//! The benchmark's matrices and the hash of a decomposition's bits, shared by
//! `examples/svd_bench.rs` and `tests/svd_bench.rs`.

#![allow(clippy::needless_range_loop, dead_code)]

use wai_quantum::quantum_svd::{C, Svd};

/// An `m × n` complex matrix from a fixed sequence, column `j` scaled by `0.995^j`.
pub fn input(m: usize, n: usize, seed: u64) -> Vec<C> {
    let mut s = seed;
    let mut next = || {
        s = s.wrapping_add(0x9e37_79b9_7f4a_7c15);
        let mut z = s;
        z = (z ^ (z >> 30)).wrapping_mul(0xbf58_476d_1ce4_e5b9);
        z = (z ^ (z >> 27)).wrapping_mul(0x94d0_49bb_1331_11eb);
        ((z ^ (z >> 31)) >> 11) as f64 / 9_007_199_254_740_992.0 - 0.5
    };
    let mut scale = vec![1.0f64; n];
    for j in 1..n {
        scale[j] = scale[j - 1] * 0.995;
    }
    let mut a = Vec::with_capacity(m * n);
    for _ in 0..m {
        for &sc in &scale {
            a.push(C { re: next() * sc, im: next() * sc });
        }
    }
    a
}

pub fn hash(f: &Svd) -> String {
    let mut bytes = Vec::with_capacity(8 * (f.s.len() + 2 * f.u.len() + 2 * f.vh.len()));
    for x in &f.s {
        bytes.extend_from_slice(&x.to_bits().to_le_bytes());
    }
    for z in f.u.iter().chain(&f.vh) {
        bytes.extend_from_slice(&z.re.to_bits().to_le_bytes());
        bytes.extend_from_slice(&z.im.to_bits().to_le_bytes());
    }
    super::common::hex(&super::common::sha256(&bytes))
}