/*  OpenTally: Open-source election vote counting
 *  Copyright © 2021 Lee Yingtong Li (RunasSudo)
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use super::{Assign, Fixed, GuardedFixed, NativeFloat64, Number, Rational};

use num_traits::{Num, One, Zero};
//use wasm_bindgen::prelude::wasm_bindgen;

use std::cmp::{Ord, Ordering};
use std::fmt;
use std::mem::ManuallyDrop;
use std::ops::{self, Deref, DerefMut};

/// Represents the underlying implementation for [DynNum]s
//#[wasm_bindgen]
pub enum NumKind {
	/// See [crate::numbers::fixed]
	Fixed,
	/// See [crate::numbers::gfixed]
	GuardedFixed,
	/// See [crate::numbers::native]
	NativeFloat64,
	/// See [crate::numbers::rational_rug] or [crate::numbers::rational_num]
	Rational,
}

/// Determines which underlying implementation to use
static mut KIND: NumKind = NumKind::Fixed;

/// Returns which underlying implementation is in use
#[inline]
fn get_kind() -> &'static NumKind {
	unsafe {
		return &KIND;
	}
}

/// A wrapper for different numeric types using dynamic dispatch
pub union DynNum {
	fixed: ManuallyDrop<Fixed>,
	gfixed: ManuallyDrop<GuardedFixed>,
	float64: NativeFloat64,
	rational: ManuallyDrop<Rational>,
}

impl DynNum {
	/// Set which underlying implementation to use
	pub fn set_kind(kind: NumKind) {
		unsafe {
			KIND = kind;
		}
	}
}

macro_rules! impl_1arg_nowrap {
	($self:expr, $arg:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					$self.fixed.$func($arg)
				}
				NumKind::GuardedFixed => {
					$self.gfixed.$func($arg)
				}
				NumKind::NativeFloat64 => {
					$self.float64.$func($arg)
				}
				NumKind::Rational => {
					$self.rational.$func($arg)
				}
			}
		}
	}
}

macro_rules! impl_assoc_nowrap {
	($func:ident) => {
		match get_kind() {
			NumKind::Fixed => {
				Fixed::$func()
			}
			NumKind::GuardedFixed => {
				GuardedFixed::$func()
			}
			NumKind::NativeFloat64 => {
				NativeFloat64::$func()
			}
			NumKind::Rational => {
				Rational::$func()
			}
		}
	}
}

impl Number for DynNum {
	fn new() -> Self {
		match get_kind() {
			NumKind::Fixed => {
				DynNum { fixed: ManuallyDrop::new(Fixed::new()) }
			}
			NumKind::GuardedFixed => {
				DynNum { gfixed: ManuallyDrop::new(GuardedFixed::new()) }
			}
			NumKind::NativeFloat64 => {
				DynNum { float64: NativeFloat64::new() }
			}
			NumKind::Rational => {
				DynNum { rational: ManuallyDrop::new(Rational::new()) }
			}
		}
	}
	
	fn describe() -> String { impl_assoc_nowrap!(describe) }
	fn pow_assign(&mut self, exponent: i32) { impl_1arg_nowrap!(self, exponent, pow_assign) }
	fn floor_mut(&mut self, dps: usize) { impl_1arg_nowrap!(self, dps, floor_mut) }
	fn ceil_mut(&mut self, dps: usize) { impl_1arg_nowrap!(self, dps, ceil_mut) }
	fn round_mut(&mut self, dps: usize) { impl_1arg_nowrap!(self, dps, round_mut) }
}

impl Drop for DynNum {
	fn drop(&mut self) {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					ManuallyDrop::drop(&mut self.fixed);
				}
				NumKind::GuardedFixed => {
					ManuallyDrop::drop(&mut self.gfixed);
				}
				NumKind::NativeFloat64 => {}
				NumKind::Rational => {
					ManuallyDrop::drop(&mut self.rational);
				}
			}
		}
	}
}

macro_rules! impl_0arg_wrap {
	($self:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					DynNum { fixed: ManuallyDrop::new($self.fixed.deref().$func()) }
				}
				NumKind::GuardedFixed => {
					DynNum { gfixed: ManuallyDrop::new($self.gfixed.deref().$func()) }
				}
				NumKind::NativeFloat64 => {
					DynNum { float64: $self.float64.$func() }
				}
				NumKind::Rational => {
					DynNum { rational: ManuallyDrop::new($self.rational.deref().$func()) }
				}
			}
		}
	}
}

impl Clone for DynNum {
	fn clone(&self) -> Self { impl_0arg_wrap!(self, clone) }
}

