package stats

import (
	"math"
	"testing"

	"salty/terrain/internal/field"
)

// The whole reason this package was rewritten: the sorts could not be afforded at planet scale. 3000 x 3000
// is about what region 12 of the 100 km template is - 9 M cells, the largest single landmass - so this is the
// cost of the biggest piece a bake ever hands over, and the planet is the sum of twenty of them.
//
// A benchmark rather than a test: it measures rather than asserts, and nothing here should fail a build.
//
//	go test ./internal/stats/ -bench Region -benchtime 1x
func BenchmarkRegionSizedAccumulate(b *testing.B) {
	const w, h, cellM = 3000, 3000, 8.0
	f := field.New(w, h, cellM)
	land := make([]bool, w*h)
	up := make([]float32, w*h)
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			i := y*w + x
			land[i] = true
			t := float64(x) / float64(w)
			f.Data[i] = float32(40 + 300*t*t + 18*math.Sin(float64(x)/9)*math.Cos(float64(y)/7))
			up[i] = float32((0.02 + 0.9*t*t*t) / 1000)
		}
	}
	in := Input{H: f, Land: land, UpliftMYr: up}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		a := New(testOptions())
		a.Add(in)
		a.AddExtent(f.Data, land, 0)
		_ = a.Report(cellM)
	}
	b.ReportMetric(float64(w*h)/1e6, "Mcells")
}