package entity

import (
	"image"
	"image/color"
	"image/draw"
	"testing"
)

func TestCollageLayout(t *testing.T) {
	if got := collageCells(0); len(got) != 0 {
		t.Fatalf("empty %d", len(got))
	}
	two := collageCells(2)
	if len(two) != 2 {
		t.Fatalf("two %d", len(two))
	}
	if two[0].Min.Y != two[1].Min.Y || two[0].Max.X >= two[1].Min.X {
		t.Fatalf("two should sit on one row: %+v", two)
	}
	nine := collageCells(9)
	if len(nine) != 9 {
		t.Fatalf("nine %d", len(nine))
	}
	if two[0].Dx() <= nine[0].Dx() {
		t.Fatalf("two-person tiles should be larger than 3x3: two=%d nine=%d", two[0].Dx(), nine[0].Dx())
	}
	three := collageCells(3)
	if len(three) != 3 {
		t.Fatalf("three %d", len(three))
	}
	if three[0].Min.X <= three[1].Min.X {
		t.Fatalf("first row should be centered: %+v", three)
	}
}

func TestCollageColors(t *testing.T) {
	red := solid(color.RGBA{R: 255, A: 255})
	green := solid(color.RGBA{G: 255, A: 255})
	blue := solid(color.RGBA{B: 255, A: 255})
	img := Collage([]image.Image{red, green, blue})
	if img.Bounds().Dx() != collageSize {
		t.Fatalf("size %d", img.Bounds().Dx())
	}
	cells := collageCells(3)
	assertNear(t, img.At(mid(cells[0]).X, mid(cells[0]).Y), color.RGBA{R: 255, A: 255})
	assertNear(t, img.At(mid(cells[1]).X, mid(cells[1]).Y), color.RGBA{G: 255, A: 255})
	assertNear(t, img.At(mid(cells[2]).X, mid(cells[2]).Y), color.RGBA{B: 255, A: 255})
}

func solid(c color.RGBA) *image.RGBA {
	img := image.NewRGBA(image.Rect(0, 0, 16, 16))
	draw.Draw(img, img.Bounds(), &image.Uniform{C: c}, image.Point{}, draw.Src)
	return img
}

func mid(r image.Rectangle) image.Point {
	return image.Pt((r.Min.X+r.Max.X)/2, (r.Min.Y+r.Max.Y)/2)
}

func assertNear(t *testing.T, got color.Color, want color.RGBA) {
	t.Helper()
	r, g, b, a := got.RGBA()
	if r>>8 != uint32(want.R) || g>>8 != uint32(want.G) || b>>8 != uint32(want.B) || a>>8 != uint32(want.A) {
		t.Fatalf("got rgba %d %d %d %d want %+v", r>>8, g>>8, b>>8, a>>8, want)
	}
}