impl Num for DynNum {
	type FromStrRadixErr = Self; // TODO
	
	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
		match get_kind() {
			NumKind::Fixed => {
				Ok(DynNum { fixed: ManuallyDrop::new(Fixed::from_str_radix(str, radix).unwrap()) })
			}
			NumKind::GuardedFixed => {
				Ok(DynNum { gfixed: ManuallyDrop::new(GuardedFixed::from_str_radix(str, radix).unwrap()) })
			}
			NumKind::NativeFloat64 => {
				Ok(DynNum { float64: NativeFloat64::from_str_radix(str, radix).unwrap() })
			}
			NumKind::Rational => {
				Ok(DynNum { rational: ManuallyDrop::new(Rational::from_str_radix(str, radix).unwrap()) })
			}
		}
	}
}

macro_rules! impl_1other_nowrap {
	($self:expr, $rhs:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					$self.fixed.deref().$func($rhs.fixed.deref())
				}
				NumKind::GuardedFixed => {
					$self.gfixed.deref().$func($rhs.gfixed.deref())
				}
				NumKind::NativeFloat64 => {
					$self.float64.$func(&$rhs.float64)
				}
				NumKind::Rational => {
					$self.rational.deref().$func($rhs.rational.deref())
				}
			}
		}
	}
}

macro_rules! impl_1other_nowrap_mut {
	($self:expr, $rhs:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					$self.fixed.deref_mut().$func($rhs.fixed.deref())
				}
				NumKind::GuardedFixed => {
					$self.gfixed.deref_mut().$func($rhs.gfixed.deref())
				}
				NumKind::NativeFloat64 => {
					$self.float64.$func(&$rhs.float64)
				}
				NumKind::Rational => {
					$self.rational.deref_mut().$func($rhs.rational.deref())
				}
			}
		}
	}
}

impl Assign for DynNum {
	fn assign(&mut self, src: Self) { impl_1other_nowrap_mut!(self, src, assign) }
}

impl Assign<&Self> for DynNum {
	fn assign(&mut self, src: &Self) { impl_1other_nowrap_mut!(self, src, assign) }
}

impl From<usize> for DynNum {
	fn from(n: usize) -> Self {
		match get_kind() {
			NumKind::Fixed => {
				DynNum { fixed: ManuallyDrop::new(Fixed::from(n)) }
			}
			NumKind::GuardedFixed => {
				DynNum { gfixed: ManuallyDrop::new(GuardedFixed::from(n)) }
			}
			NumKind::NativeFloat64 => {
				DynNum { float64: NativeFloat64::from(n) }
			}
			NumKind::Rational => {
				DynNum { rational: ManuallyDrop::new(Rational::from(n)) }
			}
		}
	}
}

impl fmt::Display for DynNum {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { impl_1arg_nowrap!(self, f, fmt) }
}

impl fmt::Debug for DynNum {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { impl_1arg_nowrap!(self, f, fmt) }
}

impl PartialEq for DynNum {
	fn eq(&self, other: &Self) -> bool { impl_1other_nowrap!(self, other, eq) }
}

impl Eq for DynNum {}

impl PartialOrd for DynNum {
	fn partial_cmp(&self, other: &Self) -> Option<Ordering> { impl_1other_nowrap!(self, other, partial_cmp) }
}

impl Ord for DynNum {
	fn cmp(&self, other: &Self) -> Ordering { impl_1other_nowrap!(self, other, cmp) }
}

macro_rules! impl_assoc_wrap {
	($func:ident) => {
		match get_kind() {
			NumKind::Fixed => {
				DynNum { fixed: ManuallyDrop::new(Fixed::$func()) }
			}
			NumKind::GuardedFixed => {
				DynNum { gfixed: ManuallyDrop::new(GuardedFixed::$func()) }
				}
			NumKind::NativeFloat64 => {
				DynNum { float64: NativeFloat64::$func() }
			}
			NumKind::Rational => {
				DynNum { rational: ManuallyDrop::new(Rational::$func()) }
			}
		}
	}
}

impl One for DynNum {
	fn one() -> Self { impl_assoc_wrap!(one) }
}

macro_rules! impl_0arg_nowrap {
	($self:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					$self.fixed.deref().$func()
				}
				NumKind::GuardedFixed => {
					$self.gfixed.deref().$func()
				}
				NumKind::NativeFloat64 => {
					$self.float64.$func()
				}
				NumKind::Rational => {
					$self.rational.deref().$func()
				}
			}
		}
	}
}

impl Zero for DynNum {
	fn zero() -> Self { impl_assoc_wrap!(zero) }
	
	fn is_zero(&self) -> bool { impl_0arg_nowrap!(self, is_zero) }
}

impl ops::Neg for DynNum {
	type Output = Self;
	fn neg(self) -> Self::Output { impl_0arg_wrap!(self, neg) }
}

