dvb-si 5.0.0

//! T2 Delivery System Descriptor — ETSI EN 300 468 §6.4.6.3 (tag_extension 0x04).
use super::*;

impl<'a> ExtensionBodyDef<'a> for T2DeliverySystem {
    const TAG_EXTENSION: u8 = 0x04;
    const NAME: &'static str = "T2_DELIVERY_SYSTEM";
}

/// One T2 cell (Table 133 inner `for`).
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct T2Cell {
    /// cell_id(16).
    pub cell_id: u16,
    /// centre_frequency list. When tfs_flag, the length-prefixed loop;
    /// otherwise exactly one frequency.
    pub centre_frequencies: Vec<u32>,
    /// subcell entries.
    pub subcells: Vec<T2Subcell>,
}

/// One T2 subcell (Table 133 innermost `for`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct T2Subcell {
    /// cell_id_extension(8).
    pub cell_id_extension: u8,
    /// transposer_frequency(32).
    pub transposer_frequency: u32,
}

/// T2_delivery_system body (Table 133). The cell loop is unfolded.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct T2DeliverySystem {
    /// PLP identifier.
    pub plp_id: u8,
    /// T2 system identifier.
    pub t2_system_id: u16,
    /// SISO_MISO(2), present iff `descriptor_length > 4` (flags block present).
    pub siso_miso: Option<u8>,
    /// bandwidth(4), present with `siso_miso`.
    pub bandwidth: Option<u8>,
    /// guard_interval(3), present with `siso_miso`.
    pub guard_interval: Option<u8>,
    /// transmission_mode(3), present with `siso_miso`.
    pub transmission_mode: Option<u8>,
    /// other_frequency_flag(1), present with `siso_miso`.
    pub other_frequency_flag: Option<bool>,
    /// tfs_flag(1), present with `siso_miso`.
    pub tfs_flag: Option<bool>,
    /// Cell loop entries (present only when flags block is present).
    pub cells: Vec<T2Cell>,
}

