#![allow(clippy::many_single_char_names)]

use super::BLOCK_SIZE;

use core::convert::TryInto;

const K: [u32; 4] = [0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6];

#[inline(always)]

fn add(a: [u32; 4], b: [u32; 4]) -> [u32; 4] {

    [

        a[0].wrapping_add(b[0]),

        a[1].wrapping_add(b[1]),

        a[2].wrapping_add(b[2]),

        a[3].wrapping_add(b[3]),

    ]

}

#[inline(always)]

fn xor(a: [u32; 4], b: [u32; 4]) -> [u32; 4] {

    [a[0] ^ b[0], a[1] ^ b[1], a[2] ^ b[2], a[3] ^ b[3]]

}

#[inline]

pub fn sha1_first_add(e: u32, w0: [u32; 4]) -> [u32; 4] {

    let [a, b, c, d] = w0;

    [e.wrapping_add(a), b, c, d]

}

fn sha1msg1(a: [u32; 4], b: [u32; 4]) -> [u32; 4] {

    let [_, _, w2, w3] = a;

    let [w4, w5, _, _] = b;

    [a[0] ^ w2, a[1] ^ w3, a[2] ^ w4, a[3] ^ w5]

}

fn sha1msg2(a: [u32; 4], b: [u32; 4]) -> [u32; 4] {

    let [x0, x1, x2, x3] = a;

    let [_, w13, w14, w15] = b;

    let w16 = (x0 ^ w13).rotate_left(1);

    let w17 = (x1 ^ w14).rotate_left(1);

    let w18 = (x2 ^ w15).rotate_left(1);

    let w19 = (x3 ^ w16).rotate_left(1);

    [w16, w17, w18, w19]

}

#[inline]

fn sha1_first_half(abcd: [u32; 4], msg: [u32; 4]) -> [u32; 4] {

    sha1_first_add(abcd[0].rotate_left(30), msg)

}

fn sha1_digest_round_x4(abcd: [u32; 4], work: [u32; 4], i: i8) -> [u32; 4] {

    match i {

        0 => sha1rnds4c(abcd, add(work, [K[0]; 4])),

        1 => sha1rnds4p(abcd, add(work, [K[1]; 4])),

        2 => sha1rnds4m(abcd, add(work, [K[2]; 4])),

        3 => sha1rnds4p(abcd, add(work, [K[3]; 4])),

        _ => unreachable!("unknown icosaround index"),

    }

}

fn sha1rnds4c(abcd: [u32; 4], msg: [u32; 4]) -> [u32; 4] {

    let [mut a, mut b, mut c, mut d] = abcd;

    let [t, u, v, w] = msg;

    let mut e = 0u32;

    macro_rules! bool3ary_202 {

        ($a:expr, $b:expr, $c:expr) => {

            $c ^ ($a & ($b ^ $c))

        };

    } // Choose, MD5F, SHA1C

    e = e

        .wrapping_add(a.rotate_left(5))

        .wrapping_add(bool3ary_202!(b, c, d))

        .wrapping_add(t);

    b = b.rotate_left(30);

    d = d

        .wrapping_add(e.rotate_left(5))

        .wrapping_add(bool3ary_202!(a, b, c))

        .wrapping_add(u);

    a = a.rotate_left(30);

    c = c

        .wrapping_add(d.rotate_left(5))

        .wrapping_add(bool3ary_202!(e, a, b))

        .wrapping_add(v);

    e = e.rotate_left(30);

    b = b

        .wrapping_add(c.rotate_left(5))

        .wrapping_add(bool3ary_202!(d, e, a))

        .wrapping_add(w);

    d = d.rotate_left(30);

    [b, c, d, e]

}

fn sha1rnds4p(abcd: [u32; 4], msg: [u32; 4]) -> [u32; 4] {

    let [mut a, mut b, mut c, mut d] = abcd;

    let [t, u, v, w] = msg;

    let mut e = 0u32;

    macro_rules! bool3ary_150 {

        ($a:expr, $b:expr, $c:expr) => {

            $a ^ $b ^ $c

        };

    } // Parity, XOR, MD5H, SHA1P

    e = e

        .wrapping_add(a.rotate_left(5))

        .wrapping_add(bool3ary_150!(b, c, d))

        .wrapping_add(t);

    b = b.rotate_left(30);

    d = d

        .wrapping_add(e.rotate_left(5))

        .wrapping_add(bool3ary_150!(a, b, c))

        .wrapping_add(u);

    a = a.rotate_left(30);

    c = c

        .wrapping_add(d.rotate_left(5))

        .wrapping_add(bool3ary_150!(e, a, b))

        .wrapping_add(v);

    e = e.rotate_left(30);

    b = b

        .wrapping_add(c.rotate_left(5))

        .wrapping_add(bool3ary_150!(d, e, a))

        .wrapping_add(w);

    d = d.rotate_left(30);

    [b, c, d, e]

}

fn sha1rnds4m(abcd: [u32; 4], msg: [u32; 4]) -> [u32; 4] {

    let [mut a, mut b, mut c, mut d] = abcd;

    let [t, u, v, w] = msg;

    let mut e = 0u32;

    macro_rules! bool3ary_232 {

        ($a:expr, $b:expr, $c:expr) => {

            ($a & $b) ^ ($a & $c) ^ ($b & $c)

