scte35-reader 0.2.0

extern crate mpeg2ts_reader;
extern crate bitreader;
#[cfg(test)]
#[macro_use]
extern crate hex_literal;
#[cfg(test)]
#[macro_use]
extern crate matches;

use std::fmt;
use mpeg2ts_reader::psi;
use mpeg2ts_reader::demultiplex;

#[derive(Debug,PartialEq)]
pub enum EncryptionAlgorithm {
    None,
    DesEcb,
    DesCbc,
    TripleDesEde3Ecb,
    Reserved(u8),
    Private(u8),
}
impl EncryptionAlgorithm {
    pub fn from_id(id: u8) -> EncryptionAlgorithm {
        match id {
            0 => EncryptionAlgorithm::None,
            1 => EncryptionAlgorithm::DesEcb,
            2 => EncryptionAlgorithm::DesCbc,
            3 => EncryptionAlgorithm::TripleDesEde3Ecb,
            _ => {
                if id < 32 {
                    EncryptionAlgorithm::Reserved(id)
                } else {
                    EncryptionAlgorithm::Private(id)
                }
            }
        }
    }
}

#[derive(Debug)]
pub enum SpliceCommandType {
    SpliceNull,
    Reserved(u8),
    SpliceSchedule,
    SpliceInsert,
    TimeSignal,
    BandwidthReservation,
    PrivateCommand,
}
impl SpliceCommandType {
    pub fn from_id(id: u8) -> SpliceCommandType {
        match id {
            0x00 => SpliceCommandType::SpliceNull,
            0x04 => SpliceCommandType::SpliceSchedule,
            0x05 => SpliceCommandType::SpliceInsert,
            0x06 => SpliceCommandType::TimeSignal,
            0x07 => SpliceCommandType::BandwidthReservation,
            0xff => SpliceCommandType::PrivateCommand,
            _ => SpliceCommandType::Reserved(id),
        }
    }
}

pub struct SpliceInfoHeader<'a> {
    buf: &'a[u8],
}
impl<'a> SpliceInfoHeader<'a> {
    const HEADER_LENGTH: usize = 11;

    pub fn new(buf: &'a[u8]) -> (SpliceInfoHeader<'a>, &'a[u8]) {
        if buf.len() < 11 {
            panic!("buffer too short: {} (expected 11)", buf.len());
        }
        let (head, tail) = buf.split_at(11);
        (SpliceInfoHeader { buf: head }, tail)
    }

    pub fn protocol_version(&self) -> u8 {
        self.buf[0]
    }
    pub fn encrypted_packet(&self) -> bool {
        self.buf[1] & 0b1000_0000 != 0
    }
    pub fn encryption_algorithm(&self) -> EncryptionAlgorithm {
        EncryptionAlgorithm::from_id((self.buf[1] & 0b0111_1110) >> 1)
    }
    pub fn pts_adjustment(&self) -> u64 {
        u64::from(self.buf[1] & 1) << 32
            |u64::from(self.buf[2]) << 24
            |u64::from(self.buf[3]) << 16
            |u64::from(self.buf[4]) << 8
            |u64::from(self.buf[5])
    }
    pub fn cw_index(&self) -> u8 {
        self.buf[6]
    }
    pub fn tier(&self) -> u16 {
        u16::from(self.buf[7]) << 4
            |u16::from(self.buf[8]) >> 4
    }
    pub fn splice_command_length(&self) -> u16 {
        u16::from(self.buf[8] & 0b00001111) << 8
            |u16::from(self.buf[9])
    }
    pub fn splice_command_type(&self) -> SpliceCommandType {
        SpliceCommandType::from_id(self.buf[10])
    }
}
impl<'a> fmt::Debug for SpliceInfoHeader<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(),fmt::Error> {
        write!(f, "SpliceInfoHeader {{ protocol_version: {:?}, encrypted_packet: {:?}, encryption_algorithm: {:?}, pts_adjustment: {:?}, cw_index: {:?}, tier: {:?} }}",
               self.protocol_version(),
               self.encrypted_packet(),
               self.encryption_algorithm(),
               self.pts_adjustment(),
               self.cw_index(),
               self.tier())
    }
}

