# extern crate libspartan;
# extern crate merlin;
# use libspartan::{Instance, SNARKGens, SNARK};
# use merlin::Transcript;
# fn main() {
    // specify the size of an R1CS instance
    let num_vars = 1024;
    let num_cons = 1024;
    let num_inputs = 10;
    let num_non_zero_entries = 1024;

    // produce public parameters
    let gens = SNARKGens::new(num_cons, num_vars, num_inputs, num_non_zero_entries);

    // ask the library to produce a synthentic R1CS instance
    let (inst, vars, inputs) = Instance::produce_synthetic_r1cs(num_cons, num_vars, num_inputs);

    // create a commitment to the R1CS instance
    let (comm, decomm) = SNARK::encode(&inst, &gens);

    // produce a proof of satisfiability
    let mut prover_transcript = Transcript::new(b"snark_example");
    let proof = SNARK::prove(&inst, &decomm, vars, &inputs, &gens, &mut prover_transcript);

    // verify the proof of satisfiability
    let mut verifier_transcript = Transcript::new(b"snark_example");
    assert!(proof
      .verify(&comm, &inputs, &mut verifier_transcript, &gens)
      .is_ok());
    println!("proof verification successful!");
# }

# extern crate libspartan;
# extern crate merlin;
# use libspartan::{Instance, NIZKGens, NIZK};
# use merlin::Transcript;
# fn main() {
    // specify the size of an R1CS instance
    let num_vars = 1024;
    let num_cons = 1024;
    let num_inputs = 10;

    // produce public parameters
    let gens = NIZKGens::new(num_cons, num_vars, num_inputs);

    // ask the library to produce a synthentic R1CS instance
    let (inst, vars, inputs) = Instance::produce_synthetic_r1cs(num_cons, num_vars, num_inputs);

    // produce a proof of satisfiability
    let mut prover_transcript = Transcript::new(b"nizk_example");
    let proof = NIZK::prove(&inst, vars, &inputs, &gens, &mut prover_transcript);

    // verify the proof of satisfiability
    let mut verifier_transcript = Transcript::new(b"nizk_example");
    assert!(proof
      .verify(&inst, &inputs, &mut verifier_transcript, &gens)
      .is_ok());
    println!("proof verification successful!");
# }

#![allow(non_snake_case)]
# extern crate curve25519_dalek;
# extern crate libspartan;
# extern crate merlin;
# use curve25519_dalek::scalar::Scalar;
# use libspartan::{InputsAssignment, Instance, SNARKGens, VarsAssignment, SNARK};
# use merlin::Transcript;
# use rand::rngs::OsRng;
# fn main() {
  // produce a tiny instance
  let (
    num_cons,
    num_vars,
    num_inputs,
    num_non_zero_entries,
    inst,
    assignment_vars,
    assignment_inputs,
  ) = produce_tiny_r1cs();

  // produce public parameters
  let gens = SNARKGens::new(num_cons, num_vars, num_inputs, num_non_zero_entries);

  // create a commitment to the R1CS instance
  let (comm, decomm) = SNARK::encode(&inst, &gens);

  // produce a proof of satisfiability
  let mut prover_transcript = Transcript::new(b"snark_example");
  let proof = SNARK::prove(
    &inst,
    &decomm,
    assignment_vars,
    &assignment_inputs,
    &gens,
    &mut prover_transcript,
  );

  // verify the proof of satisfiability
  let mut verifier_transcript = Transcript::new(b"snark_example");
  assert!(proof
    .verify(&comm, &assignment_inputs, &mut verifier_transcript, &gens)
    .is_ok());
  println!("proof verification successful!");
# }

# fn produce_tiny_r1cs() -> (
#  usize,
#  usize,
#  usize,
#  usize,
#  Instance,
#  VarsAssignment,
#  InputsAssignment,
# ) {
  // We will use the following example, but one could construct any R1CS instance.
  // Our R1CS instance is three constraints over five variables and two public inputs
  // (Z0 + Z1) * I0 - Z2 = 0
  // (Z0 + I1) * Z2 - Z3 = 0
  // Z4 * 1 - 0 = 0

  // parameters of the R1CS instance rounded to the nearest power of two
  let num_cons = 4;
  let num_vars = 5;
  let num_inputs = 2;
  let num_non_zero_entries = 5;

  // We will encode the above constraints into three matrices, where
  // the coefficients in the matrix are in the little-endian byte order
  let mut A: Vec<(usize, usize, [u8; 32])> = Vec::new();
  let mut B: Vec<(usize, usize, [u8; 32])> = Vec::new();
  let mut C: Vec<(usize, usize, [u8; 32])> = Vec::new();

  // The constraint system is defined over a finite field, which in our case is
  // the scalar field of ristreeto255/curve25519 i.e., p =  2^{252}+27742317777372353535851937790883648493
  // To construct these matrices, we will use `curve25519-dalek` but one can use any other method.

  // a variable that holds a byte representation of 1
  let one = Scalar::one().to_bytes();

  // R1CS is a set of three sparse matrices A B C, where is a row for every 
  // constraint and a column for every entry in z = (vars, 1, inputs)
  // An R1CS instance is satisfiable iff:
  // Az \circ Bz = Cz, where z = (vars, 1, inputs)

  // constraint 0 entries in (A,B,C)
  // constraint 0 is (Z0 + Z1) * I0 - Z2 = 0.
  // We set 1 in matrix A for columns that correspond to Z0 and Z1
  // We set 1 in matrix B for column that corresponds to I0
  // We set 1 in matrix C for column that corresponds to Z2
  A.push((0, 0, one));
  A.push((0, 1, one));
  B.push((0, num_vars + 1, one));
  C.push((0, 2, one));

  // constraint 1 entries in (A,B,C)
  A.push((1, 0, one));
  A.push((1, num_vars + 2, one));
  B.push((1, 2, one));
  C.push((1, 3, one));

  // constraint 3 entries in (A,B,C)
  A.push((2, 4, one));
  B.push((2, num_vars, one));

  let inst = Instance::new(num_cons, num_vars, num_inputs, &A, &B, &C).unwrap();

  // compute a satisfying assignment
  let mut csprng: OsRng = OsRng;
  let i0 = Scalar::random(&mut csprng);
  let i1 = Scalar::random(&mut csprng);
  let z0 = Scalar::random(&mut csprng);
  let z1 = Scalar::random(&mut csprng);
  let z2 = (z0 + z1) * i0; // constraint 0
  let z3 = (z0 + i1) * z2; // constraint 1
  let z4 = Scalar::zero(); //constraint 2

  // create a VarsAssignment
  let mut vars = vec![Scalar::zero().to_bytes(); num_vars];
  vars[0] = z0.to_bytes();
  vars[1] = z1.to_bytes();
  vars[2] = z2.to_bytes();
  vars[3] = z3.to_bytes();
  vars[4] = z4.to_bytes();
  let assignment_vars = VarsAssignment::new(&vars).unwrap();

  // create an InputsAssignment
  let mut inputs = vec![Scalar::zero().to_bytes(); num_inputs];
  inputs[0] = i0.to_bytes();
  inputs[1] = i1.to_bytes();
  let assignment_inputs = InputsAssignment::new(&inputs).unwrap();
  
  // check if the instance we created is satisfiable
  let res = inst.is_sat(&assignment_vars, &assignment_inputs);
  assert_eq!(res.unwrap(), true);

  (
    num_cons,
    num_vars,
    num_inputs,
    num_non_zero_entries,
    inst,
    assignment_vars,
    assignment_inputs,
  )
# }