deep-time 0.1.0-alpha.1

use crate::{ATTOS_PER_SEC, Dt, GregorianTime, Scale};

mod arithmetic;
mod constructors;
mod formatting;
mod from_str;
mod ops;
pub mod time_units;

#[cfg(feature = "alloc")]
mod to_str;

#[cfg(feature = "hifitime")]
mod from_hifitime;
#[cfg(feature = "hifitime")]
mod to_hifitime;

#[cfg(feature = "chrono")]
mod from_chrono;
#[cfg(feature = "chrono")]
mod to_chrono;

#[cfg(feature = "jiff")]
mod from_jiff;
#[cfg(feature = "jiff")]
mod to_jiff;

/// A high-precision **duration** (time span) expressed as **seconds + attoseconds**
/// (where 1 attosecond = 10⁻¹⁸ s).
///
/// `TSpan` is the time span counterpart of `Dt`.
///
/// - Precision: 10⁻¹⁸ s
/// - Range: ±~292 billion years (i64 seconds limit).
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "js", derive(tsify::Tsify))]
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct TSpan {
    /// Signed whole seconds.
    pub sec: i64,
    /// Fractional part in attoseconds (`0 ≤ attos < 10¹⁸`).
    pub attos: u64,
}

impl TSpan {
    /// Seconds field getter.
    #[inline]
    pub const fn sec(&self) -> i64 {
        self.sec
    }

    /// Subseconds field getter (attoseconds).
    #[inline]
    pub const fn attos(&self) -> u64 {
        self.attos
    }

    /// Normalizes the representation so that the attosecond part lies in the range `[0, ATTOS_PER_SEC)`.
    #[inline]
    pub const fn carry_over(&mut self) -> &mut Self {
        if self.attos >= ATTOS_PER_SEC {
            self.sec += (self.attos / ATTOS_PER_SEC) as i64;
            self.attos %= ATTOS_PER_SEC;
        }
        self
    }

    #[inline]
    pub const fn to_tai(&self, current: Scale) -> Dt {
        Dt::from(self.sec, self.attos, current)
    }

    #[inline]
    pub const fn to(&self, current: Scale, target: Scale) -> TSpan {
        Dt::from(self.sec, self.attos, current).to(target)
    }

    #[inline]
    pub const fn to_gregorian_time(&self, current: Scale) -> GregorianTime {
        Dt::from(self.sec, self.attos, current).to_gregorian_time()
    }

    #[inline]
    pub const fn to_epoch(&self, epoch: Dt, current: Scale) -> Self {
        Dt::from(self.sec, self.attos, current).to_epoch(epoch, current)
    }
}

impl Default for TSpan {
    fn default() -> Self {
        Self::ZERO
    }
}

#[cfg(feature = "wire")]
impl TSpan {
    /// 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 `TSpan` 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]`: `attos` as little-endian `u64`
    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 `TSpan` from exactly 17 bytes of wire data.
    ///
    /// Returns `None` if the version byte is unknown.
    /// Any `attos` value ≥ 10¹⁸ is automatically normalized using
    /// [`carry_over`](Self::carry_over) so the resulting `TSpan`
    /// 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.
    pub fn from_wire_bytes(bytes: &[u8]) -> Option<Self> {
        if bytes.len() != Self::WIRE_SIZE {
            return None;
        }

        // Version check for future compatibility
        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 attos = u64::from_le_bytes([
            bytes[9], bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15], bytes[16],
        ]);

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