package fluvial

import "testing"

// What the two accumulators cost per cell, which is the number a bake's wall clock is spent against. Both are
// measured on the same surface with the receivers and the stack already built, because those are shared.
func benchAccumulate(b *testing.B, mfd bool) {
	const n = 1024
	h := planarRamp(n, 8.0, 0.1, 22.5)
	g := NewGrid(n, n, 8.0, nil)
	g.SetSeed(37125)
	g.FillDepressions(h, 1e-3)
	g.ComputeReceivers(h)
	g.BuildStack()
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if mfd {
			g.AccumulateMFD(h, 1)
		} else {
			g.Accumulate()
		}
	}
	b.ReportMetric(float64(b.Elapsed().Nanoseconds())/float64(b.N)/float64(n*n), "ns/cell")
}

func BenchmarkAccumulateD8(b *testing.B)  { benchAccumulate(b, false) }
func BenchmarkAccumulateMFD(b *testing.B) { benchAccumulate(b, true) }