---- difficulty::test_target_difficulty stdout ----
thread 'difficulty::test_target_difficulty' panicked at 'assertion failed: your_bits != 0', /home/incker/.cargo/registry/src/github.com-1ecc6299db9ec823/bitcoin-0.27.1/src/util/uint.rs:493:1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

use bitcoin::{BlockHash, BlockHeader};
use bitcoin::util::uint::Uint256;
use bitcoin_hashes::Hash;
use bitcoin_hashes::hex::ToHex;

#[test]
fn test_target_difficulty() {
    struct Test {
        difficulty: u32,
        output: [u8; 32],
    }

    let difficulty_1_target_str =
        "00000000ffff0000000000000000000000000000000000000000000000000000";
    let difficulty_1_target_bytes: [u8; 32] = [
        0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00,
    ];
    let difficulty_1_target_uint256 = Uint256::from_be_bytes(difficulty_1_target_bytes);

    assert_eq!(
        &difficulty_1_target_uint256.to_be_bytes().to_hex(),
        &difficulty_1_target_str
    );

    let tests = vec![
        Test {
            difficulty: 512,
            output: [
                // 00000000007fff80000000000000000000000000000000000000000000000000
                0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x00, 0x00, 0x00, 0x00,
            ],
        },
        Test {
            difficulty: 1638,
            output: [
                // 0000000000280258258258258258258258258258258258258258258258258258
                0x00, 0x00, 0x00, 0x00, 0x00, 0x28, 0x02, 0x58, 0x25, 0x82, 0x58, 0x25, 0x82, 0x58,
                0x25, 0x82, 0x58, 0x25, 0x82, 0x58, 0x25, 0x82, 0x58, 0x25, 0x82, 0x58, 0x25, 0x82,
                0x58, 0x25, 0x82, 0x58,
            ],
        },
        Test {
            difficulty: 8192,
            output: [
                // 000000000007fff8000000000000000000000000000000000000000000000000
                0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x00, 0x00, 0x00, 0x00,
            ],
        },
    ];

    for test in tests {
        let difficulty_target_uint256 = Uint256::from_be_bytes(test.output);
        assert_eq!(
            difficulty_1_target_uint256 / BlockHeader::u256_from_compact_target(test.difficulty),
            difficulty_target_uint256
        );
    }
}