/*
 * Copyright (c) 2012-2020 MIRACL UK Ltd.
 *
 * This file is part of MIRACL Core
 * (see https://github.com/miracl/core).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

pub const HASH224: usize = 28;
pub const HASH256: usize = 32;
pub const HASH384: usize = 48;
pub const HASH512: usize = 64;
pub const SHAKE128: usize = 16;
pub const SHAKE256: usize = 32;

const ROUNDS: usize = 24;

const RC: [u64; 24] = [
    0x0000000000000001,
    0x0000000000008082,
    0x800000000000808A,
    0x8000000080008000,
    0x000000000000808B,
    0x0000000080000001,
    0x8000000080008081,
    0x8000000000008009,
    0x000000000000008A,
    0x0000000000000088,
    0x0000000080008009,
    0x000000008000000A,
    0x000000008000808B,
    0x800000000000008B,
    0x8000000000008089,
    0x8000000000008003,
    0x8000000000008002,
    0x8000000000000080,
    0x000000000000800A,
    0x800000008000000A,
    0x8000000080008081,
    0x8000000000008080,
    0x0000000080000001,
    0x8000000080008008,
];

pub struct SHA3 {
    length: u64,
    rate: usize,
    len: usize,
    s: [[u64; 5]; 5],
}

impl SHA3 {
    fn rotl(x: u64, n: u64) -> u64 {
        ((x) << n) | ((x) >> (64 - n))
    }

    fn transform(&mut self) {
        /* basic transformation step */
        let mut c: [u64; 5] = [0; 5];
        let mut d: [u64; 5] = [0; 5];
        let mut b: [[u64; 5]; 5] = [[0; 5]; 5];

        for k in 0..ROUNDS {
            c[0] = self.s[0][0] ^ self.s[0][1] ^ self.s[0][2] ^ self.s[0][3] ^ self.s[0][4];
            c[1] = self.s[1][0] ^ self.s[1][1] ^ self.s[1][2] ^ self.s[1][3] ^ self.s[1][4];
            c[2] = self.s[2][0] ^ self.s[2][1] ^ self.s[2][2] ^ self.s[2][3] ^ self.s[2][4];
            c[3] = self.s[3][0] ^ self.s[3][1] ^ self.s[3][2] ^ self.s[3][3] ^ self.s[3][4];
            c[4] = self.s[4][0] ^ self.s[4][1] ^ self.s[4][2] ^ self.s[4][3] ^ self.s[4][4];

            d[0] = c[4] ^ SHA3::rotl(c[1], 1);
            d[1] = c[0] ^ SHA3::rotl(c[2], 1);
            d[2] = c[1] ^ SHA3::rotl(c[3], 1);
            d[3] = c[2] ^ SHA3::rotl(c[4], 1);
            d[4] = c[3] ^ SHA3::rotl(c[0], 1);

            for i in 0..5 {
                for j in 0..5 {
                    self.s[i][j] ^= d[i];
                }
            }

            b[0][0] = self.s[0][0];
            b[1][3] = SHA3::rotl(self.s[0][1], 36);
            b[2][1] = SHA3::rotl(self.s[0][2], 3);
            b[3][4] = SHA3::rotl(self.s[0][3], 41);
            b[4][2] = SHA3::rotl(self.s[0][4], 18);

            b[0][2] = SHA3::rotl(self.s[1][0], 1);
            b[1][0] = SHA3::rotl(self.s[1][1], 44);
            b[2][3] = SHA3::rotl(self.s[1][2], 10);
            b[3][1] = SHA3::rotl(self.s[1][3], 45);
            b[4][4] = SHA3::rotl(self.s[1][4], 2);

            b[0][4] = SHA3::rotl(self.s[2][0], 62);
            b[1][2] = SHA3::rotl(self.s[2][1], 6);
            b[2][0] = SHA3::rotl(self.s[2][2], 43);
            b[3][3] = SHA3::rotl(self.s[2][3], 15);
            b[4][1] = SHA3::rotl(self.s[2][4], 61);

            b[0][1] = SHA3::rotl(self.s[3][0], 28);
            b[1][4] = SHA3::rotl(self.s[3][1], 55);
            b[2][2] = SHA3::rotl(self.s[3][2], 25);
            b[3][0] = SHA3::rotl(self.s[3][3], 21);
            b[4][3] = SHA3::rotl(self.s[3][4], 56);

            b[0][3] = SHA3::rotl(self.s[4][0], 27);
            b[1][1] = SHA3::rotl(self.s[4][1], 20);
            b[2][4] = SHA3::rotl(self.s[4][2], 39);
            b[3][2] = SHA3::rotl(self.s[4][3], 8);
            b[4][0] = SHA3::rotl(self.s[4][4], 14);

            for i in 0..5 {
                for j in 0..5 {
                    self.s[i][j] = b[i][j] ^ (!b[(i + 1) % 5][j] & b[(i + 2) % 5][j]);
                }
            }

            self.s[0][0] ^= RC[k];
        }
    }

    /* Initialise Hash function */
    pub fn init(&mut self, olen: usize) {
        /* initialise */
        for i in 0..5 {
            for j in 0..5 {
                self.s[i][j] = 0;
            }
        }
        self.length = 0;
        self.len = olen;
        self.rate = 200 - 2 * olen;
    }

