// timepriv.rs
//
// Copyright (C) 2019-2021  Minnesota Department of Transportation
// Copyright (C) 2019-2022  Douglas P Lau
//
//! Private module for time structs
//!
extern crate alloc;

use crate::{length, time::Unit, Length, Speed};
use core::fmt;
use core::marker::PhantomData;
use core::ops::{Add, Div, Mul, Sub};

/// _Period_, _duration_ or _interval_ of time.
///
/// Period is a base quantity with a specific [unit].
///
/// ## Operations
///
/// * f64 `*` [unit] `=>` Period
/// * i32 `*` [unit] `=>` Period
/// * Period `+` Period `=>` Period
/// * Period `-` Period `=>` Period
/// * Period `*` f64 `=>` Period
/// * f64 `*` Period `=>` Period
/// * f64 `/` Period `=>` [Frequency]
///
/// Units must be the same for operations with two Period operands.  The [to]
/// method can be used for conversion.
///
/// ```rust
/// use mag::time::{min, s};
///
/// let a = 15 * min;
/// let b = 90.0 * s;
///
/// assert_eq!(a.to_string(), "15 min");
/// assert_eq!((a + b.to()).to_string(), "16.5 min");
/// ```
/// [Frequency]: struct.Frequency.html
/// [unit]: time/index.html
/// [to]: struct.Period.html#method.to
///
#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
pub struct Period<U>
where
    U: Unit,
{
    /// Period quantity
    pub quantity: f64,

    /// Measurement unit
    unit: PhantomData<U>,
}

/// Temporal _frequency_, or _rate_ over time.
///
/// Frequency is a derived quantity with a specific [unit].
///
/// ## Operations
///
/// * f64 `/` [unit] `=>` Frequency
/// * i32 `/` [unit] `=>` Frequency
/// * Frequency `+` Frequency `=>` Frequency
/// * Frequency `-` Frequency `=>` Frequency
/// * Frequency `*` f64 `=>` Frequency
/// * f64 `*` Frequency `=>` Frequency
/// * f64 `/` [Period] `=>` Frequency
/// * f64 `/` Frequency `=>` [Period]
///
/// Units must be the same for operations with two Frequency operands.  The
/// [to] method can be used for conversion.
///
/// ```rust
/// use mag::time::{ns, s};
///
/// let a = 25.0 / s;
/// let b = 500.0 / ns;
///
/// assert_eq!(a.to_string(), "25 ㎐");
/// assert_eq!(b.to_string(), "500 ㎓");
/// ```
/// [Period]: struct.Period.html
/// [unit]: time/index.html
/// [to]: struct.Frequency.html#method.to
///
#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
pub struct Frequency<U>
where
    U: Unit,
{
    /// Frequency quantity
    pub quantity: f64,

    /// Measurement unit
    unit: PhantomData<U>,
}

impl_base_ops!(Period, Unit);
impl_base_ops!(Frequency, Unit);

impl<U> fmt::Display for Period<U>
where
    U: Unit,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.quantity.fmt(f)?;
        write!(f, " {}", U::LABEL)
    }
}

impl<U> fmt::Display for Frequency<U>
where
    U: Unit,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.quantity.fmt(f)?;
        write!(f, " {}", U::INVERSE)
    }
}

impl<U> Period<U>
where
    U: Unit,
{
    /// Create a new period quantity
    pub fn new(quantity: f64) -> Self {
        Period::<U> {
            quantity,
            unit: PhantomData,
        }
    }

    /// Convert to specified units
    pub fn to<T: Unit>(self) -> Period<T> {
        let quantity = self.quantity * U::factor::<T>();
        Period::new(quantity)
    }
}

// f64 / Period => Frequency
impl<U> Div<Period<U>> for f64
where
    U: Unit,
{
    type Output = Frequency<U>;
    fn div(self, other: Period<U>) -> Self::Output {
        Self::Output::new(self / other.quantity)
    }
}

// Length / Period => Speed
impl<L, T> Div<Period<T>> for Length<L>
where
    L: length::Unit,
    T: Unit,
{
    type Output = Speed<L, T>;
    fn div(self, per: Period<T>) -> Self::Output {
        Speed::new(self.quantity / per.quantity)
    }
}

impl<U> Frequency<U>
where
    U: Unit,
{
    /// Create a new frequency quantity
    pub fn new(quantity: f64) -> Self {
        Frequency::<U> {
            quantity,
            unit: PhantomData,
        }
    }

    /// Convert to specified units
    pub fn to<T: Unit>(self) -> Frequency<T> {
        let quantity = self.quantity / U::factor::<T>();
        Frequency::new(quantity)
    }
}

// f64 / Frequency => Period
impl<U> Div<Frequency<U>> for f64
where
    U: Unit,
{
    type Output = Period<U>;
    fn div(self, other: Frequency<U>) -> Self::Output {
        Self::Output::new(self / other.quantity)
    }
}

// Frequency * Length => Speed
impl<L, T> Mul<Length<L>> for Frequency<T>
where
    L: length::Unit,
    T: Unit,
{
    type Output = Speed<L, T>;
    fn mul(self, len: Length<L>) -> Self::Output {
        Speed::new(self.quantity * len.quantity)
    }
}

// Length * Frequency => Speed
impl<L, T> Mul<Frequency<T>> for Length<L>
where
    L: length::Unit,
    T: Unit,
{
    type Output = Speed<L, T>;
    fn mul(self, freq: Frequency<T>) -> Self::Output {
        Speed::new(self.quantity * freq.quantity)
    }
}