#[derive(Debug)]
pub enum SpliceCommand {
    SpliceNull { },
    SpliceInsert {
        splice_event_id: u32,
        reserved: u8,
        splice_detail: SpliceInsert,
    }
}

#[derive(Debug)]
pub enum NetworkIndicator {
    Out,
    In
}
impl NetworkIndicator {
    /// panics if `id` is something other than `0` or `1`
    pub fn from_flag(id: u8) -> NetworkIndicator {
        match id {
            0 => NetworkIndicator::In,
            1 => NetworkIndicator::Out,
            _ => panic!("Invalid out_of_network_indicator value: {} (expected 0 or 1)", id),
        }
    }
}

#[derive(Debug)]
pub enum SpliceInsert {
    Cancel,
    Insert {
        network_indicator: NetworkIndicator,
        splice_mode: SpliceMode,
        duration: Option<SpliceDuration>,
        unique_program_id: u16,
        avail_num: u8,
        avails_expected: u8,
    }
}

#[derive(Debug)]
pub enum SpliceTime {
    Immediate,
    Timed(Option<u64>),
}

#[derive(Debug)]
pub struct ComponentSplice {
    component_tag: u8,
    splice_time: SpliceTime,
}

#[derive(Debug)]
pub enum SpliceMode {
    Program(SpliceTime),
    Components(Vec<ComponentSplice>)
}

#[derive(Debug)]
pub enum ReturnMode {
    Automatic,
    Manual,
}
impl ReturnMode {
    pub fn from_flag(flag: u8) -> ReturnMode {
        match flag {
            0 => ReturnMode::Manual,
            1 => ReturnMode::Automatic,
            _ => panic!("Invalid auto_return value: {} (expected 0 or 1)", flag),
        }
    }
}

#[derive(Debug)]
pub struct SpliceDuration {
    return_mode: ReturnMode,
    duration: u64,
}

pub trait SpliceInfoProcessor {
    fn process(&self, header: SpliceInfoHeader, command: SpliceCommand, descriptors: SpliceDescriptorIter);
}

#[derive(Debug)]
pub enum SpliceDescriptor {
    AvailDescriptor {
        provider_avail_id: u32,
    },
    DTMFDescriptor,  // TODO
    SegmentationDescriptor,  // TODO
    TimeDescriptor,  // TODO
    Reserved {
        tag: u8,
        identifier: [u8; 4],
        private_bytes: Vec<u8>,
    },
}
impl SpliceDescriptor {
    fn parse(buf: &[u8]) -> SpliceDescriptor {
        let splice_descriptor_tag = buf[0];
        let id = &buf[2..5];
        if id != b"CUEI" {
            return SpliceDescriptor::Reserved {
                tag: splice_descriptor_tag,
                identifier: [id[0], id[1], id[2], id[3]],
                private_bytes: buf[6..].to_owned(),
            };
        }
        match splice_descriptor_tag {
            0x00 => SpliceDescriptor::AvailDescriptor {
                provider_avail_id: u32::from(buf[6])<<24 | u32::from(buf[7])<<16 | u32::from(buf[8])<<8 | u32::from(buf[9])
            },
            0x01 => SpliceDescriptor::DTMFDescriptor,
            0x02 => SpliceDescriptor::SegmentationDescriptor,
            0x03 => SpliceDescriptor::TimeDescriptor,
            _ => SpliceDescriptor::Reserved {
                tag: splice_descriptor_tag,
                identifier: [id[0], id[1], id[2], id[3]],
                private_bytes: buf[6..].to_owned(),
            }
        }
    }
}

