deep_time/

wire.rs

use crate::{
    AsciiStr, Drift, Dt, Every, GregorianTime, Meridiem, Offset, Scale, Spacetime, TimeParts,
    TimeRange, Weekday,
};

impl Dt {
    /// Current wire format version.
    pub const WIRE_VERSION: u8 = 1;

    /// Size of the canonical wire representation in bytes (17 bytes).
    pub const WIRE_SIZE: usize = 17;

    /// Serializes this `Dt` into a fixed 17-byte little-endian buffer.
    ///
    /// # Wire Format
    ///
    /// - Byte `0`: Version (`WIRE_VERSION`)
    /// - Bytes `[1..9]`: `sec` as little-endian `i64`
    /// - Bytes `[9..17]`: `subsec` as little-endian `u64`
    ///
    /// This format is stable, portable, and suitable for network transmission,
    /// file storage, or FFI. The internal representation is always TAI.
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        buf[0] = Self::WIRE_VERSION;
        buf[1..9].copy_from_slice(&self.sec.to_le_bytes());
        buf[9..17].copy_from_slice(&self.attos.to_le_bytes());
        buf
    }

    /// Deserializes a `Dt` from exactly 17 bytes of wire data.
    ///
    /// Returns `None` if the version byte is unknown.
    /// Any `subsec` value ≥ 10¹⁸ is automatically normalized using
    /// [`carry_attos`](Self::carry_attos) so the resulting `Dt`
    /// is always in canonical form.
    ///
    /// ## Security
    ///
    /// Safe to call with completely untrusted input. Fixed-size format,
    /// no allocation, no `unsafe`, and no possibility of code execution.
    /// Malicious data simply produces a normalized (but still valid) `Dt`.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }

        if bytes[0] != Self::WIRE_VERSION {
            return None;
        }

        let sec = i64::from_le_bytes([
            bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7], bytes[8],
        ]);
        let subsec = u64::from_le_bytes([
            bytes[9], bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15], bytes[16],
        ]);

        Some(Self::new(sec, subsec))
    }
}

impl Drift {
    /// Current wire format version.
    pub const WIRE_VERSION: u8 = 1;

    /// Size of the canonical wire representation in bytes.
    pub const WIRE_SIZE: usize = 3 * Dt::WIRE_SIZE; // 3 × 17 = 51

    /// Serializes this `Drift` polynomial into a fixed buffer.
    ///
    /// The layout is the concatenation of the three `Dt` fields.
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        let c = self.constant.to_wire_bytes();
        let r = self.rate.to_wire_bytes();
        let a = self.accel.to_wire_bytes();

        buf[0..Dt::WIRE_SIZE].copy_from_slice(&c);
        buf[Dt::WIRE_SIZE..2 * Dt::WIRE_SIZE].copy_from_slice(&r);
        buf[2 * Dt::WIRE_SIZE..].copy_from_slice(&a);
        buf
    }

    /// Deserializes a `Drift` from exactly `WIRE_SIZE` bytes of wire data.
    ///
    /// Returns `None` if any nested `Dt` fails validation or if the version
    /// byte is unknown.
    ///
    /// ## Security
    ///
    /// Composes the safety guarantees of
    /// [`from_wire_bytes`](docs.rs/deep-time/latest/deep_time/struct.Dt.html#method.from_wire_bytes).
    ///
    /// Fixed size and layered validation make it safe for untrusted input.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }

        if bytes[0] != Self::WIRE_VERSION {
            return None;
        }

        let constant = Dt::from_wire_bytes(&bytes[0..Dt::WIRE_SIZE])?;
        let rate = Dt::from_wire_bytes(&bytes[Dt::WIRE_SIZE..2 * Dt::WIRE_SIZE])?;
        let accel = Dt::from_wire_bytes(&bytes[2 * Dt::WIRE_SIZE..])?;

        Some(Self::new(constant, rate, accel))
    }
}

impl Spacetime {
    /// Size of the canonical wire representation in bytes (24 bytes).
    pub const WIRE_SIZE: usize = 24;

