use super::comparison::Offset;

pub fn approx_equal(a: f64, b: f64, dp: u8) -> bool {
    let p = 10f64.powi(-(dp as i32));
    (a - b).abs() < p
}

fn aprox_equal_within_percentage_range(actual: f64, expectation: f64, percentage: f64) -> bool {
    assert!(percentage.is_sign_positive() && percentage <= 100.);
    let factor = 0.01 * percentage as f64;
    actual >= expectation - (factor * expectation) && actual <= expectation + (factor * expectation)
}

fn approx_equal_within_offset_range(actual: f64, expectation: f64, offset: f64) -> bool {
    assert!(offset >= 0., "offset must be positive");
    actual >= expectation - offset && actual <= expectation + offset
}

pub fn approximate_within_range(actual: f64, expectation: f64, offset: &Offset) -> bool{
    match offset {
        Offset::Absolute(a) => approx_equal_within_offset_range(actual, expectation, *a),
        Offset::Percentage(p) => aprox_equal_within_percentage_range(actual, expectation, *p),
    }
}