use glam::DVec2;
use graphene_core::gradient::GradientStops;
use graphene_core::registry::types::{Fraction, Percentage, TextArea};
use graphene_core::{Color, Ctx, num_traits};
use log::warn;
use math_parser::ast;
use math_parser::context::{EvalContext, NothingMap, ValueProvider};
use math_parser::value::{Number, Value};
use num_traits::Pow;
use rand::{Rng, SeedableRng};
use std::ops::{Add, Div, Mul, Rem, Sub};

/// The struct that stores the context for the maths parser.
/// This is currently just limited to supplying `a` and `b` until we add better node graph support and UI for variadic inputs.
struct MathNodeContext {
	a: f64,
	b: f64,
}

impl ValueProvider for MathNodeContext {
	fn get_value(&self, name: &str) -> Option<Value> {
		if name.eq_ignore_ascii_case("a") {
			Some(Value::from_f64(self.a))
		} else if name.eq_ignore_ascii_case("b") {
			Some(Value::from_f64(self.b))
		} else {
			None
		}
	}
}

/// Calculates a mathematical expression with input values "A" and "B"
#[node_macro::node(category("Math: Arithmetic"), properties("math_properties"))]
fn math<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The value of "A" when calculating the expression
	#[implementations(f64, f32)]
	operand_a: U,
	/// A math expression that may incorporate "A" and/or "B", such as "sqrt(A + B) - B^2"
	#[default(A + B)]
	expression: String,
	/// The value of "B" when calculating the expression
	#[implementations(f64, f32)]
	#[default(1.)]
	operand_b: U,
) -> U {
	let (node, _unit) = match ast::Node::try_parse_from_str(&expression) {
		Ok(expr) => expr,
		Err(e) => {
			warn!("Invalid expression: `{expression}`\n{e:?}");
			return U::from(0.).unwrap();
		}
	};
	let context = EvalContext::new(
		MathNodeContext {
			a: operand_a.to_f64().unwrap(),
			b: operand_b.to_f64().unwrap(),
		},
		NothingMap,
	);

	let value = match node.eval(&context) {
		Ok(value) => value,
		Err(e) => {
			warn!("Expression evaluation error: {e:?}");
			return U::from(0.).unwrap();
		}
	};

	let Value::Number(num) = value;
	match num {
		Number::Real(val) => U::from(val).unwrap(),
		Number::Complex(c) => U::from(c.re).unwrap(),
	}
}

/// The addition operation (+) calculates the sum of two numbers.
#[node_macro::node(category("Math: Arithmetic"))]
fn add<U: Add<T>, T>(
	_: impl Ctx,
	/// The left-hand side of the addition operation.
	#[implementations(f64, f32, u32, DVec2, f64, DVec2)]
	augend: U,
	/// The right-hand side of the addition operation.
	#[implementations(f64, f32, u32, DVec2, DVec2, f64)]
	addend: T,
) -> <U as Add<T>>::Output {
	augend + addend
}

/// The subtraction operation (-) calculates the difference between two numbers.
#[node_macro::node(category("Math: Arithmetic"))]
fn subtract<U: Sub<T>, T>(
	_: impl Ctx,
	/// The left-hand side of the subtraction operation.
	#[implementations(f64, f32, u32, DVec2, f64, DVec2)]
	minuend: U,
	/// The right-hand side of the subtraction operation.
	#[implementations(f64, f32, u32, DVec2, DVec2, f64)]
	subtrahend: T,
) -> <U as Sub<T>>::Output {
	minuend - subtrahend
}

/// The multiplication operation (×) calculates the product of two numbers.
#[node_macro::node(category("Math: Arithmetic"))]
fn multiply<U: Mul<T>, T>(
	_: impl Ctx,
	/// The left-hand side of the multiplication operation.
	#[implementations(f64, f32, u32, DVec2, f64, DVec2)]
	multiplier: U,
	/// The right-hand side of the multiplication operation.
	#[default(1.)]
	#[implementations(f64, f32, u32, DVec2, DVec2, f64)]
	multiplicand: T,
) -> <U as Mul<T>>::Output {
	multiplier * multiplicand
}