    /// Serializes this `Spacetime` snapshot into a fixed 24-byte buffer.
    ///
    /// All fields are stored as little-endian IEEE 754 `f64`.
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        buf[0..8].copy_from_slice(&self.alpha.to_le_bytes());
        buf[8..16].copy_from_slice(&self.beta.to_le_bytes());
        buf[16..24].copy_from_slice(&self.kretschmann.to_le_bytes());
        buf
    }

    /// Deserializes a `Spacetime` from exactly 24 bytes.
    ///
    /// ## Security
    ///
    /// Accepts any `f64` bit pattern (including `NaN`/`Inf`) to match the
    /// type’s own invariants. Fixed size makes it immune to length-based
    /// attacks. Safe for untrusted input.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }
        let alpha = f64::from_le_bytes([
            bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7],
        ]);
        let beta = f64::from_le_bytes([
            bytes[8], bytes[9], bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15],
        ]);
        let kretschmann = f64::from_le_bytes([
            bytes[16], bytes[17], bytes[18], bytes[19], bytes[20], bytes[21], bytes[22], bytes[23],
        ]);
        Some(Self {
            alpha,
            beta,
            kretschmann,
        })
    }
}

impl Every {
    /// Size of the canonical wire representation in bytes (33 bytes).
    pub const WIRE_SIZE: usize = Dt::WIRE_SIZE + Dt::WIRE_SIZE;

    /// Serializes this `Every` builder into a fixed 33-byte buffer.
    ///
    /// The layout is simply the concatenation of `start` (17 bytes) and `step` (16 bytes).
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        let start = self.start.to_wire_bytes();
        let step = self.step.to_wire_bytes();
        buf[0..17].copy_from_slice(&start);
        buf[17..33].copy_from_slice(&step);
        buf
    }

    /// Deserializes an `Every` builder from exactly 33 bytes.
    ///
    /// ## Security
    ///
    /// Safe for untrusted input. Fixed size with strict validation
    /// of the inner `Dt` and `Dt`.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }
        let start = Dt::from_wire_bytes(&bytes[0..17])?;
        let step = Dt::from_wire_bytes(&bytes[17..33])?;
        Some(Self { start, step })
    }
}

impl TimeRange {
    /// Current wire format version.
    pub const WIRE_VERSION: u8 = 1;

    /// Size of the canonical wire representation in bytes.
    /// Only the logical definition is stored (runtime state is not serialized).
    pub const WIRE_SIZE: usize = 1 + 2 * Dt::WIRE_SIZE + Dt::WIRE_SIZE + 1;

    /// Serializes this `TimeRange` into a fixed buffer.
    ///
    /// Only the logical definition is stored:
    /// - `start` + `end` + `step` + `inclusive` flag
    ///
    /// Runtime iterator state (`current`, `finished`) is **not** serialized.
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        buf[0] = Self::WIRE_VERSION;

        let start = self.start.to_wire_bytes();
        let end = self.end.to_wire_bytes();
        let step = self.step.to_wire_bytes();

        let tp_size = Dt::WIRE_SIZE;
        let span_size = Dt::WIRE_SIZE;

        buf[1..1 + tp_size].copy_from_slice(&start);
        buf[1 + tp_size..1 + 2 * tp_size].copy_from_slice(&end);
        buf[1 + 2 * tp_size..1 + 2 * tp_size + span_size].copy_from_slice(&step);
        buf[1 + 2 * tp_size + span_size] = if self.inclusive { 1 } else { 0 };

        buf
    }

    /// Deserializes a `TimeRange` from exactly `WIRE_SIZE` bytes.
    ///
    /// The iterator is reconstructed in its initial state
    /// (`current = start`, `finished = false`).
    ///
    /// Returns `None` if the version is unknown or any component is invalid.
    ///
    /// ## Security
    ///
    /// Safe for untrusted input. Fixed size with layered validation
    /// of all inner types. No runtime iterator state is accepted from the wire.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }

        if bytes[0] != Self::WIRE_VERSION {
            return None;
        }

        let tp_size = Dt::WIRE_SIZE;
        let span_size = Dt::WIRE_SIZE;

        let start = Dt::from_wire_bytes(&bytes[1..1 + tp_size])?;
        let end = Dt::from_wire_bytes(&bytes[1 + tp_size..1 + 2 * tp_size])?;
        let step = Dt::from_wire_bytes(&bytes[1 + 2 * tp_size..1 + 2 * tp_size + span_size])?;
        let inclusive = bytes[1 + 2 * tp_size + span_size] != 0;