impl<'a> Parse<'a> for T2DeliverySystem {
    type Error = crate::error::Error;
    fn parse(sel: &'a [u8]) -> Result<Self> {
        if sel.len() < T2_FIXED_PREFIX_LEN {
            return Err(Error::BufferTooShort {
                need: T2_FIXED_PREFIX_LEN,
                have: sel.len(),
                what: "T2_delivery_system body",
            });
        }
        let plp_id = sel[0];
        let t2_system_id = u16::from_be_bytes([sel[1], sel[2]]);
        let mut pos = T2_FIXED_PREFIX_LEN;
        let (
            siso_miso,
            bandwidth,
            guard_interval,
            transmission_mode,
            other_frequency_flag,
            tfs_flag,
        ) = if sel.len() > T2_FIXED_PREFIX_LEN {
            if sel.len() < T2_FIXED_PREFIX_LEN + T2_FLAGS_BLOCK_LEN {
                return Err(Error::BufferTooShort {
                    need: T2_FIXED_PREFIX_LEN + T2_FLAGS_BLOCK_LEN,
                    have: sel.len(),
                    what: "T2_delivery_system body",
                });
            }
            let b0 = sel[pos];
            let b1 = sel[pos + 1];
            pos += T2_FLAGS_BLOCK_LEN;
            (
                Some(b0 >> 6),
                Some((b0 >> 2) & 0x0F),
                Some(b1 >> 5),
                Some((b1 >> 2) & 0x07),
                Some((b1 & 0x02) != 0),
                Some((b1 & 0x01) != 0),
            )
        } else {
            (None, None, None, None, None, None)
        };
        let cells = if siso_miso.is_some() {
            let tfs = tfs_flag.unwrap();
            let mut cells = Vec::new();
            while pos < sel.len() {
                if pos + 2 > sel.len() {
                    return Err(Error::BufferTooShort {
                        need: pos + 2,
                        have: sel.len(),
                        what: "T2_delivery_system body",
                    });
                }
                let cell_id = u16::from_be_bytes([sel[pos], sel[pos + 1]]);
                pos += 2;
                let centre_frequencies = if tfs {
                    if pos >= sel.len() {
                        return Err(Error::BufferTooShort {
                            need: pos + 1,
                            have: sel.len(),
                            what: "T2_delivery_system body",
                        });
                    }
                    let freq_loop_len = sel[pos] as usize;
                    pos += 1;
                    if freq_loop_len % 4 != 0 {
                        return Err(invalid(
                            "T2_delivery_system: frequency_loop_length not a multiple of 4",
                        ));
                    }
                    if pos + freq_loop_len > sel.len() {
                        return Err(Error::BufferTooShort {
                            need: pos + freq_loop_len,
                            have: sel.len(),
                            what: "T2_delivery_system body",
                        });
                    }
                    let end = pos + freq_loop_len;
                    let mut freqs = Vec::with_capacity(freq_loop_len / 4);
                    while pos < end {
                        freqs.push(u32::from_be_bytes([
                            sel[pos],
                            sel[pos + 1],
                            sel[pos + 2],
                            sel[pos + 3],
                        ]));
                        pos += 4;
                    }
                    freqs
                } else {
                    if pos + 4 > sel.len() {
                        return Err(Error::BufferTooShort {
                            need: pos + 4,
                            have: sel.len(),
                            what: "T2_delivery_system body",
                        });
                    }
                    let freq =
                        u32::from_be_bytes([sel[pos], sel[pos + 1], sel[pos + 2], sel[pos + 3]]);
                    pos += 4;
                    vec![freq]
                };
                if pos >= sel.len() {
                    return Err(Error::BufferTooShort {
                        need: pos + 1,
                        have: sel.len(),
                        what: "T2_delivery_system body",
                    });
                }
                let subcell_loop_len = sel[pos] as usize;
                pos += 1;
                if subcell_loop_len % 5 != 0 {
                    return Err(invalid(
                        "T2_delivery_system: subcell_info_loop_length not a multiple of 5",
                    ));
                }
                if pos + subcell_loop_len > sel.len() {
                    return Err(Error::BufferTooShort {
                        need: pos + subcell_loop_len,
                        have: sel.len(),
                        what: "T2_delivery_system body",
                    });
                }
                let end = pos + subcell_loop_len;
                let mut subcells = Vec::with_capacity(subcell_loop_len / 5);
                while pos < end {
                    subcells.push(T2Subcell {
                        cell_id_extension: sel[pos],
                        transposer_frequency: u32::from_be_bytes([
                            sel[pos + 1],
                            sel[pos + 2],
                            sel[pos + 3],
                            sel[pos + 4],
                        ]),
                    });
                    pos += 5;
                }
                cells.push(T2Cell {
                    cell_id,
                    centre_frequencies,
                    subcells,
                });
            }
            cells
        } else {
            Vec::new()
        };
        Ok(T2DeliverySystem {
            plp_id,
            t2_system_id,
            siso_miso,
            bandwidth,
            guard_interval,
            transmission_mode,
            other_frequency_flag,
            tfs_flag,
            cells,
        })
    }
}

