use std::thread::JoinHandle;
use std::time::Instant;
use crate::bounds::Bounds;
use crate::linear_bounds::LinearBounds;
use crate::point::Point;

const SAMPLES: u64 = 1_000_000_000;
const THREAD_CNT: u64 = 8;

mod point;
mod linear_bounds;
mod bounds;

fn f(x: f64) -> f64 {
    return  x.powi(4) - 4_f64 * x.powi(3) + 18_f64 * x.powi(2) - 12_f64 * x - 69_f64
}

fn is_inside(point: Point) -> bool {
    let y_0: f64 = f(point.get_x());
    return y_0.abs() > point.get_y().abs() && y_0 * point.get_y() >= 0_f64;
}

fn get_real_integral(bounds: LinearBounds) -> f64 {
    return big_f(bounds.get_higher()) - big_f(bounds.get_lower());
}

fn big_f(x: f64) -> f64 {
    return 0.2 * x.powi(5) - x.powi(4) + 6_f64 * x.powi(3) - 6_f64 * x.powi(2) - 69_f64 * x;
}

fn main() {
    let start: Instant = Instant::now();
    let mut points_inside: u64 = 0;
    let bounds: Bounds = Bounds::new(LinearBounds::new(0_f64, 20_f64), LinearBounds::new(-100_f64, 150000_f64));

    let mut threads: Vec<JoinHandle<u64>> = vec![];

    for _ in 0..THREAD_CNT {
        threads.push(std::thread::spawn(move || {
            let mut points_inside: u64 = 0;
            for _ in 0..SAMPLES {
                let point: Point = bounds.get_random_point();
                if is_inside(point) {
                    points_inside += 1;
                }
            }
            return points_inside;
        }))
    }

    for thread in threads {
        points_inside += thread.join().unwrap();
    }

    let total_samples: u64 = SAMPLES * THREAD_CNT;

    let approximated_integral: f64 = (points_inside as f64 / total_samples as f64) * bounds.get_area();
    println!("The approximated Integral of the function is: {:.2}", approximated_integral);

    let real_integral: f64 = get_real_integral(bounds.get_x());
    println!("The real Integral of the function is: {:.2}", real_integral);

    let error: f64 = (real_integral - approximated_integral).abs();
    println!("That's an error of {:.2} or {:.5}%", error, (error/real_integral) * 100_f64);

    println!("And the whole thing took {:.5} Seconds for {} samples", start.elapsed().as_micros() as f64 / 1000000_f64, total_samples);
}