.
pub struct Decoder<R> where R: Read + Seek {
    // further informations are boxed so that a pointer can be passed to callbacks
    data: Box<DecoderData<R>>,
}

///
pub struct PacketsIter<'a, R: 'a + Read + Seek>(&'a mut Decoder<R>);

///
pub struct PacketsIntoIter<R: Read + Seek>(Decoder<R>);

/// Errors that can happen while decoding & encoding
#[derive(Debug)]
pub enum VorbisError {
    ReadError(io::Error),
    NotVorbis,
    VersionMismatch,
    BadHeader,
    Hole,
    InvalidSetup, //         OV_EINVAL - Invalid setup request, eg, out of range argument.
    Unimplemented, //        OV_EIMPL - Unimplemented mode; unable to comply with quality level request.
}

impl std::error::Error for VorbisError {
    fn description(&self) -> &str {
        match self {
            &VorbisError::ReadError(_) => "A read from media returned an error",
            &VorbisError::NotVorbis => "Bitstream does not contain any Vorbis data",
            &VorbisError::VersionMismatch => "Vorbis version mismatch",
            &VorbisError::BadHeader => "Invalid Vorbis bitstream header",
            &VorbisError::InvalidSetup => "Invalid setup request, eg, out of range argument or initial file headers are corrupt",
            &VorbisError::Hole => "Interruption of data",
            &VorbisError::Unimplemented => "Unimplemented mode; unable to comply with quality level request.",
        }
    }

    fn cause(&self) -> Option<&std::error::Error> {
        match self {
            &VorbisError::ReadError(ref err) => Some(err as &std::error::Error),
            _ => None
        }
    }
}

impl std::fmt::Display for VorbisError {
    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        write!(fmt, "{}", std::error::Error::description(self))
    }
}

impl From<io::Error> for VorbisError {
    fn from(err: io::Error) -> VorbisError {
        VorbisError::ReadError(err)
    }
}

struct DecoderData<R> where R: Read + Seek {
    vorbis: vorbisfile_sys::OggVorbis_File,
    reader: R,
    current_logical_bitstream: libc::c_int,
    read_error: Option<io::Error>,
}

unsafe impl<R: Read + Seek + Send> Send for DecoderData<R> {}

/// Packet of data.
///
/// Each sample is an `i16` ranging from I16_MIN to I16_MAX.
///
/// The channels are interleaved in the data. For example if you have two channels, you will
/// get a sample from channel 1, then a sample from channel 2, than a sample from channel 1, etc.
#[derive(Clone, Debug)]
pub struct Packet {
    pub data: Vec<i16>,
    pub channels: u16,
    pub rate: u64,
    pub bitrate_upper: u64,
    pub bitrate_nominal: u64,
    pub bitrate_lower: u64,
    pub bitrate_window: u64,
}

impl<R> Decoder<R> where R: Read + Seek {
    pub fn new(input: R) -> Result<Decoder<R>, VorbisError> {
        extern fn read_func<R>(ptr: *mut libc::c_void, size: libc::size_t, nmemb: libc::size_t,
            datasource: *mut libc::c_void) -> libc::size_t where R: Read + Seek
        {
            use std::slice;

            /*
             * In practice libvorbisfile always sets size to 1.
             * This assumption makes things much simpler
             */
            assert_eq!(size, 1);

            let ptr = ptr as *mut u8;

            let data: &mut DecoderData<R> = unsafe { std::mem::transmute(datasource) };

            let buffer = unsafe { slice::from_raw_parts_mut(ptr as *mut u8, nmemb as usize) };

            loop {
                match data.reader.read(buffer) {
                    Ok(nb) => return nb as libc::size_t,
                    Err(ref e) if e.kind() == io::ErrorKind::Interrupted => (),
                    Err(e) => {
                        data.read_error = Some(e);
                        return 0
                    }
                }
            }
        }