/// The division operation (÷) calculates the quotient of two numbers.
///
/// Produces 0 if the denominator is 0.
#[node_macro::node(category("Math: Arithmetic"))]
fn divide<U: Div<T> + Default + PartialEq, T: Default + PartialEq>(
	_: impl Ctx,
	/// The left-hand side of the division operation.
	#[implementations(f64, f64, f32, f32, u32, u32, DVec2, DVec2, f64)]
	numerator: U,
	/// The right-hand side of the division operation.
	#[default(1.)]
	#[implementations(f64, f64, f32, f32, u32, u32, DVec2, f64, DVec2)]
	denominator: T,
) -> <U as Div<T>>::Output
where
	<U as Div<T>>::Output: Default,
{
	if denominator == T::default() {
		return <U as Div<T>>::Output::default();
	}
	numerator / denominator
}

/// The modulo operation (%) calculates the remainder from the division of two numbers. The sign of the result shares the sign of the numerator unless "Always Positive" is enabled.
#[node_macro::node(category("Math: Arithmetic"))]
fn modulo<U: Rem<T, Output: Add<T, Output: Rem<T, Output = U::Output>>>, T: Copy>(
	_: impl Ctx,
	/// The left-hand side of the modulo operation.
	#[implementations(f64, f32, u32, DVec2, DVec2, f64)]
	numerator: U,
	/// The right-hand side of the modulo operation.
	#[default(2.)]
	#[implementations(f64, f32, u32, DVec2, f64, DVec2)]
	modulus: T,
	/// Ensures the result will always be positive, even if the numerator is negative.
	#[default(true)]
	always_positive: bool,
) -> <U as Rem<T>>::Output {
	if always_positive { (numerator % modulus + modulus) % modulus } else { numerator % modulus }
}

/// The exponent operation (^) calculates the result of raising a number to a power.
#[node_macro::node(category("Math: Arithmetic"))]
fn exponent<U: Pow<T>, T>(
	_: impl Ctx,
	/// The base number that will be raised to the power.
	#[implementations(f64, f32, u32)]
	base: U,
	/// The power to which the base number will be raised.
	#[default(2.)]
	#[implementations(f64, f32, u32)]
	power: T,
) -> <U as num_traits::Pow<T>>::Output {
	base.pow(power)
}

/// The square root operation (√) calculates the nth root of a number, equivalent to raising the number to the power of 1/n.
#[node_macro::node(category("Math: Arithmetic"))]
fn root<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number for which the nth root will be calculated.
	#[default(2.)]
	#[implementations(f64, f32)]
	radicand: U,
	/// The degree of the root to be calculated. Square root is 2, cube root is 3, and so on.
	#[default(2.)]
	#[implementations(f64, f32)]
	degree: U,
) -> U {
	if degree == U::from(2.).unwrap() {
		radicand.sqrt()
	} else if degree == U::from(3.).unwrap() {
		radicand.cbrt()
	} else {
		radicand.powf(U::from(1.).unwrap() / degree)
	}
}

/// The logarithmic function (log) calculates the logarithm of a number with a specified base. If the natural logarithm function (ln) is desired, set the base to "e".
#[node_macro::node(category("Math: Arithmetic"))]
fn logarithm<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number for which the logarithm will be calculated.
	#[implementations(f64, f32)]
	value: U,
	/// The base of the logarithm, such as 2 (binary), 10 (decimal), and e (natural logarithm).
	#[default(2.)]
	#[implementations(f64, f32)]
	base: U,
) -> U {
	if base == U::from(2.).unwrap() {
		value.log2()
	} else if base == U::from(10.).unwrap() {
		value.log10()
	} else if base - U::from(std::f64::consts::E).unwrap() < U::epsilon() * U::from(1e6).unwrap() {
		value.ln()
	} else {
		value.log(base)
	}
}

/// The sine trigonometric function (sin) calculates the ratio of the angle's opposite side length to its hypotenuse length.
#[node_macro::node(category("Math: Trig"))]
fn sine<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The given angle.
	#[implementations(f64, f32)]
	theta: U,
	/// Whether the given angle should be interpreted as radians instead of degrees.
	radians: bool,
) -> U {
	if radians { theta.sin() } else { theta.to_radians().sin() }
}

