#![allow(non_snake_case)]
#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(clippy::upper_case_acronyms)]

use ark_ff::PrimeField;
use ark_r1cs_std::alloc::AllocVar;
use ark_r1cs_std::fields::fp::FpVar;
use ark_relations::r1cs::{ConstraintSystemRef, SynthesisError};
use core::marker::PhantomData;
use std::time::Instant;

use ark_bn254::{constraints::GVar, Bn254, Fr, G1Projective as Projective};
use ark_grumpkin::{constraints::GVar as GVar2, Projective as Projective2};

use folding_schemes::commitment::{kzg::KZG, pedersen::Pedersen};
use folding_schemes::folding::nova::{Nova, PreprocessorParam};
use folding_schemes::frontend::FCircuit;
use folding_schemes::transcript::poseidon::poseidon_canonical_config;
use folding_schemes::{Error, FoldingScheme};

/// This is the circuit that we want to fold, it implements the FCircuit trait. The parameter z_i
/// denotes the current state which contains 5 elements, and z_{i+1} denotes the next state which
/// we get by applying the step.
/// In this example we set z_i and z_{i+1} to have five elements, and at each step we do different
/// operations on each of them.
#[derive(Clone, Copy, Debug)]
pub struct MultiInputsFCircuit<F: PrimeField> {
    _f: PhantomData<F>,
}
impl<F: PrimeField> FCircuit<F> for MultiInputsFCircuit<F> {
    type Params = ();

    fn new(_params: Self::Params) -> Result<Self, Error> {
        Ok(Self { _f: PhantomData })
    }
    fn state_len(&self) -> usize {
        5
    }
    fn external_inputs_len(&self) -> usize {
        0
    }

    /// computes the next state values in place, assigning z_{i+1} into z_i, and computing the new
    /// z_{i+1}
    fn step_native(
        &self,
        _i: usize,
        z_i: Vec<F>,
        _external_inputs: Vec<F>,
    ) -> Result<Vec<F>, Error> {
        let a = z_i[0] + F::from(4_u32);
        let b = z_i[1] + F::from(40_u32);
        let c = z_i[2] * F::from(4_u32);
        let d = z_i[3] * F::from(40_u32);
        let e = z_i[4] + F::from(100_u32);

        Ok(vec![a, b, c, d, e])
    }

    /// generates the constraints for the step of F for the given z_i
    fn generate_step_constraints(
        &self,
        cs: ConstraintSystemRef<F>,
        _i: usize,
        z_i: Vec<FpVar<F>>,
        _external_inputs: Vec<FpVar<F>>,
    ) -> Result<Vec<FpVar<F>>, SynthesisError> {
        let four = FpVar::<F>::new_constant(cs.clone(), F::from(4u32))?;
        let forty = FpVar::<F>::new_constant(cs.clone(), F::from(40u32))?;
        let onehundred = FpVar::<F>::new_constant(cs.clone(), F::from(100u32))?;
        let a = z_i[0].clone() + four.clone();
        let b = z_i[1].clone() + forty.clone();
        let c = z_i[2].clone() * four;
        let d = z_i[3].clone() * forty;
        let e = z_i[4].clone() + onehundred;

        Ok(vec![a, b, c, d, e])
    }
}

/// cargo test --example multi_inputs
#[cfg(test)]
pub mod tests {
    use super::*;
    use ark_r1cs_std::{alloc::AllocVar, R1CSVar};
    use ark_relations::r1cs::ConstraintSystem;

    // test to check that the MultiInputsFCircuit computes the same values inside and outside the circuit
    #[test]
    fn test_f_circuit() {
        let cs = ConstraintSystem::<Fr>::new_ref();

        let circuit = MultiInputsFCircuit::<Fr>::new(()).unwrap();
        let z_i = vec![
            Fr::from(1_u32),
            Fr::from(1_u32),
            Fr::from(1_u32),
            Fr::from(1_u32),
            Fr::from(1_u32),
        ];

        let z_i1 = circuit.step_native(0, z_i.clone(), vec![]).unwrap();

        let z_iVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(z_i)).unwrap();
        let computed_z_i1Var = circuit
            .generate_step_constraints(cs.clone(), 0, z_iVar.clone(), vec![])
            .unwrap();
        assert_eq!(computed_z_i1Var.value().unwrap(), z_i1);
    }
}

/// cargo run --release --example multi_inputs
fn main() {
    let num_steps = 10;
    let initial_state = vec![
        Fr::from(1_u32),
        Fr::from(1_u32),
        Fr::from(1_u32),
        Fr::from(1_u32),
        Fr::from(1_u32),
    ];

    let F_circuit = MultiInputsFCircuit::<Fr>::new(()).unwrap();

    let poseidon_config = poseidon_canonical_config::<Fr>();
    let mut rng = rand::rngs::OsRng;

    /// The idea here is that eventually we could replace the next line chunk that defines the
    /// `type N = Nova<...>` by using another folding scheme that fulfills the `FoldingScheme`
    /// trait, and the rest of our code would be working without needing to be updated.
    type N = Nova<
        Projective,
        GVar,
        Projective2,
        GVar2,
        MultiInputsFCircuit<Fr>,
        KZG<'static, Bn254>,
        Pedersen<Projective2>,
    >;

    println!("Prepare Nova ProverParams & VerifierParams");
    let nova_preprocess_params = PreprocessorParam::new(poseidon_config, F_circuit);
    let (nova_pp, nova_vp) = N::preprocess(&mut rng, &nova_preprocess_params).unwrap();

    println!("Initialize FoldingScheme");
    let mut folding_scheme = N::init(&nova_pp, F_circuit, initial_state.clone()).unwrap();

    // compute a step of the IVC
    for i in 0..num_steps {
        let start = Instant::now();
        folding_scheme.prove_step(rng, vec![]).unwrap();
        println!("Nova::prove_step {}: {:?}", i, start.elapsed());
    }

    let (running_instance, incoming_instance, cyclefold_instance) = folding_scheme.instances();

    println!("Run the Nova's IVC verifier");
    N::verify(
        nova_vp,
        initial_state.clone(),
        folding_scheme.state(), // latest state
        Fr::from(num_steps as u32),
        running_instance,
        incoming_instance,
        cyclefold_instance,
    )
    .unwrap();
}