/*  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, Number};

use num_traits::{Num, One, Signed, Zero};

use std::cmp::{Ord, Ordering, PartialEq, PartialOrd};
use std::fmt;
use std::ops;

type RatioBase = num_bigint::BigInt;
type RatioType = num_rational::BigRational;

/// Rational number
#[derive(Clone, Debug, PartialEq, PartialOrd)]
pub struct Rational(RatioType);

impl Number for Rational {
	fn new() -> Self { Self(RatioType::zero()) }
	
	fn describe() -> String { "--numbers rational".to_string() }
	fn describe_opt() -> String { String::new() }
	
	fn pow_assign(&mut self, exponent: i32) {
		self.0 = self.0.pow(exponent);
	}
	
	fn floor_mut(&mut self, dps: usize) {
		if dps == 0 {
			self.0 = self.0.floor();
		} else {
			let factor = RatioType::from_integer(RatioBase::from(10)).pow(dps as i32);
			self.0 *= &factor;
			self.0 = self.0.floor();
			self.0 /= factor;
		}
	}
	
	fn ceil_mut(&mut self, dps: usize) {
		if dps == 0 {
			self.0 = self.0.ceil();
		} else {
			let factor = RatioType::from_integer(RatioBase::from(10)).pow(dps as i32);
			self.0 *= &factor;
			self.0 = self.0.ceil();
			self.0 /= factor;
		}
	}
	
	fn round_mut(&mut self, dps: usize) {
		if dps == 0 {
			self.0 = self.0.round();
		} else {
			// TODO: Streamline
			let mut factor = Self::from(10);
			factor.pow_assign(-(dps as i32));
			factor /= Self::from(2);
			
			*self = self.clone() - factor;
			self.ceil_mut(dps);
		}
	}
	
	fn parse(s: &str) -> Self {
		// Parse decimal
		if s.contains('.') {
			let (whole, decimal) = s.split_once('.').unwrap();
			let whole = match RatioBase::from_str_radix(whole, 10) {
				Ok(value) => RatioType::from_integer(value),
				Err(_) => panic!("Syntax Error"),
			};
			let decimal = match RatioBase::from_str_radix(decimal, 10) {
				Ok(value) => RatioType::from_integer(value),
				Err(_) => panic!("Syntax Error"),
			} / RatioBase::from(10).pow(decimal.len() as u32);
			return Self(whole + decimal);
		}
		
		// Parse integer
		if let Ok(value) = Self::from_str_radix(s, 10) {
			return value;
		} else {
			panic!("Syntax Error");
		}
	}
}

impl Num for Rational {
	type FromStrRadixErr = <RatioBase as Num>::FromStrRadixErr;
	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
		match RatioBase::from_str_radix(str, radix) {
			Ok(value) => Ok(Self(RatioType::from_integer(value))),
			Err(err) => Err(err)
		}
	}
}

impl Assign for Rational {
	fn assign(&mut self, src: Self) { self.0 = src.0 }
}

impl Assign<&Rational> for Rational {
	fn assign(&mut self, src: &Rational) { self.0 = src.0.clone() }
}

impl From<usize> for Rational {
	fn from(n: usize) -> Self { Self(RatioType::from_integer(RatioBase::from(n))) }
}

impl fmt::Display for Rational {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		if let Some(precision) = f.precision() {
			if precision == 0 {
				let result = self.0.round().to_integer().to_string();
				return f.write_str(&result);
			} else {
				let base = RatioBase::from(10).pow(precision as u32);
				let mut result = (&self.0 * base).abs().round().to_integer().to_string();
				
				let should_add_minus = (self.0 < RatioType::zero()) && result != "0";
				
				// Add leading 0s
				result = format!("{0:0>1$}", result, precision + 1);
				
				// Add the decimal point
				result.insert(result.len() - precision, '.');
				