impl Serialize for T2DeliverySystem {
    type Error = crate::error::Error;
    fn serialized_len(&self) -> usize {
        let mut len = T2_FIXED_PREFIX_LEN;
        if self.siso_miso.is_some() {
            len += T2_FLAGS_BLOCK_LEN;
            let tfs = self.tfs_flag.unwrap_or(false);
            for cell in &self.cells {
                len += 2; // cell_id
                if tfs {
                    len += 1 + cell.centre_frequencies.len() * 4;
                } else {
                    len += 4;
                }
                len += 1 + cell.subcells.len() * 5;
            }
        }
        len
    }
    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
        let len = self.serialized_len();
        if buf.len() < len {
            return Err(Error::OutputBufferTooSmall {
                need: len,
                have: buf.len(),
            });
        }
        buf[0] = self.plp_id;
        buf[1..3].copy_from_slice(&self.t2_system_id.to_be_bytes());
        let mut p = T2_FIXED_PREFIX_LEN;
        if let (Some(sm), Some(bw), Some(gi), Some(tm), Some(off), Some(tfs)) = (
            self.siso_miso,
            self.bandwidth,
            self.guard_interval,
            self.transmission_mode,
            self.other_frequency_flag,
            self.tfs_flag,
        ) {
            buf[p] = (sm << 6) | ((bw & 0x0F) << 2) | 0x03;
            buf[p + 1] = (gi << 5) | ((tm & 0x07) << 2) | (u8::from(off) << 1) | u8::from(tfs);
            p += T2_FLAGS_BLOCK_LEN;
            for cell in &self.cells {
                buf[p..p + 2].copy_from_slice(&cell.cell_id.to_be_bytes());
                p += 2;
                if tfs {
                    let freq_len = (cell.centre_frequencies.len() * 4) as u8;
                    buf[p] = freq_len;
                    p += 1;
                    for &freq in &cell.centre_frequencies {
                        buf[p..p + 4].copy_from_slice(&freq.to_be_bytes());
                        p += 4;
                    }
                } else {
                    let freq = cell.centre_frequencies.first().copied().unwrap_or(0);
                    buf[p..p + 4].copy_from_slice(&freq.to_be_bytes());
                    p += 4;
                }
                let subcell_len = (cell.subcells.len() * 5) as u8;
                buf[p] = subcell_len;
                p += 1;
                for sc in &cell.subcells {
                    buf[p] = sc.cell_id_extension;
                    buf[p + 1..p + 5].copy_from_slice(&sc.transposer_frequency.to_be_bytes());
                    p += 5;
                }
            }
        }
        Ok(len)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::descriptors::extension::test_support::*;
    use crate::descriptors::extension::{ExtensionBody, ExtensionDescriptor};

    #[test]
    fn parse_t2_minimal() {
        // body = plp + system_id = 3 bytes => no flags block
        let sel = [0x07, 0x12, 0x34];
        let bytes = wrap(0x04, &sel);
        let d = ExtensionDescriptor::parse(&bytes).unwrap();
        match &d.body {
            ExtensionBody::T2DeliverySystem(b) => {
                assert_eq!(b.plp_id, 0x07);
                assert_eq!(b.t2_system_id, 0x1234);
                assert_eq!(b.siso_miso, None);
                assert!(b.cells.is_empty());
            }
            other => panic!("expected T2DeliverySystem, got {other:?}"),
        }
        round_trip(&d);
    }