/// The cosine trigonometric function (cos) calculates the ratio of the angle's adjacent side length to its hypotenuse length.
#[node_macro::node(category("Math: Trig"))]
fn cosine<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The given angle.
	#[implementations(f64, f32)]
	theta: U,
	/// Whether the given angle should be interpreted as radians instead of degrees.
	radians: bool,
) -> U {
	if radians { theta.cos() } else { theta.to_radians().cos() }
}

/// The tangent trigonometric function (tan) calculates the ratio of the angle's opposite side length to its adjacent side length.
#[node_macro::node(category("Math: Trig"))]
fn tangent<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The given angle.
	#[implementations(f64, f32)]
	theta: U,
	/// Whether the given angle should be interpreted as radians instead of degrees.
	radians: bool,
) -> U {
	if radians { theta.tan() } else { theta.to_radians().tan() }
}

/// The inverse sine trigonometric function (asin) calculates the angle whose sine is the specified value.
#[node_macro::node(category("Math: Trig"))]
fn sine_inverse<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The given value for which the angle will be calculated. Must be in the range [-1, 1] or else the result will be NaN.
	#[implementations(f64, f32)]
	value: U,
	/// Whether the resulting angle should be given in as radians instead of degrees.
	radians: bool,
) -> U {
	if radians { value.asin() } else { value.asin().to_degrees() }
}

/// The inverse cosine trigonometric function (acos) calculates the angle whose cosine is the specified value.
#[node_macro::node(category("Math: Trig"))]
fn cosine_inverse<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The given value for which the angle will be calculated. Must be in the range [-1, 1] or else the result will be NaN.
	#[implementations(f64, f32)]
	value: U,
	/// Whether the resulting angle should be given in as radians instead of degrees.
	radians: bool,
) -> U {
	if radians { value.acos() } else { value.acos().to_degrees() }
}

/// The inverse tangent trigonometric function (atan or atan2, depending on input type) calculates:
/// atan: the angle whose tangent is the specified scalar number.
/// atan2: the angle of a ray from the origin to the specified coordinate.
///
/// The resulting angle is always in the range [0°, 180°] or, in radians, [-π/2, π/2].
#[node_macro::node(category("Math: Trig"))]
fn tangent_inverse<U: TangentInverse>(
	_: impl Ctx,
	/// The given value for which the angle will be calculated.
	#[implementations(f64, f32, DVec2)]
	value: U,
	/// Whether the resulting angle should be given in as radians instead of degrees.
	radians: bool,
) -> U::Output {
	value.atan(radians)
}

pub trait TangentInverse {
	type Output: num_traits::float::Float;
	fn atan(self, radians: bool) -> Self::Output;
}
impl TangentInverse for f32 {
	type Output = f32;
	fn atan(self, radians: bool) -> Self::Output {
		if radians { self.atan() } else { self.atan().to_degrees() }
	}
}
impl TangentInverse for f64 {
	type Output = f64;
	fn atan(self, radians: bool) -> Self::Output {
		if radians { self.atan() } else { self.atan().to_degrees() }
	}
}
impl TangentInverse for DVec2 {
	type Output = f64;
	fn atan(self, radians: bool) -> Self::Output {
		if radians { self.y.atan2(self.x) } else { self.y.atan2(self.x).to_degrees() }
	}
}

/// The random function (rand) converts a seed into a random number within the specified range, inclusive of the minimum and exclusive of the maximum. The minimum and maximum values are automatically swapped if they are reversed.
#[node_macro::node(category("Math: Numeric"))]
fn random<U: num_traits::float::Float>(
	_: impl Ctx,
	_primary: (),
	/// Seed to determine the unique variation of which number will be generated.
	seed: u64,
	/// The smaller end of the range within which the random number will be generated.
	#[implementations(f64, f32)]
	#[default(0.)]
	min: U,
	/// The larger end of the range within which the random number will be generated.
	#[implementations(f64, f32)]
	#[default(1.)]
	max: U,
) -> f64 {
	let mut rng = rand::rngs::StdRng::seed_from_u64(seed);
	let result = rng.random::<f64>();
	let (min, max) = if min < max { (min, max) } else { (max, min) };
	let (min, max) = (min.to_f64().unwrap(), max.to_f64().unwrap());
	result * (max - min) + min
}