#[derive(Debug)]
pub enum SpliceDescriptorErr {
    InvalidDescriptorLength(u8),
    NotEnoughData { expected: u8, actual: u8 }
}

pub struct SpliceDescriptorIter<'buf> {
    buf: &'buf[u8],
}
impl<'buf> SpliceDescriptorIter<'buf> {
    fn new(buf: &'buf[u8]) -> SpliceDescriptorIter {
        SpliceDescriptorIter { buf }
    }
}
impl<'buf> Iterator for SpliceDescriptorIter<'buf> {
    type Item = Result<SpliceDescriptor, SpliceDescriptorErr>;

    fn next(&mut self) -> Option<Self::Item> {
        if self.buf.is_empty() {
            return None;
        }
        if self.buf.len() < 6 {
            self.buf = &self.buf[0..0];
            return Some(Err(SpliceDescriptorErr::NotEnoughData{
                expected: 2,
                actual: self.buf.len() as u8
            }));
        }
        let descriptor_length = self.buf[1];
        if self.buf.len() < usize::from(descriptor_length+2) {
            self.buf = &self.buf[0..0];
            return Some(Err(SpliceDescriptorErr::NotEnoughData{
                expected: descriptor_length+2,
                actual: self.buf.len() as u8
            }));
        }
        if descriptor_length > 254 {
            self.buf = &self.buf[0..0];
            return Some(Err(SpliceDescriptorErr::InvalidDescriptorLength(descriptor_length)));
        }
        let (desc, rest) = self.buf.split_at(usize::from(2+descriptor_length));
        let result = SpliceDescriptor::parse(desc);
        self.buf = rest;
        Some(Ok(result))
    }
}

pub struct Scte35SectionProcessor<P>
where
    P: SpliceInfoProcessor
{
    processor: P,
}
impl<P> psi::SectionProcessor for Scte35SectionProcessor<P>
where
    P: SpliceInfoProcessor
{
    type Ret = demultiplex::FilterChangeset;

    fn start_section<'a>(&mut self, header: &psi::SectionCommonHeader, data: &'a [u8]) -> Option<Self::Ret> {
        if header.table_id == 0xfc {
            let section_data = &data[psi::SectionCommonHeader::SIZE..];
            if section_data.len() < SpliceInfoHeader::HEADER_LENGTH + 4 {
                println!("section data too short: {} (must be at least {})", section_data.len(), SpliceInfoHeader::HEADER_LENGTH + 4);
                return None
            }
            // trim off the 32-bit CRC, TODO: check the CRC!  (possibly in calling code rather than here?)
            let section_data = &section_data[..section_data.len()-4];
            let (splice_header, rest) = SpliceInfoHeader::new(section_data);
            //println!("splice header len={}, type={:?}", splice_header.splice_command_length(), splice_header.splice_command_type());
            let (payload, rest) = rest.split_at(splice_header.splice_command_length() as usize); //FIXME: validate indexes
            let descriptor_loop_length =
                u16::from(rest[0]) << 8
                    | u16::from(rest[1]);
            let descriptors = &rest[2..2+descriptor_loop_length as usize];
            let splice_command = match splice_header.splice_command_type() {
                SpliceCommandType::SpliceNull => Some(Self::splice_null(payload)),
                SpliceCommandType::SpliceInsert => Some(Self::splice_insert(payload)),
                _ => None,
            };
            if let Some(splice_command) = splice_command {
                self.processor.process(splice_header, splice_command, SpliceDescriptorIter::new(descriptors));
            } else {
                println!("unhandled command {:?}", splice_header.splice_command_type());
            }
        } else {
            println!("bad table_id for scte35: {:#x} (expected 0xfc)", header.table_id);
        }
        None
    }

    fn continue_section<'a>(&mut self, _section_data: &'a [u8]) -> Option<Self::Ret> {
        unimplemented!()
    }

    fn reset(&mut self) {
        unimplemented!()
    }
}
impl<P> Scte35SectionProcessor<P>
where
    P: SpliceInfoProcessor
{
    // FIXME: get rid of all unwrap()

    pub fn new(processor: P) -> Scte35SectionProcessor<P> {
        Scte35SectionProcessor {
            processor
        }
    }
    fn splice_null(payload: &[u8]) -> SpliceCommand {
        assert_eq!(0, payload.len());
        SpliceCommand::SpliceNull { }
    }