        Some(Self::new(start, end, step, inclusive))
    }
}

impl GregorianTime {
    /// Current wire format version.
    pub const WIRE_VERSION: u8 = 1;

    /// Size of the canonical wire representation in bytes (158 bytes).
    pub const WIRE_SIZE: usize = 158;

    /// Serializes this `GregorianTime` into a fixed 158-byte buffer.
    ///
    /// # Wire Format (Version 1)
    ///
    /// - Byte `0`: Version (`WIRE_VERSION`)
    /// - Bytes `1..17`: `unix_attosec` (`i128`)
    /// - Bytes `17..25`: `yr` (`i64`)
    /// - Bytes `25..30`: `mo`, `day`, `hr`, `min`, `sec` (`u8` × 5)
    /// - Bytes `30..38`: `attos` (`u64`)
    /// - Bytes `38..46`: `iso_yr` (`i64`)
    /// - Bytes `46..48`: `iso_wk` + `iso_wkday` (`u8` × 2)
    /// - Bytes `48..50`: `day_of_yr` (`u16`)
    /// - Byte `50`: `wkday` (`u8`)
    /// - Bytes `51..53`: `wk_of_yr_sun` + `wk_of_yr_mon` (`u8` × 2)
    /// - Bytes `53..58`: `offset_sec` (tag byte + `i32`)
    /// - Bytes `58..108`: `tz` (tag byte + `AsciiStr<49>`)
    /// - Bytes `108..158`: `tz_abbrev` (tag byte + `AsciiStr<49>`)
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        buf[0] = Self::WIRE_VERSION;
        let mut offset = 1usize;

        // unix_attosec (16 bytes)
        buf[offset..offset + 16].copy_from_slice(&self.unix_attosec.to_le_bytes());
        offset += 16;

        // yr (8 bytes)
        buf[offset..offset + 8].copy_from_slice(&self.yr.to_le_bytes());
        offset += 8;

        // mo, day, hr, min, sec (5 bytes)
        buf[offset] = self.mo;
        offset += 1;
        buf[offset] = self.day;
        offset += 1;
        buf[offset] = self.hr;
        offset += 1;
        buf[offset] = self.min;
        offset += 1;
        buf[offset] = self.sec;
        offset += 1;

        // attos (8 bytes)
        buf[offset..offset + 8].copy_from_slice(&self.attos.to_le_bytes());
        offset += 8;

        // iso_yr (8 bytes)
        buf[offset..offset + 8].copy_from_slice(&self.iso_yr.to_le_bytes());
        offset += 8;

        // iso_wk + iso_wkday (2 bytes)
        buf[offset] = self.iso_wk;
        offset += 1;
        buf[offset] = self.iso_wkday.to_wire_byte();
        offset += 1;

        // day_of_yr (2 bytes)
        buf[offset..offset + 2].copy_from_slice(&self.day_of_yr.to_le_bytes());
        offset += 2;

        // wkday (1 byte)
        buf[offset] = self.wkday;
        offset += 1;

        // wk_of_yr_sun + wk_of_yr_mon (2 bytes)
        buf[offset] = self.wk_of_yr_sun;
        offset += 1;
        buf[offset] = self.wk_of_yr_mon;
        offset += 1;

        // offset_sec (Option<i32>) — 5 bytes
        if let Some(val) = self.offset_sec {
            buf[offset] = 1;
            buf[offset + 1..offset + 5].copy_from_slice(&val.to_le_bytes());
        } else {
            buf[offset] = 0;
        }
        offset += 5;

        // tz (Option<AsciiStr<49>>) — 50 bytes
        if let Some(tz) = &self.tz {
            buf[offset] = 1;
            let tz_bytes = tz.to_wire_bytes();
            buf[offset + 1..offset + 1 + AsciiStr::<49>::WIRE_SIZE].copy_from_slice(&tz_bytes);
        } else {
            buf[offset] = 0;
        }
        offset += 1 + AsciiStr::<49>::WIRE_SIZE;

