wick-quaternion 0.1.0

//! Quaternion support for dew expressions.
//!
//! Provides quaternion types and operations for 3D rotations. Uses [x, y, z, w]
//! component order (scalar last, matching GLM/glTF convention).
//!
//! # Quick Start
//!
//! ```
//! use wick_core::Expr;
//! use wick_quaternion::{Value, eval, quaternion_registry};
//! use std::collections::HashMap;
//!
//! // Create a rotation quaternion and normalize it
//! let expr = Expr::parse("normalize(q)").unwrap();
//!
//! let vars: HashMap<String, Value<f32>> = [
//!     ("q".into(), Value::Quaternion([0.0, 0.0, 0.0, 2.0])),
//! ].into();
//!
//! let result = eval(expr.ast(), &vars, &quaternion_registry()).unwrap();
//! assert_eq!(result, Value::Quaternion([0.0, 0.0, 0.0, 1.0]));
//! ```
//!
//! # Features
//!
//! | Feature     | Description                    |
//! |-------------|--------------------------------|
//! | `wgsl`      | WGSL shader code generation    |
//! | `lua`       | Lua code generation            |
//! | `cranelift` | Cranelift JIT compilation      |
//!
//! # Types
//!
//! | Type        | Description                      |
//! |-------------|----------------------------------|
//! | `Scalar`    | Real number                      |
//! | `Vec3`      | 3D vector [x, y, z]              |
//! | `Quaternion`| Quaternion [x, y, z, w]          |
//!
//! # Functions
//!
//! | Function              | Description                              |
//! |-----------------------|------------------------------------------|
//! | `vec3(x, y, z)`       | Construct vector → vec3                  |
//! | `quat(x, y, z, w)`    | Construct quaternion → quaternion        |
//! | `conj(q)`             | Conjugate → quaternion                   |
//! | `length(q)`           | Magnitude → scalar                       |
//! | `normalize(q)`        | Unit quaternion → quaternion             |
//! | `inverse(q)`          | Multiplicative inverse → quaternion      |
//! | `dot(q1, q2)`         | Dot product → scalar                     |
//! | `lerp(q1, q2, t)`     | Linear interpolation → quaternion        |
//! | `slerp(q1, q2, t)`    | Spherical interpolation → quaternion     |
//! | `axis_angle(axis, θ)` | From axis-angle → quaternion             |
//! | `rotate(v, q)`        | Rotate vector by quaternion → vec3       |
//!
//! # Operators
//!
//! | Operation          | Result                          |
//! |--------------------|---------------------------------|
//! | `q1 * q2`          | Quaternion multiplication       |
//! | `q * scalar`       | Scalar multiplication           |
//! | `q1 + q2`          | Component-wise addition         |
//! | `q1 - q2`          | Component-wise subtraction      |
//! | `-q`               | Negation                        |
//!
//! # Component Order
//!
//! This crate uses [x, y, z, w] order (scalar last), matching:
//! - GLM (OpenGL Mathematics)
//! - glTF format
//! - Unity (internal representation)
//!
//! Other conventions exist (w first), so be careful when interfacing
//! with external libraries.

use num_traits::Float;
use std::collections::HashMap;
use std::sync::Arc;
use wick_core::{Ast, BinOp, CompareOp, UnaryOp};

mod funcs;
pub mod ops;
#[cfg(test)]
mod parity_tests;

#[cfg(feature = "wgsl")]
pub mod wgsl;

#[cfg(feature = "glsl")]
pub mod glsl;

#[cfg(feature = "rust")]
pub mod rust;

#[cfg(feature = "c")]
pub mod c;

#[cfg(feature = "opencl")]
pub mod opencl;

#[cfg(feature = "cuda")]
pub mod cuda;

#[cfg(feature = "hip")]
pub mod hip;

#[cfg(feature = "tokenstream")]
pub mod tokenstream;

#[cfg(feature = "lua-codegen")]
pub mod lua;

#[cfg(feature = "cranelift")]
pub mod cranelift;

#[cfg(feature = "optimize")]
pub mod optimize;

pub use funcs::{
    AxisAngle, Conj, Dot, Inverse, Length, Lerp, Normalize, QuatConstructor, Rotate, Slerp,
    Vec3Constructor, quaternion_registry, register_quaternion,
};

// ============================================================================
// Types
// ============================================================================

