multiavatar 1.0.10

//! 工具函数。

pub mod base64;
pub mod strings;

/// 计算 SHA-256，输出小写十六进制（与 JS CryptoJS SHA256 的 toString() 一致）。
///
/// 手写 FIPS 180-4 实现，零第三方依赖；对任意输入与 sha2 crate 输出逐字节一致。
pub fn sha256_hex(data: &[u8]) -> String {
    const K: [u32; 64] = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4,
        0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe,
        0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f,
        0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
        0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc,
        0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
        0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116,
        0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
        0xc67178f2,
    ];

    // 初始哈希值（前 8 个素数的平方根小数部分）
    let mut h: [u32; 8] = [
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab,
        0x5be0cd19,
    ];

    // 填充：原文 || 0x80 || 0x00…（使总长 mod 64 = 56）|| 64 位大端比特长度
    let bit_len = (data.len() as u64).wrapping_mul(8);
    let mut padded = Vec::with_capacity(data.len() + 9);
    padded.extend_from_slice(data);
    padded.push(0x80);
    while padded.len() % 64 != 56 {
        padded.push(0);
    }
    padded.extend_from_slice(&bit_len.to_be_bytes());

    let mut w = [0u32; 64];
    for chunk in padded.chunks_exact(64) {
        // 消息调度：前 16 字为大端 32 位，后 48 字递推
        for (i, word) in w.iter_mut().take(16).enumerate() {
            let o = i * 4;
            *word = u32::from_be_bytes([chunk[o], chunk[o + 1], chunk[o + 2], chunk[o + 3]]);
        }
        for t in 16..64 {
            let s0 = w[t - 15].rotate_right(7) ^ w[t - 15].rotate_right(18) ^ (w[t - 15] >> 3);
            let s1 = w[t - 2].rotate_right(17) ^ w[t - 2].rotate_right(19) ^ (w[t - 2] >> 10);
            w[t] = w[t - 16]
                .wrapping_add(s0)
                .wrapping_add(w[t - 7])
                .wrapping_add(s1);
        }

        // 压缩主循环
        let [mut a, mut b, mut c, mut d, mut e, mut f, mut g, mut hh] = h;
        for t in 0..64 {
            let sum1 = e.rotate_right(6) ^ e.rotate_right(11) ^ e.rotate_right(25);
            let ch = (e & f) ^ ((!e) & g);
            let temp1 = hh
                .wrapping_add(sum1)
                .wrapping_add(ch)
                .wrapping_add(K[t])
                .wrapping_add(w[t]);
            let sum0 = a.rotate_right(2) ^ a.rotate_right(13) ^ a.rotate_right(22);
            let maj = (a & b) ^ (a & c) ^ (b & c);
            let temp2 = sum0.wrapping_add(maj);
            hh = g;
            g = f;
            f = e;
            e = d.wrapping_add(temp1);
            d = c;
            c = b;
            b = a;
            a = temp1.wrapping_add(temp2);
        }
        h[0] = h[0].wrapping_add(a);
        h[1] = h[1].wrapping_add(b);
        h[2] = h[2].wrapping_add(c);
        h[3] = h[3].wrapping_add(d);
        h[4] = h[4].wrapping_add(e);
        h[5] = h[5].wrapping_add(f);
        h[6] = h[6].wrapping_add(g);
        h[7] = h[7].wrapping_add(hh);
    }

    // 输出 8 个大端 32 位字的小写十六进制
    let mut sb = String::with_capacity(64);
    for word in h {
        sb.push_str(&format!("{:08x}", word));
    }
    sb
}

/// 两位补零格式化（与 JS 中 nr.length==1 时补 '0' 的语义一致）。
pub fn two(x: i32) -> String {
    if x < 10 {
        format!("0{}", x)
    } else {
        x.to_string()
    }
}

/// 是否为空字符串（null 视为空）。
pub fn is_empty(s: Option<&str>) -> bool {
    match s {
        None => true,
        Some(v) => v.is_empty(),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// FIPS 180-4 官方测试向量 + 常见向量，验证与标准实现逐字节一致。
    #[test]
    fn sha256_known_vectors() {
        // NIST CAVP / FIPS 180-4 附录
        assert_eq!(
            sha256_hex(b""),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
        assert_eq!(
            sha256_hex(b"abc"),
            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
        );
        assert_eq!(
            sha256_hex(b"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"),
            "248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1"
        );
        // 跨 64 字节块边界（消息长度 56/64 字节整块）
        assert_eq!(
            sha256_hex(b"hello world"),
            "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
        );
        let mut long = vec![b'a'; 1_000_000];
        assert_eq!(
            sha256_hex(&long),
            "cdc76e5c9914fb9281a1c7e284d73e67f1809a48a497200e046d39ccc7112cd0"
        );
        // 63 字节（填充后单块）与 64 字节（恰好一块无补位）
        long = vec![b'x'; 63];
        let h63 = sha256_hex(&long);
        assert_eq!(h63.len(), 64);
        long = vec![b'x'; 64];
        assert_ne!(sha256_hex(&long), h63);
    }
}