// 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::integers::PrimitiveInt;
use malachite_base::num::basic::traits::Zero;
use malachite_base::num::conversion::traits::ExactFrom;
use malachite_base::num::logic::traits::{BitAccess, BitScan, SignificantBits};
use malachite_base::test_util::generators::common::GenConfig;
use malachite_base::test_util::generators::{
    unsigned_gen, unsigned_pair_gen_var_2, unsigned_vec_unsigned_pair_gen_var_16,
};
use malachite_nz::natural::Natural;
use malachite_nz::natural::logic::bit_scan::limbs_index_of_next_true_bit;
use malachite_nz::platform::Limb;
use malachite_nz::test_util::generators::{natural_gen, natural_unsigned_pair_gen_var_4};
use malachite_nz::test_util::natural::logic::index_of_next_true_bit::*;
use rug;
use std::str::FromStr;

#[cfg(feature = "32_bit_limbs")]
#[test]
fn test_limbs_index_of_next_true_bit() {
    let test = |xs, u, out| {
        assert_eq!(limbs_index_of_next_true_bit(xs, u), out);
    };
    test(&[], 0, None);
    test(&[], 100, None);
    test(&[0], 0, None);
    test(&[0], 100, None);
    test(&[0b100], 0, Some(2));
    test(&[0b100], 1, Some(2));
    test(&[0b100], 2, Some(2));
    test(&[0b100], 3, None);
    test(&[0, 0b1011], 0, Some(32));
    test(&[0, 0b1011], 20, Some(32));
    test(&[0, 0b1011], 31, Some(32));
    test(&[0, 0b1011], 32, Some(32));
    test(&[0, 0b1011], 33, Some(33));
    test(&[0, 0b1011], 34, Some(35));
    test(&[0, 0b1011], 35, Some(35));
    test(&[0, 0b1011], 36, None);
    test(&[0, 0b1011], 100, None);
    test(&[0, 0b1011, 0xfffffff, 0, 1], 91, Some(91));
    test(&[0, 0b1011, 0xfffffff, 0, 1], 92, Some(128));
}

#[test]
fn test_index_of_next_true_bit() {
    let test = |n, u, out| {
        assert_eq!(Natural::from_str(n).unwrap().index_of_next_true_bit(u), out);
        assert_eq!(
            natural_index_of_next_true_bit_alt(&Natural::from_str(n).unwrap(), u),
            out
        );
        assert_eq!(
            rug::Integer::from_str(n)
                .unwrap()
                .find_one(u32::exact_from(u))
                .map(u64::from),
            out
        );
    };
    test("0", 0, None);
    test("0", 100, None);
    test("47244640256", 0, Some(32));
    test("47244640256", 20, Some(32));
    test("47244640256", 31, Some(32));
    test("47244640256", 32, Some(32));
    test("47244640256", 33, Some(33));
    test("47244640256", 34, Some(35));
    test("47244640256", 35, Some(35));
    test("47244640256", 36, None);
    test("47244640256", 100, None);
    test("340282366925890223602069384504899796992", 91, Some(91));
    test("340282366925890223602069384504899796992", 92, Some(128));
}

#[test]
fn limbs_index_of_next_true_bit_properties() {
    let mut config = GenConfig::new();
    config.insert("mean_length_n", 32);
    config.insert("mean_stripe_n", 16 << Limb::LOG_WIDTH);
    unsigned_vec_unsigned_pair_gen_var_16().test_properties_with_config(&config, |(xs, u)| {
        assert_eq!(
            limbs_index_of_next_true_bit(&xs, u),
            Natural::from_owned_limbs_asc(xs).index_of_next_true_bit(u)
        );
    });
}

#[test]
fn index_of_next_true_bit_properties() {
    natural_unsigned_pair_gen_var_4().test_properties(|(n, u)| {
        let result = n.index_of_next_true_bit(u);
        assert_eq!(result, natural_index_of_next_true_bit_alt(&n, u));
        assert_eq!(
            rug::Integer::from(&n)
                .find_one(u32::exact_from(u))
                .map(u64::from),
            result
        );
        assert_eq!(result.is_some(), u < n.significant_bits());
        if let Some(result) = result {
            assert!(result >= u);
            assert!(n.get_bit(result));
            assert_eq!(result == u, n.get_bit(u));
        }
        assert_eq!((!n).index_of_next_false_bit(u), result);
    });

    natural_gen().test_properties(|n| {
        assert_eq!(n.index_of_next_true_bit(0), n.trailing_zeros());
    });

    unsigned_gen().test_properties(|u| {
        assert_eq!(Natural::ZERO.index_of_next_true_bit(u), None);
    });

    unsigned_pair_gen_var_2::<Limb, u64>().test_properties(|(u, index)| {
        assert_eq!(
            Natural::from(u).index_of_next_true_bit(index),
            u.index_of_next_true_bit(index)
        );
    });
}
