use bnum::{BInt,cast::As};
use typenum::{Sum,Unsigned};
use crate::traits::WideMul;

#[derive(Clone,Copy,Debug,Hash)]
pub struct Fixed<const CHUNKS:usize,Frac>{
	pub(crate)bits:BInt<{CHUNKS}>,
	pub(crate)frac:std::marker::PhantomData<Frac>,
}

impl<const CHUNKS:usize,Frac:Unsigned> Fixed<CHUNKS,Frac>{
	pub const MAX:Self=Self::from_bits(BInt::<CHUNKS>::MAX);
	pub const MIN:Self=Self::from_bits(BInt::<CHUNKS>::MIN);
	pub const ZERO:Self=Self::from_bits(BInt::<CHUNKS>::ZERO);
	pub const EPSILON:Self=Self::from_bits(BInt::<CHUNKS>::ONE);
	pub const NEG_EPSILON:Self=Self::from_bits(BInt::<CHUNKS>::NEG_ONE);
	pub const ONE:Self=Self::from_bits(BInt::<CHUNKS>::ONE.shl(Frac::U32));
	pub const TWO:Self=Self::from_bits(BInt::<CHUNKS>::TWO.shl(Frac::U32));
	pub const HALF:Self=Self::from_bits(BInt::<CHUNKS>::ONE.shl(Frac::U32-1));
	pub const NEG_ONE:Self=Self::from_bits(BInt::<CHUNKS>::NEG_ONE.shl(Frac::U32));
	pub const NEG_TWO:Self=Self::from_bits(BInt::<CHUNKS>::NEG_TWO.shl(Frac::U32));
	pub const NEG_HALF:Self=Self::from_bits(BInt::<CHUNKS>::NEG_ONE.shl(Frac::U32-1));
}
impl<const CHUNKS:usize,Frac> Fixed<CHUNKS,Frac>{
	#[inline]
	pub const fn from_bits(bits:BInt::<CHUNKS>)->Self{
		Self{
			bits,
			frac:std::marker::PhantomData,
		}
	}
	#[inline]
	pub const fn to_bits(self)->BInt<CHUNKS>{
		self.bits
	}
	#[inline]
	pub const fn raw(value:i64)->Self{
		Self::from_bits(BInt::from_bits(bnum::BUint::from_digit(value as u64)))
	}
}

impl<const CHUNKS:usize,Frac:Unsigned,T> From<T> for Fixed<CHUNKS,Frac>
	where
		BInt<CHUNKS>:From<T>
{
	fn from(value:T)->Self{
		Self::from_bits(BInt::<{CHUNKS}>::from(value)<<Frac::U32)
	}
}

impl<const CHUNKS:usize,Frac> PartialEq for Fixed<CHUNKS,Frac>{
	fn eq(&self,other:&Self)->bool{
		self.bits.eq(&other.bits)
	}
}
impl<const CHUNKS:usize,Frac> Eq for Fixed<CHUNKS,Frac>{}

impl<const CHUNKS:usize,Frac> PartialOrd for Fixed<CHUNKS,Frac>{
	fn partial_cmp(&self,other:&Self)->Option<std::cmp::Ordering>{
		self.bits.partial_cmp(&other.bits)
	}
}
impl<const CHUNKS:usize,Frac> Ord for Fixed<CHUNKS,Frac>{
	fn cmp(&self,other:&Self)->std::cmp::Ordering{
		self.bits.cmp(&other.bits)
	}
}

impl<const CHUNKS:usize,Frac> std::ops::Neg for Fixed<CHUNKS,Frac>{
	type Output=Self;
	fn neg(self)->Self{
		Self::from_bits(self.bits.neg())
	}
}

macro_rules! impl_additive_operator {
	( $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		impl<const CHUNKS:usize,Frac> core::ops::$trait for $struct<CHUNKS,Frac>{
			type Output = $output;

			fn $method(self, other: Self) -> Self::Output {
				Self::from_bits(self.bits.$method(other.bits))
			}
		}
		impl<const CHUNKS:usize,Frac:Unsigned,U> core::ops::$trait<U> for $struct<CHUNKS,Frac>
			where
				BInt::<CHUNKS>:From<U>,
		{
			type Output = $output;