        };

    } // Majority, SHA1M

    e = e

        .wrapping_add(a.rotate_left(5))

        .wrapping_add(bool3ary_232!(b, c, d))

        .wrapping_add(t);

    b = b.rotate_left(30);

    d = d

        .wrapping_add(e.rotate_left(5))

        .wrapping_add(bool3ary_232!(a, b, c))

        .wrapping_add(u);

    a = a.rotate_left(30);

    c = c

        .wrapping_add(d.rotate_left(5))

        .wrapping_add(bool3ary_232!(e, a, b))

        .wrapping_add(v);

    e = e.rotate_left(30);

    b = b

        .wrapping_add(c.rotate_left(5))

        .wrapping_add(bool3ary_232!(d, e, a))

        .wrapping_add(w);

    d = d.rotate_left(30);

    [b, c, d, e]

}

macro_rules! rounds4 {

    ($h0:ident, $h1:ident, $wk:expr, $i:expr) => {

        sha1_digest_round_x4($h0, sha1_first_half($h1, $wk), $i)

    };

}

macro_rules! schedule {

    ($v0:expr, $v1:expr, $v2:expr, $v3:expr) => {

        sha1msg2(xor(sha1msg1($v0, $v1), $v2), $v3)

    };

}

macro_rules! schedule_rounds4 {

    (

        $h0:ident, $h1:ident,

        $w0:expr, $w1:expr, $w2:expr, $w3:expr, $w4:expr,

        $i:expr

    ) => {

        $w4 = schedule!($w0, $w1, $w2, $w3);

        $h1 = rounds4!($h0, $h1, $w4, $i);

    };

}

#[inline(always)]

fn sha1_digest_block_u32(state: &mut [u32; 5], block: &[u32; 16]) {

    let mut w0 = [block[0], block[1], block[2], block[3]];

    let mut w1 = [block[4], block[5], block[6], block[7]];

    let mut w2 = [block[8], block[9], block[10], block[11]];

    let mut w3 = [block[12], block[13], block[14], block[15]];

    #[allow(clippy::needless_late_init)]

    let mut w4;

    let mut h0 = [state[0], state[1], state[2], state[3]];

    let mut h1 = sha1_first_add(state[4], w0);

    // Rounds 0..20

    h1 = sha1_digest_round_x4(h0, h1, 0);

    h0 = rounds4!(h1, h0, w1, 0);

    h1 = rounds4!(h0, h1, w2, 0);

    h0 = rounds4!(h1, h0, w3, 0);

    schedule_rounds4!(h0, h1, w0, w1, w2, w3, w4, 0);

    // Rounds 20..40

    schedule_rounds4!(h1, h0, w1, w2, w3, w4, w0, 1);

    schedule_rounds4!(h0, h1, w2, w3, w4, w0, w1, 1);

    schedule_rounds4!(h1, h0, w3, w4, w0, w1, w2, 1);

    schedule_rounds4!(h0, h1, w4, w0, w1, w2, w3, 1);

    schedule_rounds4!(h1, h0, w0, w1, w2, w3, w4, 1);

    // Rounds 40..60

    schedule_rounds4!(h0, h1, w1, w2, w3, w4, w0, 2);

    schedule_rounds4!(h1, h0, w2, w3, w4, w0, w1, 2);

    schedule_rounds4!(h0, h1, w3, w4, w0, w1, w2, 2);

    schedule_rounds4!(h1, h0, w4, w0, w1, w2, w3, 2);

    schedule_rounds4!(h0, h1, w0, w1, w2, w3, w4, 2);

    // Rounds 60..80

    schedule_rounds4!(h1, h0, w1, w2, w3, w4, w0, 3);

    schedule_rounds4!(h0, h1, w2, w3, w4, w0, w1, 3);

    schedule_rounds4!(h1, h0, w3, w4, w0, w1, w2, 3);

    schedule_rounds4!(h0, h1, w4, w0, w1, w2, w3, 3);

    schedule_rounds4!(h1, h0, w0, w1, w2, w3, w4, 3);

    let e = h1[0].rotate_left(30);

    let [a, b, c, d] = h0;

    state[0] = state[0].wrapping_add(a);

    state[1] = state[1].wrapping_add(b);

    state[2] = state[2].wrapping_add(c);

    state[3] = state[3].wrapping_add(d);

    state[4] = state[4].wrapping_add(e);

}

pub fn compress(state: &mut [u32; 5], blocks: &[[u8; BLOCK_SIZE]]) {

    let mut block_u32 = [0u32; BLOCK_SIZE / 4];

    // since LLVM can't properly use aliasing yet it will make

    // unnecessary state stores without this copy

    let mut state_cpy = *state;

    for block in blocks.iter() {

        for (o, chunk) in block_u32.iter_mut().zip(block.chunks_exact(4)) {

            *o = u32::from_be_bytes(chunk.try_into().unwrap());

        }

        sha1_digest_block_u32(&mut state_cpy, &block_u32);

    }

    *state = state_cpy;

}