use grb::prelude::*;

fn main() -> grb::Result<()> {
    // create an empty model.
    let mut model = Model::new("qcp")?;

    // add & integrate new variables.
    let x = add_ctsvar!(model, name: "x")?;
    let y = add_ctsvar!(model, name: "y")?;
    let z = add_ctsvar!(model, name: "z")?;
    // model.update().unwrap();

    // set objective funtion:
    //   f(x,y,z) = x
    model.set_objective(x, Maximize)?;

    // add linear constraints
    //  c0: x + y + z == 1
    model.add_constr("c0", c!(x + y + z == 1))?;

    // add quadratic constraints
    model.add_qconstr("qc0", c!(x * x + y * y <= z * z))?;
    model.add_qconstr("qc1", c!(x * x <= y * z))?;

    // optimize the model.
    model.optimize()?;

    // write the model to file.
    model.write("qcp.lp")?;
    model.write("qcp.sol")?;

    Ok(())
}