			fn $method(self, other: U) -> Self::Output {
				Self::from_bits(self.bits.$method(BInt::<CHUNKS>::from(other)<<Frac::U32))
			}
		}
	};
}
macro_rules! impl_additive_assign_operator {
	( $struct: ident, $trait: ident, $method: ident ) => {
		impl<const CHUNKS:usize,Frac> core::ops::$trait for $struct<CHUNKS,Frac>{
			fn $method(&mut self, other: Self) {
				self.bits.$method(other.bits);
			}
		}
		impl<const CHUNKS:usize,Frac:Unsigned,U> core::ops::$trait<U> for $struct<CHUNKS,Frac>
		where
				BInt::<CHUNKS>:From<U>,
		{
			fn $method(&mut self, other: U) {
				self.bits.$method(BInt::<CHUNKS>::from(other)<<Frac::U32);
			}
		}
	};
}

// Impl arithmetic pperators
impl_additive_assign_operator!( Fixed, AddAssign, add_assign );
impl_additive_operator!( Fixed, Add, add, Self );
impl_additive_assign_operator!( Fixed, SubAssign, sub_assign );
impl_additive_operator!( Fixed, Sub, sub, Self );
impl_additive_assign_operator!( Fixed, RemAssign, rem_assign );
impl_additive_operator!( Fixed, Rem, rem, Self );

// Impl bitwise operators
impl_additive_assign_operator!( Fixed, BitAndAssign, bitand_assign );
impl_additive_operator!( Fixed, BitAnd, bitand, Self );
impl_additive_assign_operator!( Fixed, BitOrAssign, bitor_assign );
impl_additive_operator!( Fixed, BitOr, bitor, Self );
impl_additive_assign_operator!( Fixed, BitXorAssign, bitxor_assign );
impl_additive_operator!( Fixed, BitXor, bitxor, Self );

macro_rules! impl_multiply_operator_const {
	( $width:expr, $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		impl<Frac:Unsigned> core::ops::$trait for $struct<$width,Frac>{
			type Output = $output;

			fn $method(self, other: Self) -> Self::Output {
				//this can be done better but that is a job for later
				let lhs=self.bits.as_::<BInt::<{$width*2}>>();
				let rhs=other.bits.as_::<BInt::<{$width*2}>>();
				Self::from_bits(lhs.mul(rhs).shr(Frac::U32).as_())
			}
		}
	};
}
macro_rules! impl_multiply_assign_operator_const {
	( $width:expr, $struct: ident, $trait: ident, $method: ident ) => {
		impl<Frac> core::ops::$trait for $struct<$width,Frac>{
			fn $method(&mut self, other: Self) {
				self.bits.$method(other.bits);
			}
		}
	};
}

macro_rules! impl_divide_operator_const {
	( $width:expr, $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		impl<Frac:Unsigned> core::ops::$trait for $struct<$width,Frac>{
			type Output = $output;

			fn $method(self, other: Self) -> Self::Output {
				//this can be done better but that is a job for later
				//this only needs to be $width+Frac::U32/64+1 but MUH CONST GENERICS!!!!!
				let lhs=self.bits.as_::<BInt::<{$width*2}>>().shl(Frac::U32);
				let rhs=other.bits.as_::<BInt::<{$width*2}>>();
				Self::from_bits(lhs.div(rhs).as_())
			}
		}
	};
}
macro_rules! impl_divide_assign_operator_const {
	( $width:expr, $struct: ident, $trait: ident, $method: ident ) => {
		impl<Frac> core::ops::$trait for $struct<$width,Frac>{
			fn $method(&mut self, other: Self) {
				self.bits.$method(other.bits);
			}
		}
	};
}

macro_rules! impl_multiplicatave_operator {
	( $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		impl<const CHUNKS:usize,Frac,U> core::ops::$trait<U> for $struct<CHUNKS,Frac>
			where
				BInt::<CHUNKS>:From<U>+core::ops::$trait,
		{
			type Output = $output;