    #[test]
    fn parse_t2_structured_flags_and_cells() {
        // prefix + flags block (siso=0, bw=4, gi=6, tm=3, off=0, tfs=1)
        // + 2 cells: one empty, one with 3 freqs + 2 subcells
        let b0: u8 = ((0x04 & 0x0F) << 2) | 0x03; // siso_miso=0, bandwidth=4, reserved=11
        let b1: u8 = (0x06 << 5) | ((0x03 & 0x07) << 2) | (u8::from(false) << 1) | u8::from(true);
        // cell 1: cell_id=0x1234, freq_len=0, subcell_len=0
        let cell1 = [0x12, 0x34, 0x00, 0x00];
        // cell 2: cell_id=0x5678, freq_len=12 (3 freqs), three freqs, subcell_len=10 (2 subcells), two subcells
        let f1 = 0x01020304u32;
        let f2 = 0x05060708u32;
        let f3 = 0x090A0B0Cu32;
        let sc1_id = 0x10u8;
        let sc1_freq = 0x11121314u32;
        let sc2_id = 0x20u8;
        let sc2_freq = 0x21222324u32;
        let mut cell2 = Vec::new();
        cell2.extend_from_slice(&0x5678u16.to_be_bytes());
        cell2.push(12);
        cell2.extend_from_slice(&f1.to_be_bytes());
        cell2.extend_from_slice(&f2.to_be_bytes());
        cell2.extend_from_slice(&f3.to_be_bytes());
        cell2.push(10);
        cell2.push(sc1_id);
        cell2.extend_from_slice(&sc1_freq.to_be_bytes());
        cell2.push(sc2_id);
        cell2.extend_from_slice(&sc2_freq.to_be_bytes());
        let mut sel = vec![0x07, 0x12, 0x34, b0, b1];
        sel.extend_from_slice(&cell1);
        sel.extend_from_slice(&cell2);
        let bytes = wrap(0x04, &sel);
        let d = ExtensionDescriptor::parse(&bytes).unwrap();
        match &d.body {
            ExtensionBody::T2DeliverySystem(b) => {
                assert_eq!(b.plp_id, 0x07);
                assert_eq!(b.t2_system_id, 0x1234);
                assert_eq!(b.siso_miso, Some(0x00));
                assert_eq!(b.bandwidth, Some(0x04));
                assert_eq!(b.guard_interval, Some(0x06));
                assert_eq!(b.transmission_mode, Some(0x03));
                assert_eq!(b.other_frequency_flag, Some(false));
                assert_eq!(b.tfs_flag, Some(true));
                assert_eq!(b.cells.len(), 2);
                // cell 0: empty
                assert_eq!(b.cells[0].cell_id, 0x1234);
                assert!(b.cells[0].centre_frequencies.is_empty());
                assert!(b.cells[0].subcells.is_empty());
                // cell 1: 3 freqs + 2 subcells
                assert_eq!(b.cells[1].cell_id, 0x5678);
                assert_eq!(b.cells[1].centre_frequencies, vec![f1, f2, f3]);
                assert_eq!(b.cells[1].subcells.len(), 2);
                assert_eq!(b.cells[1].subcells[0].cell_id_extension, sc1_id);
                assert_eq!(b.cells[1].subcells[0].transposer_frequency, sc1_freq);
                assert_eq!(b.cells[1].subcells[1].cell_id_extension, sc2_id);
                assert_eq!(b.cells[1].subcells[1].transposer_frequency, sc2_freq);
            }
            other => panic!("expected T2DeliverySystem, got {other:?}"),
        }
        round_trip(&d);
    }

    #[test]
    fn tsduck_t2_reference() {
        let bytes = from_hex(
            "7f240456789a13cd12340000678a0c075bcd1505e30a780fd22c320a1217ea6406fa0aa9fc59",
        );
        let d = ExtensionDescriptor::parse(&bytes).unwrap();
        match &d.body {
            ExtensionBody::T2DeliverySystem(b) => {
                assert_eq!(b.plp_id, 0x56);
                assert_eq!(b.t2_system_id, 0x789A);
                assert_eq!(b.siso_miso, Some(0));
                assert_eq!(b.bandwidth, Some(4));
                assert_eq!(b.guard_interval, Some(6));
                assert_eq!(b.transmission_mode, Some(3));
                assert_eq!(b.other_frequency_flag, Some(false));
                assert_eq!(b.tfs_flag, Some(true));
                assert_eq!(b.cells.len(), 2);

                assert_eq!(b.cells[0].cell_id, 0x1234);
                assert!(b.cells[0].centre_frequencies.is_empty());
                assert!(b.cells[0].subcells.is_empty());

                assert_eq!(b.cells[1].cell_id, 0x678A);
                assert_eq!(
                    b.cells[1].centre_frequencies,
                    vec![0x075BCD15, 0x05E30A78, 0x0FD22C32]
                );
                assert_eq!(b.cells[1].subcells.len(), 2);
                assert_eq!(b.cells[1].subcells[0].cell_id_extension, 0x12);
                assert_eq!(b.cells[1].subcells[0].transposer_frequency, 0x17EA6406);
                assert_eq!(b.cells[1].subcells[1].cell_id_extension, 0xFA);
                assert_eq!(b.cells[1].subcells[1].transposer_frequency, 0x0AA9FC59);
            }
            other => panic!("expected T2DeliverySystem, got {other:?}"),
        }
        let mut out = vec![0u8; d.serialized_len()];
        let n = d.serialize_into(&mut out).unwrap();
        assert_eq!(
            out[..n],
            bytes[..],
            "byte-exact re-serialize for tsduck T2 reference"
        );
    }
}