package geom

import (
	"math"
	"testing"
)

func TestSide(t *testing.T) {
	tests := []struct {
		name    string
		P, O, D Vec
		want    float64
	}{
		{"point left of line", V(1, 1), V(0, 0), V(1, 0), 1},
		{"point right of line", V(1, -1), V(0, 0), V(1, 0), -1},
		{"point on line", V(2, 0), V(0, 0), V(1, 0), 0},
	}
	for _, tc := range tests {
		if got := Side(tc.P, tc.O, tc.D); got < tc.want-EPS || got > tc.want+EPS {
			t.Fatalf("%s: Side()=%v want %v", tc.name, got, tc.want)
		}
	}
}

func TestSegLineIntersect(t *testing.T) {
	O := V(0, 0)
	D := V(1, 0)
	tests := []struct {
		name   string
		A, B   Vec
		wantOK bool
		wantT  float64
	}{
		{"hits interior", V(0, -1), V(0, 1), true, 0.5},
		{"parallel", V(0, 1), V(1, 1), false, 0},
		{"touches endpoint", V(0, 0), V(0, 1), false, 0},
	}
	for _, tc := range tests {
		ok, tVal := SegLineIntersect(tc.A, tc.B, O, D)
		if ok != tc.wantOK {
			t.Fatalf("%s: ok=%v want %v", tc.name, ok, tc.wantOK)
		}
		if !ok {
			continue
		}
		if diff := tVal - tc.wantT; diff > 1e-6 || diff < -1e-6 {
			t.Fatalf("%s: t=%v want %v", tc.name, tVal, tc.wantT)
		}
	}
}

func TestSplitSeg(t *testing.T) {
	O := V(0, 0)
	D := V(1, 0)
	seg := Seg{A: V(0, -1), B: V(0, 1)}
	front, back := SplitSeg(seg, O, D)
	if len(front) != 1 || len(back) != 1 {
		t.Fatalf("expected split into two pieces got front=%d back=%d", len(front), len(back))
	}
	share := func(a, b Vec) bool {
		return math.Abs(a.X-b.X) < EPS && math.Abs(a.Y-b.Y) < EPS
	}
	if !share(front[0].A, back[0].B) && !share(front[0].B, back[0].A) {
		t.Fatalf("split point mismatch: front=%v back=%v", front[0], back[0])
	}

	sameSide := Seg{A: V(0, 1), B: V(1, 1)}
	front, back = SplitSeg(sameSide, O, D)
	if len(back) != 0 || len(front) != 1 {
		t.Fatalf("expected no split for same side got front=%d back=%d", len(front), len(back))
	}
}

func TestBounds(t *testing.T) {
	pts := []Vec{V(-1, 2), V(3, -4), V(0, 0)}
	box := Bounds(pts)
	if box.Min != V(-1, -4) {
		t.Fatalf("Min=%v want (-1,-4)", box.Min)
	}
	if box.Max != V(3, 2) {
		t.Fatalf("Max=%v want (3,2)", box.Max)
	}
}