package pdf

import (
	"bytes"
	"image"
	"image/color"
	"image/png"
	"testing"
)

func testPNG(t *testing.T, w, h int) []byte {
	t.Helper()
	img := image.NewRGBA(image.Rect(0, 0, w, h))
	for x := 0; x < w; x++ {
		img.Set(x, h/2, color.Black)
	}
	var buf bytes.Buffer
	if err := png.Encode(&buf, img); err != nil {
		t.Fatal(err)
	}
	return buf.Bytes()
}

func TestDocShape(t *testing.T) {
	var d Doc
	// A 90×29 mm label at 300 dpi is 1063×343 px.
	if err := d.AddImagePage(testPNG(t, 1063, 343), 90, 29); err != nil {
		t.Fatal(err)
	}
	if err := d.AddImagePage(testPNG(t, 1063, 343), 90, 29); err != nil {
		t.Fatal(err)
	}
	b, err := d.Bytes()
	if err != nil {
		t.Fatal(err)
	}
	// Not a PDF parser — the shape a viewer needs to find its way in.
	for _, want := range []string{"%PDF-1.4", "/Count 2", "/DeviceGray", "startxref", "%%EOF"} {
		if !bytes.Contains(b, []byte(want)) {
			t.Errorf("missing %q in output", want)
		}
	}
	// 90 mm = 255.118 pt — the page size a driver prints 1:1 on the roll.
	if !bytes.Contains(b, []byte("/MediaBox [0 0 255.1181 82.2047]")) {
		t.Errorf("media box is not the label size")
	}
}

func TestEmptyDocRefused(t *testing.T) {
	var d Doc
	if _, err := d.Bytes(); err == nil {
		t.Fatal("an empty document should refuse to render")
	}
}