				// Add the sign
				if should_add_minus {
					result.insert(0, '-');
				}
				
				return f.write_str(&result);
			}
		} else {
			return self.0.fmt(f);
		}
	}
}

impl One for Rational {
	fn one() -> Self { Self(RatioType::one()) }
}

impl Zero for Rational {
	fn zero() -> Self { Self::new() }
	fn is_zero(&self) -> bool { self.0.is_zero() }
}

impl Eq for Rational {}
impl Ord for Rational {
	fn cmp(&self, other: &Self) -> Ordering { self.0.partial_cmp(&other.0).unwrap() }
}

impl ops::Neg for Rational {
	type Output = Rational;
	fn neg(self) -> Self::Output { Self(-self.0) }
}

impl ops::Add for Rational {
	type Output = Rational;
	fn add(self, rhs: Self) -> Self::Output { Self(self.0 + rhs.0) }
}

impl ops::Sub for Rational {
	type Output = Rational;
	fn sub(self, _rhs: Self) -> Self::Output {
		todo!()
	}
}

impl ops::Mul for Rational {
	type Output = Rational;
	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
}

impl ops::Div for Rational {
	type Output = Rational;
	fn div(self, rhs: Self) -> Self::Output { Self(self.0 / rhs.0) }
}

impl ops::Rem for Rational {
	type Output = Rational;
	fn rem(self, _rhs: Self) -> Self::Output {
		todo!()
	}
}

impl ops::Add<&Rational> for Rational {
	type Output = Rational;
	fn add(self, rhs: &Rational) -> Self::Output { Self(self.0 + &rhs.0) }
}

impl ops::Sub<&Rational> for Rational {
	type Output = Rational;
	fn sub(self, rhs: &Rational) -> Self::Output { Self(self.0 - &rhs.0) }
}

impl ops::Mul<&Rational> for Rational {
	type Output = Rational;
	fn mul(self, rhs: &Rational) -> Self::Output { Rational(self.0 * &rhs.0) }
}

impl ops::Div<&Rational> for Rational {
	type Output = Rational;
	fn div(self, rhs: &Rational) -> Self::Output { Rational(self.0 / &rhs.0) }
}

impl ops::Rem<&Rational> for Rational {
	type Output = Rational;
	fn rem(self, _rhs: &Rational) -> Self::Output {
		todo!()
	}
}

impl ops::AddAssign for Rational {
	fn add_assign(&mut self, rhs: Self) { self.0 += rhs.0; }
}

impl ops::SubAssign for Rational {
	fn sub_assign(&mut self, rhs: Self) { self.0 -= rhs.0; }
}

impl ops::MulAssign for Rational {
	fn mul_assign(&mut self, rhs: Self) { self.0 *= rhs.0; }
}

impl ops::DivAssign for Rational {
	fn div_assign(&mut self, rhs: Self) { self.0 /= &rhs.0; }
}

impl ops::RemAssign for Rational {
	fn rem_assign(&mut self, _rhs: Self) {
		todo!()
	}
}

impl ops::AddAssign<&Rational> for Rational {
	fn add_assign(&mut self, rhs: &Rational) { self.0 += &rhs.0; }
}

impl ops::SubAssign<&Rational> for Rational {
	fn sub_assign(&mut self, rhs: &Rational) { self.0 -= &rhs.0; }
}

impl ops::MulAssign<&Rational> for Rational {
	fn mul_assign(&mut self, rhs: &Rational) { self.0 *= &rhs.0; }
}

impl ops::DivAssign<&Rational> for Rational {
	fn div_assign(&mut self, rhs: &Rational) { self.0 /= &rhs.0 }
}

impl ops::RemAssign<&Rational> for Rational {
	fn rem_assign(&mut self, _rhs: &Rational) {
		todo!()
	}
}

impl ops::Neg for &Rational {
	type Output = Rational;
	fn neg(self) -> Self::Output { Rational(-&self.0) }
}

impl ops::Add<Self> for &Rational {
	type Output = Rational;
	fn add(self, rhs: &Rational) -> Self::Output { Rational(&self.0 + &rhs.0) }
}

impl ops::Sub<Self> for &Rational {
	type Output = Rational;
	fn sub(self, rhs: &Rational) -> Self::Output { Rational(&self.0 - &rhs.0) }
}

impl ops::Mul<Self> for &Rational {
	type Output = Rational;
	fn mul(self, rhs: &Rational) -> Self::Output { Rational(&self.0 * &rhs.0) }
}

impl ops::Div<Self> for &Rational {
	type Output = Rational;
	fn div(self, rhs: &Rational) -> Self::Output { Rational(&self.0 / &rhs.0) }
}

impl ops::Rem<Self> for &Rational {
	type Output = Rational;
	fn rem(self, _rhs: &Rational) -> Self::Output {
		todo!()
	}
}

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

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

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

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

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