        // tz_abbrev (Option<AsciiStr<49>>) — 50 bytes
        if let Some(abbrev) = &self.tz_abbrev {
            buf[offset] = 1;
            let abbrev_bytes = abbrev.to_wire_bytes();
            buf[offset + 1..offset + 1 + AsciiStr::<49>::WIRE_SIZE].copy_from_slice(&abbrev_bytes);
        } else {
            buf[offset] = 0;
        }

        buf
    }

    /// Deserializes a `GregorianTime` from exactly 158 bytes of wire data.
    ///
    /// Returns `None` if the version is unknown or any field is invalid.
    ///
    /// ## Security
    ///
    /// Safe for untrusted input. Fixed-size format with strict validation.
    /// No allocation or `unsafe` code used.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }
        if bytes[0] != Self::WIRE_VERSION {
            return None;
        }

        let mut offset = 1usize;

        // unix_attosec (16 bytes)
        let unix_attosec = i128::from_le_bytes(bytes[offset..offset + 16].try_into().ok()?);
        offset += 16;

        // yr (8 bytes)
        let yr = i64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        offset += 8;

        // mo, day, hr, min, sec (5 bytes)
        let mo = bytes[offset];
        offset += 1;
        let day = bytes[offset];
        offset += 1;
        let hr = bytes[offset];
        offset += 1;
        let min = bytes[offset];
        offset += 1;
        let sec = bytes[offset];
        offset += 1;

        // attos (8 bytes)
        let attos = u64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        offset += 8;

        // iso_yr (8 bytes)
        let iso_yr = i64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        offset += 8;

        // iso_wk + iso_wkday (2 bytes)
        let iso_wk = bytes[offset];
        offset += 1;
        let iso_wkday = Weekday::from_wire_byte(bytes[offset])?;
        offset += 1;

        // day_of_yr (2 bytes)
        let day_of_yr = u16::from_le_bytes(bytes[offset..offset + 2].try_into().ok()?);
        offset += 2;

        // wkday (1 byte)
        let wkday = bytes[offset];
        offset += 1;

        // wk_of_yr_sun + wk_of_yr_mon (2 bytes)
        let wk_of_yr_sun = bytes[offset];
        offset += 1;
        let wk_of_yr_mon = bytes[offset];
        offset += 1;

        // offset_sec (Option<i32>) — 5 bytes
        let offset_sec = if bytes[offset] == 1 {
            Some(i32::from_le_bytes(
                bytes[offset + 1..offset + 5].try_into().ok()?,
            ))
        } else {
            None
        };
        offset += 5;

        // tz (Option<AsciiStr<49>>) — 50 bytes
        let tz = if bytes[offset] == 1 {
            AsciiStr::<49>::from_wire_bytes(
                &bytes[offset + 1..offset + 1 + AsciiStr::<49>::WIRE_SIZE],
            )
        } else {
            None
        };
        offset += 1 + AsciiStr::<49>::WIRE_SIZE;

        // tz_abbrev (Option<AsciiStr<49>>) — 50 bytes
        let tz_abbrev = if bytes[offset] == 1 {
            AsciiStr::<49>::from_wire_bytes(
                &bytes[offset + 1..offset + 1 + AsciiStr::<49>::WIRE_SIZE],
            )
        } else {
            None
        };

        Some(Self {
            unix_attosec,
            yr,
            mo,
            day,
            hr,
            min,
            sec,
            attos,
            iso_yr,
            iso_wk,
            iso_wkday,
            day_of_yr,
            wkday,
            wk_of_yr_sun,
            wk_of_yr_mon,
            offset_sec,
            tz,
            tz_abbrev,
        })
    }
}

impl Meridiem {
    pub const WIRE_SIZE: usize = 1;

    #[inline]
    pub const fn to_wire_byte(self) -> u8 {
        match self {
            Meridiem::AM => 0,
            Meridiem::PM => 1,
        }
    }

    #[inline]
    pub const fn from_wire_byte(b: u8) -> Option<Self> {
        match b {
            0 => Some(Meridiem::AM),
            1 => Some(Meridiem::PM),
            _ => None,
        }
    }
}

impl Offset {
    pub const WIRE_SIZE: usize = 5; // tag (1) + i32 (4)

