use fpnum::FPNum;

use std::{

    collections::BinaryHeap,

    num::NonZeroU16,

    ops::{Add, Index, IndexMut},

};

pub type GearId = NonZeroU16;

#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug)]

#[repr(transparent)]

pub struct Millis(u32);

impl Millis {

    #[inline]

    pub fn new(value: u32) -> Self {

        Self(value)

    }

    #[inline]

    pub fn get(self) -> u32 {

        self.0

    }

    #[inline]

    pub fn to_fixed(self) -> FPNum {

        FPNum::new(self.0 as i32, 1000)

    }

}

impl Add for Millis {

    type Output = Self;

    fn add(self, rhs: Self) -> Self::Output {

        Self(self.0 + rhs.0)

    }

}

pub struct GearAllocator {

    max_id: u16,

    free_ids: BinaryHeap<GearId>,

}

impl GearAllocator {

    pub fn new() -> Self {

        Self {

            max_id: 0,

            free_ids: BinaryHeap::with_capacity(1024),

        }

    }

    pub fn alloc(&mut self) -> Option<GearId> {

        self.free_ids.pop().or_else(|| {

            self.max_id.checked_add(1).and_then(|new_max_id| {

                self.max_id = new_max_id;

                NonZeroU16::new(new_max_id)

            })

        })

    }

    pub fn free(&mut self, gear_id: GearId) {

        self.free_ids.push(gear_id)

    }

}