			fn $method(self, other: U) -> Self::Output {
				Self::from_bits(self.bits.$method(BInt::<CHUNKS>::from(other)))
			}
		}
	};
}
macro_rules! impl_multiplicatave_assign_operator {
	( $struct: ident, $trait: ident, $method: ident ) => {
		impl<const CHUNKS:usize,Frac,U> core::ops::$trait<U> for $struct<CHUNKS,Frac>
			where
				BInt::<CHUNKS>:From<U>+core::ops::$trait,
		{
			fn $method(&mut self, other: U) {
				self.bits.$method(BInt::<CHUNKS>::from(other));
			}
		}
	};
}

macro_rules! impl_operator_16 {
	( $macro: ident, $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		$macro!(1,$struct,$trait,$method,$output);
		$macro!(2,$struct,$trait,$method,$output);
		$macro!(3,$struct,$trait,$method,$output);
		$macro!(4,$struct,$trait,$method,$output);
		$macro!(5,$struct,$trait,$method,$output);
		$macro!(6,$struct,$trait,$method,$output);
		$macro!(7,$struct,$trait,$method,$output);
		$macro!(8,$struct,$trait,$method,$output);
		$macro!(9,$struct,$trait,$method,$output);
		$macro!(10,$struct,$trait,$method,$output);
		$macro!(11,$struct,$trait,$method,$output);
		$macro!(12,$struct,$trait,$method,$output);
		$macro!(13,$struct,$trait,$method,$output);
		$macro!(14,$struct,$trait,$method,$output);
		$macro!(15,$struct,$trait,$method,$output);
		$macro!(16,$struct,$trait,$method,$output);
	}
}
macro_rules! impl_assign_operator_16 {
	( $macro: ident, $struct: ident, $trait: ident, $method: ident ) => {
		$macro!(1,$struct,$trait,$method);
		$macro!(2,$struct,$trait,$method);
		$macro!(3,$struct,$trait,$method);
		$macro!(4,$struct,$trait,$method);
		$macro!(5,$struct,$trait,$method);
		$macro!(6,$struct,$trait,$method);
		$macro!(7,$struct,$trait,$method);
		$macro!(8,$struct,$trait,$method);
		$macro!(9,$struct,$trait,$method);
		$macro!(10,$struct,$trait,$method);
		$macro!(11,$struct,$trait,$method);
		$macro!(12,$struct,$trait,$method);
		$macro!(13,$struct,$trait,$method);
		$macro!(14,$struct,$trait,$method);
		$macro!(15,$struct,$trait,$method);
		$macro!(16,$struct,$trait,$method);
	}
}

impl_assign_operator_16!( impl_multiply_assign_operator_const, Fixed, MulAssign, mul_assign );
impl_operator_16!( impl_multiply_operator_const, Fixed, Mul, mul, Self );
impl_assign_operator_16!( impl_divide_assign_operator_const, Fixed, DivAssign, div_assign );
impl_operator_16!( impl_divide_operator_const, Fixed, Div, div, Self );
impl_multiplicatave_assign_operator!( Fixed, MulAssign, mul_assign );
impl_multiplicatave_operator!( Fixed, Mul, mul, Self );
impl_multiplicatave_assign_operator!( Fixed, DivAssign, div_assign );
impl_multiplicatave_operator!( Fixed, Div, div, Self );

macro_rules! impl_shift_operator {
	( $struct: ident, $trait: ident, $method: ident, $output: ty ) => {
		impl<const CHUNKS:usize,Frac> core::ops::$trait<u32> for $struct<CHUNKS,Frac>{
			type Output = $output;

			fn $method(self, other: u32) -> Self::Output {
				Self::from_bits(self.bits.$method(other))
			}
		}
	};
}
macro_rules! impl_shift_assign_operator {
	( $struct: ident, $trait: ident, $method: ident ) => {
		impl<const CHUNKS:usize,Frac> core::ops::$trait<u32> for $struct<CHUNKS,Frac>{
			fn $method(&mut self, other: u32) {
				self.bits.$method(other);
			}
		}
	};
}
impl_shift_assign_operator!( Fixed, ShlAssign, shl_assign );
impl_shift_operator!( Fixed, Shl, shl, Self );
impl_shift_assign_operator!( Fixed, ShrAssign, shr_assign );
impl_shift_operator!( Fixed, Shr, shr, Self );