/// Convert a number to an integer of the type u32, which may be the required type for certain node inputs. This will be removed in the future when automatic type conversion is implemented.
#[node_macro::node(name("To u32"), category("Math: Numeric"))]
fn to_u32<U: num_traits::float::Float>(_: impl Ctx, #[implementations(f64, f32)] value: U) -> u32 {
	let value = U::clamp(value, U::from(0.).unwrap(), U::from(u32::MAX as f64).unwrap());
	value.to_u32().unwrap()
}

/// Convert a number to an integer of the type u64, which may be the required type for certain node inputs. This will be removed in the future when automatic type conversion is implemented.
#[node_macro::node(name("To u64"), category("Math: Numeric"))]
fn to_u64<U: num_traits::float::Float>(_: impl Ctx, #[implementations(f64, f32)] value: U) -> u64 {
	let value = U::clamp(value, U::from(0.).unwrap(), U::from(u64::MAX as f64).unwrap());
	value.to_u64().unwrap()
}

/// Convert an integer to a decimal number of the type f64, which may be the required type for certain node inputs. This will be removed in the future when automatic type conversion is implemented.
#[node_macro::node(name("To f64"), category("Math: Numeric"))]
fn to_f64<U: num_traits::int::PrimInt>(_: impl Ctx, #[implementations(u32, u64)] value: U) -> f64 {
	value.to_f64().unwrap()
}

/// The rounding function (round) maps an input value to its nearest whole number. Halfway values are rounded away from zero.
#[node_macro::node(category("Math: Numeric"))]
fn round<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number which will be rounded.
	#[implementations(f64, f32)]
	value: U,
) -> U {
	value.round()
}

/// The floor function (floor) rounds down an input value to the nearest whole number, unless the input number is already whole.
#[node_macro::node(category("Math: Numeric"))]
fn floor<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number which will be rounded down.
	#[implementations(f64, f32)]
	value: U,
) -> U {
	value.floor()
}

/// The ceiling function (ceil) rounds up an input value to the nearest whole number, unless the input number is already whole.
#[node_macro::node(category("Math: Numeric"))]
fn ceiling<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number which will be rounded up.
	#[implementations(f64, f32)]
	value: U,
) -> U {
	value.ceil()
}

/// The absolute value function (abs) removes the negative sign from an input value, if present.
#[node_macro::node(category("Math: Numeric"))]
fn absolute_value<U: num_traits::float::Float>(
	_: impl Ctx,
	/// The number which will be made positive.
	#[implementations(f64, f32)]
	value: U,
) -> U {
	value.abs()
}

/// The minimum function (min) picks the smaller of two numbers.
#[node_macro::node(category("Math: Numeric"))]
fn min<T: std::cmp::PartialOrd>(
	_: impl Ctx,
	/// One of the two numbers, of which the lesser will be returned.
	#[implementations(f64, f32, u32, &str)]
	value: T,
	/// The other of the two numbers, of which the lesser will be returned.
	#[implementations(f64, f32, u32, &str)]
	other_value: T,
) -> T {
	if value < other_value { value } else { other_value }
}

/// The maximum function (max) picks the larger of two numbers.
#[node_macro::node(category("Math: Numeric"))]
fn max<T: std::cmp::PartialOrd>(
	_: impl Ctx,
	/// One of the two numbers, of which the greater will be returned.
	#[implementations(f64, f32, u32, &str)]
	value: T,
	/// The other of the two numbers, of which the greater will be returned.
	#[implementations(f64, f32, u32, &str)]
	other_value: T,
) -> T {
	if value > other_value { value } else { other_value }
}