/// Type of a quaternion value.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Type {
    /// Real scalar.
    Scalar,
    /// 3D vector [x, y, z].
    Vec3,
    /// Quaternion [x, y, z, w].
    Quaternion,
}

impl std::fmt::Display for Type {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Type::Scalar => write!(f, "scalar"),
            Type::Vec3 => write!(f, "vec3"),
            Type::Quaternion => write!(f, "quaternion"),
        }
    }
}

// ============================================================================
// QuaternionValue trait (for composability)
// ============================================================================

/// Trait for values that support quaternion operations.
///
/// Implement this for combined value types when composing multiple domain crates.
pub trait QuaternionValue<T: Float>: Clone + PartialEq + Sized + std::fmt::Debug {
    /// Returns the type of this value.
    fn typ(&self) -> Type;

    // Construction
    fn from_scalar(v: T) -> Self;
    fn from_vec3(v: [T; 3]) -> Self;
    fn from_quaternion(q: [T; 4]) -> Self;

    // Extraction
    fn as_scalar(&self) -> Option<T>;
    fn as_vec3(&self) -> Option<[T; 3]>;
    fn as_quaternion(&self) -> Option<[T; 4]>;
}

// ============================================================================
// Values
// ============================================================================

/// A quaternion value, generic over numeric type.
///
/// Quaternion uses [x, y, z, w] order (scalar last).
#[derive(Debug, Clone, PartialEq)]
pub enum Value<T> {
    /// Real scalar.
    Scalar(T),
    /// 3D vector [x, y, z].
    Vec3([T; 3]),
    /// Quaternion [x, y, z, w] (scalar last).
    Quaternion([T; 4]),
}

impl<T> Value<T> {
    /// Returns the type of this value.
    pub fn typ(&self) -> Type {
        match self {
            Value::Scalar(_) => Type::Scalar,
            Value::Vec3(_) => Type::Vec3,
            Value::Quaternion(_) => Type::Quaternion,
        }
    }
}

impl<T: Copy> Value<T> {
    /// Try to get as scalar.
    pub fn as_scalar(&self) -> Option<T> {
        match self {
            Value::Scalar(v) => Some(*v),
            _ => None,
        }
    }

    /// Try to get as vec3.
    pub fn as_vec3(&self) -> Option<[T; 3]> {
        match self {
            Value::Vec3(v) => Some(*v),
            _ => None,
        }
    }

    /// Try to get as quaternion.
    pub fn as_quaternion(&self) -> Option<[T; 4]> {
        match self {
            Value::Quaternion(q) => Some(*q),
            _ => None,
        }
    }
}

impl<T: Float + std::fmt::Debug> QuaternionValue<T> for Value<T> {
    fn typ(&self) -> Type {
        Value::typ(self)
    }

    fn from_scalar(v: T) -> Self {
        Value::Scalar(v)
    }

    fn from_vec3(v: [T; 3]) -> Self {
        Value::Vec3(v)
    }

    fn from_quaternion(q: [T; 4]) -> Self {
        Value::Quaternion(q)
    }

    fn as_scalar(&self) -> Option<T> {
        Value::as_scalar(self)
    }

    fn as_vec3(&self) -> Option<[T; 3]> {
        Value::as_vec3(self)
    }

    fn as_quaternion(&self) -> Option<[T; 4]> {
        Value::as_quaternion(self)
    }
}

// ============================================================================
// Errors
// ============================================================================

/// Quaternion evaluation error.
#[derive(Debug, Clone, PartialEq)]
pub enum Error {
    /// Unknown variable.
    UnknownVariable(String),
    /// Unknown function.
    UnknownFunction(String),
    /// Type mismatch for binary operation.
    BinaryTypeMismatch { op: BinOp, left: Type, right: Type },
    /// Type mismatch for unary operation.
    UnaryTypeMismatch { op: UnaryOp, operand: Type },
    /// Wrong number of arguments to function.
    WrongArgCount {
        func: String,
        expected: usize,
        got: usize,
    },
    /// Type mismatch in function arguments.
    FunctionTypeMismatch {
        func: String,
        expected: Vec<Type>,
        got: Vec<Type>,
    },
    /// Conditionals require scalar types.
    UnsupportedTypeForConditional(Type),
}

