// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Ported to V from Go's crypto/internal/fips140/mldsa.
module mldsa

// s. 4, table 1
pub enum Kind {
    ml_dsa_44
    ml_dsa_65
    ml_dsa_87
}

fn (k Kind) params() Params {
    return match k {
        .ml_dsa_44 { params_44 }
        .ml_dsa_65 { params_65 }
        .ml_dsa_87 { params_87 }
    }
}

pub fn (k Kind) public_key_size() int {
    return pub_key_size(k.params())
}

pub fn (k Kind) private_key_size() int {
    return priv_key_size(k.params())
}

pub fn (k Kind) signature_size() int {
    return sig_size(k.params())
}

// FIPS 204 s. 5.4: approved pre-hash functions for HashML-DSA.
pub enum PreHash {
    none // pure ML-DSA (default)
    sha2_224
    sha2_256
    sha2_384
    sha2_512
    sha2_512_224
    sha2_512_256
    sha3_224
    sha3_256
    sha3_384
    sha3_512
    shake_128
    shake_256
}

@[params]
pub struct SignerOpts {
pub:
    context       string
    deterministic bool
    prehash       PreHash
}

struct Params {
    k      int
    l      int
    eta    int
    gamma1 int
    gamma2 int
    lambda int
    tau    int
    omega  int
}

// s. 4, table 1
const params_44 = Params{
    k:      4
    l:      4
    eta:    2
    gamma1: 17
    gamma2: 88
    lambda: 128
    tau:    39
    omega:  80
}

const params_65 = Params{
    k:      6
    l:      5
    eta:    4
    gamma1: 19
    gamma2: 32
    lambda: 192
    tau:    49
    omega:  55
}

const params_87 = Params{
    k:      8
    l:      7
    eta:    2
    gamma1: 19
    gamma2: 32
    lambda: 256
    tau:    60
    omega:  75
}

pub const seed_size = 32

// s. 4, table 2
pub const public_key_size_44 = 32 + 4 * n * 10 / 8
pub const public_key_size_65 = 32 + 6 * n * 10 / 8
pub const public_key_size_87 = 32 + 8 * n * 10 / 8

// s. 4, table 2
pub const signature_size_44 = 128 / 4 + 4 * n * (17 + 1) / 8 + 80 + 4
pub const signature_size_65 = 192 / 4 + 5 * n * (19 + 1) / 8 + 55 + 6
pub const signature_size_87 = 256 / 4 + 7 * n * (19 + 1) / 8 + 75 + 8

fn pub_key_size(p Params) int {
    return 32 + p.k * n * 10 / 8
}

fn priv_key_size(p Params) int {
    eta_bitlen := bits_len(u32(p.eta * 2))
    // rho + K + tr + l*n*eta-bit s1 + k*n*eta-bit s2 + k*n*13-bit t0
    return 32 + 32 + 64 + p.l * n * eta_bitlen / 8 + p.k * n * eta_bitlen / 8 + p.k * n * 13 / 8
}

fn sig_size(p Params) int {
    return (p.lambda / 4) + p.l * n * (p.gamma1 + 1) / 8 + p.omega + p.k
}