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use num_traits as num;
use std::fmt;

/// This trait represents the operations a histogram must be able to perform on the underlying
/// counter type. The `ToPrimitive` trait is needed to perform floating point operations on the
/// counts (usually for quantiles). The `FromPrimitive` to convert back into an integer count.
/// Partial ordering is used for threshholding, also usually in the context of quantiles.
pub trait Counter:
    num::Num
    + num::ToPrimitive
    + num::FromPrimitive
    + num::Saturating
    + num::CheckedSub
    + num::CheckedAdd
    + Copy
    + PartialOrd<Self>
    + fmt::Debug
{
    /// Counter as a f64.
    fn as_f64(&self) -> f64;
    /// Counter as a u64.
    fn as_u64(&self) -> u64;
}

impl Counter for u8 {
    #[inline]
    fn as_f64(&self) -> f64 {
        f64::from(*self)
    }
    #[inline]
    fn as_u64(&self) -> u64 {
        u64::from(*self)
    }
}

impl Counter for u16 {
    #[inline]
    fn as_f64(&self) -> f64 {
        f64::from(*self)
    }
    #[inline]
    fn as_u64(&self) -> u64 {
        u64::from(*self)
    }
}

impl Counter for u32 {
    #[inline]
    fn as_f64(&self) -> f64 {
        f64::from(*self)
    }
    #[inline]
    fn as_u64(&self) -> u64 {
        u64::from(*self)
    }
}

impl Counter for u64 {
    #[inline]
    fn as_f64(&self) -> f64 {
        *self as f64
    }
    #[inline]
    fn as_u64(&self) -> u64 {
        *self
    }
}