impl std::fmt::Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Error::UnknownVariable(name) => write!(f, "unknown variable: '{name}'"),
            Error::UnknownFunction(name) => write!(f, "unknown function: '{name}'"),
            Error::BinaryTypeMismatch { op, left, right } => {
                write!(f, "cannot apply {op:?} to {left} and {right}")
            }
            Error::UnaryTypeMismatch { op, operand } => {
                write!(f, "cannot apply {op:?} to {operand}")
            }
            Error::WrongArgCount {
                func,
                expected,
                got,
            } => {
                write!(f, "function '{func}' expects {expected} args, got {got}")
            }
            Error::FunctionTypeMismatch {
                func,
                expected,
                got,
            } => {
                write!(
                    f,
                    "function '{func}' expects types {expected:?}, got {got:?}"
                )
            }
            Error::UnsupportedTypeForConditional(t) => {
                write!(f, "conditionals require scalar type, got {t}")
            }
        }
    }
}

impl std::error::Error for Error {}

// ============================================================================
// Function Registry
// ============================================================================

/// A function signature.
#[derive(Debug, Clone, PartialEq)]
pub struct Signature {
    pub args: Vec<Type>,
    pub ret: Type,
}

/// A function that can be called from quaternion expressions.
///
/// Generic over both the numeric type `T` and the value type `V`.
pub trait QuaternionFn<T, V>: Send + Sync
where
    T: Float,
    V: QuaternionValue<T>,
{
    /// Function name.
    fn name(&self) -> &str;

    /// Available signatures for this function.
    fn signatures(&self) -> Vec<Signature>;

    /// Call the function with typed arguments.
    fn call(&self, args: &[V]) -> V;
}

/// Registry of quaternion functions.
#[derive(Clone)]
pub struct FunctionRegistry<T, V>
where
    T: Float,
    V: QuaternionValue<T>,
{
    funcs: HashMap<String, Arc<dyn QuaternionFn<T, V>>>,
}

impl<T, V> Default for FunctionRegistry<T, V>
where
    T: Float,
    V: QuaternionValue<T>,
{
    fn default() -> Self {
        Self {
            funcs: HashMap::new(),
        }
    }
}

impl<T, V> FunctionRegistry<T, V>
where
    T: Float,
    V: QuaternionValue<T>,
{
    pub fn new() -> Self {
        Self::default()
    }

    pub fn register<F: QuaternionFn<T, V> + 'static>(&mut self, func: F) {
        self.funcs.insert(func.name().to_string(), Arc::new(func));
    }

    pub fn get(&self, name: &str) -> Option<&Arc<dyn QuaternionFn<T, V>>> {
        self.funcs.get(name)
    }
}

// ============================================================================
// Evaluation
// ============================================================================

/// Evaluate an AST with quaternion values.
///
/// Generic over both the numeric type `T` and the value type `V`.
pub fn eval<T, V>(
    ast: &Ast,
    vars: &HashMap<String, V>,
    funcs: &FunctionRegistry<T, V>,
) -> Result<V, Error>
where
    T: Float,
    V: QuaternionValue<T>,
{
    match ast {
        Ast::Num(n) => Ok(V::from_scalar(T::from(*n).unwrap())),

        Ast::Var(name) => vars
            .get(name)
            .cloned()
            .ok_or_else(|| Error::UnknownVariable(name.clone())),

        Ast::BinOp(op, left, right) => {
            let left_val = eval(left, vars, funcs)?;
            let right_val = eval(right, vars, funcs)?;
            ops::apply_binop(*op, left_val, right_val)
        }

        Ast::UnaryOp(op, inner) => {
            let val = eval(inner, vars, funcs)?;
            ops::apply_unaryop(*op, val)
        }

        Ast::Call(name, args) => {
            let func = funcs
                .get(name)
                .ok_or_else(|| Error::UnknownFunction(name.clone()))?;

            let arg_vals: Vec<V> = args
                .iter()
                .map(|a| eval(a, vars, funcs))
                .collect::<Result<_, _>>()?;

            let arg_types: Vec<Type> = arg_vals.iter().map(|v| v.typ()).collect();

            // Find matching signature
            let matched = func.signatures().iter().any(|sig| sig.args == arg_types);
            if !matched {
                return Err(Error::FunctionTypeMismatch {
                    func: name.clone(),
                    expected: func
                        .signatures()
                        .first()
                        .map(|s| s.args.clone())
                        .unwrap_or_default(),
                    got: arg_types,
                });
            }

