// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module seed

import time

// nr_next returns a next value based on the previous value `prev`.
@[ignore_overflow; inline]
fn nr_next(prev u32) u32 {
    return prev * 1664525 + 1013904223
}

// time_seed_array returns the required number of u32s generated from system time.
pub fn time_seed_array(count int) []u32 {
    ctime := time.sys_mono_now()
    mut seed := u32(ctime >> 32 ^ (ctime & 0x0000_0000_FFFF_FFFF))
    mut seed_data := []u32{cap: count}
    for _ in 0 .. count {
        seed = nr_next(seed)
        seed_data << nr_next(seed)
    }
    return seed_data
}

// time_seed_32 returns a 32-bit seed generated from system time.
@[manualfree]
pub fn time_seed_32() u32 {
    sa := time_seed_array(1)
    res := sa[0]
    unsafe { sa.free() }
    return res
}

// time_seed_64 returns a 64-bit seed generated from system time.
@[manualfree]
pub fn time_seed_64() u64 {
    seed_data := time_seed_array(2)
    lower := u64(seed_data[0])
    upper := u64(seed_data[1])
    unsafe { seed_data.free() }
    res := lower | (upper << 32)
    return res
}