use crate::num_traits::*;
+use crate::rand::ThreadLocalChaCha8Rng;
+use std::time::{ SystemTime, UNIX_EPOCH };
+
+const TIMESTAMP_MS_SHIFT: u8 = 128 - 54;
+
+const TIMESTAMP_MICROS_SHIFT: u8 = TIMESTAMP_MS_SHIFT - 10;
+
+const MICROSECOND_TOGGLE_SHIFT: u8 = TIMESTAMP_MICROS_SHIFT - 1;
+
+const PROC_ID_SHIFT: u8 = MICROSECOND_TOGGLE_SHIFT - 8;
+
+const COUNT_SHIFT: u8 = PROC_ID_SHIFT - 15;
+
+const MAX_COUNT: u16 = 1 << 15;
+const MAX_MICROS_COUNT: u16 = 1 << 10;
+
+const RAND_COMPONENT_MASK: u64 = 0xFF_FFFF_FFFF;
+
+pub struct IDGenerator128 {
+ gen_millis: u64,
+ gen_micros_or_2e_count: u16,
+ micros_accurate: bool,
+ proc_id: u8,
+ count: u16
+}
+
+impl IDGenerator128 {
+ pub fn new_accurate_ms(proc_id: u8) -> Self {
+ Self {
+ gen_millis: 0,
+ gen_micros_or_2e_count: 0,
+ micros_accurate: true,
+ proc_id,
+ count: 1
+ }
+ }
+
+ pub fn new_inaccurate_ms(proc_id: u8) -> Self {
+ Self {
+ gen_millis: 0,
+ gen_micros_or_2e_count: 0,
+ micros_accurate: false,
+ proc_id,
+ count: 1
+ }
+ }
+
+ pub fn next_details(&mut self) -> Option<GeneratedID128Details> {
+ let now = SystemTime::now()
+ .duration_since(SystemTime::UNIX_EPOCH)
+ .expect("we are before 01 jan 1970 lol?");
+
+ let millis = now.as_millis().into_u64_lossy();
+ let micros = (now.subsec_micros() % 1000).into_u16_lossy();
+
+ if millis > self.gen_millis {
+ self.gen_millis = millis;
+ self.gen_micros_or_2e_count = if self.micros_accurate {
+ micros
+ } else {
+ 0
+ };
+ self.count = 0;
+
+ Some(GeneratedID128Details {
+ gen_millis: self.gen_millis,
+ gen_micros_or_2e_count: self.gen_micros_or_2e_count,
+ micros_accurate: self.micros_accurate,
+ proc_id: self.proc_id,
+ count: self.count,
+ random: ThreadLocalChaCha8Rng::gen_rand()
+ })
+ } else if self.micros_accurate {
+ if micros > self.gen_micros_or_2e_count {
+ self.gen_micros_or_2e_count = micros;
+ self.count = 0;
+
+ Some(GeneratedID128Details {
+ gen_millis: self.gen_millis,
+ gen_micros_or_2e_count: self.gen_micros_or_2e_count,
+ micros_accurate: self.micros_accurate,
+ proc_id: self.proc_id,
+ count: self.count,
+ random: ThreadLocalChaCha8Rng::gen_rand()
+ })
+ } else {
+ if self.count >= MAX_COUNT { return None }
+
+ let count = self.count;
+ self.count += 1;
+
+ Some(GeneratedID128Details {
+ gen_millis: self.gen_millis,
+ gen_micros_or_2e_count: self.gen_micros_or_2e_count,
+ micros_accurate: self.micros_accurate,
+ proc_id: self.proc_id,
+ count: self.count,
+ random: ThreadLocalChaCha8Rng::gen_rand()
+ })
+ }
+ } else {
+ if self.count >= MAX_COUNT {
+ if self.gen_micros_or_2e_count >= MAX_MICROS_COUNT { return None }
+
+ self.count = 0;
+
+ let micros = self.gen_micros_or_2e_count;
+ self.gen_micros_or_2e_count += 1;
+
+ Some(GeneratedID128Details {
+ gen_millis: self.gen_millis,
+ gen_micros_or_2e_count: micros,
+ micros_accurate: self.micros_accurate,
+ proc_id: self.proc_id,
+ count: self.count,
+ random: ThreadLocalChaCha8Rng::gen_rand()
+ })
+ } else {
+ let count = self.count;
+ self.count += 1;
+
+ Some(GeneratedID128Details {
+ gen_millis: self.gen_millis,
+ gen_micros_or_2e_count: self.gen_micros_or_2e_count,
+ micros_accurate: self.micros_accurate,
+ proc_id: self.proc_id,
+ count: self.count,
+ random: ThreadLocalChaCha8Rng::gen_rand()
+ })
+ }
+ }
+ }
+}
+
+pub struct GeneratedID128Details {
+ gen_millis: u64,
+ gen_micros_or_2e_count: u16,
+ micros_accurate: bool,
+ proc_id: u8,
+ count: u16,
+ random: u64
+}
+
+impl GeneratedID128Details {
+ pub fn into_u128(self) -> u128 {
+ let mut id = self.gen_millis.into_u128() << TIMESTAMP_MS_SHIFT;
+ id |= self.gen_micros_or_2e_count.into_u128() << TIMESTAMP_MICROS_SHIFT;
+ id |= (self.micros_accurate as u128) << MICROSECOND_TOGGLE_SHIFT;
+ id |= self.proc_id.into_u128() << PROC_ID_SHIFT;
+ id |= self.count.into_u128() << COUNT_SHIFT;
+ id |= (self.random & RAND_COMPONENT_MASK).into_u128();
+ id
+ }
+}
+