    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        match self {
            Offset::Utc => buf[0] = 0,
            Offset::None => buf[0] = 1,
            Offset::Fixed(offset) => {
                buf[0] = 2;
                buf[1..5].copy_from_slice(&offset.to_le_bytes());
            }
        }
        buf
    }

    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }
        match bytes[0] {
            0 => Some(Offset::Utc),
            1 => Some(Offset::None),
            2 => {
                let offset = i32::from_le_bytes([bytes[1], bytes[2], bytes[3], bytes[4]]);
                Some(Offset::Fixed(offset))
            }
            _ => None,
        }
    }
}

impl Weekday {
    pub const WIRE_SIZE: usize = 1;

    #[inline]
    pub const fn to_wire_byte(self) -> u8 {
        self.wk_sun()
    }

    #[inline]
    pub const fn from_wire_byte(b: u8) -> Option<Self> {
        Self::from_sunday_zero_offset(b)
    }
}

impl TimeParts {
    /// Current wire format version.
    pub const WIRE_VERSION: u8 = 1;

    /// Total size of the wire representation (120 bytes).
    pub const WIRE_SIZE: usize = 120;

    /// Serializes `TimeParts` into a fixed 120-byte buffer.
    ///
    /// Layout:
    /// - Byte 0: Version (`WIRE_VERSION`)
    /// - Bytes 1..120: Data (119 bytes)
    pub fn to_wire_bytes(&self) -> [u8; Self::WIRE_SIZE] {
        let mut buf = [0u8; Self::WIRE_SIZE];
        buf[0] = Self::WIRE_VERSION;

        let mut offset = 1usize;

        // year (sentinel = i64::MIN)
        let year = self.yr.unwrap_or(i64::MIN);
        buf[offset..offset + 8].copy_from_slice(&year.to_le_bytes());
        offset += 8;

        // month
        buf[offset] = self.mo.unwrap_or(u8::MAX);
        offset += 1;

        // day
        buf[offset] = self.day.unwrap_or(u8::MAX);
        offset += 1;

        // hour
        buf[offset] = self.hr.unwrap_or(u8::MAX);
        offset += 1;

        // minute
        buf[offset] = self.min.unwrap_or(u8::MAX);
        offset += 1;

        // second
        buf[offset] = self.sec.unwrap_or(u8::MAX);
        offset += 1;

        // attos
        let attos = self.attos.unwrap_or(u64::MAX);
        buf[offset..offset + 8].copy_from_slice(&attos.to_le_bytes());
        offset += 8;

        // offset (5 bytes)
        let offset_bytes = self.offset.unwrap_or_default().to_wire_bytes();
        buf[offset..offset + 5].copy_from_slice(&offset_bytes);
        offset += 5;

        // iana_name (49 bytes)
        if let Some(name) = &self.iana_name {
            let name_bytes = name.to_wire_bytes();
            buf[offset..offset + 49].copy_from_slice(&name_bytes);
        }
        offset += 49;

        // is_leap_second
        buf[offset] = if self.is_leap_sec { 1 } else { 0 };
        offset += 1;

        // scale
        buf[offset] = self.scale as u8;
        offset += 1;

        // weekday
        buf[offset] = self.wkday.map_or(255, |w| w.to_wire_byte());
        offset += 1;

        // day_of_year
        let doy = self.day_of_yr.unwrap_or(u16::MAX);
        buf[offset..offset + 2].copy_from_slice(&doy.to_le_bytes());
        offset += 2;

        // iso_week_year
        let iso_y = self.iso_wk_yr.unwrap_or(i64::MIN);
        buf[offset..offset + 8].copy_from_slice(&iso_y.to_le_bytes());
        offset += 8;

        // iso_week
        buf[offset] = self.iso_wk.unwrap_or(u8::MAX);
        offset += 1;

        // week_sun
        buf[offset] = self.wk_sun.unwrap_or(u8::MAX);
        offset += 1;

        // week_mon
        buf[offset] = self.wk_mon.unwrap_or(u8::MAX);
        offset += 1;