    fn splice_insert(payload: &[u8]) -> SpliceCommand {
        let mut r = bitreader::BitReader::new(payload);

        let splice_event_id = r.read_u32(32).unwrap();
        let splice_event_cancel_indicator = r.read_bool().unwrap();
        let reserved = r.read_u8(7).unwrap();
        let result = SpliceCommand::SpliceInsert {
            splice_event_id,
            reserved,
            splice_detail: Self::read_splice_detail(&mut r, splice_event_cancel_indicator)
        };
        assert_eq!(r.position() as usize, payload.len()*8);
        result
    }

    fn read_splice_detail(r: &mut bitreader::BitReader, splice_event_cancel_indicator: bool) -> SpliceInsert {
        if splice_event_cancel_indicator {
            SpliceInsert::Cancel
        } else {
            let network_indicator = NetworkIndicator::from_flag(r.read_u8(1).unwrap());
            let program_splice_flag = r.read_bool().unwrap();
            let duration_flag = r.read_bool().unwrap();
            let splice_immediate_flag = r.read_bool().unwrap();
            r.skip(4).unwrap();  // reserved

            SpliceInsert::Insert {
                network_indicator,
                splice_mode: Self::read_splice_mode(r, program_splice_flag, splice_immediate_flag),
                duration: if duration_flag { Some(Self::read_duration(r)) } else { None },
                unique_program_id: r.read_u16(16).unwrap(),
                avail_num: r.read_u8(8).unwrap(),
                avails_expected: r.read_u8(8).unwrap(),
            }
        }
    }

    fn read_splice_mode(r: &mut bitreader::BitReader, program_splice_flag: bool, splice_immediate_flag: bool) -> SpliceMode {
        if program_splice_flag {
            let time = if splice_immediate_flag {
                SpliceTime::Immediate
            } else {
                SpliceTime::Timed(Self::read_splice_time(r))
            };
            SpliceMode::Program(time)
        } else {
            let component_count = r.read_u8(8).unwrap();
            let compomemts = (0..component_count).map(|_| {
                let component_tag = r.read_u8(8).unwrap();
                let splice_time = if splice_immediate_flag {
                    SpliceTime::Immediate
                } else {
                    SpliceTime::Timed(Self::read_splice_time(r))
                };
                ComponentSplice { component_tag, splice_time }
            }).collect();
            SpliceMode::Components(compomemts)
        }
    }

    fn read_splice_time(r: &mut bitreader::BitReader) -> Option<u64> {
        if r.read_bool().unwrap_or(false) {
            r.skip(6).unwrap();  // reserved
            r.read_u64(33).ok()
        } else {
            r.skip(7).unwrap();  // reserved
            None
        }
    }

    fn read_duration(r: &mut bitreader::BitReader) -> SpliceDuration {
        let return_mode = ReturnMode::from_flag(r.read_u8(1).unwrap());
        r.skip(6).unwrap();
        SpliceDuration {
            return_mode,
            duration: r.read_u64(33).unwrap(),
        }
    }
}

#[cfg(test)]
mod tests {
    use mpeg2ts_reader::psi;
    use mpeg2ts_reader::psi::SectionProcessor;
    use super::*;

    struct MockSpliceProcessor;
    impl SpliceInfoProcessor for MockSpliceProcessor {
        fn process(&self, header: SpliceInfoHeader, command: SpliceCommand, descriptors: SpliceDescriptorIter) {
            assert_eq!(header.encryption_algorithm(), EncryptionAlgorithm::None);
            assert_matches!(command, SpliceCommand::SpliceInsert{..});
            for d in descriptors {
                d.unwrap();
            }
        }
    }

    #[test]
    fn it_works() {
        let data = hex!("fc302500000000000000fff01405000000017feffe2d142b00fe0123d3080001010100007f157a49");
        let mut parser = Scte35SectionProcessor::new(
            MockSpliceProcessor
        );
        let header = psi::SectionCommonHeader::new(&data[..psi::SectionCommonHeader::SIZE]);
        parser.start_section(&header, &data[..]);
    }
}