// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

package stats

import (
	"testing"

	"sourcedock.dev/petrbalvin/tensor/internal/core"
)

// BenchmarkQuantileRegressionFit measures the interior-point quantile
// fit: the barrier Newton systems, the fraction-to-the-boundary walk
// and the primal recovery, at a size where the per-iteration system
// build is a visible share of the run.
func BenchmarkQuantileRegressionFit(b *testing.B) {
	const n, p = 400, 8
	x, vals := regDesign(b, n, p, 0x5eed0041)
	src := &randSource{state: 0x5eed0042}
	yv := make([]float64, n)
	for i := range n {
		eta := 0.5
		for c := range p {
			eta += 0.25 * vals[i*p+c]
		}
		yv[i] = eta + (src.next()-0.5)*0.5
	}
	y, err := core.FromFloats(yv, n)
	if err != nil {
		b.Fatal(err)
	}
	b.ReportAllocs()
	for b.Loop() {
		if _, err := QuantileRegression(x, y, 0.5); err != nil {
			b.Fatal(err)
		}
	}
}