/// The clamp function (clamp) restricts a number to a specified range between a minimum and maximum value. The minimum and maximum values are automatically swapped if they are reversed.
#[node_macro::node(category("Math: Numeric"))]
fn clamp<T: std::cmp::PartialOrd>(
	_: impl Ctx,
	/// The number to be clamped, which will be restricted to the range between the minimum and maximum values.
	#[implementations(f64, f32, u32, &str)]
	value: T,
	/// The left (smaller) side of the range. The output will never be less than this number.
	#[implementations(f64, f32, u32, &str)]
	min: T,
	/// The right (greater) side of the range. The output will never be greater than this number.
	#[implementations(f64, f32, u32, &str)]
	max: T,
) -> T {
	let (min, max) = if min < max { (min, max) } else { (max, min) };
	if value < min {
		min
	} else if value > max {
		max
	} else {
		value
	}
}

/// The equality operation (==) compares two values and returns true if they are equal, or false if they are not.
#[node_macro::node(category("Math: Logic"))]
fn equals<U: std::cmp::PartialEq<T>, T>(
	_: impl Ctx,
	/// One of the two numbers to compare for equality.
	#[implementations(f64, f32, u32, DVec2, &str)]
	value: T,
	/// The other of the two numbers to compare for equality.
	#[implementations(f64, f32, u32, DVec2, &str)]
	other_value: U,
) -> bool {
	other_value == value
}

/// The inequality operation (!=) compares two values and returns true if they are not equal, or false if they are.
#[node_macro::node(category("Math: Logic"))]
fn not_equals<U: std::cmp::PartialEq<T>, T>(
	_: impl Ctx,
	/// One of the two numbers to compare for inequality.
	#[implementations(f64, f32, u32, DVec2, &str)]
	value: T,
	/// The other of the two numbers to compare for inequality.
	#[implementations(f64, f32, u32, DVec2, &str)]
	other_value: U,
) -> bool {
	other_value != value
}

/// The less-than operation (<) compares two values and returns true if the first value is less than the second, or false if it is not.
/// If enabled with "Or Equal", the less-than-or-equal operation (<=) will be used instead.
#[node_macro::node(category("Math: Logic"))]
fn less_than<T: std::cmp::PartialOrd<T>>(
	_: impl Ctx,
	/// The number on the left-hand side of the comparison.
	#[implementations(f64, f32, u32)]
	value: T,
	/// The number on the right-hand side of the comparison.
	#[implementations(f64, f32, u32)]
	other_value: T,
	/// Uses the less-than-or-equal operation (<=) instead of the less-than operation (<).
	or_equal: bool,
) -> bool {
	if or_equal { value <= other_value } else { value < other_value }
}

/// The greater-than operation (>) compares two values and returns true if the first value is greater than the second, or false if it is not.
/// If enabled with "Or Equal", the greater-than-or-equal operation (>=) will be used instead.
#[node_macro::node(category("Math: Logic"))]
fn greater_than<T: std::cmp::PartialOrd<T>>(
	_: impl Ctx,
	/// The number on the left-hand side of the comparison.
	#[implementations(f64, f32, u32)]
	value: T,
	/// The number on the right-hand side of the comparison.
	#[implementations(f64, f32, u32)]
	other_value: T,
	/// Uses the greater-than-or-equal operation (>=) instead of the greater-than operation (>).
	or_equal: bool,
) -> bool {
	if or_equal { value >= other_value } else { value > other_value }
}

/// The logical or operation (||) returns true if either of the two inputs are true, or false if both are false.
#[node_macro::node(category("Math: Logic"))]
fn logical_or(
	_: impl Ctx,
	/// One of the two boolean values, either of which may be true for the node to output true.
	value: bool,
	/// The other of the two boolean values, either of which may be true for the node to output true.
	other_value: bool,
) -> bool {
	value || other_value
}

/// The logical and operation (&&) returns true if both of the two inputs are true, or false if any are false.
#[node_macro::node(category("Math: Logic"))]
fn logical_and(
	_: impl Ctx,
	/// One of the two boolean values, both of which must be true for the node to output true.
	value: bool,
	/// The other of the two boolean values, both of which must be true for the node to output true.
	other_value: bool,
) -> bool {
	value && other_value
}

/// The logical not operation (!) reverses true and false value of the input.
#[node_macro::node(category("Math: Logic"))]
fn logical_not(
	_: impl Ctx,
	/// The boolean value to be reversed.
	input: bool,
) -> bool {
	!input
}

