package world

import (
	"math"
	"testing"

	"wh/config"
	"wh/fixed"
)

func TestOrbitsAreCirclesAtCommonSpeed(t *testing.T) {
	cfg := config.Default()
	asts, _ := Generate(cfg)
	want := cfg.OrbitSpeed.Float64()
	for _, a := range asts {
		o := a.Orbit
		for _, ts := range []int64{0, 100_000, 777_777, o.Period / 3, o.Period - 1} {
			p, v := o.State(ts)
			if r := p.Len().Float64(); math.Abs(r-o.A.Float64()) > 1e-3 {
				t.Fatalf("asteroid %d t=%d: radius %g, want %g", a.ID, ts, r, o.A.Float64())
			}
			if s := v.Len().Float64(); math.Abs(s-want)/want > 1e-5 {
				t.Fatalf("asteroid %d t=%d: speed %g, want %g", a.ID, ts, s, want)
			}
			if d := p.Dot(v).Float64() / (p.Len().Float64() * want); math.Abs(d) > 1e-4 {
				t.Fatalf("asteroid %d: velocity not tangent (cos=%g)", a.ID, d)
			}
			// Inclination bounds the height above the ecliptic.
			if z := p.Z.Abs().Float64(); z > o.A.Float64()*math.Sin(o.Inc.Float64())*1.001+1e-3 {
				t.Fatalf("asteroid %d: |z|=%g exceeds inclination bound", a.ID, z)
			}
		}
		// Periodic.
		p1, _ := o.State(12345)
		p2, _ := o.State(12345 + o.Period)
		if d := p1.Sub(p2).Len().Float64(); d > 1 {
			t.Fatalf("asteroid %d not periodic, off by %g km", a.ID, d)
		}
	}
}

func TestOrbitPlaneMatchesInclination(t *testing.T) {
	o := Orbit{A: fixed.FromInt(2_000_000), Inc: fixed.FromRatio(3, 10), Node: fixed.FromInt(2)}
	o.Period = PeriodFor(o.A, fixed.FromInt(3))
	// The orbit normal is Rz(Node)Rx(Inc) applied to +Z; positions must be
	// perpendicular to it, and the maximum height is A*sin(Inc).
	n := fixed.Vec{Z: fixed.One}.RotateX(o.Inc).RotateZ(o.Node)
	var maxZ float64
	for k := int64(0); k < 50; k++ {
		p, _ := o.State(k * o.Period / 50)
		if d := p.Dot(n).Float64(); math.Abs(d) > 1e-2 {
			t.Fatalf("position not in the orbital plane: p.n = %g", d)
		}
		maxZ = math.Max(maxZ, p.Z.Float64())
	}
	if want := o.A.Float64() * math.Sin(0.3); math.Abs(maxZ-want)/want > 0.01 {
		t.Fatalf("max z = %g, want %g", maxZ, want)
	}
}

func TestGenerateDeterministic(t *testing.T) {
	cfg := config.Default()
	a1, s1 := Generate(cfg)
	a2, s2 := Generate(cfg)
	if len(a1) != cfg.AsteroidCount || s1 != s2 {
		t.Fatal("mismatch")
	}
	for i := range a1 {
		if a1[i] != a2[i] {
			t.Fatalf("asteroid %d differs", i)
		}
	}
	cfg.Seed = 2
	a3, _ := Generate(cfg)
	if a3[0] == a1[0] {
		t.Fatal("different seeds should differ")
	}
}