// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.

use malachite_base::num::basic::traits::Zero;
use malachite_base::test_util::generators::signed_pair_gen;
use malachite_nz::integer::Integer;
use malachite_nz::platform::{SignedDoubleLimb, SignedLimb};
use malachite_nz::test_util::generators::{integer_gen, integer_pair_gen, natural_pair_gen};
use num::BigInt;
use rug;
use std::str::FromStr;

#[test]
fn test_sub() {
    let test = |s, t, out| {
        let u = Integer::from_str(s).unwrap();
        let v = Integer::from_str(t).unwrap();

        let mut n = u.clone();
        n -= v.clone();
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let mut n = u.clone();
        n -= &v;
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let n = u.clone() - v.clone();
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let n = &u - v.clone();
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let n = u.clone() - &v;
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let n = &u - &v;
        assert_eq!(n.to_string(), out);
        assert!(n.is_valid());

        let n = BigInt::from_str(s).unwrap() - BigInt::from_str(t).unwrap();
        assert_eq!(n.to_string(), out);

        let n = rug::Integer::from_str(s).unwrap() - rug::Integer::from_str(t).unwrap();
        assert_eq!(n.to_string(), out);
    };
    test("0", "0", "0");
    test("0", "-123", "123");
    test("123", "0", "123");
    test("123", "-456", "579");
    test("1000000000000", "-123", "1000000000123");
    test("123", "-1000000000000", "1000000000123");
    test("12345678987654321", "-314159265358979", "12659838253013300");
    test("0", "123", "-123");
    test("123", "123", "0");
    test("123", "456", "-333");
    test("1000000000000", "123", "999999999877");
    test("123", "1000000000000", "-999999999877");
    test("12345678987654321", "314159265358979", "12031519722295342");
}

#[allow(clippy::eq_op)]
#[test]
fn sub_properties() {
    integer_pair_gen().test_properties(|(x, y)| {
        let diff_val_val = x.clone() - y.clone();
        let diff_val_ref = x.clone() - &y;
        let diff_ref_val = &x - y.clone();
        let diff = &x - &y;
        assert!(diff_val_val.is_valid());
        assert!(diff_val_ref.is_valid());
        assert!(diff_ref_val.is_valid());
        assert!(diff.is_valid());
        assert_eq!(diff_val_val, diff);
        assert_eq!(diff_val_ref, diff);
        assert_eq!(diff_ref_val, diff);

        let mut mut_x = x.clone();
        mut_x -= y.clone();
        assert!(mut_x.is_valid());
        assert_eq!(mut_x, diff);
        let mut mut_x = x.clone();
        mut_x -= &y;
        assert!(mut_x.is_valid());
        assert_eq!(mut_x, diff);

        let mut mut_x = rug::Integer::from(&x);
        mut_x -= rug::Integer::from(&y);
        assert_eq!(Integer::from(&mut_x), diff);

        assert_eq!(Integer::from(&(BigInt::from(&x) - BigInt::from(&y))), diff);
        assert_eq!(
            Integer::from(&(rug::Integer::from(&x) - rug::Integer::from(&y))),
            diff
        );
        assert_eq!(&y - &x, -&diff);
        assert_eq!(&diff + &y, x);
        assert_eq!(x - diff, y);
    });

    integer_gen().test_properties(|ref x| {
        assert_eq!(x - Integer::ZERO, *x);
        assert_eq!(Integer::ZERO - x, -x);
        assert_eq!(x - -x, x << 1);
        assert_eq!(x - x, 0);
    });

    natural_pair_gen().test_properties(|(x, y)| {
        if x >= y {
            assert_eq!(&x - &y, Integer::from(x) - Integer::from(y));
        } else {
            assert_eq!(-(&y - &x), Integer::from(x) - Integer::from(y));
        }
    });

    signed_pair_gen::<SignedLimb>().test_properties(|(x, y)| {
        assert_eq!(
            Integer::from(SignedDoubleLimb::from(x) - SignedDoubleLimb::from(y)),
            Integer::from(x) - Integer::from(y)
        );
    });
}