/// Constructs a bool value which may be set to true or false.
#[node_macro::node(category("Value"))]
fn bool_value(_: impl Ctx, _primary: (), #[name("Bool")] bool_value: bool) -> bool {
	bool_value
}

/// Constructs a number value which may be set to any real number.
#[node_macro::node(category("Value"))]
fn number_value(_: impl Ctx, _primary: (), number: f64) -> f64 {
	number
}

/// Constructs a number value which may be set to any value from 0% to 100% by dragging the slider.
#[node_macro::node(category("Value"))]
fn percentage_value(_: impl Ctx, _primary: (), percentage: Percentage) -> f64 {
	percentage
}

/// Constructs a two-dimensional vector value which may be set to any XY coordinate.
#[node_macro::node(category("Value"))]
fn coordinate_value(_: impl Ctx, _primary: (), x: f64, y: f64) -> DVec2 {
	DVec2::new(x, y)
}

/// Constructs a color value which may be set to any color, or no color.
#[node_macro::node(category("Value"))]
fn color_value(_: impl Ctx, _primary: (), #[default(Color::BLACK)] color: Option<Color>) -> Option<Color> {
	color
}

/// Gets the color at the specified position along the gradient, given a position from 0 (left) to 1 (right).
#[node_macro::node(category("Color"))]
fn sample_gradient(_: impl Ctx, _primary: (), gradient: GradientStops, position: Fraction) -> Color {
	let position = position.clamp(0., 1.);
	gradient.evaluate(position)
}

/// Constructs a gradient value which may be set to any sequence of color stops to represent the transition between colors.
#[node_macro::node(category("Value"))]
fn gradient_value(_: impl Ctx, _primary: (), gradient: GradientStops) -> GradientStops {
	gradient
}

/// Constructs a string value which may be set to any plain text.
#[node_macro::node(category("Value"))]
fn string_value(_: impl Ctx, _primary: (), string: TextArea) -> String {
	string
}

#[node_macro::node(category("Math: Vector"))]
fn dot_product(_: impl Ctx, vector_a: DVec2, vector_b: DVec2) -> f64 {
	vector_a.dot(vector_b)
}

#[cfg(test)]
mod test {
	use super::*;
	use graphene_core::Node;
	use graphene_core::generic::FnNode;

	#[test]
	pub fn dot_product_function() {
		let vector_a = DVec2::new(1., 2.);
		let vector_b = DVec2::new(3., 4.);
		assert_eq!(dot_product((), vector_a, vector_b), 11.);
	}

	#[test]
	fn test_basic_expression() {
		let result = math((), 0., "2 + 2".to_string(), 0.);
		assert_eq!(result, 4.);
	}

	#[test]
	fn test_complex_expression() {
		let result = math((), 0., "(5 * 3) + (10 / 2)".to_string(), 0.);
		assert_eq!(result, 20.);
	}

	#[test]
	fn test_default_expression() {
		let result = math((), 0., "0".to_string(), 0.);
		assert_eq!(result, 0.);
	}

	#[test]
	fn test_invalid_expression() {
		let result = math((), 0., "invalid".to_string(), 0.);
		assert_eq!(result, 0.);
	}

	#[test]
	pub fn foo() {
		let fnn = FnNode::new(|(a, b)| (b, a));
		assert_eq!(fnn.eval((1u32, 2u32)), (2, 1));
	}

	#[test]
	pub fn add_vectors() {
		assert_eq!(super::add((), DVec2::ONE, DVec2::ONE), DVec2::ONE * 2.);
	}

	#[test]
	pub fn subtract_f64() {
		assert_eq!(super::subtract((), 5_f64, 3_f64), 2.);
	}

	#[test]
	pub fn divide_vectors() {
		assert_eq!(super::divide((), DVec2::ONE, 2_f64), DVec2::ONE / 2.);
	}

	#[test]
	pub fn modulo_positive() {
		assert_eq!(super::modulo((), -5_f64, 2_f64, true), 1_f64);
	}

	#[test]
	pub fn modulo_negative() {
		assert_eq!(super::modulo((), -5_f64, 2_f64, false), -1_f64);
	}
}