/// @file rainbow_keypair.c
/// @brief implementations of functions in rainbow_keypair.h
///

#include "blas.h"
#include "blas_comm.h"
#include "rainbow_blas.h"
#include "rainbow_keypair.h"
#include "rainbow_keypair_computation.h"
#include "utils_prng.h"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>


static
void generate_S_T( unsigned char *s_and_t, prng_t *prng0 ) {
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, s_and_t, _O1_BYTE * _O2 ); // S1
    s_and_t += _O1_BYTE * _O2;
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, s_and_t, _V1_BYTE * _O1 ); // T1
    s_and_t += _V1_BYTE * _O1;
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, s_and_t, _V1_BYTE * _O2 ); // T2
    s_and_t += _V1_BYTE * _O2;
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, s_and_t, _O1_BYTE * _O2 ); // T3
}


static
unsigned generate_l1_F12( unsigned char *sk, prng_t *prng0 ) {
    unsigned n_byte_generated = 0;
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O1_BYTE * N_TRIANGLE_TERMS(_V1) );   // l1_F1
    sk += _O1_BYTE * N_TRIANGLE_TERMS(_V1);
    n_byte_generated += _O1_BYTE * N_TRIANGLE_TERMS(_V1);

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O1_BYTE * _V1 * _O1 );  // l1_F2
    n_byte_generated += _O1_BYTE * _V1 * _O1;
    return n_byte_generated;
}


static
unsigned generate_l2_F12356( unsigned char *sk, prng_t *prng0 ) {
    unsigned n_byte_generated = 0;

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O2_BYTE * N_TRIANGLE_TERMS(_V1) );   // l2_F1
    sk += _O2_BYTE * N_TRIANGLE_TERMS(_V1);
    n_byte_generated += _O2_BYTE * N_TRIANGLE_TERMS(_V1);

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O2_BYTE * _V1 * _O1 ); // l2_F2
    sk += _O2_BYTE * _V1 * _O1;
    n_byte_generated += _O2_BYTE * _V1 * _O1;

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O2_BYTE * _V1 * _O2 ); // l2_F3
    sk += _O2_BYTE * _V1 * _O1;
    n_byte_generated += _O2_BYTE * _V1 * _O1;

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O2_BYTE * N_TRIANGLE_TERMS(_O1) );   // l2_F5
    sk += _O2_BYTE * N_TRIANGLE_TERMS(_O1);
    n_byte_generated += _O2_BYTE * N_TRIANGLE_TERMS(_O1);

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( prng0, sk, _O2_BYTE * _O1 * _O2 ); // l2_F6
    n_byte_generated += _O2_BYTE * _O1 * _O2;

    return n_byte_generated;
}


static
void generate_B1_B2( unsigned char *sk, prng_t *prng0 ) {
    sk += generate_l1_F12( sk, prng0 );
    generate_l2_F12356( sk, prng0 );
}

static
void calculate_t4( unsigned char *t2_to_t4, const unsigned char *t1, const unsigned char *t3 ) {
    //  t4 = T_sk.t1 * T_sk.t3 - T_sk.t2
    unsigned char temp[_V1_BYTE + 32];
    unsigned char *t4 = t2_to_t4;
    for (unsigned i = 0; i < _O2; i++) { /// t3 width
        gfmat_prod( temp, t1, _V1_BYTE, _O1, t3 );
        gf256v_add( t4, temp, _V1_BYTE );
        t4 += _V1_BYTE;
        t3 += _O1_BYTE;
    }
}

static
void obsfucate_l1_polys( unsigned char *l1_polys, const unsigned char *l2_polys, unsigned n_terms, const unsigned char *s1 ) {
    unsigned char temp[_O1_BYTE + 32];
    while ( n_terms-- ) {
        gfmat_prod( temp, s1, _O1_BYTE, _O2, l2_polys );
        gf256v_add( l1_polys, temp, _O1_BYTE );
        l1_polys += _O1_BYTE;
        l2_polys += _O2_BYTE;
    }
}

///////////////////  Classic //////////////////////////////////

static
void _generate_secretkey( sk_t *sk, const unsigned char *sk_seed ) {
    memcpy( sk->sk_seed, sk_seed, LEN_SKSEED );

    // set up prng
    prng_t prng0;
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_set( &prng0, sk_seed, LEN_SKSEED );

    // generating secret key with prng.
    generate_S_T( sk->s1, &prng0 );
    generate_B1_B2( sk->l1_F1, &prng0 );

    // clean prng
    memset( &prng0, 0, sizeof(prng_t) );
}

void PQCLEAN_RAINBOWVCCLASSIC_CLEAN_generate_keypair( pk_t *rpk, sk_t *sk, const unsigned char *sk_seed ) {
    _generate_secretkey( sk, sk_seed );

    // set up a temporary structure ext_cpk_t for calculating public key.
    ext_cpk_t pk;

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_calculate_Q_from_F( &pk, sk, sk );    // compute the public key in ext_cpk_t format.
    calculate_t4( sk->t4, sk->t1, sk->t3 );

    obsfucate_l1_polys( pk.l1_Q1, pk.l2_Q1, N_TRIANGLE_TERMS(_V1), sk->s1 );
    obsfucate_l1_polys( pk.l1_Q2, pk.l2_Q2, _V1 * _O1, sk->s1 );
    obsfucate_l1_polys( pk.l1_Q3, pk.l2_Q3, _V1 * _O2, sk->s1 );
    obsfucate_l1_polys( pk.l1_Q5, pk.l2_Q5, N_TRIANGLE_TERMS(_O1), sk->s1 );
    obsfucate_l1_polys( pk.l1_Q6, pk.l2_Q6, _O1 * _O2, sk->s1 );
    obsfucate_l1_polys( pk.l1_Q9, pk.l2_Q9, N_TRIANGLE_TERMS(_O2), sk->s1 );
    // so far, the pk contains the full pk but in ext_cpk_t format.

    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_extcpk_to_pk( rpk, &pk );      // convert the public key from ext_cpk_t to pk_t.
}