// WIDE MUL: multiply into a wider type
// let a = I32F32::ONE;
// let b:I64F64 = a.wide_mul(a);
macro_rules! impl_wide_mul{
	($lhs:expr,$rhs:expr)=>{
		impl<A,B> WideMul<Fixed<$rhs,B>> for Fixed<$lhs,A>
			where
				A:std::ops::Add<B>,
				B:Unsigned,
		{
			type Output=Fixed<{$lhs+$rhs},Sum<A,B>>;
			fn wide_mul(self,rhs:Fixed<$rhs,B>)->Self::Output{
				Fixed::from_bits(self.bits.as_::<BInt<{$lhs+$rhs}>>()*rhs.bits.as_::<BInt<{$lhs+$rhs}>>())
			}
		}
	};
}

macro_rules! impl_wide_mul_all{
	($(($x:expr, $y:expr)),*)=>{
		$(
			impl_wide_mul!($x, $y);
		)*
	};
}

//const generics sidestepped wahoo
impl_wide_mul_all!(
	(1,1),(2,1),(3,1),(4,1),(5,1),(6,1),(7,1),(8,1),
	(1,2),(2,2),(3,2),(4,2),(5,2),(6,2),(7,2),(8,2),
	(1,3),(2,3),(3,3),(4,3),(5,3),(6,3),(7,3),(8,3),
	(1,4),(2,4),(3,4),(4,4),(5,4),(6,4),(7,4),(8,4),
	(1,5),(2,5),(3,5),(4,5),(5,5),(6,5),(7,5),(8,5),
	(1,6),(2,6),(3,6),(4,6),(5,6),(6,6),(7,6),(8,6),
	(1,7),(2,7),(3,7),(4,7),(5,7),(6,7),(7,7),(8,7),
	(1,8),(2,8),(3,8),(4,8),(5,8),(6,8),(7,8),(8,8)
);
impl<const SRC:usize,Frac> Fixed<SRC,Frac>{
	pub fn resize_into<const DST:usize>(self)->Fixed<DST,Frac>{
		Fixed::from_bits(self.bits.as_::<BInt<DST>>())
	}
}

macro_rules! impl_const{
	($n:expr)=>{
		impl<F:Unsigned> Fixed<$n,F>{
			pub fn sqrt_unchecked(self)->Self{
				//1<<max_shift must be the minimum power of two which when squared is greater than self
				//calculating max_shift:
				//1. count "used" bits to the left of the decimal, not including the sign bit (so -1)
				//2. divide by 2 via >>1 (sqrt-ish)
				//3. add on fractional offset
				//Voila
				let used_bits=self.bits.bits() as i32-1-F::I32;
				let max_shift=((used_bits>>1)+F::I32) as u32;
				let mut result=Self::ZERO;

				//multiply by one to make the types match (hack)
				let wide_self=self.wide_mul(Self::ONE);
				//descend down the bits and check if flipping each bit would push the square over the input value
				for shift in (0..=max_shift).rev(){
					let new_result=result|Self::from_bits(BInt::from_bits(bnum::BUint::power_of_two(shift)));
					if new_result.wide_mul(new_result)<=wide_self{
						result=new_result;
					}
				}
				result
			}
			pub fn sqrt(self)->Self{
				if self<Self::ZERO{
					panic!("Square root less than zero")
				}else{
					self.sqrt_unchecked()
				}
			}
			pub fn sqrt_checked(self)->Option<Self>{
				if self<Self::ZERO{
					None
				}else{
					Some(self.sqrt_unchecked())
				}
			}
		}
	}
}
impl_const!(1);
impl_const!(2);
impl_const!(3);
impl_const!(4);
impl_const!(5);
impl_const!(6);
impl_const!(7);
impl_const!(8);