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pub extern crate opensrdk_linear_algebra;
extern crate rayon;
extern crate thiserror;

pub use add::*;
pub use ard::*;
pub use constant::*;
pub use convolutional::*;
pub use exponential::*;
pub use instant::*;
pub use linear::*;
pub use mul::*;
pub use neural_network::{deep_neural_network::*, relu::*};
use opensrdk_symbolic_computation::Expression;
pub use periodic::*;
pub use rbf::*;
pub use spectral_mixture::*;

use std::fmt::Debug;

pub mod add;
pub mod ard;
pub mod constant;
pub mod convolutional;
pub mod exponential;
pub mod instant;
pub mod linear;
pub mod mul;
pub mod neural_network;
pub mod periodic;
pub mod rbf;
pub mod spectral_mixture;

pub trait Value: Clone + Debug + Send + Sync {}
impl<T> Value for T where T: Clone + Debug + Send + Sync {}

pub trait PositiveDefiniteKernel: Clone + Debug + Send + Sync {
    fn params_len(&self) -> usize;

    fn expression(
        &self,
        x: Expression,
        x_prime: Expression,
        params: &[Expression],
    ) -> Result<Expression, KernelError>;
}

#[derive(thiserror::Error, Debug)]
pub enum KernelError {
    #[error("parameters length mismatch")]
    ParametersLengthMismatch,
    #[error("invalid parameter")]
    InvalidParameter,
    #[error("invalid argument")]
    InvalidArgument,
}

// #[cfg(test)]
// mod tests {
//     use crate::*;
//     #[test]
//     fn it_works() {
//         let kernel = RBF + Constant * Linear + Constant * Periodic + Constant * ARD(3);
//         let test_value = kernel
//             .value(
//                 &vec![1.0; kernel.params_len()],
//                 &vec![1.0, 2.0, 3.0],
//                 &vec![30.0, 20.0, 10.0],
//             )
//             .unwrap();

//         println!("{}", test_value);
//     }
// }