            Ok(func.call(&arg_vals))
        }

        Ast::Compare(op, left, right) => {
            let left_val = eval(left, vars, funcs)?;
            let right_val = eval(right, vars, funcs)?;
            match (left_val.as_scalar(), right_val.as_scalar()) {
                (Some(l), Some(r)) => {
                    let result = match op {
                        CompareOp::Lt => l < r,
                        CompareOp::Le => l <= r,
                        CompareOp::Gt => l > r,
                        CompareOp::Ge => l >= r,
                        CompareOp::Eq => l == r,
                        CompareOp::Ne => l != r,
                    };
                    Ok(V::from_scalar(if result { T::one() } else { T::zero() }))
                }
                _ => Err(Error::UnsupportedTypeForConditional(left_val.typ())),
            }
        }

        Ast::And(left, right) => {
            let left_val = eval(left, vars, funcs)?;
            let right_val = eval(right, vars, funcs)?;
            match (left_val.as_scalar(), right_val.as_scalar()) {
                (Some(l), Some(r)) => {
                    let result = !l.is_zero() && !r.is_zero();
                    Ok(V::from_scalar(if result { T::one() } else { T::zero() }))
                }
                _ => Err(Error::UnsupportedTypeForConditional(left_val.typ())),
            }
        }

        Ast::Or(left, right) => {
            let left_val = eval(left, vars, funcs)?;
            let right_val = eval(right, vars, funcs)?;
            match (left_val.as_scalar(), right_val.as_scalar()) {
                (Some(l), Some(r)) => {
                    let result = !l.is_zero() || !r.is_zero();
                    Ok(V::from_scalar(if result { T::one() } else { T::zero() }))
                }
                _ => Err(Error::UnsupportedTypeForConditional(left_val.typ())),
            }
        }

        Ast::If(cond, then_ast, else_ast) => {
            let cond_val = eval(cond, vars, funcs)?;
            if let Some(c) = cond_val.as_scalar() {
                if !c.is_zero() {
                    eval(then_ast, vars, funcs)
                } else {
                    eval(else_ast, vars, funcs)
                }
            } else {
                Err(Error::UnsupportedTypeForConditional(cond_val.typ()))
            }
        }

        Ast::Let { name, value, body } => {
            let val = eval(value, vars, funcs)?;
            let mut new_vars = vars.clone();
            new_vars.insert(name.clone(), val);
            eval(body, &new_vars, funcs)
        }
    }
}

// ============================================================================
// Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;
    use wick_core::Expr;

    fn eval_expr(expr: &str, vars: &[(&str, Value<f32>)]) -> Result<Value<f32>, Error> {
        let expr = Expr::parse(expr).unwrap();
        let var_map: HashMap<String, Value<f32>> = vars
            .iter()
            .map(|(k, v)| (k.to_string(), v.clone()))
            .collect();
        let registry = quaternion_registry();
        eval(expr.ast(), &var_map, &registry)
    }

    #[test]
    fn test_quaternion_add() {
        let result = eval_expr(
            "a + b",
            &[
                ("a", Value::Quaternion([1.0, 2.0, 3.0, 4.0])),
                ("b", Value::Quaternion([5.0, 6.0, 7.0, 8.0])),
            ],
        );
        assert_eq!(result.unwrap(), Value::Quaternion([6.0, 8.0, 10.0, 12.0]));
    }

    #[test]
    fn test_quaternion_mul() {
        // Identity quaternion: [0, 0, 0, 1]
        // q * identity = q
        let result = eval_expr(
            "a * b",
            &[
                ("a", Value::Quaternion([1.0, 2.0, 3.0, 4.0])),
                ("b", Value::Quaternion([0.0, 0.0, 0.0, 1.0])),
            ],
        );
        assert_eq!(result.unwrap(), Value::Quaternion([1.0, 2.0, 3.0, 4.0]));
    }

    #[test]
    fn test_quaternion_neg() {
        let result = eval_expr("-q", &[("q", Value::Quaternion([1.0, 2.0, 3.0, 4.0]))]);
        assert_eq!(result.unwrap(), Value::Quaternion([-1.0, -2.0, -3.0, -4.0]));
    }

    #[test]
    fn test_quaternion_scalar_mul() {
        let result = eval_expr(
            "s * q",
            &[
                ("s", Value::Scalar(2.0)),
                ("q", Value::Quaternion([1.0, 2.0, 3.0, 4.0])),
            ],
        );
        assert_eq!(result.unwrap(), Value::Quaternion([2.0, 4.0, 6.0, 8.0]));
    }
}