        // meridiem
        buf[offset] = self.meridiem.map_or(255, |m| m.to_wire_byte());
        offset += 1;

        // unix_timestamp_seconds
        let unix = self.unix_timestamp_seconds.unwrap_or(i64::MIN);
        buf[offset..offset + 8].copy_from_slice(&unix.to_le_bytes());

        buf
    }

    /// Deserializes `TimeParts` from exactly 120 bytes.
    ///
    /// Returns `None` if the version byte is unknown or the data is invalid.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }
        if bytes[0] != Self::WIRE_VERSION {
            return None;
        }

        let mut dc = TimeParts::default();
        let mut offset = 1usize;

        // year (8 bytes)
        let year = i64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        if year != i64::MIN {
            dc.yr = Some(year);
        }
        offset += 8;

        // month (1 byte)
        let m = bytes[offset];
        if m != u8::MAX {
            dc.mo = Some(m);
        }
        offset += 1;

        // day (1 byte)
        let d = bytes[offset];
        if d != u8::MAX {
            dc.day = Some(d);
        }
        offset += 1;

        // hour (1 byte)
        let h = bytes[offset];
        if h != u8::MAX {
            dc.hr = Some(h);
        }
        offset += 1;

        // minute (1 byte)
        let min = bytes[offset];
        if min != u8::MAX {
            dc.min = Some(min);
        }
        offset += 1;

        // second (1 byte)
        let sec = bytes[offset];
        if sec != u8::MAX {
            dc.sec = Some(sec);
        }
        offset += 1;

        // attos (8 bytes)
        let attos = u64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        if attos != u64::MAX {
            dc.attos = Some(attos);
        }
        offset += 8;

        // offset (5 bytes) — already nice
        if let Some(offset) = Offset::from_wire_bytes(&bytes[offset..offset + 5]) {
            dc.offset = Some(offset);
        }
        offset += 5;

        // iana_name (49 bytes) — already nice
        let iana_bytes = &bytes[offset..offset + 49];
        if let Some(name) = AsciiStr::<49>::from_wire_bytes(iana_bytes)
            && !name.is_empty()
        {
            dc.iana_name = Some(name);
        }
        offset += 49;

        // is_leap_second (1 byte)
        dc.is_leap_sec = bytes[offset] != 0;
        offset += 1;

        // scale (1 byte)
        dc.scale = Scale::from_u8(bytes[offset]);
        offset += 1;

        // weekday (1 byte)
        let wd_byte = bytes[offset];
        if wd_byte != 255
            && let Some(wd) = Weekday::from_wire_byte(wd_byte)
        {
            dc.wkday = Some(wd);
        }
        offset += 1;

        // day_of_year (2 bytes)
        let doy = u16::from_le_bytes(bytes[offset..offset + 2].try_into().ok()?);
        if doy != u16::MAX {
            dc.day_of_yr = Some(doy);
        }
        offset += 2;

        // iso_week_year (8 bytes)
        let iso_y = i64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        if iso_y != i64::MIN {
            dc.iso_wk_yr = Some(iso_y);
        }
        offset += 8;

        // iso_week (1 byte)
        let iw = bytes[offset];
        if iw != u8::MAX {
            dc.iso_wk = Some(iw);
        }
        offset += 1;

        // week_sun (1 byte)
        let ws = bytes[offset];
        if ws != u8::MAX {
            dc.wk_sun = Some(ws);
        }
        offset += 1;

        // week_mon (1 byte)
        let wm = bytes[offset];
        if wm != u8::MAX {
            dc.wk_mon = Some(wm);
        }
        offset += 1;

        // meridiem (1 byte)
        let mer_byte = bytes[offset];
        if mer_byte != 255
            && let Some(m) = Meridiem::from_wire_byte(mer_byte)
        {
            dc.meridiem = Some(m);
        }

        offset += 1;

        // unix_timestamp_seconds (8 bytes)
        let unix = i64::from_le_bytes(bytes[offset..offset + 8].try_into().ok()?);
        if unix != i64::MIN {
            dc.unix_timestamp_seconds = Some(unix);
        }

        Some(dc)
    }
}