use std::f64;

use criterion::Criterion;
use criterion::{criterion_group, criterion_main};
use rand_distr::Beta;
use rv::traits::*;

fn draw_rand_distr<R: rand::Rng>(rng: &mut R) -> f64 {
    let beta = Beta::new(5.0, 2.0).unwrap();
    rng.sample(beta)
}

fn draw_rv<R: rand::Rng>(mut rng: &mut R) -> f64 {
    let beta = rv::dist::Beta::new(5.0, 2.0).unwrap();
    beta.draw(&mut rng)
}

fn draw_2u<R: rand::Rng>(rng: &mut R) -> f64 {
    let a = rng.gen::<f64>().powf(1.0 / 5.0);
    let b = rng.gen::<f64>().powf(1.0 / 2.0);
    a / (a + b)
}

fn draw_2u_recip<R: rand::Rng>(rng: &mut R) -> f64 {
    let a = rng.gen::<f64>().powf(5.0_f64.recip());
    let b = rng.gen::<f64>().powf(2.0_f64.recip());

    a / (a + b)
}

fn bench_beta_draw(c: &mut Criterion) {
    let mut group = c.benchmark_group("beta_draw");
    group.bench_function("rand_distr", |b| {
        b.iter(|| {
            let mut rng = rand::thread_rng();
            draw_rand_distr(&mut rng)
        })
    });
    group.bench_function("draw_rv", |b| {
        let mut rng = rand::thread_rng();
        b.iter(|| draw_rv(&mut rng))
    });
    group.bench_function("draw_2_uniform", |b| {
        let mut rng = rand::thread_rng();
        b.iter(|| draw_2u(&mut rng))
    });
    group.bench_function("draw_2_uniform_recip", |b| {
        let mut rng = rand::thread_rng();
        b.iter(|| draw_2u_recip(&mut rng))
    });
}

fn bench_beta_vs_kumaraswamy_ln_pdf(c: &mut Criterion) {
    let mut group = c.benchmark_group("bench_beta_vs_kumaraswamy_pdf");
    group.bench_function("beta", |b| {
        let beta = rv::dist::Beta::new(1.0, 2.0).unwrap();
        b.iter(|| {
            let _x = beta.ln_f(&0.5_f64);
        });
    });
    group.bench_function("kumaraswamy", |b| {
        let kuma = rv::dist::Kumaraswamy::new(1.0, 2.0).unwrap();
        b.iter(|| {
            let _x = kuma.ln_f(&0.5_f64);
        });
    });
}

fn bench_beta_vs_kumaraswamy_draw(c: &mut Criterion) {
    let mut group = c.benchmark_group("bench_beta_vs_kumaraswamy_draw");
    group.bench_function("beta", |b| {
        let mut rng = rand::thread_rng();
        let beta = rv::dist::Beta::new(1.0, 2.0).unwrap();
        b.iter(|| {
            let _x: f64 = beta.draw(&mut rng);
        });
    });
    group.bench_function("kumaraswamy", |b| {
        let mut rng = rand::thread_rng();
        let kuma = rv::dist::Kumaraswamy::new(1.0, 2.0).unwrap();
        b.iter(|| {
            let _x: f64 = kuma.draw(&mut rng);
        });
    });
}

criterion_group!(
    beta_benches,
    bench_beta_draw,
    bench_beta_vs_kumaraswamy_ln_pdf,
    bench_beta_vs_kumaraswamy_draw,
);
criterion_main!(beta_benches);