    pub fn new(olen: usize) -> SHA3 {
        let mut nh = SHA3 {
            length: 0,
            rate: 0,
            len: 0,
            s: [[0; 5]; 5],
        };
        nh.init(olen);
        nh
    }

    pub fn new_copy(hh: &SHA3) -> SHA3 {
        let mut nh = SHA3 {
            length: 0,
            rate: 0,
            len: 0,
            s: [[0; 5]; 5],
        };
        nh.length = hh.length;
        nh.len = hh.len;
        nh.rate = hh.rate;
        for i in 0..5 {
            for j in 0..5 {
                nh.s[i][j] = hh.s[i][j];
            }
        }
        nh
    }

    /* process a single byte */
    pub fn process(&mut self, byt: u8) {
        /* process the next message byte */
        let cnt = (self.length % (self.rate as u64)) as usize;
        let b = cnt % 8;
        let ind = cnt / 8;
        let i = ind % 5;
        let j = ind / 5;
        self.s[i][j] ^= (byt as u64) << (8 * b);
        self.length += 1;
        if cnt + 1 == self.rate {
            self.transform();
        }
    }

    /* process an array of bytes */

    pub fn process_array(&mut self, b: &[u8]) {
        for i in 0..b.len() {
            self.process(b[i])
        }
    }

    /* process a 32-bit integer */
    pub fn process_num(&mut self, n: i32) {
        self.process(((n >> 24) & 0xff) as u8);
        self.process(((n >> 16) & 0xff) as u8);
        self.process(((n >> 8) & 0xff) as u8);
        self.process((n & 0xff) as u8);
    }

    pub fn squeeze(&mut self, buff: &mut [u8], olen: usize) {
        //let olen=buff.len();
        let mut done = false;
        let mut m = 0;
        loop {
            for j in 0..5 {
                for i in 0..5 {
                    let mut el = self.s[i][j];
                    for _ in 0..8 {
                        buff[m] = (el & 0xff) as u8;
                        m += 1;
                        if m >= olen || (m % self.rate) == 0 {
                            done = true;
                            break;
                        }
                        el >>= 8;
                    }
                    if done {
                        break;
                    }
                }
                if done {
                    break;
                }
            }
            if m >= olen {
                break;
            }
            done = false;
            self.transform();
        }
    }

    /* Generate 32-byte Hash */
    pub fn hash(&mut self, digest: &mut [u8]) {
        /* pad message and finish - supply digest */
        let q = self.rate - (self.length % (self.rate as u64)) as usize;
        if q == 1 {
            self.process(0x86);
        } else {
            self.process(0x06);
            while (self.length % (self.rate as u64)) as usize != self.rate - 1 {
                self.process(0x00)
            }
            self.process(0x80);
        }
        let hlen = self.len as usize;
        self.squeeze(digest, hlen);
    }

    pub fn continuing_hash(&mut self, digest: &mut [u8]) {
        let mut sh = SHA3::new_copy(self);
        sh.hash(digest)
    }

    pub fn shake(&mut self, digest: &mut [u8], olen: usize) {
        let q = self.rate - (self.length % (self.rate as u64)) as usize;
        if q == 1 {
            self.process(0x9f);
        } else {
            self.process(0x1f);
            while (self.length % (self.rate as u64)) as usize != self.rate - 1 {
                self.process(0x00)
            }
            self.process(0x80);
        }
        self.squeeze(digest, olen);
    }

    pub fn continuing_shake(&mut self, digest: &mut [u8], olen: usize) {
        let mut sh = SHA3::new_copy(self);
        sh.shake(digest, olen);
    }
}

//916f6061fe879741ca6469b43971dfdb28b1a32dc36cb3254e812be27aad1d18
//afebb2ef542e6579c50cad06d2e578f9f8dd6881d7dc824d26360feebf18a4fa73e3261122948efcfd492e74e82e2189ed0fb440d187f382270cb455f21dd185
//98be04516c04cc73593fef3ed0352ea9f6443942d6950e29a372a681c3deaf4535423709b02843948684e029010badcc0acd8303fc85fdad3eabf4f78cae165635f57afd28810fc2
/*
fn main() {
    let s = String::from("abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu");
    let mut digest: [u8;100]=[0;100];
    let test = s.into_bytes();

    let mut sh=SHA3::new(HASH256);
    for i in 0..test.len(){
        sh.process(test[i]);
    }
    sh.hash(&mut digest);
    for i in 0..32 {print!("{:02x}",digest[i])}
    println!("");

    sh=SHA3::new(HASH512);
    for i in 0..test.len(){
        sh.process(test[i]);
    }
    sh.hash(&mut digest);
    for i in 0..64 {print!("{:02x}",digest[i])}
    println!("");

    sh=SHA3::new(SHAKE256);
    for i in 0..test.len(){
        sh.process(test[i]);
    }
    sh.shake(&mut digest,72);
    for i in 0..72 {print!("{:02x}",digest[i])}
    println!("");

} */