        extern fn seek_func<R>(datasource: *mut libc::c_void, offset: ogg_sys::ogg_int64_t,
            whence: libc::c_int) -> libc::c_int where R: Read + Seek
        {
            let data: &mut DecoderData<R> = unsafe { std::mem::transmute(datasource) };

            let result = match whence {
                libc::SEEK_SET => data.reader.seek(io::SeekFrom::Start(offset as u64)),
                libc::SEEK_CUR => data.reader.seek(io::SeekFrom::Current(offset)),
                libc::SEEK_END => data.reader.seek(io::SeekFrom::End(offset)),
                _ => unreachable!()
            };

            match result {
                Ok(_) => 0,
                Err(_) => -1
            }
        }

        extern fn tell_func<R>(datasource: *mut libc::c_void) -> libc::c_long
            where R: Read + Seek
        {
            let data: &mut DecoderData<R> = unsafe { std::mem::transmute(datasource) };
            data.reader.seek(io::SeekFrom::Current(0)).map(|v| v as libc::c_long).unwrap_or(-1)
        }

        let callbacks = {
            let mut callbacks: vorbisfile_sys::ov_callbacks = unsafe { std::mem::zeroed() };
            callbacks.read_func = read_func::<R>;
            callbacks.seek_func = seek_func::<R>;
            callbacks.tell_func = tell_func::<R>;
            callbacks
        };

        let mut data = Box::new(DecoderData {
            vorbis: unsafe { std::mem::uninitialized() },
            reader: input,
            current_logical_bitstream: 0,
            read_error: None,
        });

        // initializing
        unsafe {
            let data_ptr = &mut *data as *mut DecoderData<R>;
            let data_ptr = data_ptr as *mut libc::c_void;
            try!(check_errors(vorbisfile_sys::ov_open_callbacks(data_ptr, &mut data.vorbis,
                std::ptr::null(), 0, callbacks)));
        }

        Ok(Decoder {
            data: data,
        })
    }

    pub fn time_seek(&mut self, s: f64) -> Result<(), VorbisError> {
        unsafe {
            check_errors(vorbisfile_sys::ov_time_seek(&mut self.data.vorbis, s))
        }
    }

    pub fn time_tell(&mut self) -> Result<f64, VorbisError> {
        unsafe {
            Ok(vorbisfile_sys::ov_time_tell(&mut self.data.vorbis))
        }
    }

    pub fn packets(&mut self) -> PacketsIter<R> {
        PacketsIter(self)
    }

    pub fn into_packets(self) -> PacketsIntoIter<R> {
        PacketsIntoIter(self)
    }

    fn next_packet(&mut self) -> Option<Result<Packet, VorbisError>> {
        let mut buffer = std::iter::repeat(0i16).take(2048).collect::<Vec<_>>();
        let buffer_len = buffer.len() * 2;

        match unsafe {
            vorbisfile_sys::ov_read(&mut self.data.vorbis,
                buffer.as_mut_ptr() as *mut libc::c_char,
                buffer_len as libc::c_int, 0, 2, 1, &mut self.data.current_logical_bitstream)
        } {
            0 => {
                match self.data.read_error.take() {
                    Some(err) => Some(Err(VorbisError::ReadError(err))),
                    None => None,
                }
            },

            err if err < 0 => {
                match check_errors(err as libc::c_int) {
                    Err(e) => Some(Err(e)),
                    Ok(_) => unreachable!()
                }
            },

            len => {
                buffer.truncate(len as usize / 2);

                let infos = unsafe { vorbisfile_sys::ov_info(&mut self.data.vorbis,
                    self.data.current_logical_bitstream) };

                let infos: &vorbis_sys::vorbis_info = unsafe { std::mem::transmute(infos) };