macro_rules! impl_1other_wrap {
	($self:expr, $rhs:expr, $func:ident) => {
		// Safety: Access only correct union field
		unsafe {
			match get_kind() {
				NumKind::Fixed => {
					DynNum { fixed: ManuallyDrop::new($self.fixed.deref().$func($rhs.fixed.deref())) }
				}
				NumKind::GuardedFixed => {
					DynNum { gfixed: ManuallyDrop::new($self.gfixed.deref().$func($rhs.gfixed.deref())) }
				}
				NumKind::NativeFloat64 => {
					DynNum { float64: $self.float64.$func($rhs.float64) }
				}
				NumKind::Rational => {
					DynNum { rational: ManuallyDrop::new($self.rational.deref().$func($rhs.rational.deref())) }
				}
			}
		}
	}
}

impl ops::Add for DynNum {
	type Output = Self;
	fn add(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, add) }
}

impl ops::Sub for DynNum {
	type Output = Self;
	fn sub(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, sub) }
}

impl ops::Mul for DynNum {
	type Output = Self;
	fn mul(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, mul) }
}

impl ops::Div for DynNum {
	type Output = Self;
	fn div(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, div) }
}

impl ops::Rem for DynNum {
	type Output = Self;
	fn rem(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, rem) }
}

impl ops::Add<&Self> for DynNum {
	type Output = Self;
	fn add(self, rhs: &Self) -> Self::Output { impl_1other_wrap!(self, rhs, add) }
}

impl ops::Sub<&Self> for DynNum {
	type Output = Self;
	fn sub(self, rhs: &Self) -> Self::Output { impl_1other_wrap!(self, rhs, sub) }
}

impl ops::Mul<&Self> for DynNum {
	type Output = Self;
	fn mul(self, rhs: &Self) -> Self::Output { impl_1other_wrap!(self, rhs, mul) }
}

impl ops::Div<&Self> for DynNum {
	type Output = Self;
	fn div(self, rhs: &Self) -> Self::Output { impl_1other_wrap!(self, rhs, div) }
}

impl ops::Rem<&Self> for DynNum {
	type Output = Self;
	fn rem(self, rhs: &Self) -> Self::Output { impl_1other_wrap!(self, rhs, rem) }
}

impl ops::AddAssign for DynNum {
	fn add_assign(&mut self, rhs: Self) { impl_1other_nowrap_mut!(self, rhs, add_assign) }
}

impl ops::SubAssign for DynNum {
	fn sub_assign(&mut self, rhs: Self) { impl_1other_nowrap_mut!(self, rhs, sub_assign) }
}

impl ops::MulAssign for DynNum {
	fn mul_assign(&mut self, rhs: Self) { impl_1other_nowrap_mut!(self, rhs, mul_assign) }
}

impl ops::DivAssign for DynNum {
	fn div_assign(&mut self, rhs: Self) { impl_1other_nowrap_mut!(self, rhs, div_assign) }
}

impl ops::RemAssign for DynNum {
	fn rem_assign(&mut self, rhs: Self) { impl_1other_nowrap_mut!(self, rhs, rem_assign) }
}

impl ops::AddAssign<&Self> for DynNum {
	fn add_assign(&mut self, rhs: &Self) { impl_1other_nowrap_mut!(self, rhs, add_assign) }
}

impl ops::SubAssign<&Self> for DynNum {
	fn sub_assign(&mut self, rhs: &Self) { impl_1other_nowrap_mut!(self, rhs, sub_assign) }
}

impl ops::MulAssign<&Self> for DynNum {
	fn mul_assign(&mut self, rhs: &Self) { impl_1other_nowrap_mut!(self, rhs, mul_assign) }
}

impl ops::DivAssign<&Self> for DynNum {
	fn div_assign(&mut self, rhs: &Self) { impl_1other_nowrap_mut!(self, rhs, div_assign) }
}

impl ops::RemAssign<&Self> for DynNum {
	fn rem_assign(&mut self, rhs: &Self) { impl_1other_nowrap_mut!(self, rhs, rem_assign) }
}

impl ops::Neg for &DynNum {
	type Output = DynNum;
	fn neg(self) -> Self::Output { impl_0arg_wrap!(self, neg) }
}

impl ops::Add<Self> for &DynNum {
	type Output = DynNum;
	fn add(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, add) }
}

impl ops::Sub<Self> for &DynNum {
	type Output = DynNum;
	fn sub(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, sub) }
}

impl ops::Mul<Self> for &DynNum {
	type Output = DynNum;
	fn mul(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, mul) }
}

impl ops::Div<Self> for &DynNum {
	type Output = DynNum;
	fn div(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, div) }
}

impl ops::Rem<Self> for &DynNum {
	type Output = DynNum;
	fn rem(self, rhs: Self) -> Self::Output { impl_1other_wrap!(self, rhs, rem) }
}

/*
impl ops::Add<&&Rational> for &Rational {
	
}

impl ops::Sub<&&Rational> for &Rational {
	
}

impl ops::Mul<&&Rational> for &Rational {
	
}

impl ops::Div<&&Rational> for &Rational {
	
}

impl ops::Rem<&&Rational> for &Rational {
	
}
*/