                Some(Ok(Packet {
                    data: buffer,
                    channels: infos.channels as u16,
                    rate: infos.rate as u64,
                    bitrate_upper: infos.bitrate_upper as u64,
                    bitrate_nominal: infos.bitrate_nominal as u64,
                    bitrate_lower: infos.bitrate_lower as u64,
                    bitrate_window: infos.bitrate_window as u64,
                }))
            }
        }
    }
}

impl<'a, R> Iterator for PacketsIter<'a, R> where R: 'a + Read + Seek {
    type Item = Result<Packet, VorbisError>;

    fn next(&mut self) -> Option<Result<Packet, VorbisError>> {
        self.0.next_packet()
    }
}

impl<R> Iterator for PacketsIntoIter<R> where R: Read + Seek {
    type Item = Result<Packet, VorbisError>;

    fn next(&mut self) -> Option<Result<Packet, VorbisError>> {
        self.0.next_packet()
    }
}

impl<R> Drop for Decoder<R> where R: Read + Seek {
    fn drop(&mut self) {
        unsafe {
            vorbisfile_sys::ov_clear(&mut self.data.vorbis);
        }
    }
}

fn check_errors(code: libc::c_int) -> Result<(), VorbisError> {
    match code {
        0 => Ok(()),

        vorbis_sys::OV_ENOTVORBIS => Err(VorbisError::NotVorbis),
        vorbis_sys::OV_EVERSION => Err(VorbisError::VersionMismatch),
        vorbis_sys::OV_EBADHEADER => Err(VorbisError::BadHeader),
        vorbis_sys::OV_EINVAL => Err(VorbisError::InvalidSetup),
        vorbis_sys::OV_HOLE => Err(VorbisError::Hole),

        vorbis_sys::OV_EREAD => unimplemented!(),

        vorbis_sys::OV_EIMPL => Err(VorbisError::Unimplemented),

        // indicates a bug or heap/stack corruption
        vorbis_sys::OV_EFAULT => panic!("Internal libvorbis error"),
        _ => panic!("Unknown vorbis error {}", code)
    }
}

#[derive(Debug)]
pub enum VorbisQuality {
    VeryHighQuality,
    HighQuality,
    Quality,
    Midium,
    Performance,
    HighPerforamnce,
    VeryHighPerformance,
}

pub struct Encoder {
    e: vorbis_encoder::Encoder,
}

impl Encoder {
    pub fn new(channels: u8, rate: u64, quality: VorbisQuality) -> Result<Self, VorbisError> {
        let quality = match quality {
            VorbisQuality::VeryHighQuality => {1.0f32},
            VorbisQuality::HighQuality => {0.8f32},
            VorbisQuality::Quality => {0.6f32},
            VorbisQuality::Midium => {0.4f32},
            VorbisQuality::Performance => {0.3f32},
            VorbisQuality::HighPerforamnce => {0.1f32},
            VorbisQuality::VeryHighPerformance => {-0.1f32},
        };
        Ok(Encoder {
            e: match vorbis_encoder::Encoder::new(channels as u32, rate, quality) {
                Ok(e) => {e},
                Err(i) => {
                    match check_errors(i) {
                        Ok(()) => panic!("Unexpected behavior, call hossein.noroozpour@gmail.com"),
                        Err(err) => return Err(err),
                    }
                }
            }
        })
    }

    // data is an interleaved array of samples
    pub fn encode(&mut self, data: &Vec<i16>) -> Result<Vec<u8>, VorbisError> {
        Ok(
            match self.e.encode(&data) {
                Ok(d) => {d},
                Err(i) => {
                    match check_errors(i) {
                        Ok(()) => panic!("Unexpected behavior, call hossein.noroozpour@gmail.com"),
                        Err(err) => return Err(err),
                    }
                }
            }
        )
    }

    pub fn flush(&mut self) -> Result<Vec<u8>, VorbisError> {
        Ok(
            match self.e.flush() {
                Ok(d) => {d},
                Err(i) => {
                    match check_errors(i) {
                        Ok(()) => panic!("Unexpected behavior, call hossein.noroozpour@gmail.com"),
                        Err(err) => return Err(err),
                    }
                }
            }
        )
    }
}